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227 results on '"Kim, Myungjun"'

77. The Growth Response of Balloon Flower (Platycodon grandiflorum A. DC.) Plantlets In Vitro as Affected by Air Exchanges and Light Intensity

Author

Lim HoiChun, Ryu JeOng, Kim MyungJun, Eun JongSeon, Choi SoRa, and Ahn MinSil

Subjects
chemistry.chemical_compound, Horticulture, Light intensity, Murashige and Skoog medium, chemistry, Micropropagation, Germination, Chlorophyll, Botany, Shoot, Biology, Sugar, In vitro
Abstract

Shoots of balloon flower (Platycodon grandiflorum A. DC.) derived from in vitro germinated seeds were cultured on MS medium containing NAA under various photosynthetic photon flux (PPF) 33, 66, and with or without membrane filter. Number of air exchanges per hour (NAEH) of the culture vessel with membrane filter on the lid was and that without membrane filter was Plantlets grown in NAEH showed greater growth than in NAEH. According to increase of PPF, plantlets growth decreased in NAEH while it increased in NAEH. At the same PPF, fresh weight and sugar content in plantlets in NAEH were above 1.9, 2.0 times higher than those in NAEH, respectively. Also they were enhanced in NAEH by increase of PPF whereas no significance in NAEH. The percentage of water content of plantlets in NAEH was lower than those in and no difference in PPF. The content of total chlorophyll in plantlets in NAEH was higher F.W. than that in NAEH. By increase of PPF, it was decreased in NAEH while had no significant difference in NAEH. Guard and subsidiary cells of leaves in NAEH were more developed than in NAEH. Especially, in leaves in NAEH had undeveloped subsidiary cells and wide open stomata whereas those in NAEH had well-developed subsidiary cells.

Published
2005

78. Edge-On MoS2Thin Films by Atomic Layer Deposition for Understanding the Interplay between the Active Area and Hydrogen Evolution Reaction

Author

Ho, Thi Anh, Bae, Changdeuck, Lee, Seonhee, Kim, Myungjun, Montero-Moreno, Josep M., Park, Jong Hyeok, and Shin, Hyunjung

Abstract

The edge sites of molybdenum disulfide (MoS2) have been shown to be efficient electrocatalysts for the hydrogen evolution reaction (HER). To utilize these structures, two main strategies have been proposed. The first strategy is to use amorphous structures, which should be beneficial in maximizing the area of the edge-site moieties of MoS2. However, these structures experience structural instability during HER. The other strategy is nanostructuring, in which, to enhance the resulting HER performance, the exposed surfaces of MoS2cannot be inert basal planes. Therefore, MoS2may need critical nanocrystallinity to produce the desired facets. Here, we first describe that when atomic layer deposition (ALD) is applied to layered materials such as MoS2, MoS2exhibits the nonideal mode of ALD growth on planar surfaces. As a model system, the ALD of MoCl5and H2S was studied. This nonideality does not allow for the conventional linear relationship between the growth thickness and the number of cycles. Instead, it provides the ability to control the relative ratios of the edge sites and basal planes of MoS2to the exposed surfaces. The number of edge sites produced was carefully characterized in terms of the geometric surface area and effective work function and was correlated to the HER performance, including Tafel slopes and exchange current densities. We also discussed how, as a result of the low growth temperature, the incorporation of chlorine impurities affected the electron doping and formation of mixed 2H and 1T phases. Remarkably, the resulting 1T phase was stable even upon thermal annealing at 400 °C. With the simple, planar MoS2films, we monitored the resulting catalytic performance, finding current densities of up to 20 mA cm–2at −0.3 V versus the reversible hydrogen electrode (RHE), a Tafel slope of 50–60 mV/decade, and an onset potential of 143 mV versus RHE.

Published
2024
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86. An inference method from multi-layered structure of biomedical data.

Author

Myungjun Kim, Yonghyun Nam, Hyunjung Shin, Kim, Myungjun, Nam, Yonghyun, and Shin, Hyunjung

Subjects
METABOLOMICS, PROTEOMICS, ALGORITHMS, SYMPTOMS, DISEASES, COMPARATIVE studies, DIAGNOSIS, LIFE sciences, RESEARCH methodology, MEDICAL cooperation, RESEARCH, COMORBIDITY, BIOINFORMATICS, EVALUATION research
Abstract

Background: Biological system is a multi-layered structure of omics with genome, epigenome, transcriptome, metabolome, proteome, etc., and can be further stretched to clinical/medical layers such as diseasome, drugs, and symptoms. One advantage of omics is that we can figure out an unknown component or its trait by inferring from known omics components. The component can be inferred by the ones in the same level of omics or the ones in different levels.Methods: To implement the inference process, an algorithm that can be applied to the multi-layered complex system is required. In this study, we develop a semi-supervised learning algorithm that can be applied to the multi-layered complex system. In order to verify the validity of the inference, it was applied to the prediction problem of disease co-occurrence with a two-layered network composed of symptom-layer and disease-layer.Results: The symptom-disease layered network obtained a fairly high value of AUC, 0.74, which is regarded as noticeable improvement when comparing 0.59 AUC of single-layered disease network. If further stretched to whole layered structure of omics, the proposed method is expected to produce more promising results.Conclusion: This research has novelty in that it is a new integrative algorithm that incorporates the vertical structure of omics data, on contrary to other existing methods that integrate the data in parallel fashion. The results can provide enhanced guideline for disease co-occurrence prediction, thereby serve as a valuable tool for inference process of multi-layered biological system. [ABSTRACT FROM AUTHOR]

Published
2017
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92. CLASH: Complementary Linkage with Anchoring and Scoring for Heterogeneous biomolecular and clinical data.

