• Journal of the Korean Solar Energy Society
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• v.39 no.6
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• pp.15-25
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• 2019

As the installation of photovoltaic systems increases, fire accidents of PV system grow every year. Most of PV system fires have been reported to be caused by electrical components. The majority of fire accidents occurred in combiner box, which is presumed to be short-circuit accidents due to dustproof and waterproof failures or heat deterioration of blocking diode. For this reason, the blocking diode installation became optional by revised PV combiner regulation. In this paper, according to the revised regulation, reverse current that generated by voltage mismatch was measured and analyzed in PV array without a blocking diode. The factors that cause voltage mismatch in array are assumed to be shaded PV module and short circuit failure of bypass diode. As the result of experiment, there is no reverse current to flow under shading condition in module, but reverse current flows on the failure of bypass diode in module. According to the module's I-V characteristic curve analysis, open voltage was slightly reduced due to operation of bypass diode in shading. However, it showed that open circuit voltage has decreased significantly in the failure of bypass diode. This indicates that the difference in open voltage reduction of voltage mismatch factor causes reverse current to flow.

• Journal of Cadastre & Land InformatiX
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• v.50 no.1
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• pp.125-141
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• 2020

This study investigated the time-series relationship between housing consumer sentiment and housing prices in the five major districts in Seoul and also analyzed the effect of the housing consumer sentiment on housing prices using Granger Causality and VEC (Vector Error Correction) models. To describe the key results, first of all, housing consumer sentiment and regional housing market prices were closely related to each other, and the consumer sentiment strongly affected the change of housing prices. Second, the housing consumer sentiment was confirmed to have a discriminatory effect on the housing prices among the districts in Seoul in the short term. Specifically, the housing price of the east southern district (ESD) was the main reason for the change in housing consumer sentiment in Seoul, and that the resulting impact was transferred to other districts. Third, it was analyzed that regions other than the ESD would increase the housing prices in the long term as the housing consumer sentiment turned positive, but that the ESD would see a steady tone. Fourth, in the case of relative influence by district, housing (apartment) price fluctuation in a district was generally found to be most affected by adjacent or competitive districts. Through these findings, this study confirmed that there is a clear causality between housing consumer sentiment and housing prices in each district of Seoul and that there is a discriminatory influence on housing consumer sentiment among the districts.

• Molecules and Cells
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• v.41 no.6
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• pp.582-590
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• 2018

Endothelial progenitor cells (EPCs) and outgrowth endothelial cells (OECs) play a pivotal role in vascular regeneration in ischemic tissues; however, their therapeutic application in clinical settings is limited due to the low quality and quantity of patient-derived circulating EPCs. To solve this problem, we evaluated whether three priming small molecules (tauroursodeoxycholic acid, fucoidan, and oleuropein) could enhance the angiogenic potential of EPCs. Such enhancement would promote the cellular bioactivities and help to develop functionally improved EPC therapeutics for ischemic diseases by accelerating the priming effect of the defined physiological molecules. We found that preconditioning of each of the three small molecules significantly induced the differentiation potential of $CD34^+$ stem cells into EPC lineage cells. Notably, long-term priming of OECs with the three chemical cocktail (OEC-3C) increased the proliferation potential of EPCs via ERK activation. The migration, invasion, and tube-forming capacities were also significantly enhanced in OEC-3Cs compared with unprimed OECs. Further, the cell survival ratio was dramatically increased in OEC-3Cs against $H_2O_2$-induced oxidative stress via the augmented expression of Bcl-2, a pro-survival protein. In conclusion, we identified three small molecules for enhancing the bioactivities of ex vivo-expanded OECs for vascular repair. Long-term 3C priming might be a promising methodology for EPC-based therapy against ischemic diseases.

• Korean Journal of Agricultural and Forest Meteorology
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• v.13 no.2
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• pp.87-92
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• 2011

In order to better understand the role of litter layer on hydrological cycle in forest, we estimated the interception storage capacity of the litter layer at Gwangneung deciduous forest. We first made a thickness map of the litter layer at the study site based on field survey and then collected representative litter samples for the laboratory experiment. We constructed a measurement device consisting of sample tray, drain collector, tipping bucket, and a data logger. Using this device, we examined the relationship between the interception storage capacity ($C_i$) and the thickness (d) of the litter layer. For the range of d from 25 to 100 mm, there was a simple linear relationship between $C_i$ and d, which changed with the intensity of the simulated rain. The results were extrapolated to d smaller than 25 mm by considering that no interception occurs without litter layer. Overall, $C_i$ increased rapidly when d was low (< 25 mm) but the rate of increase decreased as d increased due to clumping. With an average thickness of 59 mm, the estimated $C_i$ at the site was 0.94 (${\pm}0.39$) mm. Such an interception storage capacity of the litter layer is comparable to that of the forest canopy, suggesting that the litter layer can play an important role in the forest water cycle.

• Korean Journal of Medicinal Crop Science
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• v.16 no.4
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• pp.242-254
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• 2008

The chemical composition and content of essential oils extracted by ASTM standard D 889-93 method from the leaves of thirty introduced varieties in Perilla frutescens Britton var. japonica $H_{ARA}$ was investigated and compared. The oil was analysed by gas chromatography. More than forty compounds were found and thirteen compounds were identified. The major three constituents representing about $56{\sim}88%$ of total oil were shown caryophyllene and 2 unknown oils in 25 varieties. The chemical composition and content had much differences in each of varieties. This result seemed to be corresponding to introduce that varieties had diverse essential oils.

