67 results on '"Seunghyun Hong"'
Search Results
2. Ion-Selective Separation Using MXene-Based Membranes: A Review
- Author
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Seunghyun Hong, Faisal Al Marzooqi, Jehad K. El-Demellawi, Noora Al Marzooqi, Hassan A. Arafat, and Husam N. Alshareef
- Subjects
General Chemical Engineering ,Biomedical Engineering ,General Materials Science - Published
- 2023
3. Microstructure-based fatigue life modeling methodology for ferritic-pearlitic hypo-eutectoid steels
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Minwoo Park, Hyunki Kim, Minwoo Kang, Seunghyun Hong, and Yoon Suk Choi
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Biomaterials ,Metals and Alloys ,Ceramics and Composites ,Surfaces, Coatings and Films - Published
- 2022
4. Porous Ti3C2Tx MXene Membranes for Highly Efficient Salinity Gradient Energy Harvesting
- Author
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Seunghyun Hong, Jehad K. El-Demellawi, Yongjiu Lei, Zhixiong Liu, Faisal Al Marzooqi, Hassan A. Arafat, and Husam N. Alshareef
- Subjects
General Engineering ,General Physics and Astronomy ,General Materials Science - Published
- 2022
5. DAVE: Deep Learning-Based Asymmetric Virtual Environment for Immersive Experiential Metaverse Content
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Yunsik Cho, Seunghyun Hong, Mingyu Kim, and Jinmo Kim
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asymmetric virtual environment ,gesture interface ,text interface ,immersive interaction ,virtual reality ,augmented reality ,deep learning ,immersive experiential metaverse content ,Computer Networks and Communications ,Hardware and Architecture ,Control and Systems Engineering ,Signal Processing ,Electrical and Electronic Engineering - Abstract
In this study, we design an interface optimized for the platform by adopting deep learning in an asymmetric virtual environment where virtual reality (VR) and augmented reality (AR) users participate together. We also propose a novel experience environment called deep learning-based asymmetric virtual environment (DAVE) for immersive experiential metaverse content. First, VR users use their real hands to intuitively interact with the virtual environment and objects. A gesture interface is designed based on deep learning to directly link gestures to actions. AR users interact with virtual scenes, objects, and VR users via a touch-based input method in a mobile platform environment. A text interface is designed using deep learning to directly link handwritten text to actions. This study aims to propose a novel asymmetric virtual environment via an intuitive, easy, and fast interactive interface design as well as to create metaverse content for an experience environment and a survey experiment. This survey experiment is conducted with users to statistically analyze and investigate user interface satisfaction, user experience, and user presence in the experience environment.
- Published
- 2022
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6. Designing a next generation solar crystallizer for real seawater brine treatment with zero liquid discharge
- Author
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Renyuan Li, Yusuf Shi, Seunghyun Hong, Peng Wang, Hongxia Li, Le Shi, Sifei Zhuo, TieJun Zhang, and Chenlin Zhang
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Seawater reverse osmosis ,Solar thermal energy ,Multidisciplinary ,Waste management ,Science ,General Physics and Astronomy ,02 engineering and technology ,General Chemistry ,010501 environmental sciences ,021001 nanoscience & nanotechnology ,01 natural sciences ,Zero liquid discharge ,Article ,General Biochemistry, Genetics and Molecular Biology ,law.invention ,Brining ,law ,Environmental science ,Seawater ,Civil engineering ,Crystallization ,0210 nano-technology ,Salt crystallization ,0105 earth and related environmental sciences - Abstract
Proper disposal of industrial brine has been a critical environmental challenge. Zero liquid discharge (ZLD) brine treatment holds great promise to the brine disposal, but its application is limited by the intensive energy consumption of its crystallization process. Here we propose a new strategy that employs an advanced solar crystallizer coupled with a salt crystallization inhibitor to eliminate highly concentrated waste brine. The rationally designed solar crystallizer exhibited a high water evaporation rate of 2.42 kg m−2 h−1 under one sun illumination when treating real concentrated seawater reverse osmosis (SWRO) brine (21.6 wt%). The solar crystallizer array showed an even higher water evaporation rate of 48.0 kg m−2 per day in the outdoor field test, suggesting a great potential for practical application. The solar crystallizer design and the salt crystallization inhibition strategy proposed and confirmed in this work provide a low-cost and sustainable solution for industrial brine disposal with ZLD., Proper disposal of industrial brine remains a critical environmental challenge. Here, the authors devise a solar crystallizer and propose a salt crystallization inhibition strategy, which together provide a low-cost and sustainable solution for industrial brine disposal with zero liquid discharge.
- Published
- 2021
7. Photothermoelectric Response of Ti3C2Tx MXene Confined Ion Channels
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Husam N. Alshareef, Guodong Zou, Dazhen Huang, Seunghyun Hong, Peng Wang, and Hyunho Kim
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Materials science ,Diffusion ,General Engineering ,General Physics and Astronomy ,Ionic bonding ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Ion ,Temperature gradient ,Chemical physics ,Seebeck coefficient ,General Materials Science ,Lamellar structure ,0210 nano-technology ,MXenes ,Ion channel - Abstract
With recent growing interest in biomimetic smart nanochannels, a biological sensory transduction in response to external stimuli has been of particular interest in the development of biomimetic nanofluidic systems. Here we demonstrate the MXene-based subnanometer ion channels that convert external temperature changes to electric signals via preferential diffusion of cations under a thermal gradient. In particular, coupled with a photothermal conversion feature of MXenes, an array of the nanoconfined Ti3C2Tx ion channels can capture trans-nanochannel diffusion potentials under a light-driven axial temperature gradient. The nonisothermal open-circuit potential across channels is enhanced with increasing cationic permselectivity of confined channels, associated with the ionic concentration or pH of permeant fluids. The photothermoelectric ionic response (evaluated from the ionic Seebeck coefficient) reached up to 1 mV·K-1, which is comparable to biological thermosensory channels, and demonstrated stability and reproducibility in the absence and presence of an ionic concentration gradient. With advantages of physicochemical tunability and easy fabrication process, the lamellar ion conductors may be an important nanofluidic thermosensation platform possibly for biomimetic sensory systems.
- Published
- 2020
8. Photovoltaic panel cooling by atmospheric water sorption–evaporation cycle
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Renyuan Li, Peng Wang, Yusuf Shi, Seunghyun Hong, and Mengchun Wu
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Global and Planetary Change ,Ecology ,Renewable Energy, Sustainability and the Environment ,business.industry ,Geography, Planning and Development ,Photovoltaic system ,Evaporation ,Environmental engineering ,Management, Monitoring, Policy and Law ,Solar energy ,Urban Studies ,Electricity generation ,Heat generation ,Water cooling ,Environmental science ,business ,Solar power ,Nature and Landscape Conservation ,Food Science ,Efficient energy use - Abstract
More than 600 GW of photovoltaic panels are currently installed worldwide, with the predicted total capacity increasing very rapidly every year. One essential issue in photovoltaic conversion is the massive heat generation of photovoltaic panels under sunlight, which represents 75–96% of the total absorbed solar energy and thus greatly increases the temperature and decreases the energy efficiency and lifetime of photovoltaic panels. In this report we demonstrate a new and versatile photovoltaic panel cooling strategy that employs a sorption-based atmospheric water harvester as an effective cooling component. The atmospheric water harvester photovoltaic cooling system provides an average cooling power of 295 W m–2 and lowers the temperature of a photovoltaic panel by at least 10 °C under 1.0 kW m–2 solar irradiation in laboratory conditions. It delivered a 13–19% increase in electricity generation in a commercial photovoltaic panel in outdoor field tests conducted in the winter and summer in Saudi Arabia. The atmospheric water harvester based photovoltaic panel cooling strategy has little geographical constraint in terms of its application and has the potential to improve the electricity production of existing and future photovoltaic plants, which can be directly translated into less CO2 emission or less land occupation by photovoltaic panels. As solar power is taking centre stage in the global fight against climate change, atmospheric water harvester based cooling represents an important step toward sustainability. Photovoltaic panel conversion generates heat that reduces the energy efficiency and lifetime of the panel. A photovoltaic panel cooling strategy by a sorption-based atmospheric water harvester is shown to improve the productivity of electricity generation with important sustainability advantages.
