• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.242-242
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• 2015

Monitoring the land cover changes in Nakdong River Basins using the multi-temporal remote sensing datasets is necessary for preserving properties in the river basins and monitoring the environmental changes in the river basins after the 4 major river restoration project. This research aims to monitor the land cover changes using the multi-temporal Landsat imageries and the airborne topographic LiDAR data. Firstly, the river basin boundaries are determined by using the LiDAR data, and the multiple river basin imageries are generated from the multi-temporal Landsat imageries by using the river basin boundaries. Next the classification method is employed to identify the multiple land covers in the generated river basin imageries. Finally, monitoring the land cover changes is implemented by comparing the differences of the same clusters in the multi-temporal river basin imageries.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.12
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• pp.821-827
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• 2014

The 4major river project has caused changes in flow and water quality patterns in major rivers in Korea including the Nakdong River where several toxicant release accidents have had occurred. Three dimensional hydrodynamic model, the Environmental Fluid Dynamics Code (EFDC), was applied to evaluate the effect of geomorphological change of the river on the advection and dispersion patterns of a conservative toxic pollutant. A hypothetical scenario was developed using historical data by assuming a toxic release from an upstream location. If there is a toxic release at the Gumi Industrial Complex, the toxic material would be detected after 2.22 and 9.83 days at Chilgok and Gangjung weir, respectively, in the new river system. It was estimated that they took at least 12 times longer than those with the river conditions before the project. Effect of relocation of intake towers for Daegu Metro City to upstream of Gumi City was also evaluated using the developed modeling system. It was observed that hydraulic residence time would be increased due to decreased flow rate and thus due to lowered water level. However, peak concentration differences were found to be about 2% lower in both places due to increased dispersion effect after the relocation.

• Journal of the Korean Association of Geographic Information Studies
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• v.16 no.4
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• pp.171-188
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• 2013

Landuse changes and cadastral information error categories in the four major river areas were analyzed for the use of policy data as cadastral re-arrangement of national and public lands would be required, using high-resolution air-photographs and cadastral maps before and after the river development. The study sites were the river areas of 40km around four dams of the Nakdong river where their landuses were changed most. As the results, national and public lands reached 79.9% of land parcels and 93.3% of land areas of the study sites similar with those of the four river areas, 84.3% of land parcels and 85.5% of land areas. The landuse classification of the study sites before the four river development was consisted most of 'river'(71.6%) and 'rice field'(12.3%), but after the development the 'river' was reduced to 42.7% and 'park area'(19.6%) including sport fields and 'mixed lots'(20.8%) were increased. Also, 86.7% of land parcels before the development could be reduced after the development if administrative districts and land ownerships were not considered. Cadastral information error categories can be found as cadastral polygon missing, polygon overlap, location and boundary non-coincidence, small polygon generation, and non-coincidence between cadastral boundary and river boundary. Landuse change monitoring method using air-photographs will be useful to analyze landuse state through fast information aquisition and to manage properties of national and public lands such as river areas.

• Proceedings of the Korean Sanitation Conference
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• 2006.11a
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• pp.33-42
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• 2006

We decided Miomotegawa river was the object of our investigation since it is one of the most important salmon rivers in Japan. A great number of salmonshave returned to the river, and it was expected to contain relatively lower cation concentrations since granite is widely distributed in the river catchment area. The concentration of calcium and magnesium were less than a half of that of other major rivers. The concentration of analyzed parameters indicating water quality effect on salmons, $NO_{3},\;SO_{4}\;and\;NH_{4}$, were 1.37, 4.08 and 0.01mg/l, respectively. Most parameters down stream were greater in concentration than in the upper stream.

• Environmental Analysis Health and Toxicology
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• v.16 no.4
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• pp.161-170
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• 2001

In aqueous ecosystems, the level of toxicity is highly responsive dependant to multiple variables, including rainfall, sunlight, pH, adhesion, etc. Because Korea has particularly distinct wet and dry seasons, the toxicity of pollutants in rivers or streams is dependant on the sampling season and time. In order to examine the effects of rainfall on toxicity, sediment samples were collected from five sites along the Keumho river. It was found that Microtox toxicity levels were generally higher during the dry season than the wet season. It indicated that river pollutants are carried off more quickly by the water during the wet season. As a result, it was recommended that the point sources of pollutants of the Keumho river would be placed between KH3 (Paldalgyo) and KH4(Keumhogyo), KH4(Keumhogyo) and KH5(Dasa).

• Journal of the Korean Association of Geographic Information Studies
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• v.18 no.2
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• pp.135-148
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• 2015

This research is carried out for the land cover change detection in the Nakdong River basin before and after the 4 major rivers restoration project using the LiDAR DEM(Digital Elevation Model) and the multi-temporal Landsat imagery. Firstly the river basin polygon is generated by using the levee boundaries extracted from the LiDAR DEM, and the four river basin imagery are generated from the multi-temporal Landsat-5 TM(Thematic Mapper) and Landsat-8 OLI(Operational Land Imager) imagery by using the generated river basin polygon. Then the main land covers such as river, grass and bare soil are separately generated from the generated river basin imagery by using the image classification method, and the ratio of each land cover in the entire area is calculated. The calculated land cover changes show that the areas of grass and bare soil in the entire area have been significantly changed because of the seasonal change, while the area of the river has been significantly increased because of the increase of the water storage. This paper contributes to proposing an efficient methodology for the land cover change detection in the Nakdong River basin using the LiDAR DEM and the multi-temporal satellite imagery taken before and after the 4 major rivers restoration project.

