36 results on '"Song, Youngseok"'
Search Results
2. Superior Capacity in Electric Double-Layer Capacitors Employing Three-Dimensional Titanium Foam Electrodes
- Author
-
Han, Gigap, Song, Youngseok, Thirumalraj, Balamurugan, Beak, Mincheol, Kádár, Csilla, Gubicza, Jenő, Nam, Ho-Seok, Kwon, Kyungjung, and Choe, Heeman
- Published
- 2023
- Full Text
- View/download PDF
3. Improved lithospheric seismic velocity and density model of the Korean Peninsula from ambient seismic noise data using machine learning
- Author
-
Song, Youngseok, Lee, Jaewook, Yeeh, Zeu, Kim, Minki, and Byun, Joongmoo
- Published
- 2023
- Full Text
- View/download PDF
4. Role of stabilization heat treatment inducing γ′-γ″ co-precipitates and grain boundary η phase on tensile and creep behaviors of Inconel 706
- Author
-
Kim, Chiwon, Park, Jiun, Hong, Hyun-Uk, Gu, Jiho, and Song, Youngseok
- Published
- 2022
- Full Text
- View/download PDF
5. Structural and optical characteristics of cobalt ferrite nanoparticles
- Author
-
Jeevanantham, B., Song, Youngseok, Choe, Heeman, and Shobana, M.K.
- Published
- 2021
- Full Text
- View/download PDF
6. Analysis of Economic Ripple Effects in the Agricultural Field Using Input–Output Analysis: Drought Damage in Korea in 2018.
- Author
-
Song, Youngseok, Park, Moojong, Kim, Sangdan, and Kim, Sang Yeob
- Subjects
- *
DROUGHT management , *INPUT-output analysis , *NATURAL disasters , *INDUCTIVE effect , *FISHERY products , *SUSTAINABLE development , *DROUGHTS - Abstract
This study investigates the economic impact of the 2018 agricultural drought in Korea on the agricultural field through input–output analysis. Using industry linkage tables provided by the Bank of Korea, various economic impacts, including socio-economic and industry linkage effects, such as production, value added inducement effects, and employment inducement effects in the agricultural field, were analyzed. Our findings show the following: (1) It was found that an increase of 1 billion KRW (South Korean won) in output of agricultural, forestry, and fishery products induces an average of 0.6544 KRW in production inducement effects in other industries, 0.23756 KRW in value-added inducement effects, and 3.11363 in employment inducement effects per 1 billion KRW. (2) The supply shortage effect of agricultural, forestry, and fishery products was analyzed to cause a decrease in production of 2.3932 KRW across all industries, and the price inducing effect of a 10% increase in price was found to be 0.19400%, on average. The highest production inducement effects in the food and beverage industry (0.16514 KRW) and the highest value-added inducement effects (0.04391 KRW) came from agricultural, forestry, and fishery products. (3) In the industry linkage effect analysis, agricultural, forestry, and fishery products were found to have a forward linkage coefficient of 0.95652 and a backward linkage coefficient of 0.98911. It is implied by this result that the economic impact of agriculture on other industrial sectors is not significant. This study emphasizes the economic importance of agriculture by providing analytical results that can be utilized in agricultural policy formulation and economic decision-making. It can be used as an important basis for policy development for sustainable development and economic stability of the agricultural field. It can also contribute to a better understanding of how agriculture interacts with other industrial sectors and to the development of effective response strategies to natural disasters such as agricultural drought. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
7. Development and Applicability Evaluation of Damage Scale Analysis Techniques for Agricultural Drought.
- Author
-
Song, Youngseok, Joo, Jingul, Kim, Hayong, and Park, Moojong
- Subjects
DROUGHT management ,AGRICULTURE ,CLIMATE change ,DEPRECIATION ,NATURAL disasters ,DROUGHTS ,SOCIAL impact - Abstract
In recent years, the intensity and frequency of droughts have been increasing with the advent of the climate crisis. Agricultural droughts have a significant economic and social impact. Agricultural drought is not only a natural disaster but also leads to food security threats and reduced economic activities, such as decreased productivity. Therefore, it is very important to specify the scale of agricultural drought and quantitatively estimate the economic damage. In this study, we developed an analytical methodology to quantitatively assess the economic damage of agricultural drought and estimated the damage of agricultural drought in 2018 and 2019 for the Republic of Korea. The 2018 agricultural drought was estimated to have caused USD 4.438 million in damage cost and USD 5.180 million in recovery cost. The 2019 drought was less damaging than the previous year, with an estimated damage cost of USD 286,000 and recovery costs of USD 218,000. The results suggest that the economic impact of agricultural drought varies by region depending on the frequency and intensity of the drought and confirm the importance of regional strategies for effective drought management and response. The impacts of agricultural drought go beyond short-term agricultural losses and lead to long-term economic burdens. Therefore, the results of this study are expected to be used as a basis for understanding the impacts of agricultural drought on national economies and for developing policies and strategies to minimize impacts. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
8. Regularization of multidimensional sparse seismic data using Delaunay tessellation
- Author
-
Yeeh, Zeu, Song, Youngseok, Byun, Joongmoo, Seol, Soon-Jee, and Kim, Ki-Young
- Published
- 2020
- Full Text
- View/download PDF
9. Adverse Effects of an Edge Diffractor in Seismic Reflection Interferometry
- Author
-
Song, Youngseok, Kim, Ki Young, Byun, Joongmoo, and René, Raymond M.
- Published
- 2020
- Full Text
- View/download PDF
10. Adequacy Analysis Using UAV of Heavy Rainfall Disaster Reduction Facilities According to Urban Development in Republic of Korea.
