• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.544-544
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• 2015

국내에는 17,500여개의 농업용 저수지가 전국적으로 분포하고 있으며, 이들 저수지는 인공호소이다. 농업용 저수지의 총 유효저수량은 2,838백만$m^3$에 달하고 있으며, 전체 수리답의 약 76%에 해당하는 593천ha의 농경지에 물을 관개하고 있다(2013농업생산기반통계연보). 최근 농어촌지역의 도농복합형태 개발 및 관광지, 유원지화로 농업용 저수지 유역의 오염원이 지속적으로 증가하는 추세에 있으며, 이로 인해 농업용수 수질이 지속적으로 악화되고 있다. 특히, 늦봄에서 초가을까지 외기온도 상승 및 저수율 저하와 함께 부영양화 증가, 녹조 대발생 등으로 수질오염도가 급상승하고 있으며, 이로 인해 호 내 물고기 폐사, 악취발생 등으로 민원이 다수 발생하고 있다. 본 연구에서는 농업용 저수지의 물리적 특성을 분석하여 농업용 저수지 수질개선을 위한 기초자료로 활용하고자 하였다. 농업용 저수지 17,489개소를 수혜면적별로 분류해 보면 5ha이하가 7,808개소(44.7%), 5~10ha이하 4,277개소(24.5%), 10~20ha 2,772개소(15.9%), 20~30ha 797개소(4.6%), 30~40ha 385개소(2.2%), 40~50ha 238개소(1.4%), 50ha이상 1,201개소(6.9%)로 구성되어 있어 50ha이하가 전체의 93.1%에 이르고 있다. 유효저수량별 분포현황은 10천$m^3$이하가 7,996개소(45.7%), 10~50천$m^3$ 6,420개소(36.7%), 50~100천$m^3$ 1,003개소(5.7%), 100~300천$m^3$ 868개소(5.0%)로 전체 시설 중 50천$m^3$이하가 전체 저수지의 82.4%로 대부분이 소규모 저수지임을 알 수 있다. 농업용 저수지를 유효수심별로 구분해보면 1m이하가 전체의 26.6%, 3m이하가 전체의 77.1%, 5m이하가 전체의 91.1%로 국내 대부분의 저수지들은 수심이 5m 이하의 저류지 형태의 저수지임을 알 수 있다. 저수지를 유역배율(유역면적/만수면적)에 따라 구분해보면 유역배율 3이하가 전체의 1.2%이고, 5이상이 전체의 97.4%를 차지하고 있다. 일반적으로 유역배율이 3이상이면 부영양화에 취약한 호소로 분류되고 있다. 국내 농업용 저수지는 대부분이 수심이 낮고, 유효저수량이 소규모이며, 유역배율이 3이상인 호소가 대부분으로 태생적으로 수질오염 및 부영양화에 취약한 구조로 되어 있음을 알 수 있다. 농업용 저수지 수질개선을 위한 종합계획 수립시에는 유입수 및 호내 대책과 함께 호소의 물리적 조건을 개선시키는 방안에 대해서도 검토가 요구된다. 특히 저수지 신규 설치시에는 수량관리 뿐만 아니라 수질도 함께 고려된 물리적 인자에 대한 설계가 이루어져야 할 것으로 판단된다.

• Journal of Wetlands Research
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• v.15 no.3
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• pp.387-396
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• 2013

Non-point pollution source is difficult to control due to uncertain outflow path and emission. So, There are many development and research to Best Management Practices(BMP) established to manage the Non-point pollution source. Besides, various methods of estimated efficiency to exact assessment of BMP is presented. In this study, the impact about length of Grassed Swale on reduction efficiency based on monitoring results of Grassed Swale by length is studied. By estimating Grassed Swale reduction efficiency in a variety of methods, the difference between the methods of estimated efficiency was compared with those that. Estimated efficiency method using ER, SOL, ROL, ROF, SOLF, and ROLF methods is analyzed. EMC analysis result is high inflow and outflow concentration distinction organic compound for nutritive salts The result of efficiency analysis along Grassed Swale length sharply increases in a Grassed Swale inlet. After this increase, the efficiency gradually decreases. This is expected that cistern installed in the end of the front. To obtain a stable reduction efficiency of Grassed Swale, minimum length 30m of Grassed Swale should be enough. Also, in order to efficiently and economically design Grassed Swale, the researches on length of Grassed Swale are needed rather than simple analysis of efficiency.

