• The Korean Journal of Physiology and Pharmacology
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• v.15 no.3
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• pp.137-142
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• 2011

Extremely low frequency magnetic fields (ELF-MF) have the ability to produce a variety of behavioral and physiological changes in animals. The stomach, as the most sensitive part of the neuroendocrine organ of the gastrointestinal tract, is crucial for the initiation of a full stress response against all harmful stress. Thus, the purpose of this study was to examine whether ELF-MF stimuli induce changes in the activity of neuroendocrine cells, considering their involvement in endocrine or paracrine effect on surrounding cells. The exposure to ELF-MF (durations of 24 h and 1 or 2 weeks, 60 Hz frequency, 0.1 mT intensity) altered the distribution and occurrence of gastrin, ghrelin and somatostatinpositive endocrine cells in the stomach of rats. The change, however, in the secretion of those hormones into blood from endocrine cells did not appear significantly with ELF-MF exposure. Comparing with sham control, ELF-MF exposure for 1 and 2 week induced an increase in $BaSO_4$ suspension propelling ratio of gastrointestinal tract, indicating that ELF-MF affects gastrointestinal motility. Our study revealed that ELF-MF exposure might influence the activity of endocrine cells, an important element of the intrinsic regulatory system in the digestive tract. The pathophysiological character of these changes and the mechanism responsible for neuroendocrine cell are still unclear and require further studies.

• Journal of Korea Water Resources Association
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• v.38 no.11
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• pp.963-972
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• 2005

This study searched the criterion of AMC with respect to the rainfall amount for the periods of antecedent 5 to 2 days. This criterion was decided as the rainfall amount with which the frequency of the observed CN(I) and CN(III) events being categorized as the true CN(I) and CW(III) become highest. Among four cases considered, the cases with antecedent 4 and 5 days provided a reasonable results, but the others not due to limited rainfall events available. For both cases with antecedent 4 and 5 days, the frequency of AMC-II increases, but that of AMC-III decreases significantly to become a more reasonable distribution. Among the cases with antecedent 4 and S days, the latter seems to be better as the occurrence of AMC-II and the relative frequency of CN(I) are higher. If adopting the rainfall amount of antecedent 5 days for the AMC, the criteria for AMC-I and AMC-III for the Jangpyung subbasin becomes 22 mm and 117 mm, respectively.

• Korean Journal of Ichthyology
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• v.11 no.1
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• pp.72-85
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• 1999

A study on the larval fish assemblage around the front area was conducted in the Korea Strait in August, 1993. The front was found in the shelf break located in $35{\sim}36^{\circ}N$. A total of 125 species were found in the study area. Of these Engraulis japonicus was the most dominant species comprising 84.3% of the total fish larvae collected and followed by Maurolicus muelleri accounting for 7.7%. Gobiidae, Callionymidae and Pomacentridae showed higher frequency of occurrence. These five species can be divided into three groups. First group was comprised in the larval fish species such as E. japonicus and Callionymidae which were found in the whole study area. The second group was comprised of Gobiidae and Pomacentridae which were found in the warm area located in the southern part of the front area. The other species was M. muelleri found in the cold area located in the northern part of the front area including the front area. The assemblage, geological distribution and body length composition of the fish larvae in the Korea Strait would be mainly determined by the spawning ecology of the fishes, and the geological distribution and structure of the front which is formed in the ocean boundary between the Tsushima Current and the East Sea Cold Water.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.7
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• pp.76-81
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• 2011

A new via cutting structure in 2-layer DRAM package substrate has been fabricated to lower its power distribution network(PDN) impedance. In new structure, part of the via is cut off vertically and its remaining part is designed to connect directly with the bonding pad on the package substrate. These via structure and substrate design not only provide high routing density but also improve the PDN impedance by shortening effectively the path from bonding pad to VSSQ plane. An additional process is not necessary to fabricate the via cutting structure because its structure is completed at the same time during a process of window area formation. Also, burr occurrence is minimized by filling the via-hole inside with a solder resist. 3-dimensional electromagnetic field simulation and S-parameter measurement are carried out in order to validate the effects of via cutting structure and VDDQ/VSSQ placement on the PDN impedance. New DRAM package substrate has a superior PDN impedance with a wide frequency range. This result shows that via cutting structure and power/ground placement are effective in reducing the PDN impedance.

• Journal of Environmental Science International
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• v.11 no.12
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• pp.1243-1252
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• 2002

This paper aims to find the characteristics of concentration distribution of coastal urban air pollutants. For this purpose, It was used the daily meteorological data and the hourly concentration data for $O_3$and NO$_2$ in Busan metropolitan city from 1994 to 1996. It was investigated the annual and monthly distribution of ozone and nitrogen dioxide concentration at each site in Busan, and also investigated the characteristics of concentration change of air pollutants with time under the sea breeze. As a results, the concentration of nitrogen dioxide and ozone tend to be increased every year and nitrogen dioxide concentration is higher than ozone concentration at all sites in Busan. The concentration of ozone is high in summer season and low in winter season, but the concentration of nitrogen dioxide have a reversed trend. The monthly peak concentration of ozone occurred in April and September, while the monthly minimum concentration of nitrogen dioxide occurred in August. Their trend were identified by sites near the coastline than sites stands apart from the coastline. The sea breeze occurred annual mean 81 day in Busan from 1994 to 1996. The main wind direction of sea breeze was classified into southwesterly and southeasterly. In case of southwesterly, It was pronounced the south wind and southwest wind. In case of southeasterly, the occurrence frequency of east wind was high. Especially, the concentrations of urban air pollutants, such as ozone and nitrogen dioxide, were high on time which the sea breeze flow, and the areas that ozone concentration was high moved from outside part to central part of city with time. In costal urban such as Busan, the wind direction of sea breeze is influenced the change of ozone and nitrogen dioxide concentration on time which the sea breeze flow at each site and also influenced the change of air pollutants concentration of sites on the pathway of sea breeze.