- Published
- 2020
9. Ultrathin graphene oxide membrane with constructed tent-shaped structures for efficient and tunable molecular sieving
- Author
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Baoliang Chen, Xiaoying Zhu, Seunghyun Hong, Kun Zhang, Kaijie Yang, and Tingting Pan
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Aqueous solution ,Materials science ,Graphene ,Materials Science (miscellaneous) ,Oxide ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Molecular sieve ,01 natural sciences ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,Membrane ,chemistry ,law ,Molecule ,0210 nano-technology ,Selectivity ,Filtration ,General Environmental Science - Abstract
Graphene oxide membranes (GOMs) continue to attract intense interest because of their promising two-dimensional channels. However, finely adjusting a GOM's interplanar spacing for tunable molecular separation is still challenging in aqueous solution. Herein, we report tent-shaped interplanar channels that can be constructed by loading SiO2 nanospheres (diameter ≈ 30 nm) into ultrathin GOMs (thickness ≈ 20 nm). The tent-shaped structure takes advantage of the augmented space to accelerate the flux while utilizing the preserved circumjacent nano-channel as a molecular sieve. Particularly, by adjusting the density of intercalated SiO2 nanospheres, the concomitant interlayer channel can be finely tuned with molecular-level accuracy. Precise selectivity makes the SiO2 loaded GOM (SGM) capable of separating molecules with sub-nanometer differences. At the same time, under the premise of the same rejection, tunable channels endow SGMs with 1.3–63 times higher permeability than that of a pristine ultrathin GOM. This tent-shaped structure supplies a new avenue for GOM structural regulation, and the impressive performance demonstrates its great potential in the fields of water purification and membrane filtration.
- Published
- 2020
10. Porous Ti
- Author
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Seunghyun, Hong, Jehad K, El-Demellawi, Yongjiu, Lei, Zhixiong, Liu, Faisal Al, Marzooqi, Hassan A, Arafat, and Husam N, Alshareef
- Subjects
chemical nanopore etching ,titanium carbide ,nanoconfined fluidic channels ,salinity gradient power generation ,Article ,lamellar structured membranes - Abstract
Extracting osmotic energy through nanoporous membranes is an efficient way to harvest renewable and sustainable energy using the salinity gradient between seawater and river water. Despite recent advances of nanopore-based membranes, which have revitalized the prospect of blue energy, their energy conversion is hampered by nanomembrane issues such as high internal resistance or low selectivity. Herein, we report a lamellar-structured membrane made of nanoporous Ti3C2Tx MXene sheets, exhibiting simultaneous enhancement in permeability and ion selectivity beyond their inherent trade-off. The perforated nanopores formed by facile H2SO4 oxidation of the sheets act as a network of cation channels that interconnects interplanar nanocapillaries throughout the lamellar membrane. The constructed internal nanopores lower the energy barrier for cation passage, thereby boosting the preferential ion diffusion across the membrane. A maximum output power density of the nanoporous Ti3C2Tx MXene membranes reaches up to 17.5 W·m–2 under a 100-fold KCl gradient at neutral pH and room temperature, which is as high as by 38% compared to that of the pristine membrane. The membrane design strategy employing the nanoporous two-dimensional sheets provides a promising approach for ion exchange, osmotic energy extraction, and other nanofluidic applications.
- Published
- 2022
11. Distinct Stage-Wise Environmental Energy Harvesting Behaviors within Solar-Driven Interfacial Water Evaporation Coupled with Convective Airflow
- Author
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Chenlin Zhang, Yusuf Shi, Wenbin Wang, Hongxia Li, Renyuan Li, Seunghyun Hong, and Peng Wang
- Subjects
History ,Polymers and Plastics ,Renewable Energy, Sustainability and the Environment ,General Materials Science ,Electrical and Electronic Engineering ,Business and International Management ,Industrial and Manufacturing Engineering - Published
- 2022
12. Fast transient heat transfer by sinusoidal pulse power
- Author
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Dong Hoon Kam, Satbyoul Jung, Jun-young Kang, SeungHyun Hong, Yong-Seok Choi, Byong Guk Jeon, Jong-Kuk Park, and Sang-Ki Moon
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General Chemical Engineering ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics - Published
- 2023
13. Muscle Fatigue Sensor Based on Ti
- Author
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Kang Hyuck, Lee, Yi-Zhou, Zhang, Hyunho, Kim, Yongjiu, Lei, Seunghyun, Hong, Shofarul, Wustoni, Adel, Hama, Sahika, Inal, and Husam N, Alshareef
- Subjects
Titanium ,Wearable Electronic Devices ,Polyvinyl Alcohol ,Muscle Fatigue ,Electric Conductivity ,Humans ,Equipment Design ,Hydrogen-Ion Concentration ,Exercise ,HeLa Cells - Abstract
MXene-based hydrogels have received significant attention due to several promising properties that distinguish them from conventional hydrogels. In this study, it is shown that both strain and pH level can be exploited to tune the electronic and ionic transport in MXene-based hydrogel (M-hydrogel), which consists of MXene (Ti
- Published
- 2021
14. Inhibitory Effect of Black Radish Extract (Raphanus sativus L. var. niger) on Adipogenesis in 3T3-L1 Cells
- Author
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Dawun Yang, Seunghyun Hong, Nam Ho Lee, Shin, Tae-Kyun, Hak-Sung Lee, and kim gi-ok
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Nutrition and Dietetics ,biology ,Traditional medicine ,Chemistry ,Adipogenesis ,Anti obesity ,3T3-L1 Cells ,Raphanus ,AMPK ,BLACK RADISH ,biology.organism_classification ,Inhibitory effect ,Food Science - Published
- 2019
15. Two-Dimensional Ti3C2Tx MXene Membranes as Nanofluidic Osmotic Power Generators
- Author
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Renyuan Li, Husam N. Alshareef, Peng Wang, Fangwang Ming, Chuyang Y. Tang, In S. Kim, Yusuf Shi, and Seunghyun Hong
- Subjects
Chemical substance ,Materials science ,Energy conversion efficiency ,General Engineering ,General Physics and Astronomy ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Membrane ,Chemical engineering ,Osmotic power ,Energy transformation ,General Materials Science ,Lamellar structure ,Surface charge ,0210 nano-technology ,Power density - Abstract
Salinity-gradient is emerging as one of the promising renewable energy sources but its energy conversion is severely limited by unsatisfactory performance of available semipermeable membranes. Recently, nanoconfined channels, as osmotic conduits, have shown superior energy conversion performance to conventional technologies. Here, ion selective nanochannels in lamellar Ti3C2Tx MXene membranes are reported for efficient osmotic power harvesting. These subnanometer channels in the Ti3C2Tx membranes enable cation-selective passage, assisted with tailored surface terminal groups, under salinity gradient. A record-high output power density of 21 W·m-2 at room temperature with an energy conversion efficiency of up to 40.6% is achieved by controlled surface charges at a 1000-fold salinity gradient. In addition, due to thermal regulation of surface charges and ionic mobility, the MXene membrane produces a large thermal enhancement at 331 K, yielding a power density of up to 54 W·m-2. The MXene lamellar structure, coupled with its scalability and chemical tunability, may be an important platform for high-performance osmotic power generators.