• Research in Community and Public Health Nursing
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• v.27 no.4
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• pp.346-357
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• 2016

Purpose: This study attempted to investigate the prevalence and related factors of Clonorchiasis among five major riverside residents in South Korea. Methods: This study is descriptive research, nationwide survey, and the subjects are 23,492 residents selected by convenience sampling. Data collection was conducted between March 1 and June 30, 2011, and stool collection and questionnaire survey were conducted by affiliated public health centers in 38 cities and Gun's. Results: The prevalence rates of Clonorchiasis in the five major riversides were as follows: the Guem River 15.2%; the Nakdong River 11.9%; the Seomjin River 10.9%; the Han River 5.7%; and the Yeongsan River 3.9%. The prevalence rates were shown to be significantly high among people who had highly frequent experiences of eating and cooking freshwater raw fish, were diagnosed with liver and/or biliary tract diseases, and drank less than once a month. Conclusion: These results suggest that it is necessary to improve awareness of Clonorchiasis and provide intensive public health education for the riverside residents. And the target groups should be set up by reflecting the characteristics of at-risk groups, and it is necessary to prepare customized strategies for prevention and management of Clonorchiasis.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.4
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• pp.453-457
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• 2005

The genetic variations in three major river populations viz. the Halda, the Jamuna and the Padma of the Indian major carp, Catla catla were analyzed by Random Amplified Polymorphic DNA (RAPD) markers. Four decamer primers were used for amplifying DNA of 10 individuals from each population. The proportion of polymorphic loci and the gene diversity estimates were 59.4 and 0.20 for the Halda, 37.5 and 0.14 for the Jamuna and 46.9 and 0.16 for the Padma populations respectively indicating the existence of a relatively high level of genetic variation in the Halda river population. The inter-population similarity indices, gene flow and genetic distance values indicated that the Jamuna-Padma population pair of catla was genetically closer than the Halda-Jamuna and the Halda-Padma population pairs in compliance with the geographical distances among them. The coefficient of gene differentiation ($G_{ST}$=0.13) reflects some degree of genetic differentiation among three populations of catla studied. The data suggest that the RAPD technique could be used to discriminate different river populations of catla.

• The Journal of Fisheries Business Administration
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• v.51 no.4
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• pp.1-18
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• 2020

The paper aims to explore existence and degree of remaining fisheries damages after the completion of undertaking the Four Major Rivers Project focusing on the case of Yeongsan river. The paper seeks to show the necessity of consideration of periods of fishery resources recovery in the estimation of ex-post fisheries damages of the project by inferring the analysis of the annual variation of environmental indicators in the river. Therefore, the paper suggests three years of remaining periods of fisheries damages of the project utilizing the variation trend of ex-ante and ex-post annual output data of inland fisheries in Jeonnam province and individual catch of fisheries. In the measurement of the annual degree of fisheries damages during periods of fishery resources recovery, the paper attempts to suggest the method of comparision of day catch data per vessel between ex-ante and ex-post periods of the project, which were investigated by the same institute. Here the paper tries to make correction of ex-post catch data for holding the same catching condition as ex-ante situation by adopting the concept of competitive intensity of catching which was derived from the decreasing rate of number of fishing households in the area of Yeongsan river.

• Journal of Korea Water Resources Association
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• v.55 no.8
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• pp.577-588
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• 2022

This study aims to identify the limiting nutrient for algal growth in the Geum River and the significant pollutant sources from the tributaries affecting the water quality and to provide a management alternative for an improvement of water quality. An eight-year of daily data (2013~2020) were collected from the Water Environment Information System (water.nier.go.kr) and Water Resources Management Information System (wamis.go.kr). 14 water quality variables were analyzed at five water quality monitoring stations in the Geum River (WQ1-WQ5). In the Geum River, the water quality variables, especially Chl-a vary greatly in downstream of the river. In the open weir gate operation, TP (total phosphorus) and water temperature greatly influence the growth of algae in downstream of the river. A correlation analysis was used to identify the relationship between variables and investigate the factor affecting algal growth in the Geum River. At the downstream station (WQ5), TP and Temp have shown a strong correlation with Chl-a, indicating they significantly influence the algal bloom. The principal component analysis (PCA) was applied to identify and prioritize the major pollutant sources of the two major tributaries of the river, Gab-cheon and Miho-cheon. PCA identifies three major pollutant sources for Gab-cheon and Miho-cheon, respectively. For Gab-cheon, wastewater treatment plant, urban, and agricultural pollutions pollution are identified as significant pollutant sources. For Miho-cheon, agricultural, urban, and forest land are identified as major pollutant sources. PCA seems to be effective in identifying water pollutant sources for the Geum River and its tributaries in detail and thus can be used to develop water quality management strategies.