• Journal of Environmental Science International
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• v.20 no.12
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• pp.1635-1646
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• 2011

This April 5th dam and Hwanggang dam, which are located in Imjin river, North Korea, become the main causes of water shortages and damages in Imjin river downstream. April 5th dam is assumed a small or medium-sized dam, its total storage volume reaches about 88 million $m^3$. And Hwanggang dam, multi-purposed dam of total storage volume approximately 0.3 billion $m^3$ to 0.4 billion $m^3$ is used as source of residental or industrial water in Gaeseong Industrial Complex. North Korea, which has April 5th dam and Hwanggang dam in Imjin river, manages water of approximately 0.39 billion $m^3$ to 0.49 billion $m^3$ directly. As water is storaged or discharged through dam, it causes a severe damage to areas in Yeoncheon-gun and Paju city, South Korea. Therefore, this study intends to analyze and estimate runoff through dam construction by using hydrological observation data and artificial data such as service water supply and agricultural water in Imjin river, water shortage and damage correctly.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.11a
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• pp.99-102
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• 2003

The different methods such as HPLC, indirect- and direct-ELISA were employed for the analysis of microtoxins and the results of each method were compared in terms of the detection limit and accurary. Three toxins, microcystin-RR, -LR and -YR were clearly separated by HPLC using 0.05 M methanol and phosphate buffer used as a solvent system. The calibration curves for the toxins were linear in the range of 5 ng to 50 ng. The standard curves for the immunoassay of microcystin obtained by direct and indirect ELISA are compared. The linear responses of inhibitions of binding by microcystin in the direct and indirect competitive ELISA were in the range of 10 ng to 1000 ng and 50 pg to 160 pg, respectively. Distribution of microtoxins at 11 sites in the Nakdong river and several lakes in Korea was also studied. The most dominant microcystin variant in the test sites was found to be microcystin-RR.

• KIEAE Journal
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• v.10 no.6
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• pp.47-54
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• 2010

The significant aim of this research is to suggest the applicable data for the future urban ecological restoration of rivers' activity and the direction of the future eco-experience program found by analyzing the state and progress of the restoration of the river ecological experience program. For this purpose, we researched the eco-experience program's outline and details of its operation and method from six rivers among all of the rivers going through restoration. We also carried out telephone interviews and in-depth interviews with the office staff that takes care about each river at the district office to investigate the specific details not revealed by our analysis, the number of operations, and the number of participants. We compared the number of operations to the number of participants and the frequency of participation of each river in a year. As a result, they have revealed that the participants of the eco-experience program ranged in variety including local students, families, and local citizens as a whole. Also the intimate observation and experience with nature gave the participants a better understanding of the ecosystem. In addition, it is revealed that the cheonggye river goes through its own standard of strict inspections and management daily. It is quite easy to notice that the cheonggye river shows a higher level of participation and operating activity than other rivers.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.405-408
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• 2008

Up to now, a lot of houses, roads and other urban facilities have been damaged by natural disasters such as flash floods and landslides. It is reported that the size and frequency of disasters are growing greatly due to global warming. In order to mitigate such disaster, flood forecasting and alerting systems have been developed for the Han river, Geum river, Nak-dong river and Young-san river. These systems, however, do not help small municipal departments cope with the threat of flood. In this study, a real-time urban flood forecasting service (U-FFS) is developed for ubiquitous computing city which includes small river basins. A test bed is deployed at Tan-cheon in Gyeonggido to verify U-FFS. It is found that U-FFS can forecast the water level of outlet of river basin and provide real-time data through internet during heavy rain. Furthermore, it is expected that U-FFS presented in this study can be applied to ubiquitous computing city (u-City) and/or other cities which have suffered from flood damage for a long time.

• Korean Journal of Ecology and Environment
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• v.41 no.1
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• pp.26-33
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• 2008

To understand the effect of water temperature on growth pattern of Stephanodiscus sp., we weekly or biweekly investigated in the lower part of the Nakdong River from 1994 to 2006 and performed a laboratory experiment. Stephanodiscus was the most dominant species among phytoplankton in winter when low flow persisted and the high abundances of the species were maintained from December to February. Three strains of Stephanodiscus sp. were isolated for the in vitro experiment from the Nakdong River in January 2005. Over the water temperature range of $4^{\circ}C$ to $20^{\circ}C$, the growth patterns of Stephanodiscus sp. were different in the short-term batch culture. The maximum cell density of Stephanodiscus sp. was observed at approximately $5^{\circ}C$ in the river systems, but the optimum water temperature of Stephanodiscus sp. was $10^{\circ}C$ for the growth in the laboratory experiment. However, the proliferation of Stephanodiscus sp. was related to low water temperature in the Nakdong River.