• Journal of Korea Water Resources Association
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• v.51 no.11
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• pp.977-987
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• 2018

The purpose of the water distribution system is gradually changing to increase the flexibility for responding to various abnormal situations. In addition, it is essential to improve resilience through preparing emergency plans against water supply failure. The most efficient way is emergency interconnections which supply water from interconnected adjacent blocks. To operate successful interconnections, it is essential to evaluate the supply performance in spatial and temporal aspects. The spatial and temporal aspects are dominated by its interconnected pipes and interconnected reservoirs respectively. In this study, an emergency interconnection scenario where problem occurred in reservoir 1 at 0:00hr in A city, Korea. An Advanced-Pressure Driven Analysis model was used to simulate the volume and inflow volume of the interconnected reservoirs. Based on the hydraulic analysis results, a multi-dimensional evaluation of the supply performance was conducted by applying possible water supply range indicator (PWSRI) and possible water supply temporal indicator (PWSTI) which are based on fuzzy membership functions. As a result, it was possible to evaluate the supply performance on the sides of consumers in spatio-temporal aspects and to review whether established plans mitigate the damage as intended. It is expected to be used for decision making on structural and non-structural emergency plan to improve the performance of an emergency interconnection.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.257-266
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• 2021

Urban areas can often suffer flood damage because of the more frequent catastrophic rainfall events from climate change. Flood mitigation measures consist of (1) structural and (2) non-structural measures. In this study, the proposed method focused on operating an urban drainage system among non-structural measures. The combined inland-river operation technique estimates the inflow of pump stations based on the water level obtained from a preselected monitoring point, and the pump station expels the stored rainwater to the riverside based on those estimates. In this study, the proposed method was applied to the Mokgam drainage watershed, where catastrophic rainfall events occurred (i.e., 2010- and 2011-years), and severe flood damage was recorded in Seoul. Using the proposed method, the efficiency of flood reduction from the two rainfall events was reduced by 34.9 % and 54.4 %, respectively, compared to the current operation method. Thus, the proposed method can minimize the flood damage in the Mokgam drainage watershed by reserving the additional storage space of a reservoir. In addition, flooding from catastrophic rainfall can be prevented, and citizens' lives and property in urban areas can be protected.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.5
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• pp.137-145
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• 2008

In this study, to reduce the flood damage caused by flood discharge exceeding project flood, the primary technology was applied to determining the optimal location and size for underground sluiceway. The Jungrang Stream was selected for this study because the stream was overflowed and the embankment section of the stream was destroyed owing to localized torrential rainfall in 1998 and 2001. Considering 200-year frequency storm, the inlets of the underground discharge channel were located at Seoul City limits, the confluence of Danghyun Stream, Wolgye 1-gyo, and the confluence of Mukdong Stream. The outlets were located at the estuary of Jungrang Stream and rightbank of Banpo Bridge in Han River. The transverse discharge according to the variation of overflow depth at the inlet of underground discharge channel was estimated and the effect of inundation reduction was analyzed. To examine the appropriate scale of the underground discharge channel, the 8 operation methods for the management of outlet discharge were compared considering four rules (only storage, the constant discharge rate, the constant discharge volume, and the mixture of the constant discharge rate and discharge volume). As a result, the effect of inundation reduction was most significantly improved when the inlet was located at the confluence of Danghyun Stream. The appropriate size of underground sluiceway for 200-year frequency storm was studied, and as a result, the appropriate diameters of the underground discharge channel were 12 m in case of only storage(Rule D), 9m in 50% of discharge(Rule E), 8 m in constant discharge volume(Rule F), and 7 m in mixture method(Rule G). This investigation process can be applied to design the underground discharge channel when the inundation damage is significant in coastal area due to embankment overflow. The underground discharge channel in Jungrang Stream can also be used as an underground road to link Seoul City to Uijeongbu City during dry season.