- Author
-
Song, Youngseok, Park, Moojong, and Joo, Jingul
- Subjects
- *
URBAN growth , *RAINFALL , *DRONE aircraft , *CITIES & towns , *RAINSTORMS , *DISASTERS - Abstract
Urban development is a project that enhances human life, but its hydrological impact increases runoff by expanding impervious areas. Furthermore, localized and intense rainfall resulting from the effects of climate change is exacerbating damage to urban areas. The Republic of Korea has established detention ponds as reduction facilities for heavy rainfall disasters, and the law stipulates that the impact of disasters that increase due to the development projects will remain unchanged from before. However, ensuring precision in millimeter or centimeter units during the design of reduction facilities is challenging. In this study, our aim is to assess the suitability of using unmanned aerial vehicles (UAVs) for the detention pond, a facility that reduces runoff resulting from urban development. The target area is a detention pond located in Innovation City, Ulsan Metropolitan City, Republic of Korea. We compared and analyzed design drawings and topographical data. The increased runoff due to the development project was 0.59 m3/s, and the effectiveness of disaster reduction was evaluated by the installation of a detention pond. The detention pond's reduction effect was analyzed to be 1.16 m3/s for the design drawing and 1.57 m3/s for the topographical analysis. The detention pond currently in place in the target area was found to provide additional disaster reduction benefits compared to the original design plan. The findings of this study can be utilized in relevant laws and guidelines as a method to evaluate the suitability of future reduction facilities. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
11. Study on Calculating Appropriate Impact Assessment for LID Facility Using A-I-R Curve.
- Author
-
Song, Youngseok, Park, Yoonkyung, Park, Moojong, and Joo, Jingul
- Subjects
CONTAINER gardening ,RAINFALL - Abstract
Low impact development (LID) facilities are designed to maintain water circulation functions on the surface and subsurface. LID facilities can be applied to various areas and are expected to have both short-term and long-term effects, making them widely installed in urban areas. In this study, our objective is to calculate the A-I-R (Area ratio-rainfall Intensity-Runoff reduction rate) curve by applying design standards to tree filter boxes, garden plant pots, infiltration ditches, and rain barrels among various LID facilities. The analysis was conducted by constructing a SWMM-LID model and analyzing 209 items, considering the area ratio (A) and rainfall intensity (I) of the LID facilities. The runoff reduction rate (R) varies by LID facility according to the A-I-R curve. It reaches up to 100.0% for rain barrels, up to 30.0% for infiltration ditches, up to 20.0% for garden plant pot, and up to 12.0% for tree filter boxes. If the A-I-R curve of the LID facility is applied to the design standards, it is expected to facilitate the design of the facility's size and inlet according to the target reduction rate. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
12. Study on the Calculation Method of Carbon Emissions in the Construction Industry: Targeting Small River Maintenance Projects in Korea.
- Author
-
Song, Youngseok, Park, Moojong, and Joo, Jingul
- Subjects
CARBON emissions ,CONSTRUCTION industry ,EMBANKMENTS - Abstract
The construction industry, responsible for approximately 30% of global carbon emissions, is closely linked to national development, making carbon reduction challenging. While national development is of paramount importance, it is essential to prioritize individual projects and establish a direction for reducing carbon emissions. The starting point should involve calculating the carbon emissions for each project and comprehending their quantitative impact. In this study, we calculated the carbon emissions for a small river maintenance project aimed at disaster prevention in the construction industry in Yongin-si, Gyeonggi-do, Korea. The total carbon emissions generated by the small river maintenance project in the target area amounted to 2016.6 tonCO
2 . By process, the embankment construction was responsible for 789.7 tonCO2 , while the revetment construction contributed 1226.9 tonCO2 . The analysis revealed that the carbon emissions generated by the small river maintenance project equated to 10.2 tonCO2 /km of river length. Additionally, we developed an equation by applying the double-log function model (log–log) to small river length and carbon emissions. The coefficient of determination for the calculation equation is 0.42, which may not yield highly precise results. However, it is believed that this equation will provide a rough estimate of the carbon emissions associated with the small river maintenance project. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
13. Modified Supporting Materials to Fabricate Form Stable Phase Change Material with High Thermal Energy Storage.
- Author
-
Yu, Chengbin and Song, Youngseok
- Subjects
- *
HEAT storage , *PHASE transitions , *MICROENCAPSULATION , *PHASE change materials , *LATENT heat , *AEROGELS , *LEAKAGE - Abstract
Thermal energy storage (TES) is vital to the absorption and release of plenty of external heat for various applications. For such storage, phase change material (PCM) has been considered as a sustainable energy material that can be integrated into a power generator. However, pure PCM has a leakage problem during the phase transition process, and we should fabricate a form stable PCM composite using some supporting materials. To prevent the leakage problem during the phase transition process, two different methods, microencapsulation and 3D porous infiltration, were used to fabricate PCM composites in this work. It was found that both microsphere and 3D porous aerogel supported PCM composites maintained their initial solid state without any leakage during the melting process. Compared with the microencapsulated PCM composite, the 3D porous aerogel supported PCM exhibited a relatively high weight fraction of working material due to its high porosity. In addition, the cross-linked graphene aerogel (GCA) could reduce volume shrinkage effectively during the infiltration process, and the GCA supported PCM composite kept a high latent heat (∆H) and form stability. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