- Published
- 2019
16. Simultaneous production of fresh water and electricity via multistage solar photovoltaic membrane distillation
- Author
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Chi Siang Ong, Seunghyun Hong, Le Shi, Peng Wang, Wenbin Wang, Chenlin Zhang, Renyuan Li, Yong Jin, Sifei Zhuo, Yusuf Shi, and Jian Chang
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0301 basic medicine ,Energy storage ,Power station ,Science ,General Physics and Astronomy ,02 engineering and technology ,Membrane distillation ,General Biochemistry, Genetics and Molecular Biology ,Article ,law.invention ,03 medical and health sciences ,law ,Latent heat ,Solar cell ,lcsh:Science ,Distillation ,Multidisciplinary ,Waste management ,business.industry ,Energy harvesting ,Photovoltaic system ,General Chemistry ,021001 nanoscience & nanotechnology ,030104 developmental biology ,Electricity generation ,Environmental science ,lcsh:Q ,Electricity ,0210 nano-technology ,business - Abstract
The energy shortage and clean water scarcity are two key challenges for global sustainable development. Near half of the total global water withdrawals is consumed by power generation plants while water desalination consumes lots of electricity. Here, we demonstrate a photovoltaics-membrane distillation (PV-MD) device that can stably produce clean water (>1.64 kg·m−2·h−1) from seawater while simultaneously having uncompromised electricity generation performance (>11%) under one Sun irradiation. Its high clean water production rate is realized by constructing multi stage membrane distillation (MSMD) device at the backside of the solar cell to recycle the latent heat of water vapor condensation in each distillation stage. This composite device can significantly reduce capital investment costs by sharing the same land and the same mounting system and thus represents a potential possibility to transform an electricity power plant from otherwise a water consumer to a fresh water producer., The increasing demand for energy and clean water has become a grand global challenge. Here the authors develop a membrane-distillation device that exploits sunlight and the heat dissipated by an integrated solar cell unit, enabling simultaneous efficient production of electricity and drinkable water.
- Published
- 2019
17. Janus Graphene Oxide-Doped, Lamellar Composite Membranes with Strong Aqueous Stability
- Author
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In S. Kim, Renyuan Li, Peng Wang, Seunghyun Hong, and Chang-Min Kim
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Aqueous solution ,Materials science ,Renewable Energy, Sustainability and the Environment ,Graphene ,General Chemical Engineering ,Doping ,Composite number ,Oxide ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,Membrane ,chemistry ,Chemical engineering ,law ,Environmental Chemistry ,Lamellar structure ,Janus ,0210 nano-technology - Abstract
Nanostructured graphene oxide (GO) membranes offer outstanding mass transport performances such as ultrahigh water flux and precise molecular sieving and thus have a great potential as a novel filt...
- Published
- 2019
18. Reflood experiments at elevated pressures using intact and deformed rod bundles to simulate small and medium break loss-of-coolant accidents
- Author
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SeungHyun Hong, Jongrok Kim, Jong-Kuk Park, Sarah Kang, and Sang-Ki Moon
- Subjects
Quenching ,Nuclear and High Energy Physics ,Materials science ,020209 energy ,Mechanical Engineering ,Flow (psychology) ,02 engineering and technology ,Mechanics ,Deformation (meteorology) ,Cladding (fiber optics) ,01 natural sciences ,Rod ,010305 fluids & plasmas ,Coolant ,Flow conditions ,Nuclear Energy and Engineering ,High pressure ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,General Materials Science ,Safety, Risk, Reliability and Quality ,Waste Management and Disposal - Abstract
Reflood experiments at elevated pressures for small and medium break loss-of-coolant accidents were performed to investigate the influence of fuel deformation on the peak cladding temperature and local quenching behaviors. The typical experimental parameters such as initial water level, power, reflood rate, system pressure, initial wall temperature, and fluid temperature were varied to cover a wide range of flow conditions under a medium and high pressure. The experimental results showed remarkable differences in the peak cladding temperature and local quenching behaviors between the intact and deformed rod bundles due to the flow blockage effect. The present results implied that the fuel rod deformation can enhance the coolability of fuel rods by the flow blockage in the present fully blocked channel. Any bypass in a partially blocked channel may change those results due to a crossflow between intact and deformed rods. The experimental results were then used to validate the system analysis code, Multi-dimensional Analysis of Reactor Safety-KINS Standard (MARS-KS). The MARS-KS code showed good prediction of the present experimental data for most of the flow conditions.
- Published
- 2018
19. Dave: Deep Learning Based Asymmetric Virtual Environment
- Author
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Yunsik Cho, Seunghyun Hong, Mingyu Kim, and Jinmo Kim
- Published
- 2021
20. Photothermoelectric Response of Ti
- Author
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Seunghyun, Hong, Guodong, Zou, Hyunho, Kim, Dazhen, Huang, Peng, Wang, and Husam N, Alshareef
- Subjects
photothermal conversion ,nanoconfined cation channels ,thermo-osmosis ,thermoelectric Seebeck coefficient ,titanium carbide ,MXene lamellar membranes ,Article - Abstract
With recent growing interest in biomimetic smart nanochannels, a biological sensory transduction in response to external stimuli has been of particular interest in the development of biomimetic nanofluidic systems. Here we demonstrate the MXene-based subnanometer ion channels that convert external temperature changes to electric signals via preferential diffusion of cations under a thermal gradient. In particular, coupled with a photothermal conversion feature of MXenes, an array of the nanoconfined Ti3C2Tx ion channels can capture trans-nanochannel diffusion potentials under a light-driven axial temperature gradient. The nonisothermal open-circuit potential across channels is enhanced with increasing cationic permselectivity of confined channels, associated with the ionic concentration or pH of permeant fluids. The photothermoelectric ionic response (evaluated from the ionic Seebeck coefficient) reached up to 1 mV·K–1, which is comparable to biological thermosensory channels, and demonstrated stability and reproducibility in the absence and presence of an ionic concentration gradient. With advantages of physicochemical tunability and easy fabrication process, the lamellar ion conductors may be an important nanofluidic thermosensation platform possibly for biomimetic sensory systems.
- Published
- 2020
21. Antimelanogenic Effects ofRaphanus sativusL. var.nigerRoots on α-MSH Stimulated B16F10 Melanoma Cells
- Author
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Yeon Jeong Jo, Yang Da Wun, Gi Ok Kim, Seunghyun Hong, Jung Eun Kim, Nam Ho Lee, and Ha Na Ko
- Subjects
biology ,Chemistry ,Raphanus ,General Chemistry ,biology.organism_classification ,01 natural sciences ,Molecular biology ,0104 chemical sciences ,010404 medicinal & biomolecular chemistry ,03 medical and health sciences ,0302 clinical medicine ,030220 oncology & carcinogenesis ,B16f10 melanoma ,BLACK RADISH - Published
- 2018
22. Solar Evaporator with Controlled Salt Precipitation for Zero Liquid Discharge Desalination
- Author
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Jian Chang, Yusuf Shi, Chi Siang Ong, Sifei Zhuo, Chenlin Zhang, Seunghyun Hong, Yong Jin, Renyuan Li, Le Shi, and Peng Wang
- Subjects
Salinity ,High energy ,Origin of water on Earth ,Environmental engineering ,02 engineering and technology ,General Chemistry ,Sodium Chloride ,Wastewater ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Zero liquid discharge ,Desalination ,Water Purification ,0104 chemical sciences ,law.invention ,Brine ,law ,Sunlight ,Environmental Chemistry ,Environmental science ,0210 nano-technology ,Energy source ,Distillation ,Evaporator - Abstract
A sustainable supply of clean water is essential for the development of modern society, which has become increasingly dependent on desalination technology since 96.5% of the water on Earth is salt water. Thousands of desalination plants are producing massive waste brine as byproduct, and the direct discharge of brine raises serious concerns about its ecological impact. The concept of zero liquid discharge (ZLD) desalination is regarded as the solution, but the current ZLD technologies are hampered by their intensive use of energy and high cost. In this work, a 3D cup shaped solar evaporator was fabricated to achieve ZLD desalination with high energy efficiency via solar distillation. It produces solid salt as the only byproduct and uses sunlight as the only energy source. By rationally separating the light absorbing surface from the salt precipitation surface, the light absorption of the 3D solar evaporator is no longer affected by the salt crust layer as in conventional 2D solar evaporators. Therefore, it can be operated at an extremely high salt concentration of 25 wt % without noticeable water evaporation rate decay in at least 120 h. This new solar evaporator design concept offers a promising technology especially for high salinity brine treatment in desalination plants to achieve greener ZLD desalination as well as for hypersaline industrial wastewater treatment.
