• Journal of Korean Society on Water Environment
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• 제26권3호
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• pp.387-398
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• 2010

SWAT model would be applied to evaluate the pollutant removal capacity with various best management practices (BMPs) in Kyongan stream watershed which plays an important role in water quality conservation and improvement of Paldang reservoir. The methods for the representation of various BMPs scenarios with SWAT is developed and evaluated. Riparian buffer strip, agricultural conservation practices to reduce fertilizer, sediment, and nutrients occurring from farm field (Grassed swale, Contour farming/Parallel terrace, Field border, Farm retention pond, Grade stabilization structure), and washland such as wetland and pond to extend detention and improve water quality are represented in SWAT. And to represent the expansion of existing Waste Water Treatment Plants (WWTPs) in Soil and Water Assessment Tool (SWAT), reduction effect for point source pollutants was simulated. As the result of simulation, the removal rates of SS, TN, TP from scenarios of Kyongan stream watershed are the average annual SS yield by 5.2% to 69.2%, the average annual TN yield by 0.5% to 26.3%, and the average annual TP yield by 1.3% to 32.5%, respectively. This study has demonstrated that the SWAT is a very reliable and useful water quality and quantity assessment tool, and the BMPs representation in SWAT for watershed management is able to effectively simulate in Kyongan Stream watershed.

• Journal of Environmental Science International
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• 제14권1호
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• pp.23-32
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• 2005

Surface sediments (0$\~$4 cm) were sampled at 40 stations from Ulsan Bay and its adjacent areas of Korea, to evaluate the contamination by sewage-derived organic matters using fecal sterols. Some sterols were quantified by gas chromatography coupled to mass spectrometry (GC/MS). Total concentrations of eight sterols (co­prostanol, cholesterol, cholestanol, epicholestanol, epicoprostanol, ${\beta}-sitosterol,$ brassicasterol, and stigmasterol) in the sediments from Ulsan Bay and its vicinity varied from 929 to 23,444 ng/g dry weight. The most predom­inant sterols were cholesterol and coprostanol, accounting for $33\~72{\%}$ of total sterols. The concentration of coprostanol known as the indicator of human feces ranged from 141 to 8,257 ng/g dry weight. In particular, the coprostanol concentrations in the sediments from Jansaengpo Harbor and Taehwa River exceeded the value of 1,000 ng/g dry weight, suggesting that these areas could be considered as the hot-spot zones by municipal sewage contamination. Some molecular indices and multivariate data analysis were used to assess the origin of these sterols in the sediments. Results showed that the major routes of sewage contamination in Ulsan Bay and its vicinity were the input through Jansaengpo Harbor and Taehwa River.

• Journal of Korean Society of Water and Wastewater
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• 제25권3호
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• pp.391-398
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• 2011

This study is to develop highly efficient coagulation system(HECS) that runs treatment with a short retention time to cover the overflow in the rain, which coagulation, mixing and settling are contacted in a single reactor and to estimate the applicability. Setting up 100ton/day-size pilot scale plant, the results of continuous operation in case of runoff, maintaining 20 minute-retention time at optimum chemical injection condition(Alum 100mg/L, Polymer 1.0mg/L) shows the highest removal efficiency(Turbidity 93.1%, TCODcr 80.6%, BOD 81.8%, SS 92.5%, TN 72.3% and T-P 87.3%). It was estimated that the large amount of cost for separate sewage system and the size of area for system instruction can be reduced if the HECS is applied for CSOs treatment because the HECS is so compact and quickly. When we see the results, HECS from this study could be able to treat the pollutant quickly within a short retention time only with coagulant and polymer, which could show high applicability.