• The Journal of Engineering Geology
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• v.22 no.2
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• pp.195-205
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• 2012

We evaluated the results of pumping tests, the amount of groundwater used by Protected Cultivation with Water Curtain (PCWC), and monthly depth to water table (DTW) at the Wangjeon-ri area, Nonsan City, to elucidate the cause of a decrease in pumping rate during the winter PCWC season. The transmissivity and storage coefficient at eight sites where the major aquifer is alluvium, vary from 119.9 to $388.1m^2/d$ and $1.5{\times}10^{-4}$ to $5.5{\times}10^{-4}$, respectively. The pumping rate for PCWC during three months (Dec. to Feb.) averaged about $8,100m^3/d$ and the maximum water level in the area varied by about 10 m. Groundwater levels had fully recovered by August-five months after pumping for PCWC had ceased. These observations indicate that the pumping rate during the winter PCWC season was excessive compared with groundwater productivity in the area. Groundwater level in the central PCWC area varied from -3.0 to 4.38 m, exceeding the water level of the Nosung Stream for only three months (Aug. to Oct.). This result indicates that Nosung Stream recharges the area during the period from November to July. To solve the problem of reduced pumping rate during the winter PCWC season, it would be necessary to reduce the amount of groundwater used for PCWC or to develop an artificial recharge system using recycled groundwater.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.2
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• pp.126-135
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• 2015

Increase of delivery effect of pollutant loads and surface runoff due to urbanization of catchment area results in serious environmental problems in receiving urban streams. This study aims to develop integrated stormwater management system to assist efficient urban stream flow and water quality control using information from the Storm Water Management Model (SWMM), real time water level and quality monitoring system and remote or automatic treatment facility control system. Based on field observations in the study site, most of the pollutant loads are flushed within 4 hours of the rainfall event. SWMM simulation results indicates that the treatment system can store up to 6 mm of cumulative rainfall in the study catchment area, and this means any type of normal rainfall situation can be treated using the system. Relationship between rainfall amount and fill time were developed for various rainfall duration for operation of stormwater treatment system in this study. This study can further provide inputs of river water quality model and thus can effectively assist integrated water resources management in urban catchment and streams.

• Journal of the Korean Geotechnical Society
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• v.30 no.6
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• pp.23-39
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• 2014

An artificial rainwater reservoir installed in urban areas for recycling rainwater is an eco-friendly facility for reducing storm water effluence. However, in order to recycle the rainwater directly, the artificial rainwater reservoir requires an auxiliary system that can remove non-point source pollutants included in the initial rainfall of urban area. Therefore, the conventional soil filtration technology is adopted to capture non-point source pollutants in an economical and efficient way in the purification system of artificial rainwater reservoirs. In order to satisfy such a demand, clogging characteristics of the sand filter layers with different grain-size distributions were studied with real non-point source pollutants. For this, a series of lab-scale chamber tests were conducted to make a prediction model for removal of non-point source pollutants, based on the clogging theory. The laboratory chamber experiments were carried out by permeating two types of artificially contaminated water through five different types of sand filter layers with different grain-size distributions. The two artificial contaminated waters were made by fine marine-clay particles and real non-point source pollutants collected from motorcar roads of Seoul, Korea. In the laboratory chamber experiments, the concentrations of the artificial contaminated water were measured in terms of TSS (Total Suspended Solids) and COD (Chemical Oxygen Demand) and compared with each other to evaluate the performance of sand filter layers. In addition, the accumulated weight of pollutant particles clogged in the sand filter layers was estimated. This paper suggests a prediction model for removal of non-point source pollutants with theoretical consideration of the physical characteristics such as the grain-size distribution and composition, and change in the hydraulic conductivity and porosity of sand filter layers. The lumped parameter ${\theta}$ related with the clogging property was estimated by comparing the accumulated weight of pollutant particles obtained from the laboratory chamber experiments and calculated from the prediction model based on the clogging theory. It is found that the lumped parameter ${\theta}$ has a significant influence on the amount of the pollutant particles clogged in the pores of sand filter layers. In conclusion, according to the clogging prediction model, a double-sand-filter layer consisting of two separate layers: the upper sand-filter layer with the effective particle size of 1.49 mm and the lower sand-filter layer with the effective particle size of 0.93 mm, is proposed as the optimum system for removing non-point source pollutants in the field-sized artificial rainwater reservoir.