- Published
- 2018
23. Nature-Inspired, 3D Origami Solar Steam Generator toward Near Full Utilization of Solar Energy
- Author
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Peng Wang, Yong Jin, Yusuf Shi, Seunghyun Hong, Renyuan Li, and Chenlin Zhang
- Subjects
Materials science ,Global challenges ,Convective heat transfer ,Graphene ,business.industry ,Boiler (power generation) ,02 engineering and technology ,Carbon nanotube ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Solar energy ,01 natural sciences ,Engineering physics ,0104 chemical sciences ,law.invention ,law ,Physics::Space Physics ,Radiative transfer ,Astrophysics::Solar and Stellar Astrophysics ,General Materials Science ,Astrophysics::Earth and Planetary Astrophysics ,Nature inspired ,0210 nano-technology ,business - Abstract
Solar steam generation, due to its capability of producing clean water directly by solar energy, is emerging as a promising eco-friendly and energy-efficient technology to address global challenges of water crisis and energy shortage. Although diverse materials and architectures have been explored to improve solar energy utilization, high efficiency in solar steam generation could be accomplished only with external optical and thermal management. For the first time, we report a deployable, three-dimensional (3D) origami-based solar steam generator capable of near full utilization of solar energy. This auxetic platform is designed based on Miura-ori tessellation and is able to efficiently recover radiative and convective heat loss as well as to trap solar energy via its periodic concavity pattern. The 3D solar steam generator device with a nanocarbon composite of graphene oxide and carbon nanotubes being photothermal component in this work shows a very strong dependence between its solar energy efficiency and surface areal density. The device yields an extraordinary solar energy efficiency close to 100% under 1 sun illumination at a highly folded configuration. The 3D origami device can withstand a great number of folding and unfolding cycles and shows unimpaired solar steam generation performances. The unique structural feature of the 3D origami structure offers a new insight into the future development of highly efficient and easily deployable solar steam generator.
- Published
- 2018
24. A 3D Photothermal Structure toward Improved Energy Efficiency in Solar Steam Generation
- Author
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Sifei Zhuo, Yusuf Shi, Seunghyun Hong, Yong Jin, Le Shi, Jian Chang, Peng Wang, Renyuan Li, and Kim Choon Ng
- Subjects
Work (thermodynamics) ,Materials science ,Oxide ,02 engineering and technology ,Photothermal therapy ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Engineering physics ,0104 chemical sciences ,chemistry.chemical_compound ,General Energy ,chemistry ,Thermal radiation ,Thermal stability ,Diffuse reflection ,0210 nano-technology ,Evaporator ,Efficient energy use - Abstract
Summary The energy efficiency in solar steam generation by 2D photothermal materials has approached its limit. In this work, we fabricated 3D cylindrical cup-shaped structures of mixed metal oxide as solar evaporator, and the 3D structure led to a high energy efficiency close to 100% under one-sun illumination due to the capability of the cup wall to recover the diffuse reflectance and thermal radiation heat loss from the 2D cup bottom. Additional heat was gained from the ambient air when the 3D structure was exposed under one-sun illumination, leading to an extremely high steam generation rate of 2.04 kg m −2 h −1 . The 3D structure has a high thermal stability and shows great promise in practical applications including domestic wastewater volume reduction and seawater desalination. The results of this work inspire further research efforts to use 3D photothermal structures to break through the energy efficiency limit of 2D photothermal materials.
- Published
- 2018
25. A highly flexible and washable nonwoven photothermal cloth for efficient and practical solar steam generation
- Author
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Yong Jin, Le Shi, Yusuf Shi, Peng Wang, Seunghyun Hong, and Jian Chang
- Subjects
Materials science ,Renewable Energy, Sustainability and the Environment ,business.industry ,Evaporation ,chemistry.chemical_element ,Nanoparticle ,02 engineering and technology ,General Chemistry ,Photothermal therapy ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Solar energy ,01 natural sciences ,Electrospinning ,0104 chemical sciences ,law.invention ,Chemical engineering ,chemistry ,law ,Nanofiber ,General Materials Science ,0210 nano-technology ,business ,Carbon ,Distillation - Abstract
Solar-driven water evaporation is emerging as a promising solar-energy utilization process. In the present work, a highly stable, flexible and washable nonwoven photothermal cloth is prepared by electrospinning for efficient and durable solar steam evaporation. The cloth is composed of polymeric nanofibers as the matrix and inorganic carbon black nanoparticles encapsulated inside the matrix as light absorbing components. The photothermal cloth with an optimized carbon loading shows desirable underwater black properties, absorbing 94% of the solar spectrum and giving rise to a state-of-the-art solar energy utilization efficiency of 83% during the pure water evaporation process. Owing to its compositions and special structural design, the cloth possesses anti-photothermal-component-loss properties and is highly flexible, mechanically strong, and chemically stable in various harsh environments such as strong acid, alkalis, organic solvents and salty water. It can be hand-washed more than 100 times without degrading its performance and thus offers a potential mechanism for foulant cleaning during practical solar steam generation and distillation processes. The results of this work stimulate more research in durable photothermal materials aiming at real world applications.
- Published
- 2018
26. Improvements of COBRA-TF on the effect of flow blockage during a LB LOCA with consideration of fuel relocation phenomenon
- Author
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Ngoc Hung Nguyen, Sang-Ki Moon, Jongrok Kim, SeungHyun Hong, and Chul-Hwa Song
- Subjects
Nuclear and High Energy Physics ,Materials science ,Convective heat transfer ,business.industry ,020209 energy ,Mechanical Engineering ,Heat transfer enhancement ,Flow (psychology) ,02 engineering and technology ,Structural engineering ,Mechanics ,Nuclear reactor ,law.invention ,Flow separation ,Nuclear Energy and Engineering ,law ,Heat transfer ,0202 electrical engineering, electronic engineering, information engineering ,General Materials Science ,Decay heat ,Safety, Risk, Reliability and Quality ,business ,Waste Management and Disposal ,Boiler blowdown - Abstract
Coolability of the partially blocked core in a large break loss-of-coolant accident (LB LOCA) is one of the most important thermal-hydraulic concerns for nuclear reactor safety analysis. During blowdown phase and early stage of reflooding phase in the LB LOCA, the prevailing wall-to-vapor convective heat transfer plays an important role on the decay heat removal process. Experiments on single-phase convective heat transfer to vapor were conducted in 5 × 5 heater rod bundles containing 3 × 3 ballooned rods of 90% flow blockage ratio with consideration of fuel relocation phenomenon. The obtained experimental data were used to assess the single-phase heat transfer enhancement models of the COBRA-TF code. The assessment results showed underprediction of local heat transfer downstream of the flow blockage. Therefore, a new correlation has been proposed to improve the prediction capability of the conventional models by more accurately describing the flow blockage effect. The new correlation predicted the local heat transfer satisfactorily within a 20% discrepancy of the experimental data for various kinds of flow blockage configurations.
- Published
- 2017
27. Muscle Fatigue Sensor Based on Ti 3 C 2 T x MXene Hydrogel
- Author
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Husam N. Alshareef, Seunghyun Hong, Yongjiu Lei, Shofarul Wustoni, Adel Hama, Sahika Inal, Kang Hyuck Lee, Hyunho Kim, and Yizhou Zhang
- Subjects
Materials science ,Muscle fatigue ,General Materials Science ,General Chemistry ,Composite material - Published
- 2021
28. Scalable Graphene-Based Membranes for Ionic Sieving with Ultrahigh Charge Selectivity
- Author
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Juan Alfredo Guevara Carrió, Slaven Garaj, Charlotte Constans, Marcos Vinicius Surmani Martins, Seunghyun Hong, and Y. C. Seow
- Subjects
Chemistry ,Mechanical Engineering ,Analytical chemistry ,Ionic bonding ,Bioengineering ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Electrostatics ,01 natural sciences ,0104 chemical sciences ,Ion ,Ionic potential ,Membrane ,Solvation shell ,Chemical engineering ,General Materials Science ,Nanofiltration ,Surface charge ,0210 nano-technology - Abstract
Nanostructured graphene-oxide (GO) laminate membranes, exhibiting ultrahigh water flux, are excellent candidates for next generation nanofiltration and desalination membranes, provided the ionic rejection could be further increased without compromising the water flux. Using microscopic drift-diffusion experiments, we demonstrated the ultrahigh charge selectivity for GO membranes, with more than order of magnitude difference in the permeabilities of cationic and anionic species of equivalent hydration radii. Measuring diffusion of a wide range of ions of different size and charge, we were able to clearly disentangle different physical mechanisms contributing to the ionic sieving in GO membranes: electrostatic repulsion between ions and charged chemical groups; and the compression of the ionic hydration shell within the membrane's nanochannels, following the activated behavior. The charge-selectivity allows us to rationally design membranes with increased ionic rejection and opens up the field of ion exchange and electrodialysis to the GO membranes.