• Proceedings of the Korea Water Resources Association Conference
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• 한국수자원학회 2011년도 학술발표회
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• pp.347-347
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• 2011

하천에서의 유사량의 추정은 하천유사 해결을 위한 자료획득이 기본이고, 하천내의 수리구조물의 설계 및 유지관리, 하천개수 및 하도의 안정, 홍수터 관리, 저수지의 설계 및 운영 등 하천계획에 필요한 기본적 요소 중 하나이다. 유사량을 추정하는 방법은 Einstein(1950) 공식이나 Toffaleti(1968) 공식 등과 같은 하천 유사량 공식을 이용한 간접적인 계산방법과 현장 실측을 통한 직접적인 방법이 있다. 그러나 유사량 공식을 이용한 추정은 아직도 그 신뢰성이 떨어지며, 대부분의 기존 유사량 공식들이 하상토 유사량을 위주로 추정하여, 소류사가 지배적인 경우에는 이런 공식들을 이용하여도 어느 정도 신뢰성이 확보되는 결과를 얻을 수 있을 것으로 판단되나, 부유사가 지배적인 하천의 경우 정확도가 많이 떨어지는 것으로 알려져 있다. 따라서, 현재까지 가장 신뢰할 수 있는 방법은 현장실측에 의한 방법이며, 유사량 공식은 부득이한 경우에만 이용하는 것이 바람직하다. 실측 유사량 산정을 위하여 하천 규모에 따라 구분하였으며, 국가하천인 경우 임진강을 대상으로 민간인 출입이 가능한 구간(L = 84.5km), 중소규모하천인 경우 안성천 수계의 황구지천과 인천의 계양천을 대상으로 하였고, 임진강의 경우에는 부유사의 대부분이 이토나 점토로 구성되어 있고 중 상류에서 하상재료의 구성이 대체로 호박돌이나 암반으로 이루어진 부분이 많아 주로 모래로 이루어진 충적하천에서 이용되는 수정 Einstein(1955) 방법에 의한 총 유사랑 추정은 의미가 없기 때문에(한국건설기술연구원, 1992) 본 조사에서는 임진강의 총유사량을 부유사양으로 간주하였으며 다른 유사량 공식을 이용한 부유사량과 비교를 통하여 공식을 제안하였다. 유사량 측정은 하천별로 2007년부터 2009년까지 평수기와 홍수기로 구분하여 측정하였으며, 수리량과 하상토자료를 이용하여 종유사량을 산정하는 Einstein(1950) 공식, Rijn(1984) 공식, Toffaleti(1968) 공식, Shen & Hung(1971) 공식, Yang(1973) 공식, Yang(1979)공식, Ackers & White(1973) 공식, Engelud & Hansen(1967) 공식, Ranga Raju(1981) 공식을 이용하여 결과 값을 비교하였다.

• Journal of Korea Water Resources Association
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• 제48권3호
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• pp.233-243
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• 2015

The bimodal flocculation of cohesive sediments in water environments describes the aggregation and breakage process developing a bimodal floc size distribution with dense flocculi and floppy flocs. A two class population balance equation (TCPBE) was tested for simulating the bimodal flocculation by a model-data fitting analysis with two sets of experimental data (low and high turbulent flows) from 1-D flocculation-settling column tests. In contrast to the Single-Class PBE (SCPBE), the TCPBE could simulate interactions between flocculi and flocs and the flocculation mechanism by differential settling in a low turbulent flow. Also, the TCPBE could perform the same quality of simulation as the elaborate Multi-Class PBE (MCPBE), with a small number of floc size classes and differential equations. Thus, the TCPBE was proven to be the simplest model that is capable of simulating the bimodal flocculation of cohesive sediments in water environments and water, wastewater treatment systems.

• Journal of Korean Society on Water Environment
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• 제29권5호
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• pp.656-665
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• 2013

This research was conducted to investigate pollutant load unit factor from aquacultural farms. Pollutant load unit factors were investigated on the 13 kinds of fish type, i.e., Trout, Leather Carp, Eel, Carp, Cartfish, Freshwater Eel, Crucian Carp, Colored Carp, Sturgeon, Marsh Snail, Sweetfish, Pond Snail, Eriocheir Sinensis. Water qualities in aquacultural farms were investigated wide range of values by fish type and pollutant items. High BOD and COD values were observed at the Leather Carp (Ponded water system), Cartfish (Ponded water system) and Freshwater Eel (Recirculating System). TOC and DOC values were relatively high at the Freshwater Eel (Recirculating System) and Eriocheir Sinensis (Extensive). Eel (Ponded water system) and Freshwater Eel (Recirculating System) produced high concentrated nutrient pollutants, i.e., T-N, T-P. Pollutant load unit factors are dependent on fish type, aquacultural type, water quality items, etc. If some fishes have similar basic unit values, those could be applied for TMDLs as a group of fish having same pollutant load unit. The water quality concentrations of post treatment facilities' (mainly reservoir tank) effluent were higher than those of fish raising bath because of extracting pollutant from sediment in the reservoir tank. Therefore, it needs to the management and regulations about post treatment facilities.