• Journal of Environmental Science International
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• v.30 no.7
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• pp.507-517
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• 2021

In this study, the bathymetric data acquired from 2018 to 2020 and the precipitation and suspended sediment data were analyzed for changes in bathymetry owing to the discharge from the Nakdong River barrier and environmental factors, especially the torrential rain in 2020. Sediment erosion and deposition processes are repeated because of complex environmental factors such as discharge from the Nakdong River barrier and the influence of waves generated from the external sea. In the first half of the year after the dry season, bathymetric data showed relative erosion trends, whereas in the second half after the flood season, deposition trends were identified owing to the increase in sediment transport. However, the data from the second half of 2020 showed a large amount of erosion, resulting in tendencies different to those of erosion in the first half and deposition in the second half of the year. This result is judged to be influenced by the weather in the summer of 2020. The torrential rain in the summer of 2020 resulted in a higher force of erosion than that of deposition. In summary, the tendency for erosion is more significant than that of sedimentation, especially in the main channel area of the Nakdong River.

• Korean Journal of Environmental Biology
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• v.23 no.2 s.58
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• pp.120-128
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• 2005

This study was compared the flora and distribution of hydrophytes with physicochemical environment in the 14 sites selected in Yeongsan River through Gwangju Metropolitan city from March to October, 2003. In this survey, hydrophytes were classified 94 taxa; 35 families, 68 genera, 85 species and 9 varieties. It was compared the physicochemical characters with the hydrophytes distribution in each stream according to the index of contamination. Persicaria japonica and Rumex crispus were dominated at Youduk-Dong, the most contaminated area. Aquatic contamination sensitive floating-leaved plants and submerged plants were not identified. Hwangroung River and Yeongsan River area were a little contaminated area, appeared to good vegetation such as Phragmites japonica, Persicaria thunbergii and Miscanthus sacchariflorus. The stream of Youduk-Dong, the lower reaches of Gwangju-cheon was not grown with hydrophytes because of contamination by inflow of life sewage; therefore it is required to persevere in the townsmen's efforts for improvement of water environment.

• Journal of the Korean association of regional geographers
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• v.10 no.2
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• pp.341-355
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• 2004

This thesis is to analyze characteristic of sustainable development in the Nak-dong River. The results are summarized in the followings. 1) The principles which did not consider the equilibrium between development and environment, ecosystem, security. precautionary measure, equity could devise a plan, changes of economic land area, sand & gravel extractions from the riverbed, the river contamination cleanup, dam build 2) The rules which disregard polluter pay and opening participation in public affairs could input of too much province budget and manpower, project team. The measures to solve these problems could be proposed expansion of environmental infrastructure, sustainable sand & gravel extractions from the riverbed, fortifying the assistance of the residents who live in Dam construction site and the peripheral area of Dam, lower local fund rates in national projects, and the creation of management organization.

• Journal of Urban Science
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• v.8 no.2
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• pp.7-12
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• 2019

In this study, the DongPieHong Ditch were taken as the research object, five sampling points were set to measure the COD, NH₃-N,TNandTPindexes. The correlation and principal component analysis were used to judge the main pollution sources and calculate pollution contribution rate. According to the population in the basin, the load of point source pollution into the river was estimated. As a result, the load of COD, NH₃-N and TP into the river was 323.04t/a, 43.8t/a and 3.9t/a, respectively. According to the statistics of the rainfall in the basin, the concentrations of COD, TP and NH₃-N in the initial rainwater were measured and calculated for non-point source pollution, and the results shown that the inflow loads of COD, NH₃-N and TP into the river were 34.59t/a, 0.12t/a and 0.71t/a, respectively. It was found that the main cause of the pollution in the east flash flood gully was point source pollution, and the proportions of COD, NH₃-N and TP into the river were 90.33%, 99.72% and 84.61%, respectively.

• Journal of Korea Water Resources Association
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• v.54 no.11
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• pp.849-862
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• 2021

Laws, administrative rules, and task manuals have been revised to build a modern river maintenance system in Korea for the last decade. And various researches and technology developments have been carried out to resolve related issues. However, the recent enactment of the new Act and the catastrophe of flood damage in 2020 have accelerated more emphasis on the reorganization and reinforcement of the river maintenance system in terms of political and social aspects. In this study, we suggested promising directions for strengthening the technical and institutional competencies of river maintenance with respect to policy, R&D, planning, and technology. The open discussion was held with the participation of industry, academia, research institutes, and government officials, and all participants conducted the related survey to collect their opinions effectively. These results are expected to be used as a reference to secure the justification for integration of government organizations, planning of R&D, the introduction of new river maintenance, and related technology development when reestablishing and reinforcing the river management system in the future.