- Published
- 2017
29. Two-Dimensional Ti
- Author
-
Seunghyun, Hong, Fangwang, Ming, Yusuf, Shi, Renyuan, Li, In S, Kim, Chuyang Y, Tang, Husam N, Alshareef, and Peng, Wang
- Abstract
Salinity-gradient is emerging as one of the promising renewable energy sources but its energy conversion is severely limited by unsatisfactory performance of available semipermeable membranes. Recently, nanoconfined channels, as osmotic conduits, have shown superior energy conversion performance to conventional technologies. Here, ion selective nanochannels in lamellar Ti
- Published
- 2019
30. Variations of the optimal fin spacing according to Prandtl number in natural convection
- Author
-
Bum-Jin Chung and Seunghyun Hong
- Subjects
Materials science ,020209 energy ,Prandtl number ,General Engineering ,Thermodynamics ,Film temperature ,02 engineering and technology ,Heat transfer coefficient ,Mechanics ,Condensed Matter Physics ,Annular fin ,Churchill–Bernstein equation ,Nusselt number ,symbols.namesake ,020303 mechanical engineering & transports ,0203 mechanical engineering ,Heat transfer ,0202 electrical engineering, electronic engineering, information engineering ,symbols ,Turbulent Prandtl number - Abstract
Numerical and experimental analyses of open channel natural convection heat transfer of a finned plate were carried out. By varying the fin spacing, the heat transfer rates were calculated using FLUENT 6.3.26 for Prandtl numbers in the range 0.7 ≤ Pr ≤ 2000. Mass transfer experiments were carried out to verify the simulated data, exploiting the analogy between heat and mass transfer. The optimal fin spacing increased as the Prandtl number decreased. The calculated velocity and temperature profiles revealed the interaction between the thermal boundary layers on adjacent fins as a function of the Prandtl number. The observations of the overlap of the thermal boundary layers that develops at the corners of the fins, led the derivation of a simple heat transfer correlation that can be used to predict the heat transfer rate of a finned plate, based on an existing heat transfer correlation for a planar surface.
- Published
- 2016
31. Improving atmospheric water production yield: Enabling multiple water harvesting cycles with nano sorbent
- Author
-
Renyuan Li, Yusuf Shi, Seunghyun Hong, Mengchun Wu, and Peng Wang
- Subjects
Materials science ,Sorbent ,Renewable Energy, Sustainability and the Environment ,Environmental engineering ,Sorption ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Rainwater harvesting ,Atmospheric water generator ,Yield (chemistry) ,Desorption ,Nano ,General Materials Science ,Electrical and Electronic Engineering ,0210 nano-technology ,Water vapor - Abstract
Clean water shortage has long been a challenge in remote and landlocked communities especially for the impoverished. Atmospheric water is now considered as an unconventional but accessible fresh water source and sorption-based atmospheric water generator (AWG) has been successfully demonstrated a reliable way of harvesting atmospheric water. The water vapor sorbents with high water uptake capacity and especially fast vapor sorption/desorption kinetics have become the bottleneck to a desirable clean water productivity in AWG. In this work, we developed a new nano vapor sorbent composed of a nano carbon hollow capsule with LiCl inside the void core. The sorbent can capture water vapor from ambient air as much as 100% of its own weight under RH 60% within 3 h and quickly release the sorbed water within just half hour under 1 kW/m2 sunlight irradiation. A batch-mode AWG device was able to conduct 3 sorption/desorption cycles within 10 h during one day test in the outdoor condition and produced 1.6 kgwater/kgsorbent. A prototype of continuous AWG device was designed, fabricated, and successfully demonstrated, hinting a possible way of large-scale deployment of AWG for practical purposes.
- Published
- 2020
32. Design and validation of a fuel assembly simulator for PGSFR reactor flow distribution test facility
- Author
-
Dong Jin Euh, SeungHyun Hong, Hae Seob Choi, Sun Rock Choi, and Woo Shik Kim
- Subjects
Pressure drop ,Nuclear and High Energy Physics ,Materials science ,Internal flow ,020209 energy ,Mechanical Engineering ,Orifice plate ,02 engineering and technology ,01 natural sciences ,010305 fluids & plasmas ,Volumetric flow rate ,Nuclear Energy and Engineering ,Venturi effect ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Mass flow rate ,General Materials Science ,Safety, Risk, Reliability and Quality ,Waste Management and Disposal ,Reactor pressure vessel ,Body orifice ,Simulation - Abstract
A test facility to investigate the flow characteristics inside reactor vessel for the Prototype Gen-IV Sodium-cooled Fast Reactor was constructed. In the test facility, reactor vessel and the main in-vessel components are linearly reduced at a scaling ratio of 1/5 and water is used as the working fluid. In the reactor vessel of the test facility, the main components such as core, UIS, PHTS pump and IHX are installed. The exteriors of the main components are conserved following the scaling ratio of 1/5, but the internal flow paths inside the fuel assemblies and IHXs are uniquely designed for precise measurement of flow rate and conserving the pressure drop characteristics. In order to determine the configuration and specific dimension of the internal flow path, separate analysis and experiment for validation are required. In the present paper, the basic design concept of internal flow path for fuel assembly simulator used for the reactor flow distribution test was established, and the detailed size of main design factors were estimated using commercial CFD code. The internal flow path of the simulator is composed of a receptacle, variable-resistance rotating orifice spool, venturi tube, and connection lines. The flow rate through the simulator could be estimated by measuring the differential pressure between inlet section and the throat of the venturi tube. The orifice spool is installed at the downstream of the receptacle, by which entire pressure drop through the simulator is controlled. A series of CFD analysis was conducted to estimate the throat diameter of the venturi tube and the size of the holes at the orifices. The geometry of the orifice is determined to obtain target pressure drop when the angle between two orifice plates is from 0° to 45°. The design specifications were applied to the fabrication of the fuel assembly simulators, and the performance of them was verified experimentally. The pressure drop of 112 fuel assembly simulators was successfully adjusted to be within ±1% of the target pressure drop. The relationship between the mass flow rate and differential pressure of the venturi tube was also obtained, and empirical correlation was suggested.
