• 생태와환경
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• 제50권1호
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• pp.169-185
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• 2017

Physicochemical properties of water quality were analyzed to understand the long-term variations in Lake Youngrang from 1998 to 2015. Nonparametric statistical methods were applied to deduct correlation among water quality parameters and water quality trend. In total observations(N=64), the Secchi depth (SD) transparency showed significant positive correlation with salinity (r=0.458) and highly significant negative correlation with chlorophyll-a (r= -0.649) for p<0.0001 in two-tailed test of Spearman's rank correlation. Significant negative correlations of SD were observed with chemical oxygen demand (COD), total phosphorus (TP) and total nitrogen (TN). These correlation patterns were very similar in rainy (N=25) and non-rainy (N=39) periods too. Chlorophyll-a (Chl-a) had significant correlation with COD. Sen's slope test was performed along with Mann-Kendall trend test (significance ${\alpha}=0.05$, two-tailed) to find water quality trend. Positive trends were observed for SD and salinity with Sen's slopes 0.012 and 0.385, respectively (p<0.0001). Negative significant trends were observed for total nitrogen (TN) and Chl-a with Sen's slopes -0.02 (p<0.0001) and -0.346 (p=0.0010), respectively. Temperature, COD and phosphorus components had no trends. Carlson's trophic state index (TSI) for SD, TP and Chl-a were obtained in the ranges of 46~80, 37~82 and 39~82, respectively. Trophic index values suggest that Lake Youngrang was mesoeutrophic to eutrophic and there could be possibility of anoxia during the summer and dominance of blue-green algae. Excess nutrient inputs from external and internal sources were the causes of eutrophication in this lake. The findings of this study would be helpful to recognize water quality variables to manage the water body.

• 한국농림기상학회지
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• 제6권3호
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• pp.196-203
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• 2004

본 연구는 우리나라 특산식물인 히어리가 군락을 형성하고 있는 전남 곡성군 죽곡면과 오곡면 지역을 대상으로 히어리 군락지의 보존과 합리적인 관리를 위한 기초자료를 제공하고자 수행되었다. 히어리 군락은 평균 토양 pH 5.05, 유기물함량 5.22%, 전질소 함량 0.24%, 유효인산 3.25ppm인 토양환경에서 군락이 발달하고 있었다 조사지역의 교목층에 있어서의 중요치는 죽곡이 소나무, 굴참나무, 오곡이 신갈나무, 졸참나무, 소나무가 높게 나타났으며, 아교목층과 관목층에서는 두 지역 모두 히어리의 중요치가 가장 높게 나타났다. 죽곡과 오곡 조사지역의 히어리가 주로 분포하고 있는 아교목층의 종다양도는 각각 0.567, 0.779, 균재도는 0.401, 0.509, 우점도는 0.599, 0.491로 나타났다. 그리고, 관목층의 종다양도는 죽곡 1.453,오곡 1.266, 균재도는 죽곡 0.920, 오곡 0.866, 우점도는 죽곡 0.080, 오곡 0.134로 조사되었다. Morisita's index에 의한 히어리의 분포형은 아교목층과 관목층에 있어서 모두 임의분포하는 것으로 나타났다.

• Spatial Information Research
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• 제3권1호
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• pp.47-53
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• 1995

GIS의 농업분야 이용으로서는 농작물 적지선정, 토양비옥도 지도작성, 병충해 발생양상 및 확산예측, 잡초분포현황, 주요 농작물의 작황 및 수량예측, 농업환경 영향평가, 기후변동과 농작물생육 등 활용도가 매우 높은 편이다. 1992년 농촌진흥청이 주관하여 우리 나라 전국 논 잡초조사(총 2459개 지점)를 9개도에 걸쳐 121시군의 벼 재배포장에서 논 특성, 작부양식, 재배양식, 이앙시기, 경운 방법별로 구분하여 벼 파종후 60일 (직파재배)및 40-5-(이앙재배)에 초종별 발생본수 및 검물중등을 각각 조사하였다. SPANS(Spatial Anyalysis System)를 이용 Vector, Quadtree, Provincial map을 기본으로 하여 절대 미 상대밀도, 절대 및 상대빈도, 중요도, Simpson's Index, 종합우점도에서 주요 우점 초종중 가장 우점도가 높았던 올방개의 전국적인 분포지도를 작성하였다. 생태학적 분석에 으한 종합우점도, 중요값, Simpon's Index에서는 올방개의 발생이 전국에 걸쳐 가장 높게 나타나 전 농가에서 이 잡초의 효과적인 방제가 요구되었지만 GIS 이용 전국적인 지도작성에서는 가장 극심한 지역으로서 경기남부지역으로 나타나 이 지역 농가에서 특히 체계적, 중점적 방제가 요구되어 방제전략을 제시해주었다.

