• Journal of Environmental Impact Assessment
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• v.23 no.3
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• pp.177-186
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• 2014

Depending on the change of lifestyle and the improvement of people's living standards and rapid industrialization, urbanization of recent, demand for water is increasing rapidly. So emissions of domestic wastewater and various industrial waste water has increased, and water quality is worsening day by day. Therefore, in order to provide a measure against the occurrence of water pollution accident, this study was tried to simulate water pollution accident. This study simulated 2008 Gimcheon phenol accident using 1,2-D model, and analyze scenario for prevent of water pollution accident. Consequently the developed 1-D model presents high reappearance when compared with 2-D model, and has been able to obtain results in a short simulation run time. This study will contribute to the water pollution incident response prediction system and water quality analysis in the future.

• Journal of Environmental Impact Assessment
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• v.3 no.2
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• pp.33-45
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• 1994

Water quality of Chongju and Daejeon Water Intake Tower Region, embayments in Daechong Reservoir was found to be worse than that of main lake after analysis of water which were sampled during April, July, October in 1993. Concentration of COD and SS at those two water intake tower sites were 2.8-5.6 mg/l and 2.2-3.2 mg/l, higher than that of main lake. T-N concentration of those two sites was 1.1-1.9 mg/l similar to that of main lake, and T-P concentration of those two sites was 0.14-0.18 mg/l, higher than that of main lake. This study used water quality model of embayment which can analyse pollutant loads from stream and surrounding land use, advection, decay, and diffusion transport between embayment and main lake. The model can predict water quality of embayment according to the change of pollutant load, water elevation of embayment, quantity of water intake in order to suggest water quality management. This study suggests embayment water quality management alternatives, 1) construction of waste water treatment facilities at embayment and main lake for the decrease of pollutant loading, 2) water intake at main lake less polluted or eutrophicated than embayment, and 3) outflow elevation selection for polluted hypolimnion water outflow during stratification.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.5
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• pp.572-581
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• 2005

This research is conducted to develop predictable method of real scale nanofiltration treatability with small scale nanofiltration experiments. As a result of comparing calculated values with measured values, they are in a good agreement for the concentrations in filtered water and concentrated water. The results of that are not affected by change of system recovery from 20% to 95%. The proposed method is produced using constant recovery of elements, that is, no considering the pressure change. we can predict filtrated flux and contaminant concentrations with the method. The method has the following steps. (1) Calculate recovery of each element with water quality level after fixing recovery elements, (2) Predict system recovery with recovery of elements in 1, 2, 3, and 4 banks, (3) Run small scale nanofiltration experiments in predicted water quality and (4) Simulate large scale nanofiltration system for forecasting actual water quality. As the cost for nanofiltration pretest will reduced if we use the proposed method, it will be a promising method for introducing nanofiltration to supply safe drinking water.

• 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 Korean Society on Water Environment
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• v.38 no.1
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• pp.19-30
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• 2022

Climate change has increased the average air temperature. Rising air temperature are absorbed by water bodies, leading to increasing water temperature. Increased water temperature will cause eutrophication and excess algal growth, which will reduce water quality. In this study, long-term trends of air and water temperatures in the Han-river basin over the period of 1997-2020 were discussed to assess the impacts of climate change. Future (~2100s) levels of air temperature were predicted based on the climate change scenarios (Representative concentration pathway (RCP) 2.6, 4.5, 6.0, and 8.5). The results showed that air and water temperatures rose at an average rate of 0.027℃ year^-1 and 0.038℃ year^-1 respectively, over the past 24 years (1997 to 2020). Future air temperatures under RCP 2.6, 4.5, 6.0, and 8.5 increased up to 0.32℃ 1.18℃, 2.14℃, and 3.51℃, respectively. An increasing water temperature could dissolve more minerals from the surrounding rock and will therefore have a higher electrical conductivity. It is the opposite when considering a gas, such as oxygen, dissolved in the water. Water temperature also governs the kinds of organisms that can live in rivers and lakes. Fish, insects, zooplankton, phytoplankton, and other aquatic species all have a preferred temperature range. As temperatures get too far above or below this preferred range, the number of individuals of the species decreases until finally there are none. Therefore, changes of water temperature that are induced by climate change have important implications on water supplies, water quality, and aquatic ecosystems of a watershed.

