• Current Applied Physics
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• v.18 no.12
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• pp.1496-1506
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• 2018

Organic/inorganic ultraviolet photodetector was fabricated using thermal evaporation technique. Organic/inorganic heterojunction based on thermally evaporated copper (II) acetylacetonate thin film of thickness 200 nm deposited on an n-type silicon substrate is introduced. I-V characteristics of the fabricated heterojunction were investigated under UV illumination of intensity $65mW/cm^2$. The diode parameters such as ideality factor, n, barrier height, ${\Phi}_B$, and reverse saturation current, $I_s$, were determined using thermionic emission theory. The series resistance of the fabricated diode was determined using modified Nord's method. The estimated values of series resistance and barrier height of the diode were about $0.33K{\Omega}$ and 0.72 eV, respectively. The fabricated photodetector exhibited a responsivity and specific detectivity about 9 mA/W and $4.6{\times}10^9$ Jones, respectively. The response behavior of the fabricated photodetector was analyzed through ON-OFF switching behavior. The estimated values of rise and fall time of the present architecture under UV illumination were about 199 ms and 154 ms, respectively. Finally, enhancing the photoresponsivity of the fabricated photodetector, post-deposition plasma treatment process was employed. A remarkable modification of the device performance was noticed as a result of plasma treatment. These modifications are representative in a decrease of series resistance and an increase of photoresponsivity and specific detectivity. The process of plasma treatment achieved an increment of external quantum efficiency from 5.53% to 8.34% at -3.5 V under UV illumination.

• Korean Journal of Ichthyology
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• v.22 no.4
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• pp.230-237
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• 2010

Histological observation on the seasonal variation of mucus cells of the mud loach Misgurnus mizolepis inhabiting a natural stream was carried out on three skin regions (dorsal, lateral and occiput) from March 2008 to February 2009. Our results showed no differences in general morphology by season, but the mucus cells of the epidermis showed significant seasonal change in their size and number as the water temperature changed. The ratio of surface area of the mucus cell layer and mucus cells, and the number of mucus cells in surface area of the epidermis were the greatest in the cold winter and the least in the hot summer in all regions of the epidermis. In particular, the occiput seemed to be a very sensitive region in response to environmental change, showing wide fluctuations in the size of mucus cells throughout the year and a great change in between seasons, especially from late autumn to early winter when the temperature decreased. As the temperature became colder, a small and spherical-shaped mucus cell was transformed into a large and elongated columnar form with a lot of secreted mucus material in a superficial layer of the epidermis. From our results, we can safely surmise that cold temperature is an important environmental factor having a close relationship with the modification of mucus cells of M. mizolepis in winter.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.11
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• pp.4635-4642
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• 2010

Latex modification of concrete provides the material with higher flexural strength, as well as high bond strength and reduced water permeability. One of the most advantages of the very early-strength latex-modified concrete (VES-LMC) could be the similar contraction and expansion behaviour to normal concrete substrate, which enable to ensure long-term performance. The purpose of this study was to parametric nonlinear flexural nonlinear analysis of RC beam rehabilitated by VES-LMC. The results were as follows; The flexural nonlinear analysis model of RC beam overlaid by VES-LMC in ABAQUS was proposed to predict the load-deflection response, interfacial stress, and ultimate strength. The proposed FE analysis model was verified by comparison of an experimental data and the FE analysis results. The FE analysis results showed that yield point as well as flexural stiffness increased as the depth increased; the stiffness of beam overall increased as the bond stiffness became larger; the bond strength between two different materials is a key factor in composite beam. A parametric study showed that an overlay thickness was a main influencing factor to the behavior of RC beam overlaid by VES-LMC.

• Tuberculosis and Respiratory Diseases
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• v.46 no.2
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• pp.185-194
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• 1999

Background: NF-$\kappa$B is a characteristic transcriptional factor whose functional activity is determined by post-translational modification of protein and subsequent change of subcellular localization. The involvement of the NF-$\kappa$B family of the transcription factors in the control of such vital cellular functions as immune response, acute phase reaction, replication of certain viruses and development and differentiation of cells has been clearly documented in many previous studies. Several recent observations have suggested that the NF-$\kappa$B might also be involved in the carcinogenesis of some hematological and solid tumors. Investigating the possibility that members of the NF-$\kappa$B family participate in the molecular control of malignant cell transformation could provide invaluable information on both molecular pathogenesis and cancer-related gene therapy. Method: To determine the expression patterns and functional roles of NF-$\kappa$B family transcription factors in human lung cancer cell lines NCI-H792, NCI-H709, NCI-H226 and NCI-H157 were analysed by western blot, using their respective antibodies. The nuclear and the cytoplasmic fraction of protein extract of these cell lines were subsequently obtained and NF-$\kappa$B expression in each fraction was again determined by western blot analysis. The type of NF-$\kappa$B complex present in the cells was determined by immunoprecipitation. To detect the binding ability of cell-line nuclear extracts to the KB consensus oligonucleotide, electrophoretic mobility shift assay(EMSA) was performed. Results: In the cultured human lung cancer cell lines tested, transcription factors of the NF-$\kappa$B family, namely the p50 and p65 subunit were expressed and localized in the nuclear fraction of the cellular extract by western blot analysis and immunocytochemistry. Immunoprecipitation assay showed that in the cell, the p50 and p65 subunits made NF-$\kappa$B complex. Finally it was shown by Electrophoretic Mobility Shift Assay(EMSA) that nuclear extracts of lung cancer cell lines are able to bind to NF-$\kappa$B consensus DNA sequences. Conclusion: These data suggest that in human lung cancer cell lines the NF-$\kappa$B p50/p65 complex might be activated. and strengthen the hypothesis that NF-$\kappa$B family transcription factors might be involved in the carcinogenesis of human lung cancer.