- Published
- 2020
33. Black Radish (Raphanus sativus L. var. niger) Extract Mediates Its Hepatoprotective Effect on Carbon Tetrachloride-Induced Hepatic Injury by Attenuating Oxidative Stress
- Author
-
Nam-Ho Lee, Giok Kim, Jung Eun Kim, Hana Ko, Seunghyun Hong, Jeongtae Kim, Meejung Ahn, and Taekyun Shin
- Subjects
0301 basic medicine ,Male ,NF-E2-Related Factor 2 ,Medicine (miscellaneous) ,Raphanus ,medicine.disease_cause ,Protective Agents ,Liver disorder ,Rats, Sprague-Dawley ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Non-alcoholic Fatty Liver Disease ,Nonalcoholic fatty liver disease ,medicine ,Animals ,Humans ,BLACK RADISH ,Aspartate Aminotransferases ,Carbon Tetrachloride ,Nutrition and Dietetics ,Traditional medicine ,biology ,Plant Extracts ,fungi ,food and beverages ,Alanine Transaminase ,Cytochrome P-450 CYP2E1 ,Hep G2 Cells ,medicine.disease ,biology.organism_classification ,Rats ,Oxidative Stress ,030104 developmental biology ,chemistry ,Hepatoprotection ,Liver ,030220 oncology & carcinogenesis ,Carbon tetrachloride ,Oxidative stress - Abstract
Nonalcoholic fatty liver disease is a serious liver disorder associated with oxidative stress. Black radish (Raphanus sativus L. var. niger) extract (BRE) can lower the risk of this disease. The hepatoprotective effect of BRE containing 3-(E)-(methylthio)methylene-2-pyrrolidinethione was evaluated in human hepatocyte carcinoma (HepG2) cells and in rat livers with carbon tetrachloride (CCl
- Published
- 2018
34. A new 1200 V HVIC with high side edge trigger in order to solve the latch on failure by the negative VS surge
- Author
-
Seunghyun Hong, Oh Wonhi, Kinam Song, Sangmin Park, and Jinkyu Choi
- Subjects
010302 applied physics ,Computer science ,business.industry ,020208 electrical & electronic engineering ,Electrical engineering ,02 engineering and technology ,Integrated circuit ,01 natural sciences ,BCDMOS ,Signal ,law.invention ,law ,Logic gate ,Power module ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Enhanced Data Rates for GSM Evolution ,Surge ,business ,Reset (computing) - Abstract
This paper investigates the root cause of the latch on failure by a short turn-on input signal with a negative VS surge and proposes a new 1200 V HVIC with a high side edge trigger in order to solve the latch on failure. The proposed HVIC is fabricated using a 1.2 μm 1200 V BCDMOS process. The experimental results show the latch on failure no longer occurs on the new 1200 V HVIC because it doesn't overlap the VS recovery period and the RESET pulse period. The proposed HVIC can be applied to IPM modules (intelligent power modules) and APM modules (automotive power modules) which require a more robust HVIC solution.
- Published
- 2018
35. Graphene-Templated Synthesis of c-Axis Oriented Sb2Te3 Nanoplates by the Microwave-Assisted Solvothermal Method
- Author
-
Swati Singh, Hyunjung Shin, Sung Wng Kim, Gi Duk Kwon, Jae-Yeol Hwang, Didier Pribat, Dongmok Lee, Seunghyun Hong, Wonjae Jeon, Seulky Lim, and Seunghyun Baik
- Subjects
Materials science ,Convective heat transfer ,Graphene ,Chalcogenide ,General Chemical Engineering ,Nanotechnology ,General Chemistry ,Crystal structure ,Exfoliation joint ,Chemical synthesis ,law.invention ,chemistry.chemical_compound ,chemistry ,law ,Materials Chemistry ,Microwave ,Graphene oxide paper - Abstract
The successful mechanical exfoliation and chemical synthesis of graphene has attracted considerable attention for the synthesis of other two-dimensional materials on graphene template. Chalcogenide materials such as Sb2Te3 are of interest due to the rhombohedral lattice structure with two-dimensional hexagonally closed-packed atomic layers along the c-axis. Here we synthesized c-axis-oriented Sb2Te3 nanoplates (NPs) on graphene substrates by the microwave-assisted solvothermal method. The microwave irradiation resulted in a higher temperature of graphene, compared with the synthesis solution, which was revealed by the single-mode microwave experiments and an analytical model based on energy balance and convective heat transfer. Besides, the lattice mismatch between c-axis-oriented Sb2Te3 and bridge sites of graphene was only 4%, which is also favorable for the graphene-templated Sb2Te3 synthesis. c-Axis-oriented single-crystalline Sb2Te3 NPs as large as 7 μm could be successfully synthesized on graphene w...
- Published
- 2015
36. A Research on Performance Improvement of iBeacon Using Transmission and Reception of Different Beacon Signals
- Author
-
Cheolhoon Kim, Sung Won Lee, and Seunghyun Hong
- Subjects
Scheme (programming language) ,computer.internet_protocol ,business.industry ,Computer science ,Real-time computing ,iBeacon ,law.invention ,Bluetooth ,Transmission (telecommunications) ,law ,Performance improvement ,business ,computer ,computer.programming_language ,Bluetooth Low Energy ,Computer network - Abstract
In this paper, we propose a different kind of Beacon signals transmission and receipt scheme to express more information in existing iBeacon. Because the user can only use Major and Minor of iBeacon, information available for the user is limited to 4byte. The proposed scheme makes it possible to use more information by transmitting consecutively a different kind of Beacon signals that major and minor are different. When it comes to using more information of iBeacon, it is possible to recognize people and objects using iBeacon and utilization range of iBeacon is widened further. Also, we verify operation of the proposed scheme through application implementation.
- Published
- 2015
37. Single-Phase Heat Transfer Enhancement in Partially Blocked Rod Bundles
- Author
-
SeungHyun Hong, Sang-Ki Moon, Ngoc Hung Nguyen, Chul-Hwa Song, and Jongrok Kim
- Subjects
Convection ,Materials science ,Heat transfer enhancement ,Heat transfer ,Single phase ,Molecular physics - Abstract
Wall-to-vapor convective heat transfer is the dominant heat transfer mechanism in the reactor core during the blowdown phase and the early stage of reflooding phase in a postulated large-break loss-of-coolant-accident (LB LOCA). Experiments on single-phase convective heat transfer to vapor were conducted in partially blocked rod bundles of 90% flow blockage ratio. The experimental results showed increase in local heat transfer just downstream of the blockage caused by flow separation phenomenon. The single-phase heat transfer enhancement models implemented in the COBRA-TF code underpredicted the local heat transfer in the downstream region of the flow blockage. Hence, a new correlation was proposed to improve the prediction capability of the COBRA-TF models by more accurately describing the flow separation effect. The new correlation predicted well various sets of experimental data within 20% discrepancy.
- Published
- 2017
38. Experimental Study For The Reflood Behavior of Nuclear Reactor In Medium And High Pressure Conditions Using 3x3 Heater Bundle
- Author
-
Jong-Kuk Park, Hae Seob Choi, Young-Jung Youn, SeungHyun Hong, Jongrok Kim, Sang-Ki Moon, and Seok Cho
- Subjects
Materials science ,law ,Nuclear engineering ,High pressure ,Bundle ,Nuclear reactor ,law.invention - Published
- 2017
39. SINGLE-PHASE CONVECTIVE HEAT TRANSFER IN A ROD BUNDLE CONTAINING PARTIAL BLOCKAGE
- Author
-
Ngoc Hung Nguyen, Jongrok Kim, Chul-Hwa Song, Sang-Ki Moon, and SeungHyun Hong
- Subjects
Materials science ,Convective heat transfer ,Bundle ,Mechanics ,Single phase - Published
- 2017
40. Dielectrophoretic separation of metallic arc-discharge single-walled carbon nanotubes in a microfluidic channel
- Author
-
Duckjong Kim, Beibei Wang, Jung Jun Bae, Hosung Kang, Seunghyun Hong, Seunghyun Baik, Chang Soo Han, and Young Hee Lee
- Subjects
Nanotube ,Materials science ,Mechanical Engineering ,Metals and Alloys ,Nanotechnology ,Carbon nanotube ,Dielectrophoresis ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,law.invention ,Electric arc ,Microelectrode ,Crystallinity ,Mechanics of Materials ,law ,Electrode ,Materials Chemistry ,Deposition (law) - Abstract
Electronic type-dependent separation of single-walled carbon nanotubes (SWNTs), preserving pristine crystallinity and length, is of great interest since mixtures of semiconducting and metallic species are produced by current synthesis methods. Here we separated highly-enriched metallic SWNTs, synthesized by the arc-discharge method, by dielectrophoresis in a microfluidic channel. The design of microelectrodes was optimized to prevent the nanotube deposition on the electrodes for prolonged operation of the microfluidic chip. The average length of separated highly crystalline metallic SWNTs was relatively long (2–2.4 μm).