• Journal of Korean Society of Water and Wastewater
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• 제24권5호
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• pp.629-639
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• 2010

To evaluate the performance of high rate coagulation system(HRCS) for CSOs treatment, fundamental function of lab scale HRCS has been tested by using the Jar tester and lab scale HRCS. The optimum pH dose by Streaming Current value was found in the range of 5.3~6.0 in Fe(III), and in the range of 5.8~6.6 in Al(III) and the optimum chemical dose were 0.44mM of $Al_2(SO_4)_3$ and 0.93mM of $FeCl_3$. The removal efficiencies at optimum $Al_2(SO_4)_3$ dose were 75%($TCOD_{Cr}$), 97%(TP), 95%(SS) and 96%(turbidity), respectively. And the removal efficiency of particles with less than $5{\mu}m$ of diameter was 70% and that of particles with higher than $5{\mu}m$ of diameter was 90%. The optimum alum dose in lab scale HRCS was 150mg/L, and the treatment efficiency was the best with addition of 1.0mg/L polymer. The effect of Micro sand addition was not clear, because the depth of the sediment tank in lab scale HRCS was not long enough. But the HRT of this lab scale HRCS was able to be shorten less then 7 minutes by adding the micro sand. The surface loading rates with respect to using different chemicals were 0.43m/h with alum only, 5.78m/h with alum and polymer and 6.22m/h with alum, polymer and micro sand. As a result, HRCS using coagulant, polymer and micro sand developed in this study was evaluated to be very effective for CSOs treatment.

• Proceedings of the Korea Water Resources Association Conference
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• 한국수자원학회 2010년도 학술발표회
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• pp.605-609
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• 2010

기상변화와 지구온난화로 인해 국지성 호우의 강도와 빈도가 늘어나고 있으며 이로 인해 소양강, 도암댐, 임하댐 유역의 탁수 문제 등, 토양 유실에 관한 문제가 심각해지고 있다. 정확한 토양 유실 모의를 위하여 지난 수 십 년간 Universal Soil Loss Equation(USLE) 등의 모형이 사용되었지만 이러한 모형들에 관한 연구 중 강한 집중 호우에 의해 발생하는 걸리 침식(Gully Erosion)을 적용한 경우는 많지 않다. 이에 본 연구에서는 걸리 침식을 고려한 토양 유실량 및 유사량 산정을 위하여 입력자료가 간단하고 ArcView GIS를 기반으로 융합이 가능한 Sediment Assessment Tool for Effective Erosion Control (SATEEC) system, nLS, Unit Stream Power-based Erosion/Deposition (USPED) 연계 모형을 개발하여 강원도 양구군 해안면 유역에 적용하였다. 기존 SATEEC system에서는 강우 시 유역에서 발생하는 면상 침식(Sheet Erosion), 세류 침식(Rill Erosion)의 모의만이 가능하였지만, 본 연구에서 개발한 연계모형에서는 nLS 모형을 이용한 걸리 헤드 발생 지역 선정과 USPED 모형을 이용한 걸리 발생 지역에서의 토양 유실량 산정이 가능하기 때문에, 걸리 침식을 고려한 토양 유실량 산정이 가능하다. 연계 모형의 모의 결과 해안면 유역의 최종 유출구에서 발생하는 평균 유사량은 101,933 ton/year 로 산정 되었다. 토양 유실량과 유사량을 모의함에 있어, 면상, 세류, 걸리 침식을 종합적으로 고려해야 실제 지형에서 발생하는 토양 유실량 및 유사량을 좀 더 정확하게 예측할 수 있을 것이며, 본 연구에서 개발된 연계 모형을 이용한다면 실제 유역에서 발생하는 여러 형태의 토양 유실을 모의 할 수 있을 것이라 판단된다.