• 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 Environmental Impact Assessment
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• v.8 no.1
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• pp.93-105
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• 1999

Lately water quality of Daechong Reservoir has become more eutrophicated than ever before and there has been much concern over especially the eutrophication of the embayment near Daejon and Chongju Water Intake Tower every summer. The purpose of this study is to predict the impact of change in the pollutant loading, flowrate, nitrogen and phosphorus release from sediment, SOD(sediment oxygen demand) upon the water quality of Daechong Reservoir by WASP5/EUTR05 in order to suggest water quality management alternatives. The data of Sep. 1995 were used for the calibration of the model and those of Sep. 1997 was for verification. The result of the modeling can be summarized as follows. 1. The 50% increase(decrease) of pollutant loading has caused that of T-N concentration by 0.10-0.14 mg/l, T-P concentration by 0.003-0.005 mg/l, and CBOD concentration by 0.16-0.18 mg/l. But the ratio of DO change by the change of pollutant loading was relatively small. 2. The sensitivity test of NH4 flux to T-N and that of P04 flux to T-P shows that T-N and T-P concentration were changed more in the epilimnion segments (SEG4, SEG5, SEG6, SEG7) than the other segments. As SOD increases, DO was predicted to decrease more especially in the hypolimnion (SEG9-SEG14). 3. As flowrate increase, the concentration of T-N, T-P, and CBOD were predicted to decrease, but DO concentration increased especially in the hypolimnion segments(SEG11, SEG12, SEG13, and SEG14). As the flowrate changed from $119m^3/sec$ to $50m^3/sec$, the concentration of T-N and CBOD in the hypolimnion was predicted to decrease.

• Journal of Korea Water Resources Association
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• v.45 no.11
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• pp.1121-1130
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• 2012

Projected changes and their impacts on water quality are simulated in response to climate change stressors. CGHR (T63) simulation on the A1B scenario is converted to regional scale data using a statistical down-scaling method and applied to SWAT model to assess water quality impacts in Nakdong River basin. The results demonstrate that rainfall-runoff and pollutant loading in the future (2011~2100) will clearly increase as compared to the last 30-year average. The rate of pollutant loading increase is expected to continue its acceleration until 2040s. Runoff also shows similar patterns to the precipitation, increasing by 60%. Accordingly, the runoff increase results in escalation of pollutant loading by 35~45% for TSS and 5~20% for T-P. This phenomenon is more pronounced in the upper basin during winter and spring season.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.563-567
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• 2004

During drought season, the self-purification capacities of the four major rivers in Korea are significantly controlled by environmental maintenance flows supplied from the mid- or upstream large dams. Therefore, it is obviously important to operate the dams considering not only water quantity aspects but also conservation of downstream water quality and aquatic ecosystems. Mathematical water quality models can be efficiently used to serve as a decision support tool for evaluating the effects of operational alternatives of upstream dams on the downstream aquatic environment. In this study, an unsteady one-dimensional water quality model, KORIV1-WIN was developed based on the theoretical and numerical algorithms for hydrodynamics and water quality simulations of CE-QUAL-RIV1. It consists of hydrodynamic(KORIV1H) and water quality(KORIV1Q) modules, and pre- and post-processors for input data preparations and output displays. The model can be used to predict one-dimensional hydraulic and water quality variations in rivers with highly unsteady flows such as dam outflow change, rainfall-runoff, and chemical spill events.

• Journal of Industrial Technology
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• v.36
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• pp.9-16
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• 2016

In the face of increasing impact of climate change due to human activities, there has been an urgent need to resolve the problem in water resources planning management and environmental engineering. Therefore SWAT model was used to identify the impacts and change in hydrological cycle and environmental aspect. The most important step for the development of SWAT model is calibration procedure. Therefore, SWAT-CUP automatic calibration module was used to find some optimal parameters in SWAT model. After calibration in the cheongmicheon basin, SWAT model is used for the projected precipitation and temperature of RCP 4.5 and 8.5 climate change scenarios in AR5. The quantity and quality using SWAT model from 2014 to 2100 were identified. Finally, this study can provide the reasonable finding on impact by climate change.