• The Korean Journal of Ecology
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• v.11 no.1
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• pp.29-36
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• 1988

This present study has been carried out to examine the correlation between the distribution of the coliform bacterial plasmids and the viability test against heavy metals in the upper stream of Han river(Gapyung; clean water) and the its basin (Anyang Cheon; polluted water). And the distribution of plasmids were examined to be used as trophic indicator for analysis between the clean and polluted waters. 1. A total of 110 isolates were analyzed for the presence of plasmids by means of the boiling method and agarose gel techniques. Plasmids were significantly more frequent in the strains which had been isolated from the clean water (14.3%). Also, there were much higher multiplicity of plasmids at the polluted water(41.0%), compared with the clean water (33.0%). By the comparision between molecular weight of bacterial plasmids in the clean water and those of polluted water, there were no significant differences of the clean water from the polluted water, to such extent as 30.0%, 28.6%, respectively, in frequency for occurrence of high molecular weight plasmids iver 35.8% Mdal. 2. Each isolate was carried out the resistance test for mercury(10-5M), nickel(10-3M) and arsenic (0.1%). At the polluted site, the survival ability of the plasmid-carrying straings(Hg, 31.0%l Ni, 5.7%; As, 65.7%) was higher than that of the non plasmid-carrying strains(Hg, 12.1%; Ni, 3.0%; As, 54.6%). This trend was more remarkable in the clean site (plasmid-carrying strains: 16.7%,-,-). As a result it is suggested that plasmids could be used as an indicator of a certain types of water pollution. In addition, heavy metals might have inflyenced, some extent, to the distribution of plasmids in the environment which has been surveyed in the present study.

• Korean Journal of Weed Science
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• v.30 no.2
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• pp.59-67
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• 2010

The distribution of exotic weeds in 4 island area such as Baengnyeong-do, Heuksan-do, Chuja-do, and Geomun-do in Korea was investigated. Baengnyeong-do, Heuksan-do, Chuja-do, and Geomun-do have different weed flora, 41 species included 13 families, 32 species included 11 families, 23 species included 9 families and 30 species included 12 families were observed in the 4 islands, respectively. 18 families 70 species were occurred in 4 island. Most troublesome exotic weeds were Ambrosia artemisiifolia var. elatior, Solanum carolinense, Cuscuta pentagona. Occurrence frequency of Conyza canadensis, Erigeron annuus, Dactylis glomerata, Bromus catharticus and Lolium multiflorum were the highest in each island, respectively. Also, result of divided life cycle, annual weeds were 28 species occupied 40% in total, biennial weeds were 21 species (30%) and perennial weeds were 21 species (30%).

• Journal of Korea Water Resources Association
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• v.32 no.6
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• pp.617-625
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• 1999

Global warming has begun since the industrial revolution and it is getting worse recently. Even though the increase of greenhouse gases such as $CO_2$ is thought to be the main cause for global warming, its impact on global climate has not been revealed clearly in rather quantitative manners. However, researches using General Circulation Models(GCMs) has shown the accumulation of greenhouse gases increases the global mean temperature, which in turn impacts on the global water circulation pattern. This changes in global water circulation pattern result in abnormal and more frequent meteorological events such as severe floods and droughts, generally more severe than the normal ones, which are now common around the world and is referred as a indirect proof of global warming. Korean peninsula also cannot be an exception and have had several extremes recently. The main objective of this research is to analyze the impact of global warming on the change of flood and drought frequency. Based on the assumption that now is a point in a continuously changing climate due to global warming, we analyzed the observed daily rainfall data to find out how the increase of annual rainfall amount affects the distribution of daily rainfall. Obviously, the more the annual rainfall depth, the more frequency of much daily rainfall, and vice versa. However, the analysis of the 17 points data of Keum river basin in Korea shows that especially the number of days of under 10mm or over 50mm daily rainfall depth is highly correlated with the amount of annual rainfall depth, not the number of dry days with their correlation coefficients quite high around 0.8 to 0.9.

• The Journal of Bigdata
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• v.1 no.2
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• pp.45-63
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• 2016

According to changes of recent climate social structures, frequency of occurrence new or complex disasters are increasing. So the importance of disaster prevention is increasing. To provide useful information of disaster prevention activities, We use the "Safety Sinmungo" main processing practices included Facility safety management in Ministry of Public Safety and Security. Facility safety management is the most and common disaster prevention activities. We identified the keywords in the risk report and facilities to residents report and analyzed the seasonal and inter-regional facilities report distribution process. We also utilized social network analysis techniques to configure a 1-mode, 2-mode facilities around the keyword for differences.

• Korean Journal of Health Education and Promotion
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• v.28 no.4
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• pp.51-61
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• 2011

Objectives: The main purpose of this study was to examine factors associated with depression of middle school students in relation to self-esteem, type A behavior pattern, and locus of control. Methods: A survey was administered to a convenience sample of 309 middle school students. The data analysis procedure included frequency distribution, t-test, ANOVA, Pearson correlation coefficients, and stepwise multiple regression using depression as the dependent variable. Results: The prevalence of depression was 27.2%. Stepwise multiple regression revealed that the factors such as self-esteem(${\beta}$=0.422, p<0.001), type A behavior pattern(${\beta}$=0.166, p<0.001), and locus of control(${\beta}$=-0.165, p<0.001) turned out to be significant affecting factors. Forty nine percent of variance in depression was explained by these factors(40% of variance by self-esteem). Conclusions: The findings suggest that personal internalizing variables should be considered when developing mental health education program to prevent the occurrence of depression for middle school students.