• Korean Journal of Microbiology
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• v.44 no.4
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• pp.271-276
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• 2008

Ribosome stalling by nascent sticky peptide has been reported in several organisms across the kingdom. To test whether small subunit (SSU) rRNA is involved in this phenomenon, we developed a genetic system that utilized the specialized ribosome system to isolate SSU rRNA mutants that enable ribosomes to bypass the SecM-derived sticky peptide in protein synthesis. In this system, CAT-SecM mRNA, which encodes CAT protein containing the sticky peptide derived from SecM, is only translated by specialized ribosomes. These ribosomes were shown to transiently stall on CAT-SecM mRNA followed by the synthesis of the sticky peptide. Expression of specialized ribosomes resulted in the decreased steady-state level of CAT-SecM mRNA, which is consistent with a notion that ribosome stalling induces mRNA degradation. Isolation and characterization of SSU rRNA mutations using this genetic system that are sufficient to circumvent ribosome stalling induced by the SecM-derived sticky peptide will provide evidence of SSU rRNA function in mRNA cleavage.

• Journal of the Korean Geographical Society
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• v.42 no.6
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• pp.863-878
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• 2007

The time-spatial distribution of Scrub typhus and its relationship with environmental ecology, such as climate, and habitat change are analyzed in respect of the geography of disease. Scrub typhus was firstly reported in 1951, and reemerged in 1986 mainly in southwestern Korea. later it has sharply increased and spreaded out toward whole country in 1998 and 2004, except mid-eastern mountainous region. Hwasung City is the typical example of sudden upsurge of Scrub typhus. High incidence of Scrub typhus patients might due to elevated temperature and decreased precipitation during the summer, as well as milder autumn. Sharp increase of Scrub typhus patients at rural area since 1980's might also be the result of the rapid changes of land use pattern, which eventually have contributed for the active development of dense vegetation and propagation of chigger mites around cultivated land.

• Tuberculosis and Respiratory Diseases
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• v.54 no.6
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• pp.628-634
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• 2003

Bronchiectasis is defined as an abnormal, irreversible dilatation of the bronchi, which may result from a number of possible causes, and the recognition of these causes may lead to a specific management strategy. Immunodeficiency is known as one of the conditions associated with bronchiectasis. X-linked agammaglobulinemia is a rare inheritable immunodeficiency disorder, caused by a differentiation block, leading almost to the complete absence of B lymphocytes and plasma cells. The affected protein is a cytoplasmic protein tyrosine kinase, Bruton's tyrosine kinase. The early detection and treatment with immunoglobulin replacement are most important for the management of recurrent infections and for reducing severe complications. We report a 20-year-old male patient, with X-linked agammaglobulinemia associated with bilateral bronchiectasis, carrying a missense mutation(R520P) in the BTK gene.

• Journal of Ecology and Environment
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• v.41 no.10
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• pp.290-301
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• 2017

Background: Forest edges create distinctive ecological space as adjacent constituents, which distinguish between different ecosystems or land use types. These edges are made by anthropogenic or natural disturbance and affects both abiotic and biotic factors gradually. This study was carried out to assess edge effects on disturbed landscape at the pine-dominated clear-cut area in a genetic resources reserve in Uljin-gun, eastern Korea. This study aims to estimate the distance of edge influence by analyzing changes of abiotic and biotic factors along the distance from forest edge. Further, we recommend forest management strategy for sustaining healthy forest landscapes by reducing effects of deforestation. Results: Distance of edge effect based on the abiotic factors varied from 8.2 to 33.0 m. The distances were the longest in $Mg^{2+}$ content and total nitrogen, $K^+$, $Ca^{2+}$ contents, canopy openness, light intensity, air humidity, $Na^+$ content, and soil temperature followed. The result based on biotic factors varied from 6.8 to 29.5 m, coverage of tree species in the herb layer showed the longest distance and coverage of shrub plant in the herb layer, evenness, species diversity, total coverage of herb layer, and species richness followed. As the result of calculation of edge effect by synthesizing 26 factors measured in this study, the effect was shown from 11.0 m of the forest interior to 22.4 m of the open space. In the result of stand ordination, Rhododendron mucronulatum, R. schlippenbachii, and Fraxinus sieboldiana dominated arrangement of forest interior sites and Quercus mongolica, Vitis amurensis, and Rubus crataegifolius dominated spatial distribution of the open area plots. Conclusions: Forest interior habitat lies within the influence of both abiotic and biotic edge effects. Therefore, we need a forest management strategy to sustain the stability of the plant and further animal communities that depend on its stable conditions. For protecting forest interior, we recommend selective logging as a harvesting method for minimizing edge effects by anthropogenic disturbance. In fact, it was known that selective logging contributes to control light availability and wind regime, which are key factors affecting microclimate. In addition, ecological restoration applying protective planting for the remaining forest in the clear-cut area could contribute to prevent continuous disturbance in forest interior.

• KSBB Journal
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• v.27 no.1
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• pp.1-8
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• 2012

Recently, translational research (TR) in health technology (HT) has been considered as an emerging alternative research system for the improvement of human health. TR from bench to bedside involves a strong bidirectional relationship between basic science discovery and clinical practice. To support R&D planning and policy in HT effectively, the performance of TR programs was analyzed and evaluated in a R&D project on health and medical technology. TR programs were classified into three parts: unilateral TR, bilateral TR and multilateral TR. Bibliometrics and citation analysis were performed to assess research papers and gather information for the performance analysis of TR programs. In addition, both quantitative and qualitative analysis were successfully carried out using ISI Web of Science, Google Scholar Citations, SCOPUS and Knowledgematrix. In conclusion, the performance analysis of TR programs could significantly improve the efficiency of R&D plans, R&D management and evaluation for a safe and healthy life.