Author

Yonghyun Nam, Myungjun Kim, Kyungwon Lee, Hyunjung Shin, Nam, Yonghyun, Kim, Myungjun, Lee, Kyungwon, and Shin, Hyunjung

Subjects
TEXT mining, ALGORITHMS, ANCHORING effect, METABOLIC disorders, PROTEIN-protein interactions, MEDLINE, METABOLISM, ARTIFICIAL neural networks, ONLINE information services, DATA mining
Abstract

Background: The study on disease-disease association has been increasingly viewed and analyzed as a network, in which the connections between diseases are configured using the source information on interactome maps of biomolecules such as genes, proteins, metabolites, etc. Although abundance in source information leads to tighter connections between diseases in the network, for a certain group of diseases, such as metabolic diseases, the connections do not occur much due to insufficient source information; a large proportion of their associated genes are still unknown. One way to circumvent the difficulties in the lack of source information is to integrate available external information by using one of up-to-date integration or fusion methods. However, if one wants a disease network placing huge emphasis on the original source of data but still utilizing external sources only to complement it, integration may not be pertinent. Interpretation on the integrated network would be ambiguous: meanings conferred on edges would be vague due to fused information.Methods: In this study, we propose a network based algorithm that complements the original network by utilizing external information while preserving the network's originality. The proposed algorithm links the disconnected node to the disease network by using complementary information from external data source through four steps: anchoring, connecting, scoring, and stopping.Results: When applied to the network of metabolic diseases that is sourced from protein-protein interaction data, the proposed algorithm recovered connections by 97%, and improved the AUC performance up to 0.71 (lifted from 0.55) by using the external information outsourced from text mining results on PubMed comorbidity literatures. Experimental results also show that the proposed algorithm is robust to noisy external information.Conclusion: This research has novelty in which the proposed algorithm preserves the network's originality, but at the same time, complements it by utilizing external information. Furthermore it can be utilized for original association recovery and novel association discovery for disease network. [ABSTRACT FROM AUTHOR]

Published
2016
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98. Nanotubular Heterostructure of Tin Dioxide/Titanium Dioxide as a Binder-Free Anode in Lithium-Ion Batteries.

Author

Kim, Myungjun, Lee, Joobong, Lee, Seonhee, Seo, Seongrok, Bae, Changdeuck, and Shin, Hyunjung

Subjects
STANNIC oxide, TITANIUM oxides, HETEROSTRUCTURES, ANODES
Abstract

Titanium dioxide (TiO2), tin dioxide (SnO2), and heterostructured TiO2/SnO2 nanotube (NT) arrays have been fabricated by template-assisted atomic-layer deposition (ALD) for use as anodes in a lithium-ion battery (LIB). TiO2 NT arrays with 8 nm thick walls showed higher capacity (≈250 mA h g−1 after the 50th cycle at a rate of C/10) than the typical theoretical capacity of bulk TiO2 and a radically improved capacity retention property upon cycling. SnO2 NT arrays with different wall thicknesses (8, 10, 13, and 20 nm) were also fabricated and their electrochemical performances were measured. All of the SnO2 NT arrays showed substantially higher initial irreversible capacity and higher reversible capacity than those of bulk TiO2. Thinner walls of the SnO2 NTs result in better capacity retention. Heterotubular structures of TiO2 (5 nm)/SnO2 (10 nm)/TiO2 (5 nm) were successfully fabricated, and displayed a sufficiently high capacity (≈300 mA h g−1 after 50 cycles) with exceptionally improved cycling performance up to the 50th cycle. [ABSTRACT FROM AUTHOR]

Published
2015
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99. Interface Properties of Atomic-Layer-Deposited Al2O3Thin Films on Ultraviolet/Ozone-Treated Multilayer MoS2Crystals

Author

Park, Seonyoung, Kim, Seong Yeoul, Choi, Yura, Kim, Myungjun, Shin, Hyunjung, Kim, Jiyoung, and Choi, Woong

Abstract

We report the interface properties of atomic-layer-deposited Al2O3thin films on ultraviolet/ozone (UV/O3)-treated multilayer MoS2crystals. The formation of S–O bonds on MoS2after low-power UV/O3treatment increased the surface energy, allowing the subsequent deposition of uniform Al2O3thin films. The capacitance–voltage measurement of Au–Al2O3–MoS2metal oxide semiconductor capacitors indicated n-type MoS2with an electron density of ∼1017cm–3and a minimum interface trap density of ∼1011cm–2eV–1. These results demonstrate the possibility of forming a high-quality Al2O3–MoS2interface by proper UV/O3treatment, providing important implications for their integration into field-effect transistors.

Published
2016
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