• Journal of The Korean Association For Science Education
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• v.25 no.3
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• pp.400-410
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• 2005

According to the cognitive conflict process model, student anxiety factor is known to have both positive and negative effects on student response behaviors in a conflict situation for conceptual change learning. However, there is little research that reveals what type of anxiety, either constructive or destructive, is related when conducting step-by-step experiments to resolve cognitive conflicts. This study attempted to learn the characteristic of explanatory hypothesis according to anxiety type after conducting five step-by-step experiments related to action and reaction concept. Results found that students who belonged to the types of 'conviction in logical misconception', 'insisting on additional variables', and 'reasonable modification' suggested explanatory hypothesis close to physical nature. On the other hand, those who showed the other five types of anxiety ('compatible predictions', 'dependence on others', 'fusion of past experience', 'lack of confidence', and 'conflict with past experience') suggested temporary supported hypothesis or simple explanatory hypothesis according to student intuition and simple observation. These results indicate that students in the above-mentioned five categories need more external interactions with instructors based on the type of anxiety related to student behavior. In addition, the results present student characteristics which instructors should be more attentive to when using step-by-step experiments to resolve cognitive conflicts.

• Journal of the Korea Concrete Institute
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• v.16 no.2 s.80
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• pp.249-260
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• 2004

The longitudinal steel connection of reinforced concrete bridge column is sometimes practically unavoidable, however the current Korean bridge design specifications have no special provisions about lap-splices of longitudinal steel. This paper reports experimental results of a research program investigating the seismic performance of circular RC bridge columns with respect to longitudinal steel connection detailing. Twenty-one circular column specimens were tested under quasi-static test. The columns with the entire longitudinal steel lap-spliced within plastic hinge region show relatively sudden strength degradation and low ductility than the columns with continuous longitudinal steel and the columns with half of longitudinal steel lap-spliced. However, the seismic performance of the column with mechanically connected longitudinal steel is similar to that of the column with continuous longitudinal steel. The final objectives of this study are to suggest appropriate longitudinal reinforcement connection details for the limited ductility design concept and to provide quantitative reference data and tendency for performance or damage assessment based on the performance levels such as cracking, yielding, collapse, etc. Ultimate displacement/drift ratio, displacement ductility, response modification factor, equivalent viscous damping ratio, residual deformation index, and effective stiffness are investigated and discussed in this paper.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.2
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• pp.287-297
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• 2015

In concrete structural design provisons, there is a minimum allowable strain of steel to ensure a ductility of RC members and a c/d is limited for the same purpose in EC2. In general, a ductility capacity of RC members is evaluated by a displacement ductility which is a ratio of ultimate displacement to yield displacement, and it is necessary to calculate accurately a yield displacement and an ultimate displacement to evaluate a displacement ductility. But a displacement in members is affected by various member characteristics, so it is hard to calculate a displacement exactly. In this study, a displacement ductility is calculated by calculating a yield displacement and an ultimate displacement through a moment-curvature relationship. The main variables examined are concrete strength, yield strength, steel ratio, spacing of confinement, axial force ratio and concrete ultimate strain. As results, as a concrete strength is increased, a ductility displacement is increased. But as yield strength, steel ratio, spacing of confinement and axial force ratio are increased, a displacement ductility is decreased. And a displacement ductility is necessary to calculate a response modification factor (R) of columns for seismic design, so it is appeared that it is important to calculate a displacement ductility more accurately.