14. Imaging subsurface structure over the Xiadian fault using P waves extracted from urban traffic noise.
- Author
-
Song, Youngseok, Seol, Soon Jee, Byun, Joongmoo, Hayashi, Koichi, and Tan, Shunjia
- Subjects
- *
TRAFFIC noise , *CITY traffic , *TRAFFIC signs & signals , *FAULT location (Engineering) , *MICROSEISMS - Abstract
The imaging of subsurface structures is an essential task in subsurface engineering projects; it provides information regarding the locations of active faults and layer boundaries. Among the methods available for imaging of subsurface structures, the body wave imaging method using urban traffic noise has recently attracted attention because it permits continuous measurement at low cost in urban areas. However, because the urban traffic noise signal used for imaging on the engineering scale has characteristics that differ from the ambient noise used on the crustal scale, the conventional crustal-scale data processing workflow should be modified through systematic data analysis. In this study, traffic noise sources were systematically analysed using field data obtained over the Xiadian fault in Hebei province, China. The traffic noise signals were recorded in various patterns because of diverse incoming directions and show marked amplitude changes depending on time of recording. The overlapping signals originating from opposite directions generate spurious events and noise in the seismic interferometry images; constant processing parameters cannot respond to the large amplitude changes. In this study, to remove surface waves with markedly changing amplitude, we applied actively varying threshold values to each set of traces using the moving average of amplitude changes within the trace. In addition, the signals originating from diverse directions were separated into negative and positive slopes through the f–k filter; the interference generated by overlapping signals was minimized by applying data processing (e.g. median filtering and high amplitude removal) separately to the negative and positive slopes of each simultaneously acquired trace gather. Due to the modified data processing workflow, most spurious events were successfully suppressed in the final stacked image compared with those produced using the conventional data processing workflow, and reflections were imaged more clearly. Fault spatial locations and layer boundary depth variation in the final image obtained by the modified processing workflow were similar to those reported in previous studies. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
15. A Study on the Determination Methods of Monitoring Point for Inundation Damage in Urban Area Using UAV and Hydrological Modeling.
- Author
-
Song, Youngseok, Lee, Hyeongjun, Kang, Dongho, Kim, Byungsik, and Park, Moojong
- Subjects
DRONE aircraft ,STANDARD deviations ,FLOOD damage ,DIGITAL elevation models ,HYDROLOGIC models ,CADASTRAL maps - Abstract
Recently, unmanned aerial vehicles (UAVs) have been used in various fields, such as military, logistics, transportation, construction, and agriculture, making it possible to apply the limited activities of humans to various and wide ranges. In addition, UAVs have been utilized to construct topographic data that are more precise than existing satellite images or cadastral maps. In this study, a monitoring point for preventing flood damage in an urban area was selected using a UAV. In addition, the topographic data were constructed using a UAV, and the flow of rainwater was examined using the watershed analysis in an urban area. An orthomosaic, a digital surface model (DSM), and a three-dimensional (3D) model were constructed for the topographic data, and a precision of 0.051 m based on the root mean square error (RMSE) was achieved through the observation of ground control points (GCPs). On the other hand, for the watershed analysis in the urban area, the point in which the flow of rainwater converged was analyzed by adjusting the thresholds. A monitoring point for preventing flood damage was proposed by examining the topographic characteristics of the target area related to the inflow of rainwater. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
16. One-Year Outcome of Combination Therapy with Full or Reduced Photodynamic Therapy and One Anti-Vascular Endothelial Growth Factor in Pachychoroid Neovasculopathy.
- Author
-
Sato-Akushichi, Miki, Ono, Shinji, Taneda, Tatsuro, Klose, Gerd, Sasamori, Asuka, and Song, Youngseok
- Subjects
ENDOTHELIAL growth factors ,PHOTODYNAMIC therapy ,VASCULAR endothelial growth factor antagonists ,CHOROID ,TREATMENT effectiveness - Abstract
This paper evaluates a one-year treatment outcome after full or reduced photodynamic therapy (PDT) and anti-vascular endothelial growth factor (VEGF) combination therapy for pachychoroid neovasculopathy (PNV). After the initial combination therapy, a total of 29 eyes from 29 patients (16 for full treatment and 13 for reduced treatment), exhibited reduced, central retinal thickness and central choroidal thickness, and the improvements were maintained for 1 year after the initial combination therapy. Twenty-two eyes (75.9%) required no additional treatments for 1 year. The recurrence rate was 31.3% in the full treatment and 15.4% in the reduced treatment, with no significant differences between them. One shot of anti-VEGF and full or reduced PDT combination therapy had similar efficacy in treating PNV. Further prospective, large-scale, and long-term studies are required to determine a better treatment for PNV. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
17. Effect of insulin treatment on pulsatility ratio and resistance index of the retinal artery in patients with type 2 diabetes.
- Author
-
Omae, Tsuneaki, Song, Youngseok, Yoshioka, Takafumi, Tani, Tomofumi, and Yoshida, Akitoshi
- Subjects
- *
RETINAL artery , *TYPE 2 diabetes , *OPTICAL coherence tomography , *BLOOD flow , *PEOPLE with diabetes , *TREATMENT effectiveness - Abstract
This study aimed to evaluate whether long-term insulin treatment is associated with abnormalities in retinal circulation in type 2 diabetic patients. We evaluated 19 eyes of nondiabetic individuals and 68 eyes of type 2 diabetic patients. The eyes of diabetic patients were classified into two groups according to the presence or absence of long-term insulin therapy. We used a Doppler optical coherence tomography flowmeter to measure diameter, velocity, and blood flow in the major temporal retinal artery. The pulsatility ratio (PR) and resistance index (RI), indices of vascular rigidity, were calculated from the blood velocity profile. PR and RI were significantly elevated in type 2 diabetic patients compared with nondiabetic subjects (P < 0.05). In type 2 diabetes patients, PR and RI were significantly higher in patients receiving long-term insulin treatment than in those without (P < 0.01). There was a significant difference in velocity (P < 0.05), but not diameter and blood flow, between nondiabetic subjects and type 2 diabetes patients. No significant difference in diameter, velocity, or blood flow was observed between the groups with and without long-term insulin treatment. Long-term insulin treatment can affect PR and RI, which might be associated with vascular rigidity of the retinal artery in patients with type 2 diabetes. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
18. Nonparallel transcriptional divergence during parallel adaptation.
- Author
-
Fischer, Eva K., Song, Youngseok, Hughes, Kimberly A., Zhou, Wen, and Hoke, Kim L.
