• Journal of Korean Society of Water and Wastewater
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• v.20 no.4
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• pp.573-584
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• 2006

This study was carried out to investigate the causes of fish kills in the Yudeung Stream in Daejeon, Korea using literature reviews, governmental and our water quality monitoring data of the study site, rainfall data, intensive water quality monitoring during rainfall events, sediment pollutant contents and laboratory bioassay tests. Fish kill in urban streams can be caused by combined effect of reduction in dissolved oxygen concentration, increase in toxic material or increase in turbidity in waterbody due to introduction of surface runoff or effluent of combined sewer overflows after rainfall from the watershed areas. Despite of extensive and intensive field surveys and laboratory tests, it was found that those conventional methods have limitations to identify causes of fish kills in urban streams. It would be necessary to use dynamic water quality modeling to predetermine the range and level of water pollution in the stream and automatic water quality monitoring system that can collect water samples and detect water quality continuously.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.2
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• pp.49-55
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• 2017

Recently climate change and urbananization have been increased surface runoff, resulting in flooding. Retention basins have been constructed to control urban flooding by reducing peak flow rate. Recently, the retention basin plays a role in controlling combined sewer overflows (CSOs) as well as urban flooding. In this study, the retention basin with a rotatable bucket was suggested and scale down experiments was performed for the optimum design of the retention basin. Scaled down model was produced using a 3D printer after it was designed as law of similarity. Two times for operating a rotary bucket is required to sweep out the sediments deposited on the bottom of the basin. Optimized dimensions for the retention basin were width of 5 m, height of 5 m, bucket radius of 0.5 m, and bottom slope of 5.0 %. It can be concluded that the results obtained from this study can be used to design the retention basin with a rotatable bucket which does not require energy to operate.

• Journal of Korean Society on Water Environment
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• v.25 no.1
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• pp.37-47
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• 2009

This study analyzes the effect of alternatives and estimates alternatives evaluation index (AEI) using PCSWMM and weighted summation method. PCSWMM considering combined sewer overflows (CSOs) in the Mokgamcheon watershed was used and effectiveness analysis of alternative was conducted to develop not only flowrate but also the pollutant of BOD and SS. Indicators of AEI are selected using sustainability evaluation concept, driver-pressure-state-impact-response (DPSIR) framework and calculated by weighted summation method. After estimating AEI, alternatives was classified into three groups G (Good), A (Acceptable) and P (Poor) grade. As a results, it is analyzed that alternatives applied to Oryucheon were G grade and those of Yeokgokcheon were P grade and the remainings were 'A' grade. This result will be effective to the integrated watershed management for sustainablility.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.1
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• pp.159-167
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• 2000

In recent years, combined and separated sewer overflows (CSOs, SSOs) have been recognized as a significant pollution problem. To solve this problem a series of experiments were performed in a small scale Rapid Floc Settler (RFS) device to determine its ability in removing micro particles and dissolved materials from polluted waters. The RFS device is a compact physico-chemical wasterwater treatment system. Polyacrylamide (PAM) is used as a coagulant for treating stormwater in the RFS. The results of Jar test showed that PAM could be an excellent coagulant as compared with aluminum sulfate. and ferric chloride. In several experimental conditions, the influence of different variation parameters was tested to measure the efficiency of the RFS. Tests have been carried out with typical CSOs concentrations (50~1.000mg SS/L). The treatment efficiency with regard to SS and COD, which can be obtained at an overflow rate of $130m^3/m^2/day$, are 90% and 80%, respectively. Comparing other sedimentation technologies with RFS, the overflows rate of RFS is ten times faster. The distribution of particle size and number were analyzed. The RFS is suitable for the treatment of CSOs and also the removal of settleable and dissolved materials in urban stormwater runoff.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.92-96
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• 2008

최근에 이상기후로 인한 집중호우는 단시간의 높은 강우 강도의 발생을 증가시켜 재해 유발의 측면에서 뿐만 아니라 유역 내 비점오염원이 합류식 관거의 월류수인 CSOs(Combined Sewer Overflows)의 형태로 강우와 함께 유입되어 수질 및 환경을 오염시키는 문제점이 발생한다. 이에 따라 월류수의 유출특성에 대한 정량적인 분석을 통하여 유량 및 수질 등의 오염부하량에 대한 적절한 저감 방안이 요구되고 있는 실정이다. 이에 본 연구에서는 비점오염원의 농도가 상대적으로 높은 도시유역에 강우로 인한 월류수의 유출 특성 변화를 분석함과 동시에 월류수가 하천에 방류되었을 때의 하천에 미치는 영향 분석을 통하여 하천의 효율적인 수질 관리 방안을 제시하고자 한다. 경기도 구리시를 대상유역으로 선정하였으며, 도시 강우-유출 모델인 SWMM을 사용하여 유역의 유출량 및 월류수의 수질 모의를 수행하였으며, 유역의 최종 방류구에 비점오염 저감을 위해 설치된 저류지를 통해 하천으로 배출되는 유출수와의 연계는 미국 환경청에서 개발된 WASP 모델을 적용하여 왕숙천 본류에 대한 월류수 변화가 하천에 미치는 영향을 분석하였다. 저류지 설치 전 후의 하천에 월류수가 미치는 영향을 BOD 농도를 중심으로 비교 분석하였다. 분석 결과 저류지 설치 후 BOD 농도의 저감율은 설치 전 보다 최소 1.9%, 최대 81.2%의 저감 효과가 있는 것으로 분석되었다. 향후 신뢰도 높은 수질모의를 위해서는 월류수 발생시 월류수와 하천의 지속적인 모니터링을 통해 현장 여건을 반영할 수 있는 입력변수의 도출이 매우 중요한 것으로 나타났다.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.4
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• pp.443-451
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• 2010