• Proceedings of the Korea Water Resources Association Conference
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• 한국수자원학회 2012년도 학술발표회
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• pp.48-48
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• 2012

유역 내 고농도의 탁수문제는 수자원의 효용 가치 하락, 댐 기능의 저하 및 관광 자원으로써의 가치 하락으로 인한 경제적 손실을 발생시킨다. 또한 자원으로서의 토양손실을 야기시켜 토양 재조성을 위한 시간적, 비용적 문제를 발생시킨다. 하천의 탁수저감, 자원으로써의 토양 보전 관리를 위해서는 토양유실 저감 대책을 세우는 것이 필요하며, 이를 위해서는 정확한 토양유실량 및 유사량을 평가하여야 한다. 토양유실량 및 유사량을 평가하기 위해 Sediment Assessment Tool for Effective Erosion Control (SATEEC)이 널리 사용되어 오고 있으며, SATEEC System은 다양한 모듈 보완을 통하여 현재 SATEEC System ver. 2.2까지 개발되었다. SATEEC System ver. 2.2는 시공간변화를 고려한 일단위 R factor산정이 가능하며, 이 R factor산정 모듈은 단일강우를 고려할 수 있는 Williams, Foster, Cooley, CREAMS의 R factor산정 공식을 기반으로 하고 있다. 그리고 SATEEC System ver. 2.2에서는 같은 속성의 셀에 대해서는 함께 연산이 이루어지기 때문에, 유역의 크기나 셀크기에 상관없이 최대 연산시간은 비슷하다. 본 연구에서는 이렇게 개발된 SATEEC System ver. 2.2룰 이용하여 낙동강 수계에 위치한 임하댐유역의 유사량을 평가하였으며, 유사량 평가를 위한 유달률 산정을 위하여 유전자 알고니즘 기반의 SATEEC SDR모듈을 사용하였다. 유사량 평가 결과 보정기간동안 $R^2$ = 0.591, NSE = 0.573, 검정기간 동안 $R^2$ = 0.927, NSE = 0.911로 높은 적용성을 보이는 것으로 나타났다. 본 연구에서 사용된 SATEEC System ver. 2.2는 표토 보전 및 관리를 위한 예비 단계 평가 툴로 활용될 수 있을 것이라 판단된다.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.799-802
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• 2008

General behaviors based on hydraulic characteristics of natural streams and channels have been recently analyzed and developed via various numerical models. However in the states of natural hydraulics, an experimental research must be performed simultaneously with the mathematical analysis due to effects of hydraulic properties such as meander, sediment, and so on. In this study based on 2-D advection-dispersion equation, flow and tracer experiments were performed in the S-curved meandering laboratory channel with a rectangular cross-section. The channel was equipped with instrument carriages which was equipped with an auto-traversing system to be used with velocity measuring sensors throughout the depth and breadth of the flow field. To measure concentration distribution of the salt solution was adjusted to that of the flume water by adding methanol and a red dye (KMnO4) was added to aid the visualization of the tracer cloud, the tracer was instantaneously injected into the flow as a full-depth vertical line source by the instantaneous injector and the initial concentration of the tracer was 100,000 mg/l. The secondary current as well as the primary flow pattern was analyzed to investigate the flow distribution in the meandering channels. The velocity distribution of the primary flow for all cases skewed toward the inner bank at the first bend, and was almost symmetric at the crossovers, and then shifted toward the inner bank again at the next alternating bend. Thus, one can clearly notice that the maximum velocity occurs taking the shortest course along the channel, irrespective of the flow conditions. The result of the tracer tests shows that pollutant clouds are spreading following the maximum velocity lines in each cases with various mixing patterns like superposition, separation, and stagnation of pollutant clouds. Flow characteristics in each cases performed in this study can be compared with tracer dispersion characteristics with using evaluation of longitudinal and transverse dispersion coefficients(LDC, TDC). As expected, LDC and TDC in meandering parts have been evaluated with increasing distribution and straight parts have effected to evaluate minimum of LDC and TDC due to symmetric flow patterns and attenuations of secondary flow.