- Published
- 2013
41. Enhanced Electrical Potential of Thermoelectric Power Waves by Sb2Te3-Coated Multiwalled Carbon Nanotube Arrays
- Author
-
Seunghyun Hong, Seungmin Hyun, Seong-jae Jeon, Won-Young Kim, Seong Chu Lim, Young Hee Lee, Hoo-Jeong Lee, and Seunghyun Baik
- Subjects
Exothermic reaction ,Nanotube ,Materials science ,business.industry ,Nanotechnology ,Heterojunction ,Carbon nanotube ,Chemical reaction ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,Chemical energy ,General Energy ,Sputtering ,law ,Seebeck coefficient ,Optoelectronics ,Physical and Theoretical Chemistry ,business - Abstract
Thermoelectric power waves, where multiwalled carbon nanotubes coated with cyclotrimethylene trinitramine (MWCNT/TNA) directly convert chemical energy to electricity, have received considerable attention recently. However, the low Seebeck coefficient of carbon nanotubes has been regarded as a hurdle to increasing the electrical potential. Here, we present Sb2Te3-coated MWCNT arrays prepared by a sputtering method. An analytical model predicts an increase in Seebeck coefficient of the annular multishell structure by ∼75%. The heterostructure coupled with exothermic chemical reaction of TNA demonstrates an increase in peak electrical potential of 175% (∼198 mV), compared with typical outputs of bare MWCNT/TNA (∼72 mV). A serial connection of two repeating units increased the peak potential by up to 406 mV.
- Published
- 2013
42. Wearable Device Control Platform Technology for Network Application Development
- Author
-
Misun Ahn, Heejung Kim, Seunghyun Hong, SeungGwan Lee, and Sungwon Lee
- Subjects
Application programming interface ,Article Subject ,Computer Networks and Communications ,business.industry ,Computer science ,Software development ,Information technology ,Wearable computer ,020206 networking & telecommunications ,02 engineering and technology ,TK5101-6720 ,Computer Science Applications ,law.invention ,Bluetooth ,law ,Native API ,Embedded system ,0202 electrical engineering, electronic engineering, information engineering ,Telecommunication ,020201 artificial intelligence & image processing ,business ,Information exchange ,Wearable technology - Abstract
Application development platform is the most important environment in IT industry. There are a variety of platforms. Although the native development enables application to optimize, various languages and software development kits need to be acquired according to the device. The coexistence of smart devices and platforms has rendered the native development approach time and cost consuming. Cross-platform development emerged as a response to these issues. These platforms generate applications for multiple devices based on web languages. Nevertheless, development requires additional implementation based on a native language because of the coverage and functions of supported application programming interfaces (APIs). Wearable devices have recently attracted considerable attention. These devices only support Bluetooth-based interdevice communication, thereby making communication and device control impossible beyond a certain range. We propose Network Application Agent (NetApp-Agent) in order to overcome issues. NetApp-Agent based on the Cordova is a wearable device control platform for the development of network applications, controls input/output functions of smartphones and wearable/IoT through the Cordova and Native API, and enables device control and information exchange by external users by offering a self-defined API. We confirmed the efficiency of the proposed platform through experiments and a qualitative assessment of its implementation.
- Published
- 2016
43. Medication Repurposing: New Uses for Old Drugs
- Author
-
Amy E. Lodolce, Irene Seunghyun Hong, Heather J Ipema, and Michael Gabay
- Subjects
medicine.medical_specialty ,business.industry ,Alternative medicine ,Lack of efficacy ,Pharmaceutical Science ,Medicine ,Pharmacology ,business ,Intensive care medicine ,Repurposing - Abstract
Background: Medication repurposing, the practice of using old drugs in new ways, is becoming more common. Old drugs that had previously fallen out of favor due to safety concerns, lack of efficacy, or development of more desirable therapeutic alternatives have been resurfacing in the literature and on pharmacy shelves. Developing new uses for old drugs may provide patients with access to helpful therapies but may also present challenges and risks. Objective: To explore the rationale for, and historical context of, the developing trend of recycling existing drugs for new, innovative uses, and to provide pharmacy practitioners with information about how to find clinical evidence regarding these new uses. Data Synthesis: The process of obtaining marketing approval for new drugs can take an average of over 10 years and exceed $1 billion. Repurposing old drugs (both approved and unapproved) for new uses requires considerably fewer resources since information about production needs, pharmacology, and pharmacokinetics is already known. Other advantages of using old drugs include faster availability for patient use and known safety concerns for the original indication. Disadvantages of new uses for old drugs may include lack of clinical evidence, unknown safety for the new clinical context, limited availability of information about new uses, and liability or legal concerns. Several methods of identifying potential new uses exist, including the observance of previously unknown desirable pharmacologic effects during clinical use, new knowledge of a mechanism of action leading to exploration of innovative therapeutic areas, or screening compound libraries for targeted clinical activity. Conclusions: There are many examples of recycling existing medications for new purposes. Pharmacy practitioners should be aware of this developing trend and know how to find information about utilizing old drugs in new ways.
- Published
- 2011
44. Anticholinergic Use in Children and Adolescents After Initiation of Antipsychotic Therapy
- Author
-
Jeffrey R. Bishop and Irene Seunghyun Hong
- Subjects
Male ,Dibenzothiazepines ,Pediatrics ,medicine.medical_specialty ,Adolescent ,medicine.drug_class ,medicine.medical_treatment ,Aripiprazole ,Quinolones ,Cholinergic Antagonists ,Piperazines ,Article ,Quetiapine Fumarate ,Pharmacotherapy ,Basal Ganglia Diseases ,Extrapyramidal symptoms ,Anticholinergic ,medicine ,Humans ,Pharmacology (medical) ,Child ,Antipsychotic ,Psychiatry ,Retrospective Studies ,Risperidone ,business.industry ,Age Factors ,Child, Preschool ,Quetiapine ,Drug Therapy, Combination ,Female ,medicine.symptom ,business ,Antipsychotic Agents ,Follow-Up Studies ,medicine.drug - Abstract
Background: Second-generation antipsychotics (SGAs) are thought to have a lower likelihood of inducing extrapyramidal symptoms (EPS) than are first-generation antipsychotics (FGAs). Clinical observations suggest that younger patients may be more sensitive to SGA-associated EPS than are adults and require therapy with anticholinergic agents. Objective: To determine the proportion of patients 5–18 years of age who received anticholinergic therapy during the initial stages of antipsychotic treatment, as well as to compare anticholinergic utilization across patients receiving aripiprazole, risperidone, and quetiapine. SGAs previously identified as the most commonly prescribed at the academic institution studied. Methods: Patients 5–18 years of age who were initiating a course of an antipsychotic between January 1, 2005, and September 1, 2008, were identified in a retrospective review of prescription and medical records. Data on demographic characteristics, antipsychotic and anticholinergic utilization, indications, diagnoses, and concomitant medications were collected from the medical record. Only the first therapeutic course of an antipsychotic identified was analyzed. Anticholinergic utilization at antipsychotic initiation and after 30 days was assessed. Results: A total of 235 antipsychotic treatment courses were identified. Of these, 152 patients met our inclusion criteria. Anticholinergic utilization at any time during the first 30 days of treatment was identified in 32 patients (21%), while EPS was documented for 12 patients (8%). FGA or polypharmacy (simultaneous use of ≥2 scheduled antipsychotic) use versus SGA use (OR 18.98; 95% CI 4.74 to 75.95) was the primary characteristic significantly associated with anticholinergic utilization within 30 days after initiation. Of the most commonly used SGAs, risperidone was the drug with which anticholinergics were most frequently prescribed (p = 0.03). Conclusions: Anticholinergic prescribing exceeded the incidence of EPS, as documented in the medical record (21% vs 8%), and differed across individual medications and antipsychotic class. Utilization of FGAs or polypharmacy was a key predictor of anticholinergic use.