This study was conducted to confirm the CSOs characteristics, and to estimate treatment efficiency of CSO treatment process. Flowrate was average $53,500m^3$/d, maximum $58,100m^3$/d during dry season, but after rain-fall, the flowrate was increased more than twice that of the dry season. And, water pollution concentrations, such as $COD_{Cr}$, SS, $BOD_5$, TN and TP of after rain-fall, were also increased. Thus, for more efficient treatment of pollutants during rainy season, The vortex separator and continuous fiber filter devices were used. From the results on particle range, removal efficiency of particle was 99.7% at the particle size range of $40{\sim}100{\mu}m$ but decreased as 55-80% at the below $40{\mu}m$. The removal efficiencies of $COD_{Cr}$, SS, TN and TP were approx. 70, 60, 70 and 50, respectively during the dry season and approx. 50, 50, 8 and 18% during the rainy season. Also, when compared with the primary sediment basin, $COD_{Cr}$, SS, TN and TP removal efficiencies were high. especially, at the case of TN and TP, TN was more removed than TP because of higher conversion factor value. But we needed more study for the injection of a coagulants to get more stable treatment efficiency for soluble pollutants. Consequently, This process can be used for CSOs treatment as well as replace the primary sedimentation basin during the dry season.

• Journal of Korean Society on Water Environment
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• v.25 no.4
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• pp.615-623
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• 2009

The research of the determination of event mean concentration (EMC) was focussed combined sewer overflows and highway runoff in korea. But those of non-urban areas are few. In this study, EMC and unit loading on land use types in Nogok watershed were estimated by runoff loading of non-point source (NPS) on non-urban area. Two monitoring sites were equipped with an automatic velocity meter, flow meter, and water sampler. Monitoring was conducted at two monitering site during the rainy season. The results show that the EMC ranges in forest land use are 1.3~2.6 mg/L for BOD, 2.0~16.1 mg/L for SS, 0.1~2.1 mg/L for TN, and 0.12~0.49 mg/L for TP. The unit loading of NPS in this study was difficult to compare directly with that used conventionally because of the difference of field investigation. In near future, it needs to conduct more systematic and long-term research about NPS within the watershed. The results of this research can be used to estimate the total pollution load management system (TPLMS) program in korea.

• Journal of Soil and Groundwater Environment
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• v.20 no.1
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• pp.36-40
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• 2015

This study examined the disinfection in combined sewer overflows (CSOs) by pulsed ultraviolet (PUV). The reflectors (stainless steel. mirror, aluminium foil, aluminium (1050), aluminium (6061), aluminium (5052), and aluminium mirror) of PUV irradiation was performed in a 90 L stainless reactor at a constant temperature of $20^{\circ}C$ and an applied power of 4000 W. The reflection efficiency of reflectors were showed 1.00 (aluminium mirror) ~ 1.48 (aluminium foil) does. The case of a rough surface analysis using SEM showed high reflectance, was the case of a smooth surface and a low reflectivity. Pseudo first-order rate constant calculated results, has a higher reflectivity values were more than twice as high compared to the low reflectivity. Affected Total coliforms disinfection time, depending on the type of reflector is considered.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.3270-3278
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• 2014

Many researches has been conducted as extreme rainfall in hydrology and extreme rainfall analysis is not proper for determination of CSOs treatment capacity. In this study, runoff is calculated by tranformation from rainfall to runoff according to Interevent Time Definition. The capacity of sewage treatment plant is designed by 3 times of DWF(Dry Weather Flow) and the efficiency of present sewage treatment plant is very low becauseat at present. Also, The sewage treatment plant can not control CSOs. In this research, the pollution load is calculated by EMC(Event Mean Concentration) and pollution concetration of total runoff is a standard deciding suitablility of present sewage treatment plant. Finally, CSOs treatment capacity is determinated considering pollution load.

• Journal of Korean Society on Water Environment
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• v.35 no.1
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• pp.9-18
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• 2019

Recently, it was realized that a significant portion of pollution from urban areas originates from non-point sources such as construction sites, washoff from impervious surfaces, and sewage input from unsewered areas and combined sewer overflows. Especially, Urban stormwater runoff is one of the most extensive cause of the deterioration of the water quality in streams located in urban area. The objective of this study was to investigate runoff characteristics of non-point pollutants source at the urban area in the Suyeong River. Water quality variations were investigated at two points of Suyeong River during a period of 10 rainfall events. Concentration difference of non-point pollution source appeared big by precedent number of days of no rainfall. In addition, Event mean Concentration (EMCs) that well represents runoff characteristics of storm water during rainfall, was calculated, and runoff pollutants loading was also examined. The probability distribution of EMCs of BOD, COD, TOC, T-N, T-P, and TSS were analyzed and the mean values of observed EMC and the median values of estimated EMCs compared through probability distribution. Other objectives of this study were the characterization of discharge from non-point source, the analysis of the pollutant loads and an establishment of a management plan for non-point source of Suyeong River. Also, It was established that the most important thing for the administration of non-point pollution source is to come up with the solution for the reduction of effluent at the beginning.