- Subjects
- *
GENE expression , *PHENOTYPIC plasticity , *GUPPIES , *GENES , *SPECIES , *PHYSIOLOGICAL adaptation - Abstract
How underlying mechanisms bias evolution toward predictable outcomes remains an area of active debate. In this study, we leveraged phenotypic plasticity and parallel adaptation across independent lineages of Trinidadian guppies (Poecilia reticulata) to assess the predictability of gene expression evolution during parallel adaptation. Trinidadian guppies have repeatedly and independently adapted to high‐ and low‐predation environments in the wild. We combined this natural experiment with a laboratory breeding design to attribute transcriptional variation to the genetic influences of population of origin and developmental plasticity in response to rearing with or without predators. We observed substantial gene expression plasticity, as well as the evolution of expression plasticity itself, across populations. Genes exhibiting expression plasticity within populations were more likely to also differ in expression between populations, with the direction of population differences more likely to be opposite those of plasticity. While we found more overlap than expected by chance in genes differentially expressed between high‐ and low‐predation populations from distinct evolutionary lineages, the majority of differentially expressed genes were not shared between lineages. Our data suggest alternative transcriptional configurations associated with shared phenotypes, highlighting a role for transcriptional flexibility in the parallel phenotypic evolution of a species known for rapid adaptation. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
19. Rainfall Standard of Disaster Prediction for Agricultural Droughts in S. Korea.
- Author
-
Song, Youngseok and Park, Moojong
- Subjects
DROUGHT management ,RAINFALL ,DROUGHTS ,FORECASTING ,EMERGENCY management ,NATURAL disasters ,DROUGHT forecasting - Abstract
With the climate change adding to the frequency and intensity of natural disasters, drought has devastated large areas of lands in South Korea. Still, the exact beginning and end of the drought is difficult to identify, and this impedes the development and implementation of disaster predictions. Although the drought phenomenon has been well-documented, predictions thereof are limited due to the non-linear and complex temporal fluctuations of the hydrologic factors. Hence, this study set up some reference points for disaster-prediction rainfall based on South Korea's agricultural drought damage data, to help in drought relief. To set up the proposed reference points for disaster-prediction rainfall, we analyzed rainfall in light of the disaster-prevention relevance to agricultural droughts and the disaster reduction. As an analysis method, rainfall of municipality was calculated through Thiessen's polygonal method, to apply rainfall weighting value for each rainfall observatory. In addition, the linear regression analysis was applied to suggest the calculation formula for setting the annual disaster reduction rainfall. The results of this study, standard of judgment point for disaster prevention of agricultural drought at the time of disaster management, were analyzed for rainfall for local governments and the whole country. Rather than using various drought indices that are currently developed, policy makers or public servant made suggestions based on rainfall that is most accessible and convenient for judging the timing of agricultural drought. As the disaster-prevention rainfall with agricultural droughts is expected to occur, we established the average annual rainfall of ≤1200 or 100 mm below the preceding year's average annual rainfall. Moreover, as the disaster-reduction rainfall for agricultural droughts to end, we determined the average monthly rainfall of ≥150 mm. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
20. Synthesis of a High‐Capacity NiO/Ni Foam Anode for Advanced Lithium‐Ion Batteries.
- Author
-
Song, Youngseok, Hwang, Junesun, Lee, Sukyung, Thirumalraj, Balamurugan, Kim, Jae-Hun, Jenei, Péter, Gubicza, Jenő, and Choe, Heeman
- Subjects
ANODES ,LITHIUM-ion batteries ,TRANSITION metal oxides ,SODIUM ions ,CRYSTAL defects ,FOAM ,SCANNING electron microscopy ,SOLID oxide fuel cells - Abstract
In recent years, lithium‐ion batteries (LIBs) are used in a range of energy storage applications, such as mobile phones, electronic devices, and automobiles. Some recent research on LIBs has looked at replacing carbonaceous anode materials with transition metal oxides due to their high theoretical capacity, ranging from 500 to 1000 mAh g−1. In particular, NiO is considered as one of the most promising options due to its high theoretical capacity (718 mAh g−1). Herein, a porous NiO/Ni anode is fabricated via freezing/drying followed by thermal oxidation. The fabricated porous NiO/Ni anode is then characterized using X‐ray diffraction scanning electron microscopy, and energy‐dispersive X‐ray spectroscopy. The cycling performance of the freeze‐cast NiO/Ni anode is evaluated using a half‐coin cell test, and it demonstrates superior electrochemical performance and good cycling stability during the charging/discharging process. The freeze‐cast NiO/Ni anode also exhibits a higher rate performance when compared with that of commercial Ni foam and a conventional graphite anode. It is revealed that the initial crystalline surface oxide layer is amorphized, and the lattice defect density increases in the Ni struts during the lithiation process. However, these microstructure changes did not influence considerably the good electrochemical performance of the material. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
21. Development of Driftwood Capture Trellis for Capturing Driftwood in Agricultural Drainage Ditches.
- Author
-
Song, Youngseok and Park, Moojong
- Subjects
DRAINAGE ,DITCHES ,DRAINAGE pipes ,WATER depth ,SOLIFLUCTION - Abstract
The flow of driftwood and soil into drainage from agricultural areas accelerates sedimentation and inflicts overflow damage after rainfall events due to insufficient discharge capacity, causing flooding on agricultural land. However, there have been few efforts to develop a driftwood capture trellis for agricultural drainage ditches, except for some suggested design criteria. In this study, we developed a driftwood capture trellis to capture driftwood in agricultural drainage ditches and evaluated its performance based on hydraulic characteristics. The facility was designed considering criteria for drainage and driftwood control barriers, as well as the properties of driftwood found near agricultural drainage ditches. Performance evaluation was conducted through hydraulic experiments. Driftwood capture trellises were installed in 400 mm drainage pipes and a total of 216 experimental runs were conducted: six runs each in six different velocity variations and six water depth variations. The results showed that the driftwood capture efficiency of the facility exceeded 60% at a velocity of 0.144 m³/s. Limited conditions for hydraulic experiments should be considered. The driftwood capture trellis for agricultural drainage ditches developed in this study could contribute to a reduction in overflow damage caused by driftwood sedimentation. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
22. Retinal blood flow reduction after panretinal photocoagulation in Type 2 diabetes mellitus: Doppler optical coherence tomography flowmeter pilot study.