- Published
- 2010
45. Chemically driven carbon-nanotube-guided thermopower waves
- Author
-
Changsik Song, Wonjoon Choi, Nitish Nair, Seunghyun Hong, Jae-Hee Han, Seunghyun Baik, Joel T. Abrahamson, and Michael S. Strano
- Subjects
Exothermic reaction ,Materials science ,Mechanical Engineering ,Molecular electronics ,Nanotechnology ,General Chemistry ,Carbon nanotube ,Condensed Matter Physics ,Chemical reaction ,law.invention ,Conductor ,Thermal conductivity ,Mechanics of Materials ,law ,Seebeck coefficient ,General Materials Science ,Composite material ,Electronic materials - Abstract
Theoretical calculations predict that by coupling an exothermic chemical reaction with a nanotube or nanowire possessing a high axial thermal conductivity, a self-propagating reactive wave can be driven along its length. Herein, such waves are realized using a 7-nm cyclotrimethylene trinitramine annular shell around a multiwalled carbon nanotube and are amplified by more than 10(4) times the bulk value, propagating faster than 2 m s(-1), with an effective thermal conductivity of 1.28+/-0.2 kW m(-1) K(-1) at 2,860 K. This wave produces a concomitant electrical pulse of disproportionately high specific power, as large as 7 kW kg(-1), which we identify as a thermopower wave. Thermally excited carriers flow in the direction of the propagating reaction with a specific power that scales inversely with system size. The reaction also evolves an anisotropic pressure wave of high total impulse per mass (300 N s kg(-1)). Such waves of high power density may find uses as unique energy sources.
- Published
- 2010
46. Annihilation of Photochemical Reactivity of Photo-Alignment Layer
- Author
-
Seung Geol Lee, Seunghyun Hong, Y. J. Hwang, and Dong-Myeong Shin
- Subjects
chemistry.chemical_classification ,Materials science ,Double bond ,Biomedical Engineering ,Bioengineering ,General Chemistry ,Condensed Matter Physics ,Photochemistry ,chemistry ,Liquid crystal ,Side chain ,General Materials Science ,Contrast ratio ,Irradiation ,Anisotropy ,Spectroscopy ,Polyimide - Abstract
The gas-polymer and liquid-polymer interfacial reactions of photosensitive polyimide can annihilate photo-reactive carbon–carbon double bonds, which remain after photo-alignment process. The annihilation processes dramatically affect voltage holding ratio and reorientation of photo-active functional groups. Photochemical dimerizations were identified using UV-visible and FT-IR spectroscopy. Polyimide films containing cinnamate groups were irradiated by linear polarized ultra violet (LPUV) light. Schadt et al. claims that the photo-alignment results from the anisotropy depletion of the cinnamate side chains as a consequence of the (2 + 2) cycloaddition reactions.1 The photoaligned polyimide induces the orientation of nematic liquid crystals perpendicular to the polarization axis.1,2 However, the un-reacted photo-sensitive functional groups generate problems such as image sticking and reduced contrast ratio. Voltage holding ratio and photo-fading observed from photo-alignment layer can be dramatically improved by annihilation process of remnant photoreactive groups.
- Published
- 2008
47. Neutralized fluorine radical detection using single-walled carbon nanotube network
- Author
-
Sehun Jung, Jae-Boong Choi, Geun Young Yeom, Seunghyun Hong, Young Jin Kim, Byoung-Jae Park, and Seunghyun Baik
- Subjects
Chemistry ,Radical ,Analytical chemistry ,chemistry.chemical_element ,General Chemistry ,Carbon nanotube ,Dielectrophoresis ,Photochemistry ,law.invention ,Condensed Matter::Materials Science ,symbols.namesake ,X-ray photoelectron spectroscopy ,Covalent bond ,law ,Physics::Atomic and Molecular Clusters ,symbols ,Fluorine ,General Materials Science ,Physics::Chemical Physics ,Selectivity ,Raman spectroscopy - Abstract
It is known that single-walled carbon nanotubes (SWCNTs) can be functionalized by fluorine gas. Here, we report neutralized fluorine radical detection using a matted sheet of SWCNTs, prepared by alternating current dielectrophoresis. Upon exposure to neutralized radicals containing fluorine atoms in a plasma, as model analytes, the conductance of the SWCNT matt showed fast modulation. The transduction mechanism was investigated by electrical transport measurements, X-ray photoelectron spectroscopy and Raman spectroscopy. Metallic nanotubes were shown to react covalently to the near exclusion of semiconducting species. The selectivity was promoted by the curvature-induced strain of the nanotubes. The results open new opportunities for the detection of fluorine radicals at specific locations inside the reaction zone using a simple, miniaturized carbon nanotube network.
- Published
- 2008
48. Effects of Activin A on Pancreatic Ductal Cells in Streptozotocin-Induced Diabetic Rats
- Author
-
In Kyung Jeong, Mi-Kyung Park, Seunghyun Hong, Tae Young Yang, Hyo Sup Kim, Myung-Shik Lee, Moon-Kyu Lee, Jung Hyun Noh, Chul Han, Kwang-Won Kim, Young-Jin Lee, and Kyung-Hee Lee
- Subjects
Male ,endocrine system ,medicine.medical_specialty ,medicine.medical_treatment ,Cell ,Enteroendocrine cell ,Biology ,Polymerase Chain Reaction ,Diabetes Mellitus, Experimental ,Rats, Sprague-Dawley ,Internal medicine ,Insulin Secretion ,medicine ,Animals ,Insulin ,Progenitor cell ,Cells, Cultured ,Transplantation ,geography ,geography.geographical_feature_category ,Pancreatic Ducts ,Glucagon ,Streptozotocin ,Islet ,Activins ,Rats ,Glucose ,medicine.anatomical_structure ,Endocrinology ,Amylases ,Pancreas Transplantation ,Subrenal Capsule Assay ,Pancreas ,medicine.drug - Abstract
The shortage of islets for transplantation has led to find alternative insulin producing cells. Pancreatic progenitor cells in the duct have the potential to grow and differentiate into endocrine cells. In this study, we examined whether activin A can promote the expansion and/or differentiation of ductal cells into insulin-producing cells.Pancreatic ductal cells were treated with activin A for differentiation into endocrine cells, and transplanted into the renal subcapsular space of streptozotocin (STZ)-induced diabetic rats. The identity of the endocrine cells was confirmed by immunostaining and analysis of the expression of transcription factors and endocrine genes by reverse-transcriptase polymerase chain reaction.Activin A treatment significantly increased the DNA synthesis and the expression of insulin I, insulin II, PDX-1, Nkx 6.1, Glut-2, Pax-4, Pax-6, and Ngn-3. De novo synthesis of insulin in activin A-treated ductal cells was observed by the immunocytochemical detection of C-peptide and the differentiated ductal cells secreted significantly increased amount of insulin compared to nontreated ductal cells in response to glucose stimulation. When activin A-treated ductal cells were transplanted on STZ-induced diabetic rats, blood glucose levels were normalized and the removal of the transplanted kidney resulted in return to hyperglycemia.The pancreatic ductal cells could be efficiently differentiated into insulin secreting cells by activin A treatment in vitro and normalize hyperglycemia in vivo.
- Published
- 2007
49. A research on flexible enterprise WLAN system based web of place access points
- Author
-
Seunghyun Hong and Sungwon Lee
- Subjects
Wi-Fi array ,business.industry ,Computer science ,Wireless network ,Distributed computing ,Network Access Device ,Wireless WAN ,Wireless LAN controller ,Networking hardware ,law.invention ,law ,Scalability ,Enterprise private network ,The Internet ,Wi-Fi ,Mobile telephony ,business ,Heterogeneous network ,Municipal wireless network ,Computer network - Abstract
Open Source Hardware is widely used as enterprise standard device because it has high performance for its price. Traditional enterprise Wireless Local Area Network has the limitation of functionality and scalability by the deployed network equipment. To solve this problem, we propose ‘Web of Place Access Point’ using raspberry pi that enable to manage the scale of the network and to provide enterprise suitable network function.
- Published
- 2015
50. A research on the QR Code recognition improvement using the cloud-based pre-generated image matching scheme
- Author
-
Seunghyun Hong, Sungwon Lee, and Misun Ahn
- Subjects
Scheme (programming language) ,Computer science ,business.industry ,Image matching ,Server ,Code (cryptography) ,Computer vision ,Cloud computing ,Artificial intelligence ,business ,computer ,computer.programming_language - Abstract
This paper describes a method to recognize a Quick Response Code (QR) a novel. The QR Code is a two-dimensional code, which is currently used in various fields. According to the salient growth smartphone market, the recognition distance of QR Code is increased but the recognition angle is still limited. To tackle the issue, we propose a QR Code recognition method using ‘cloud-based pre-generated image matching’. Our experimental results show the efficiency of the proposed method.
- Published
- 2015
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