• The Korean Journal of Ecology
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• 제24권4호
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• pp.233-237
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• 2001

Changes of the oribatid mite species composition during the litter decomposition was investigated in the north-facing and south-facing slopes with different lower vegetation (annual herbaceous plants in north and perennial Sasa in south) in the altitude 1,000 m of Mt. Jumbong, a nature reserve area in Korea, from August 1994 to September 1995. Total 58 species of oribatid mites were collected. The values of O1son's negative exponential index (k) were -0.56 in the south-facing slope and -0.49 in the north-facing slope, but there was no significant difference between them. The decomposition rate of litter increased rapidly until Oct. 1994, and decreased thereafter. Intensive settlement of the forest litter by oribatid mites was recorded in the autumn periods and it decreased in the next spring and summer. Species diversity index (H'), and species evenness (J') ranged from 1.74 to 2.69, and from 0.57 to 0.93, respectively, and the values were lowest in spring. In the successive periods of growing season, there followed great changes in the structure of species dominance. Heminothrus minor was one of the most dominant species in autumn in the first year when litter were placed, but was never recovered next seasons. In contrast, Platynothrus yamasakii was also dominant in the first autumn, then decreased very low in numbers in next spring and summer, but regained its number in autumn. On the other hand, an increase of the number during these periods was observed by Epidamaeus sp.2. Ceratopia bipilis and Epidamaeus sp.1 were abundant both in the north-and south-facing slopes. Trichogalumna nipponica was only found in the south-facing slope, and Nanhermannia elegantula was only found in the north-facing slope.

• 한국유기농업학회지
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• 제19권spc호
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• pp.25-29
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• 2011

This study was performed to analyze the improvement of soil physical property and soil biota characteristics through cultivation of green manure crops for a one-year period before creation of a tea plantation as follows. The study revealed that the contents of available phosphate tended to decrease after sod-culture by green manure cultivation and open-pollination, when compared to the level before cultivation. The ratio soil porosity increased by approximately 30% when Crotalaria juncea and Sorghum bicolar L. Moench were cultivated, while the soil bacteria and fungi also increased. In a research on microfauna using a pit fall trap, the population number of the microfauna was 174 of 27 species in the plot of open-pollinated sod-culture and no organic matter application, and 268 of 26 species in the plot of Sorghum bicolar L. Moench. Consequently, the culturing tool of Crotalaria juncea recorded the highest level of species diversity at 2.5, the evenness index at 3.7 and richness at 4.6, with the lowest level of a dominance index. The ecological quotient of microfauna was 0.76 in the plot of Sorghum bicolar L. Moench, and 0.63 in the plot of Crotalaria juncea.

• Investigative Magnetic Resonance Imaging
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• 제23권1호
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• pp.55-64
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• 2019

Purpose: One of the suggested potential mechanisms of tinnitus is an alteration in perception in the neural auditory pathway. The aim of this study was to investigate the difference in laterality in functional connectivity between tinnitus patients and healthy controls using resting state functional MRI (rs-fMRI). Materials and Methods: Thirty-eight chronic tinnitus subjects and 45 age-matched healthy controls were enrolled in this study. Connectivity was investigated using independent component analysis, and the laterality index map was calculated based on auditory (AN) and dorsal attention (DAN), default mode (DMN), sensorimotor, salience (SalN), and visual networks (VNs). The laterality index (LI) of tinnitus subjects was compared with that of normal controls using region-of-interest (ROI) and voxel-based methods and a two-sample unpaired t-test. Pearson correlation was conducted to assess the associations between the LI in each network and clinical variables. Results: The AN and VN showed significant differences in LI between the two groups in ROI analysis (P < 0.05), and the tinnitus group had clusters with significantly decreased laterality of AN, SalN, and VN in voxel-based comparisons. The AN was positively correlated with tinnitus distress (tinnitus handicap inventory), and the SalN was negatively correlated with symptom duration (P < 0.05). Conclusion: The results of this study suggest that various functional networks related to psychological distress can be modified by tinnitus, and that this interrelation can present differently on the right and left sides, according to the dominance of the network.