- Author
-
Song, Youngseok, Tani, Tomofumi, Omae, Tsuneaki, Ishibazawa, Akihiro, Yoshioka, Takafumi, Takahashi, Kengo, Akiba, Masahiro, and Yoshida, Akitoshi
- Subjects
- *
RETINAL blood vessels , *LIGHT coagulation , *TYPE 2 diabetes , *OPTICAL coherence tomography , *DIABETIC retinopathy - Abstract
To use a Doppler optical coherence tomography (DOCT) flowmeter to investigate segmental retinal blood flow (RBF) and sum of the segmental RBFs (SRBF) changes after panretinal photocoagulation (PRP) was used to treat type 2 diabetes mellitus with severe diabetic retinopathy (DR). Data from five patients with proliferative DR (PDR) (mean age 51.9 ± 10.5 years) was analyzed. The vessel diameter (D), average velocity (V), and retinal blood flow (RBF) in veins were measured using a DOCT flowmeter before and four weeks after PRP. Segmental RBF from inferotemporal (IT), superotemporal (ST), inferonasal (IN), and superonasal (SN) veins were measured, and SRBF was defined as the sum of these measurements. All data were analyzed by Wilcoxson test. After PRP, there were statistically significant decreases in the every segmental D, V, RBF (P<0.03) and SRBF (P = 0.002). The other parameters showed no statistically significant differences (P>0.05). The DOCT flowmeter has the potential to be a clinically useful tool to noninvasively evaluate the changes in retinal circulation during PRP in patients with PDR. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
23. Clinical Prediction Performance of Glaucoma Progression Using a 2-Dimensional Continuous-Time Hidden Markov Model with Structural and Functional Measurements.
- Author
-
Song, Youngseok, Ishikawa, Hiroshi, Wu, Mengfei, Liu, Yu-Ying, Lucy, Katie A., Lavinsky, Fabio, Liu, Mengling, Wollstein, Gadi, and Schuman, Joel S.
- Subjects
- *
GLAUCOMA , *GLAUCOMA diagnosis , *MEDICAL informatics , *MARKOV processes , *VISUAL field measurement , *PROGNOSIS - Abstract
Purpose Previously, we introduced a state-based 2-dimensional continuous-time hidden Markov model (2D CT HMM) to model the pattern of detected glaucoma changes using structural and functional information simultaneously. The purpose of this study was to evaluate the detected glaucoma change prediction performance of the model in a real clinical setting using a retrospective longitudinal dataset. Design Longitudinal, retrospective study. Participants One hundred thirty-four eyes from 134 participants diagnosed with glaucoma or as glaucoma suspects (average follow-up, 4.4±1.2 years; average number of visits, 7.1±1.8). Methods A 2D CT HMM model was trained using OCT (Cirrus HD-OCT; Zeiss, Dublin, CA) average circumpapillary retinal nerve fiber layer (cRNFL) thickness and visual field index (VFI) or mean deviation (MD; Humphrey Field Analyzer; Zeiss). The model was trained using a subset of the data (107 of 134 eyes [80%]) including all visits except for the last visit, which was used to test the prediction performance (training set). Additionally, the remaining 27 eyes were used for secondary performance testing as an independent group (validation set). The 2D CT HMM predicts 1 of 4 possible detected state changes based on 1 input state. Main Outcome Measures Prediction accuracy was assessed as the percentage of correct prediction against the patient's actual recorded state. In addition, deviations of the predicted long-term detected change paths from the actual detected change paths were measured. Results Baseline mean ± standard deviation age was 61.9±11.4 years, VFI was 90.7±17.4, MD was −3.50±6.04 dB, and cRNFL thickness was 74.9±12.2 μm. The accuracy of detected glaucoma change prediction using the training set was comparable with the validation set (57.0% and 68.0%, respectively). Prediction deviation from the actual detected change path showed stability throughout patient follow-up. Conclusions The 2D CT HMM demonstrated promising prediction performance in detecting glaucoma change performance in a simulated clinical setting using an independent cohort. The 2D CT HMM allows information from just 1 visit to predict at least 5 subsequent visits with similar performance. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
24. Choroidal Volume Evaluation after Photodynamic Therapy Using New Optical Coherence Tomography Imaging Algorithm.
- Author
-
Sato-Akushichi, Miki, Ono, Shinji, Klose, Gerd, and Song, Youngseok
- Subjects
PHOTODYNAMIC therapy ,CHOROID ,OPTICAL coherence tomography ,ALGORITHMS ,MAXIMA & minima ,STANDARD deviations - Abstract
To evaluate choroidal volume and thickness changes after photodynamic therapy (PDT) for chronic central serous chorioretinopathy (CSC). Chronic CSC eyes with a history of PDT were selected. Average choroidal volume, average choroidal thickness, the maximum and minimum choroidal thickness of the macula irradiated area and peripheral non-irradiated areas before and after one and three months of treatment were examined. A total of 14 patients with chronic CSC and 9 controls without any eye pathology were enrolled. The mean choroidal volume in CSC before and, and after one and three months of treatment were 2.36 (standard deviation: 0.70), 1.90 (0.69), 1.86 (0.66) mm
3 for the central area, 1.25 (0.38), 1.14 (0.35), 1.13 (0.34) mm3 for superior nasal area, 1.47 (0.41), 1.28 (0.43), 1.26 (0.43) mm3 for superior temporal area, 1.07 (0.49), 0.95 (0.38), 0.93 (0.35) mm3 for inferior nasal area, 1.17 (0.38), 1.04 (0.32), 1.03 (0.33) mm3 for inferior temporal area. This study revealed the choroidal volume changes in a short period after PDT and a decrease in unirradiated choroidal volume was also shown after the treatment. The algorithm provided on the ARI Network enables to evaluate the choroidal changes quantitatively and qualitatively. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