• Journal of Ginseng Research
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• v.47 no.6
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• pp.714-725
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• 2023

Background: Our previous investigation indicated that the preparation of Panax ginseng Meyer (P. ginseng) inhibited melanogenesis. It comprised salicylic acid (SA), protocatechuic acid (PA), p-coumaric acid (p-CA), vanillic acid (VA), and caffeic acid (CA). In this investigation, the regulatory effects of P. ginseng phenolic acid monomers on melanin production were assessed. Methods: In vitro and in vivo impact of phenolic acid monomers were assessed. Results: SA, PA, p-CA and VA inhibited tyrosinase (TYR) to reduce melanin production, whereas CA had the opposite effects. SA, PA, p-CA and VA significantly downregulated the melanocortin 1 receptor (MC1R), cycle AMP (cAMP), protein kinase A (PKA), cycle AMP-response element-binding protein (CREB), microphthalmia-associated transcription factor (MITF) pathway, reducing mRNA and protein levels of TYR, tyrosinase-related protein 1 (TYRP1), and TYRP2. Moreover, CA treatment enhanced the cAMP, PKA, and CREB pathways to promote MITF mRNA level and phosphorylation. It also alleviated MITF protein level in α-MSH-stimulated B16F10 cells, comparable to untreated B16F10, increasing the expression of phosphorylation glycogen synthase kinase 3β (p-GSK3β), β-catenin, p-ERK/ERK, and p-p38/p38. Furthermore, the GSK3β inhibitor promoted p-GSK3β and p-MITF expression, as observed in CA-treated cells. Moreover, p38 and ERK inhibitors inhibited CA-stimulated p-p38/p38, p-ERK/ERK, and p-MITF increase, which had negative binding energies with MC1R, as depicted by molecular docking. Conclusion: P. ginseng roots' phenolic acid monomers can safely inhibit melanin production by bidirectionally regulating melanin synthase transcription. Furthermore, they reduced MITF expression via MC1R/cAMP/PKA signaling pathway and enhanced MITF post-translational modification via Wnt/mitogen-activated protein kinase signaling pathway.

• Korean Journal of Agricultural and Forest Meteorology
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• v.1 no.1
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• pp.1-11
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• 1999

Rice yield and primary productivity (NPP) are dependent upon the variability of climate and soil. The variability and regionality of the rice yield and net primary productivity were evaluated with the meteorological data collected from Korea Meteorology Administration and the actual rice yield data from the Ministration of Agriculture and Forestry, Korea. The estimated NPP using the three models, dependent upon temperature(NPP-T), precipitation(NPP-P) and net radiation(NPP-R), ranged from 10.87 to 17.52 Mg ha$^{-1}$ with average of 14.69 Mg ha$^{-1}$ in the South Korea and was ranged 6.47 to 15.58 Mg ha$^{-1}$ with average of 12.59 Mg ha$^{-1}$ in the North Korea. The primary limiting factor of NPP in Korea was net radiation, and the secondary limiting factor was temperature. Spectral analysis on the long term change in air temperature in July and August showed periodicity. The short periodicity was 3 to 7 years and the long periodicity was 15 to 43 years. The coefficient of variances, CV, of the rice yield from 1989 to 1998 ranged 3.23 percents to 12.37 percents which were lower than past decades. The CV's in Kangwon and Kyeongbuk were high while that in Chonbuk was the lowest. The prediction model based on th e yield index and yield response to temperature obtain ed from the field crop situation showed reasonable results and thus the spatial distributions of rice yield and predicted yield could be expressed in the maps. The predicted yields was well fitted with the actual yield except Kyungbuk. For better prediction, modification should be made considering radiation factor in further development.

• Journal of Plant Biotechnology
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• v.38 no.4
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• pp.285-292
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• 2011

In plants, heteroblasty reflects the morphological adaptation during leaf development according to the external environmental condition and affects the final shape and size of organ. Among parameters displaying heteroblasty, leaf index is an important and typical one to represent the shape and size of simple leaves. Leaf index factor is eventually determined by cell proliferation and cell expansion in leaf blades. Although several regulators and their mechanisms controlling the cell division and cell expansion in leaf development have been studied, it does not fully provide a blueprint of organ formation and morphogenesis during environmental changes. To investigate genes and their mechanisms controlling leaf index during leaf development, we carried out molecular-genetic and physiological experiments using an Arabidopsis mutant. In this study, we identified macrophylla (mac) which had enlarged leaves. In detail, the mac mutant showed alteration in leaf index and cell expansion in direction of width and length, resulting in not only modification of leaf shape but also disruption of heteroblasty. Molecular-genetic studies indicated that mac mutant had point mutation in ROTUDIFOLIA3 (ROT3) gene involved in brassinosteroid biosynthesis and was an allele of rot3-1 mutant. We named it mac/rot3-5 mutant. The expression of ROT3 gene was controlled by negative feedback inhibition by the treatment of brassinosteroid hormone, suggesting that ROT3 gene was involved in brassinosteroid biosynthesis. In dark condition, in addition, the expression of ROT3 gene was up-regulated and mac/rot3-5 mutant showed lower response, compare to wild type in petiole elongation. This study suggests that ROT3 gene has an important role in control of leaf index during leaf expansion process for proper environmental adaptation, such as shade avoidance syndrome, via the control of brassinosteroid biosynthesis.