• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.445-452
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• 2015

Transcranial direct current stimulation (tDCS) is a neuromodulatory technique that delivers a low-intensity direct current to the cortical areas, thereby facilitating or inhibiting spontaneous neuronal activity. This study was designed to examine the changes in various sensory functions after tDCS. A single-center, single-blinded, randomized trial was conducted to determine the effect of a single session (August 4 to August 29) of tDCS with the current perception threshold (CPT) in 50 healthy volunteers. Nerve conduction studies (NCS) were performed in relation to the median sensory and motor nerves on the dominant hand to discriminate peripheral nerve lesions. The subjects received anodal tDCS with 1mA for 15 minutes under two different conditions, with 25 subjects in each group. The conditions were as follows: tDCS on the dorsolateral prefrontal cortex (DLPFC) and sham tDCS on DLPFC. The parameters of the CPT was recorded with a Neurometer$^{(R)}$ at frequencies of 2000, 250 and 5 Hz in the dominant index finger to assess the tactile sense, fast pain and slow pain, respectively. In the test to measure the CPT values of the DLPFC in the anodal tDCS group, the values increased significantly in all of 250 and 5 Hz. All CPT values decreased for the sham tDCS. These results showed that DLPFC anodal tDCS can modulate the sensory perception and pain thresholds in healthy adult volunteers. This study suggests that tDCS may be a useful strategy for treating central neurogenic pain in rehabilitation medicine.

• Korean Journal of Weed Science
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• v.8 no.3
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• pp.291-294
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• 1988

About 136 weed species belonging to 44 families occurring in summer observed in Cheju island. The Compositae was the most widely occurring family covering 29 weed species, followed by 16 species in Graminae, 14 in Leguminosae, 13 in Rosaceae, 10 in Polygonaceae etc., The dominant weed species detected in range areas of Cheju island were Trifolium repens, Botrychium virginianum, Rosa multiflora, Miscanthus sinensis, Imperata cylindrica. The range areas of Cheju island consisted of the communities of Artemisia princeps-Botrychium virginianum, Artemisia princeps-Erigeron borariensis and Dianthus sinensis, and Artemisia-Lespedeza bicolor and Miscanthus sinensis and then the differential species of their communities were Botrychium virginianum, Erigeron boriensis, and Lespedeza bicolor and Miscanthus sinensis, respectively. The species of the high frequencies occurring in investigated sites were Artemisia princeps, Cirsium rhinoceros, Hydrocotyle ramijlora, Rosa multiflora, Sanguisorba officinalis, Rubus crataegifolius, Potentilla fragariodes, Erigeron annus, Plantago asiatica, Oxalis corniculata, Mosla dianthera in order.

• Journal of the Korean Society for Railway
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• v.15 no.5
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• pp.485-497
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• 2012

Recently, with increasing social interests on noise and vibration induced by railway traffic, the application of floating slab track that can efficiently reduce the railway vibration is increasing. In this study, to more accurately understand the dynamic behavior of the floating slab track, a laboratory mock-up test has been performed, and the static and dynamic behaviors at frequency range near the system resonance frequency were explored. Based on the test results, the design of the floating slab track and the structural analysis model used in the design have been verified. The analytic and test results demonstrate that the dominant frequency of the floating slab track occurs at the frequencies between vertical rigid body mode natural frequency and bending mode natural frequency, and the dominant deformation mode is close to the bending mode. This suggests that in the design of the floating slab track, the bending rigidity of the slab and the boundary conditions at slab joints and slab ends should be taken into consideration. Also, the analytic results by the two-dimensional finite element analysis model using Kelvin-Voigt model, such as static and dynamic deflections and force transmissibility, are found in good agreement with the test results, and thus the model used in this study has shown the reliability suitable to be utilized in the design of the floating slab track.

• Journal of Life Science
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• v.20 no.5
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• pp.799-804
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• 2010