25. Impact of the Pressure-Free Yutori Education Program on Myopia in Japan.
- Author
-
Ishiko, Satoshi, Kagokawa, Hiroyuki, Nishikawa, Noriko, Song, Youngseok, Sugawara, Kazuhiro, Nakagawa, Hiroaki, Kawamura, Yuichiro, and Yoshida, Akitoshi
- Subjects
MYOPIA ,MEDICAL students ,REFRACTIVE errors ,JAPANESE students ,EDUCATION policy - Abstract
This study aimed to investigate the influence of educational pressure on myopia. A less-intense school curriculum was introduced nationally in Japan beginning in 2012 based on a pressure-free education policy. In this retrospective observational study, a total of 1025 Japanese medical students of Asahikawa Medical University underwent measurements of the cycloplegic refractive error and axial length (AL), from 2011 to 2020. The spherical equivalent (SE) and AL were correlated significantly with the fiscal year of births (p = 0.004 and p = 0.034, respectively) only during enforcement of the system of high-pressure education. The SE and AL regression rates during the two educational approaches differed significantly (p = 0.004 and p = 0.037, respectively). The prevalence of high myopia was correlated significantly (p < 0.001) only during the system of high-pressure education. The regression of the prevalence rate of high myopia during the two education approaches differed significantly (p = 0.010). The progression rates of myopia and increased prevalence of high myopia were observed only during high-pressure education, suggesting that not only ophthalmologists but also educators and the government should work on together to control the progression of myopia. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
26. A Study on the Development of Reduction Facilities' Management Standards for Agricultural Drainage for Disaster Reduction.
- Author
-
Song, Youngseok and Park, Moojong
- Abstract
The agricultural drainage in rural area plays important roles in water supply and drainage for crop cultivation. Various kinds of debris near agricultural drainage, however, causes sedimentation in the drainage during rainfall. The debris introduced into the agricultural drainage moves out of the drainage under a high flow rate. This causes a reduction in the flow rate, which may affect the discharge capacity, resulting in crop damage. This study developed a reduction facility to reduce debris entering agricultural drainage and analyzed the performance by measuring the capture efficacy in the hydraulic experiment. A total of 648 runs were performed for 216 experiment conditions where three replications and error ranges were calculated depending on the inflow characteristics of debris. This study also evaluated the performance of the reduction facility and established the design criteria by developing a capture efficacy equation by flow rate and type of reduction facility. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
27. A Study on the Appropriateness of the Drought Index Estimation Method Using Damage Data from Gyeongsangnamdo, South Korea.
- Author
-
Song, Youngseok and Park, Moojong
- Subjects
- *
DROUGHTS , *STANDARD deviations , *CLUSTER analysis (Statistics) , *DROUGHT management - Abstract
Drought is one of the disasters that causes the most extensive and severe damage. Therefore, drought prevention must be performed for administrative districts at the national level rather than the individual level. This study proposes a drought index estimation method for Gyeongsangnamdo, South Korea that evaluates its appropriateness through a comparison with damage data over several years. The standardized precipitation index (SPI) by duration was used as the drought index that was estimated for 13 rainfall stations located inside and outside Gyeonsangnam-do using the Thiessen method and cluster analysis. The SPI of Gyeongsangnamdo by duration based on the Thiessen method and cluster analysis for the years when drought damage occurred was compared with an SPI value of −2.0, which is the extreme drought condition, to determine its appropriateness. For the evaluation of the appropriateness, the performance indicators of the mean absolute deviation (MAD), mean squared error (MSE), and root mean square error (RMSE) were used. The analysis results showed that SPI by duration based on the cluster analysis method was more appropriate for damage data over many years than that based on the Thiessen method. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
28. Effect of Heat Treatment on the Microstructure and Performance of Cu Nanofoams Processed by Dealloying.
- Author
-
Gubicza, Jenő, Jenei, Péter, Han, Gigap, Hung, Pham-Tran, Song, Youngseok, Park, Dahye, Szabó, Ábel, Kádár, Csilla, Kim, Jae-Hun, Choe, Heeman, and Marsavina, Liviu
- Subjects
EFFECT of heat treatment on microstructure ,MECHANICAL heat treatment ,HEAT treatment ,LITHIUM-ion batteries - Abstract
Cu nanofoams are promising materials for a variety of applications, including anodes in high-performance lithium-ion batteries. The high specific surface area of these materials supports a high capacity and porous structure that helps accommodate volume expansion which occurs as batteries are charged. One of the most efficient methods to produce Cu nanofoams is the dealloying of Cu alloy precursors. This process often yields nanofoams that have low strength, thus requiring additional heat treatment to improve the mechanical properties of Cu foams. This paper provides the effects of heat treatment on the microstructures, mechanical properties, and electrochemical performance of Cu nanofoams. Annealing was conducted under both inert and oxidizing atmospheres. These studies ultimately reveal the underlying mechanisms of ligament coarsening during heat treatment. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
29. Tranexamic acid-induced ligneous conjunctivitis with renal failure showed reversible hypoplasminogenaemia.
- Author
-
Song, Youngseok, Izumi, Naohiro, Potts, Luke Benjamin, and Yoshida, Akitoshi
- Published
- 2014
- Full Text
- View/download PDF
30. Intermittent Fasting Aggravates Lupus Nephritis through Increasing Survival and Autophagy of Antibody Secreting Cells in MRL/lpr Mice.