• 한국환경과학회지
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• 제31권2호
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• pp.149-169
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• 2022

Hwapocheon stream is located in Gimhae-si, Gyeongsangnam-do, and a part was declared a protected wetland area in 2017. In 2020 and 2021, we investigated the community structure of benthic macroinvertebrates of the Hwapocheon stream to provide ecological information for the management of the wetland. As a result, 4 phyla, 6 classes, 20 orders, 51 families, 83 species, and 2,621 individuals of benthic macroinvertebrates were identified. The average indices of diversity, richness, and evenness were the highest in the midstream area, whereas the highest average index of dominance was observed upstream. Seven biological water quality evaluations based on the distribution of benthic macroinvertebrates showed that the Biological Monitoring Working Party was an extremely suitable method for environmental evaluation of the Hwapocheon stream. Regarding functional feeding groups, the number of species of predators and gathering-collectors was the highest, and considering habitual dwelling groups, the number of species of clingers and sprawlers was the highest. The species number of Odonata, Hemiptera, and Coleoptera increased toward the downstream area, whereas the community loss index was the highest upstream. We also investigated relative resistance and resilience based on the distribution of aquatic insects and found that community stability was the highest downstream, whereas the lowest upstream.

• 한국전산유체공학회지
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• 제8권2호
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• pp.16-23
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• 2003

A numerical study of the mixing of two fluids(pure water and a solution of glycerol in water) in a microchannel was carried out. By varying the glycerol content of the glycerol/water solution, the variation in mixing behavior with changes in the difference of the properties of the two fluids(e.g., viscosity, density, diffusivity) was investigated. The mixing phenomena were tested for three micromixers: a square mixer, a three-dimensional serpentine mixer, and a staggered herringbone mixer. The governing equations of continuity, momentum and solute mass fraction were solved numerically. To evaluate mixing performance, a criterion index of mixing of mixing uniformity was proposed. In the systems considered, the Reynolds numbers based on averaged properties were 1 and 10. For low Reynolds number (Re = 1), the mixing performance varied inversely with mass fraction of glycerol due to the dominance of molecular diffusion. The mixing performance by diffusion deteriorated due to a significant reduction in the residence time of the fluid inside the mixers.

• The Korean Journal of Ecology
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• 제16권2호
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• pp.209-227
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• 1993

Aquatic insects were collected from 18 sites in the Yongsan River System from August, 1988 to July, 1989. The monthly fluctuation and distributional pattern of the aquatic insects along the environmental factors were investigated. Quantitatively collected aquatic insects were identified, and numbers, standing biomass, dominance indices and diversity indices in each site and month were determined. The aquatic insect faun of the Yongsan River System was composed of 146 species, 82 genera, 38 families in 7 orders including 44 species of mayflies, 32 species of caddisflies, 24 species of stoneflies, 21 species of flies, 16 species of beetles, 6 species of dragonflies and 3 species of dobsonflies. Seasonal occurrence of species were more diversified in winter and spring than in summer. Also, the number of individuals occurred was higher in winter and spring than in summer while it was the highest in upper stream and the lowest in Kwang-ju stream. Component ratio of the number of individuals according to the insect orders was as follows: Mayflies 38.71%, Flies 36.97%, Stoneflies 10.21%, Caddisflies 6.80%, Beetles 2.96%, Dobbsonflies 2.74%, Dragonflies 0.95%. Percentage of standing biomass according to insect orders were as follows: Mayfiles 32.81%, Stoneflies 26.51%, Caddisflies 17.58%, Dobbsonflies 14.84%, Flies 3.74%, Beetles 3.08%, Dragonflies 1.45%, The highest standing biomass occurred in spring and the lowest in summer.

• 한국환경복원기술학회지
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• 제11권2호
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• pp.55-65
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• 2008

This study was surveyed to analyze vegetation structure of mountainous wetlands in Chung-ju city and around area from September to November, 2006. 6 sites of total 15 potential mountainous wetlands were discriminated throughout field survey. By classification system of mountainous wetlands presented in manual of forest wetlands research, types of wetlands were classified into slant and a flat. Many sites were covered with land plants as Pueraria thunbergiana and so on. To understand vegetation structure of mountainous wetlands, Height, DBH (diameter at breast height), DI (Dominance Index), Sociability and Constancy were surveyed and Based on this result, a projection chart was drawn. As results, Salix koreensis in tree layer and Persicaria thunbergii and Impatiens textori in herb layer were surveyed as broadly distributed species. This study is mainly focused on vegetation condition of mountainous wetlands. But, it will be needed studying on classification system of mountainous wetland type and functional assessment for conservation or management of wetlands.