• Water Engineering Research
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• v.3 no.2
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• pp.143-153
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• 2002

As the natural flows in rivers dramatically decrease during drought season in Korea, a deterioration of river water quality is accelerated. Thus, consideration of downstream water quality responding to changes in reservoir release is essential for an integrated watershed management with regards to water quantity and quality. In this study, water quality models based on artificial neural networks (ANNs) method were developed using historical downstream water quality (rm $\NH_3$-N) data obtained from a water treatment plant in Geum river and reservoir release data from Daechung dam. A nonlinear multiple regression model was developed and compared with the ANN models. In the models, the rm NH$_3$-N concentration for next time step is dependent on dam outflow, river water quality data such as pH, alkalinity, temperature, and rm $\NH_3$-N of previous time step. The model parameters were estimated using monthly data from Jan. 1993 to Dec. 1998, then another set of monthly data between Jan. 1999 and Dec. 2000 were used for verification. The predictive performance of the models was evaluated by comparing the statistical characteristics of predicted data with those of observed data. According to the results, the ANN models showed a better performance than the regression model in the applied cases.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.695-700
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• 1999

Stream and groundwater qualities of two rural watershes in the upper North Han river basin were monitored for 14months. Six to eight stream sampling sites and two to there groundwater monitoring wells were chosen and water samples were regularyl collected and analyzed with respect to total nitrogen(T-N), total phosphorus(T-P) and total suspended solids(TSS). Monitoring data were graphically analyzed with respect to time.Rainfall amout and intensity seemed to have an impact on stream T-N and T-P concentration changes. TSS concentrations were generally lower than the first class stream water quality standared, Both stream and groundwater qualities near livesstock feetlot areas were degraded indicating the feedlots have an impact on water quality.

• KCID journal
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• v.4 no.2
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• pp.25-37
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• 1997

Flow rate and selected water quality of 2 small rural streams located in Kangwon-do, Korea, were monitored and land use of the watersheds was investigated to describe the trend of stream water quality for 2 years. Water qualities were analyzed with respec

• KCID journal
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• v.11 no.2
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• pp.82-94
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• 2004

This study was carried out to investigate the change of stream water quality in the downstream of the Mangyeong river. Water samples were taken at 6 sampling sites for 11 months from November,2003 to September,2004. Water quality was analyzed with respect

• Journal of Environmental Science International
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• v.31 no.5
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• pp.373-388
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• 2022

This study analyzed the temporal and spatial characteristics of water quality for five hydropower dam reservoirs in South Korea. Water temperature, pH, dissolved oxygen, and chlorophyll-a (Chl-a) showed high fluctuations in summer and autumn at all reservoirs, indicating the existence of seasonal effects. At all five reservoirs, the concentrations of suspended solids (SS) and total nitrogen (TN) fell under the "slightly bad" category and those of total organic carbon (TOC) fell under the "slightly good" category or higher, according to "the standard for living environment of lake water quality." Variations in the concentration ranges and degrees of change in SS, TN, and TOC among reservoirs were observed, indicating the influences of rainfall, surrounding environments, and seasonal changes. Daecheong and Namgang Dam showed high Chl-a concentrations in summer, indicating that the metabolism of microbial communities, such as algae, was active.

• Journal of the Korean earth science society
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• v.43 no.1
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• pp.110-118
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• 2022

Frequent drought damage has resulted in the polarization of water resources. In Korea, local periodic abnormal droughts continued to occur between 2011 and 2017, resulting in decreased water storage rates of small-scale reservoirs designed with a frequency of 10-year droughts. This decrease can degrade water quality and limit the use of already secured quantities. Therefore, to prepare for and overcome drought, quality management and recalculation of drought frequency are required. This study estimates the potential pollutants causing quality changes in the reservoir. In addition, it reviews the decrease in storage and consequent changes in the quality of a reservoir during drought.

• Journal of Environmental Health Sciences
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• v.31 no.6
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• pp.489-497
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• 2005

A numerical method for the mathematical water modeling in 2-dimensional flow has been developed. The model based on a split operator technique, in which, the advection term is calculated using the upwind scheme. The diffusion term is one- dimensionalized and calculated using Crank-Nicholson's implicit finite difference scheme to reduce the numerical errors from large time steps and variable spacings. It also provides a relatively simple and economic method for more accurate simulation of pollutant dispersion. Water depths and flow velocities in the Boreyong reservoir during the normal water periods were predicted by numerical experiments with a 2-dimensional flow model so as to provide current field data for the study of advection and diffusion of pollutants. Developed 2-dimensional water quality model is applied to Boreyong reservoir to simulate a spatial and periodical changes of water quality.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.532-533
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• 2005

• Journal of Ocean Engineering and Technology
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• v.22 no.2
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• pp.34-41
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• 2008

As a basic study for developing a forecasting/estimating system that predicts water quality changes when Deep Sea Water (DSW) drains to the ocean after using it, this study was carried out as follows: 1) numerical simulation of the present state at DSW developing region in the East sea using SWEM, 2) numerical prediction of water quality changes by effluent DSW, 3) analysis of influence degree 'With defined DEI (DSW effect index) at F station. On the whole, when DSW drained to the ocean, Chl-a, COD and water-temperature were decreased and DIN, DIP and DO were increased by effluent DSW, and Salinity was steady. According to analysis of influence degree, the influence degree of DIN was the highest and it was high in order of Chl-a, COD, Water-temperature, DO, DIP and Salinity. The influence degree classified by DSW effluent position was predicted that suiface outflow was lower than bottom outflow. Ad When DSW discharge increased 10 times, the influence degree increased about $5{\sim}14$ times.

• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.697-704
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• 2007

This study proposes an integrated technique of Genetic Algorishim (GA) and Geographic Information System (GIS) for designing the water quality monitoring networks. To develop solution scheme of the integrated system, fitness functions are defined by the linear combination of five criteria which stand for the operation objectives of water quality monitoring stations. The criteria include representativeness of a river system, compliance with water quality standards, supervision of water use, surveillance of pollution sources and examination of water quality changes. The fitness level is obtained through calculations of the fitness functions and input data from GIS. To find the most appropriate parameters for the problems, the sensitivity analysis is performed for four parameters such as number of generations, population sizes, probability of crossover, and probability of mutation. Using the parameters resulted from the sensitivity analysis, the developed system proposed 110 water quality monitoring stations in the Nakdong River. This study demonstrates that the integrated technique of GA and GIS can be utilized as a decision supporting tool in optimized design for a water quality monitoring network.