- Author
-
Hong, Seung-Min, Lee, Jaeseon, Jang, Se Gwang, Song, Youngseok, Kim, Minjun, Lee, Jennifer, Cho, Mi-La, Kwok, Seung-Ki, and Park, Sung-Hwan
- Subjects
INTERMITTENT fasting ,LUPUS nephritis ,IMMUNE complexes ,PLASMA cells ,SYSTEMIC lupus erythematosus ,AUTOPHAGY ,AUTOANTIBODIES - Abstract
Systemic lupus erythematosus (SLE) is an autoimmune disease in which the main contributors to organ damage are antibodies against autoantigens, such as double-stranded DNA (dsDNA). Calorie restriction and intermittent fasting (IF) have been shown to improve autoimmune disease symptoms in patients and animal models. Here, we tested the hypothesis that IF might improve symptoms in MRL/lpr mice, which spontaneously develop an SLE-like disease. Groups of mice were fed every other day (IF) or provided food ad libitum (controls), and various lupus-associated clinicopathological parameters were analyzed for up to 28 weeks. Contrary to expectations, anti-dsDNA antibody levels, immune complex deposition in the kidney, and glomerular injury were higher in the IF group than the control group, although there were no differences in spleen and lymph node weights between groups. Proteinuria was also worsened in the IF group. IF also increased the abundance of B cells, plasmablasts, and plasma cells and elevated autophagy in plasma cells in the spleen and lymph nodes. Secretion of anti-dsDNA antibody by splenocytes in vitro was reduced by chloroquine-induced inhibition of autophagy. These results suggest that IF exacerbates lupus nephritis in MRL/lpr mice by increasing autoantibody immune complex formation. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
31. Blood Banking in Living Droplets
- Author
-
Samot, Josh, Moon, Sangjun, Shao, Lei, Zhang, Xiaohui, Xu, Feng, Song, YoungSeok, Keles, Hasan Onur, Matloff, Laura, Markel, Jordan, and Demirci, Utkan
- Subjects
biology ,biotechnology ,bioengineering ,tissue engineering ,engineering ,biomedical engineering ,medicine ,critical care and emergency medicine ,hematology ,transfusion medicine - Abstract
Blood banking has a broad public health impact influencing millions of lives daily. It could potentially benefit from emerging biopreservation technologies. However, although vitrification has shown advantages over traditional cryopreservation techniques, it has not been incorporated into transfusion medicine mainly due to throughput challenges. Here, we present a scalable method that can vitrify red blood cells in microdroplets. This approach enables the vitrification of large volumes of blood in a short amount of time, and makes it a viable and scalable biotechnology tool for blood cryopreservation.
- Published
- 2011
- Full Text
- View/download PDF
32. Deterioration of Retinal Blood Flow Parameters in Branch Retinal Vein Occlusion Measured by Doppler Optical Coherence Tomography Flowmeter.
- Author
-
Takahashi, Kengo, Song, Youngseok, Sogawa, Kenji, Yoshioka, Takafumi, Tani, Tomofumi, Ishiko, Satoshi, and Yoshida, Akitoshi
- Subjects
- *
RETINAL vein occlusion , *OPTICAL coherence tomography , *BLOOD flow , *ENDOTHELIAL growth factors , *ABSOLUTE value - Abstract
Background: Doppler optical coherence tomography (DOCT) flowmeter can be used to measure retinal blood flow (RBF) parameters, including vessel diameter, blood velocity, and the absolute value of RBF within 2.0 s. We investigated the RBF parameters in eyes with branch retinal vein occlusion (BRVO) using a DOCT flowmeter. Methods: Seventeen patients with unilateral BRVO were enrolled. All subjects underwent comprehensive ophthalmologic examinations. The RBF parameters were assessed from three veins, i.e., (1) an occluded vein, (2) a non-occluded vein in the BRVO eyes, and (3) an equivalent (superior or inferior) vein in the fellow eye (non-affected vein), using prototype DOCT flowmeter (Topcon, Tokyo, Japan). Moreover, the correlation between RBF parameters and the best corrected visual acuity (BCVA) was examined. We investigated the correlation between (1) the RBF parameters and the time from the initial visit, (2) the RBF parameters and the time from the last injection, and (3) the RBF parameters and the number of anti-vascular endothelial growth factor injections (VEGF). Results: The diameter of the occluded vein (95.9 ± 24.7 µm) was smaller than that of the non-occluded vein (127.9 ± 23.7 µm) and that of the healthy veins (116.4 ± 13.9 µm). The RBF was lower in the occluded veins (4.7 ± 3.7 µL/min) than that in the non-occluded veins (10.3 ± 5.1 µL/min; p < 0.01) and in the fellow eyes (8.6 ± 4.0 µL/min; p = 0.013). In contrast, the blood velocity was not significantly different among the three types of veins. BCVA was correlated with the diameter of the occluded vein (ρ = 0.711, p = 0.001) but not with the RBF and blood velocity. The time from the initial visit, the time from the last injection, and the total number of anti-VEGF injections were not associated with any RBF parameters on the occluded vein. Conclusions: The RBF was significantly lower in the occluded veins than that in the other veins, and the diameter of the occluded vein was significantly smaller than that of the other veins in patients with BRVO. However, neither the time from the initial visit, nor the time from the last injection, nor the number of anti-VEGF injections were correlated with the RBF parameters on the occluded vein. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