In humans, CYP2C19, a member of the cytochrome P450 subfamily, metabolizes arachidonic acid to produce epoxyicosanoid acids, which are involved in vascular tone and regulation of blood pressure (BP). Recent findings suggest that CYP2C19 gene polymorphisms might be considered as a novel candidate gene for cardiovascular disease. We thus focused on the Korean population to explore the association of two polymorphisms ($CYP2C19^*2$ and $^*3$) in this gene and essential hypertension (EH). A total of 1,241 participants (537 hypertensive subjects and 704 healthy controls) were recruited from the Yonsei Cardiovascular Genome Center in Korea. The CYP2C19 polymorphisms were genotyped using the $SNaPShot^{TM}$ assay. The allele and genotype frequencies of $CYP2C19^*3$ showed significant difference between hypertensives and normotensives (P=0.019 and P=0.023, respectively). Logistic regression analysis indicated that the $CYP2C19^*3$ A allele carriers were significantly associated with EH (OR, 0.723; 95% CI, 0.538-0.972, P=0.032) under a dominant model. In addition, CYP2C19 G-A haplotype ($2C19^*2\;G-^*3$ A combination) was found to significantly reduce EH risk (OR, 0.714, P=0.015). We believe this provides evidence that $CYP2C19^*3$ polymorphism may contribute to a protective effect in the development of EH.

• Korean Journal of Remote Sensing
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• v.37 no.6_2
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• pp.1837-1847
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• 2021

This study investigated wind corridors for the entire Suwon-city area using a geographic information system and a computational fluid dynamics model. We conducted numerical simulations for 16 inflow wind directions using the average wind speeds measured at the Suwon automated synoptic observation system (ASOS) for recent ten years. We analyzed the westerly (dominant wind direction) and easterly cases (not dominant but strong wind speed) in detail and investigated the characteristics of a wind speed distribution averaged using the frequencies of 16 wind directions as weighting factors. The characteristics of the wind corridors in Suwon city can be summarized as; (1) In the northern part of Suwon, complicated flows were formed by the high mountainous terrain, and strong (weak) winds and updrafts (downdrafts) were simulated on the windward (leeward) mountain slope. (2) On the leeward mountain slope, a wind corridor was formed along a valley, and relatively strong airflow flowed into the residential area. (3) The strong winds were simulated in a wide and flat area in the west and south part of Suwon city. (4) Due to the friction and flow blocking by buildings, wind speeds decreased, and airflows became complicated in the downtown area. (5) Wind corridors in residential areas were formed along wide roads and areas with few obstacles, such as rivers, lakes, and reservoirs.

• Korean Journal of Poultry Science
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• v.49 no.2
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• pp.99-108
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• 2022

Avian leukosis virus (ALV) is a highly contagious retrovirus that causes tumors and has resulted in great economic loss worldwide owing to its high transmission rate. Various ALV viral subgroups exist, with infections occurring via specific host receptors. The susceptibility or resistance of avian species to the ALV-A and K subgroups is determined by the host receptor, the tumor virus locus A (tva) gene, while that to ALV-B depends on another host receptor, the tumor virus locus B (tvb) gene. The resistance alleles of tva and tvb have primarily been identified in China, but none have beendetected in Korea. We analyzed the frequencies of tva and tvb genotypes in White Leghorn (WL), Korean Ogye (KO), and Korean native chicken (KNC) breeds, and assessed the resistance to ALV subgroups. In WL, both tva and tvb had various genotypes, including susceptibility and resistance alleles, whereas in KO, tva and tvb resistance alleles were dominant. In KNC, tva susceptibility and resistance alleles were mixed, whereas tvb resistance alleles were dominant. In addition, we showed that there were differences in the splicing pattern of tva transcripts and the expression level of tvb transcripts within breeds. Finally, we confirmed that ALV resistance depended on KO and KNC genotypes by in vitro infection of chicken embryonic fibroblasts with ALV. These results highlight that some KO and KNC individuals are naturally resistant to ALV subgroups A, B, and K, and will facilitate the preservation of economically superior traits through selective breeding.

• The Korean Journal of Mycology
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• v.51 no.4
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• pp.511-519
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• 2023

Red pine (Pinus densiflora) is a dominant tree species in Korean forests. The diversity of endophytic fungi was investigated by isolating fungi from different parts of a red pine tree during the fall and spring seasons. One hundred and fifty-two strains of endophytic fungi were isolated and classified into 42 species belonging to 29 genera. Among these, 74 (49%), 47 (31%) and 31 strains (20%) were isolated from branches, leaves, and stems, respectively. The most frequently isolated species were Daldinia childiae and Biscogniauxia maritima (28.9% and 9.8%, respectively). D. childiae was the dominant endophytic fungus on branches (20 strains) and leaves (19 strains). B. maritima was most frequently isolated from branches. The isolation frequencies on stems of B. maritima (6 strains) and D. childiae (5 strains) were also high. Fifty-seven isolates belonging to 19 species and 17 genera were isolated in the spring, and 95 strains belonging to 35 species and 24 genera were isolated in the fall. D. childiae was the most frequently isolated fungus in both spring and fall (21 and 23 strains, respectively). B. maritima was also frequently isolated in both spring (7 strains) and fall (8 strains).

• Korean Journal of Environment and Ecology
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• v.25 no.2
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• pp.132-144
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• 2011

We studied the forest environment and characteristics of bird community between April and September of 2010 on the Hyangjeokbong area(A), Baekryunsa area(B) and Anseong area(C), all in the Deogyusan National Park. Hyangjeokbong area of the high latitude ridge was characterized by the Taxus cuspidata and Abies koreana etc., and deciduous broadleaf forest species, such as the Quercus mongolica, with abundance of subalpine zone coniferous trees, the Hemerocallis fulva and the Rhododendron schlippenbachii, while the areas Baekryunsa and Anseong were primarily characterized by deciduous broadleaf forests, with the valleys showing Fraxinus mandshurica colonies. In terms of the DBH(diameter at breast height) of trees, between 11 and 20cm showed the highest frequencies, while over 30cm was the highest in Baekryunsa area and the lowest in Hyangjeokbong area. Furthermore, in terms of coverage in relation to layers, in Hyangjeokbong area, the coverage volume of the lower layer was very high, in Baekryunsa area, the coverage volume of the middle layer between 8 and 12m was the highest, and in Anseong area, the coverage volume of the upper layer over 18m was the highest. A total of 53 bird species were observed during the study period at the Deogyusan National Park. The numbers of species and density of areas were 25 species and 45.20 Ind./km for Hyangjeokbong area, 50 species and 58.63 Ind./km for Baekryunsa area and 35 species and 66.89 Ind./km for Anseong area, with Baekryunsa area showing the highest number of species and Anseong area showing the highest level of density. In terms of dominant species, in Hyangjeokbong area, Cettia diphone, along with species which inhabit in grassland and shrubs, were the dominant species, and species which live in the canopy layer, including the Aegithalos caudatus, were found to be dominant in Baekryunsa and Anseong areas. For guild structure, bush nesting guild and bush foraging guild species were the highest in all areas, and the hole nesting guild and the air foraging guild species showed the lowest proportion. This seems to be the result of the low number of trees with diameter at breast height of over 30cm, which results in the lack of nesting grounds for hole nesting guild species.

• Journal of the Korean Institute of Telematics and Electronics
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• v.11 no.4
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• pp.29-37
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• 1974

Theoretical analysis is carried out for the curtoff wavelength characteristics of rectangular waveguide containing a step-ridge. In order to obtain the cutoff wavelength of step-rigde waveguide, an transmission matriz is formulated by the method of equivalent transverse resonance. The characteristic equation, in which the wavelength is obtainable by the numerical method, is derived from the equation. An approximate determination of the dominant mode fields in step-ridge waveguides at all frequencies has been made. Using these fields, the characteristic impedance equation is derived from power considerations. Analyzing the results of the calculations, the following characteristics are noted. The values of λ /a of TE10 mode increase with decreasing gap lengths and with increasing step width S or S , or both. Experimental results of cutoff characteristics are in good agreement with the theoretical analusis. It is shown that a waveguide within which a step-ridge is placed has a lower cutoff frequency and impedance than empty guide without it. Therefore, the role of a step-ridge guide is to broadening the bandwidth 2 to 3 times more than that of an empty guide of the same demension.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.6
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• pp.585-592
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• 2013

To estimate the effect of long-term fertilization on metabolically active bacterial communities in a rice field, RNA was extracted from endosphere (rice root), rhizosphere, and bulk soil that had been subjected to different fertilization regimes for 59 years, and the 16S rRNAs were analyzed using the pyrosequencing method. The richness and diversity of metabolically active bacteria were higher in bulk soil than in the endosphere and rhizosphere, and showed no significant difference between non-fertilized and fertilized plots. Weighted UniFrac analysis showed that each compartment had characteristic bacterial communities and that the effect of long-term fertilization on the structure of bacterial community was more pronounced in bulk soil than in the endosphere and rhizosphere. The 16S rRNAs affiliated with Alphaproteobacteria and Firmicutes were more abundant in the endosphere than in bulk soil while those affiliated with Chloroflexi and Acidobacteria were more abundant in bulk soil than in the endosphere. Several dominant operational taxonomic units (clustered at a 97% similarity cut-off) showed different frequencies between non-fertilized and fertilized plots, suggesting that the fertilization affected their activities in the rice field.