33. Assessment of Quantitative Standards for Mega-Drought Using Data on Drought Damages.
- Author
-
Song, Youngseok and Park, Moojong
- Abstract
Among natural disasters, droughts can affect a large area for a prolonged period of time. If a drought happens, an appropriate response requires a lot of time and manpower from beginning to end, and continuous management is necessary for further prevention. Using data on drought damages from 1900 to 2018 in 148 countries in six continents around the world, this study was able to set quantitative standards for mega-droughts. According to data on the status of annual drought damages, the frequency of drought damages (1900–2018) and the subsequent damage costs (1965–2018) are increasing, while human losses (1900–2018) are decreasing. Additionally, Africa had the highest frequency of drought damages, while Africa and Asia were ranked at the top of the list in terms of human losses and damage costs, respectively. Droughts persisted for continuous periods ranging from 1 to 17 years, and the total number of cases involving drought damage was estimated to be 600 in total, with total human losses of 11,731,294 people and total accumulated damage costs of $17,367,007,000. This study provided quantitative standards for the frequency of drought damages, human losses, and damage costs for mega-droughts in consideration of continuous drought periods. This study set the quantitative standards for a mega-drought as follows: (1) if drought damages continue to occur in a country for more than seven years, (2) if human losses continue to occur in a country for more than seven years, and (3) if mean annual damage costs of $17,000,000 continue to occur in a country for more than seven years. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
34. A Study on Setting Disaster-Prevention Rainfall by Rainfall Duration in Urban Areas Considering Natural Disaster Damage: Focusing on South Korea.
- Author
-
Song, Youngseok and Park, Moojong
- Subjects
RAINSTORMS ,NATURAL disasters ,CITIES & towns ,METROPOLITAN areas ,RAINFALL ,RAINFALL frequencies ,URBAN heat islands - Abstract
Inundation damage occurs in urban regions due to short flood reach time and increased surface runoff caused by urbanized impervious areas. Furthermore, heavy rainfall frequency has increased because of climate change, thus exceeding the design frequency and resulting in sewer pipes' lack of flood control capacity, with damage expanding from low-lying areas. Despite many urban disaster-mitigation policies, complex causes and uncertainties make reducing urban inundation damage difficult. This study established a rainfall-related disaster-prevention standard by time duration considering rainfall characteristics targeting urban disaster-induced inundation damage. Based on the South Korean urbanization rate and population, seven target regions were selected. Rainfall by time duration was analyzed with respect to disaster length (number of days) from 2010–2017. The average rainfall for durations from 1–24 h were analyzed according to disaster length (1–13 days). Using the results, an equation was proposed for rainfall estimation by length of disaster resulting in urban inundation damage, through multiple regression analysis. An equation was developed for rainfall-related disaster-prevention in urban areas considering the length of disaster and rainfall duration. This was accomplished by selecting a duration whereby the average rainfall of duration corresponded to 50% of total rainfall during the disaster period. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
35. Flood Forecasting and Warning System Structures: Procedure and Application to a Small Urban Stream in South Korea.
- Author
-
Song, Yangho, Park, Yoonkyung, Lee, Jungho, Park, Moojong, and Song, Youngseok
- Abstract
The runoff from heavy rainfall reaches urban streams quickly, causing them to rise rapidly. It is therefore of great importance to provide sufficient lead time for evacuation planning and decision making. An efficient flood forecasting and warning method is crucial for ensuring adequate lead time. With this objective, this paper proposes an analysis method for a flood forecasting and warning system, and establishes the criteria for issuing urban-stream flash flood warnings based on the amount of rainfall to allow sufficient lead time. The proposed methodology is a nonstructural approach to flood prediction and risk reduction. It considers water level fluctuations during a rainfall event and estimates the upstream (alert point) and downstream (confluence) water levels for water level analysis based on the rainfall intensity and duration. We also investigate the rainfall/runoff and flow rate/water level relationships using the Hydrologic Engineering Center's Hydrologic Modeling System (HEC-HMS) and the HEC's River Analysis System (HEC-RAS) models, respectively, and estimate the rainfall threshold for issuing flash flood warnings depending on the backwater state based on actual watershed conditions. We present a methodology for issuing flash flood warnings at a critical point by considering the effects of fluctuations in various backwater conditions in real time, which will provide practical support for decision making by disaster protection workers. The results are compared with real-time water level observations of the Dorim Stream. Finally, we verify the validity of the flash flood warning criteria by comparing the predicted values with the observed values and performing validity analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
36. Can Macula and Optic Nerve Head Parameters Detect Glaucoma Progression in Eyes with Advanced Circumpapillary Retinal Nerve Fiber Layer Damage?
- Author
-
Lavinsky, Fabio, Wu, Mengfei, Schuman, Joel S., Lucy, Katie A., Liu, Mengling, Song, Youngseok, Fallon, Julia, de Los Angeles Ramos Cadena, Maria, Ishikawa, Hiroshi, and Wollstein, Gadi
- Subjects
- *
RETINAL degeneration , *OPTIC nerve , *VISUAL pathways , *DISEASE progression , *DISEASE remission - Abstract
Purpose To evaluate the ability of OCT optic nerve head (ONH) and macular parameters to detect disease progression in eyes with advanced structural glaucomatous damage of the circumpapillary retinal nerve fiber layer (cRNFL). Design Longitudinal study. Participants Forty-four eyes from 37 patients with advanced average cRNFL damage (≤60 μm) followed up for an average of 4.0 years. Methods All patients were examined with spectral-domain OCT and visual field (VF) assessment during at least 4 visits. Main Outcome Measurements Visual field mean deviation (MD) and VF index. OCT cRNFL (average, superior, and inferior quadrants), ganglion cell–inner plexiform layer (GCIPL) (average, superior, and inferior), rim area, cup volume, average cup-to-disc (C:D) ratio, and vertical C:D ratio. Results At baseline, patients had a median VF MD of –10.18 dB and mean cRNFL of 54.55±3.42 μm. The rate of change for MD and VF index were significant. No significant rate of change was noted for cRNFL, whereas significant (P < 0.001) rates were detected for GCIPL (–0.57±0.05 μm/year) and ONH parameters such as rim area (–0.010±0.001 mm2/year). Conclusions Macula GCIPL and ONH parameters may be useful in tracking progression in patients with advanced glaucoma. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.