• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2021년도 학술발표회
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• pp.316-316
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• 2021

Erosion in a watershed is one of the main sources of sediment inflow in dams. While sediment management practices can be performed to reduce and manage sedimentation in reservoirs, managing the sediment inflow before it reaches the reservoir should also be consider. The accurate location of areas with high erosion and deposition rates should be determined in order to propose an appropriate sediment management procedure such as the construction of check dams. In this study, the projected rainfall from HadGEMRA-3 for RCP 8.5, was used in C-SEM, a distributed rainfall-erosion model, to determine the projected spatial erosion patterns in Cheoncheon catchment, which is located in the upstream part of Yongdam Dam.

• 한국물환경학회지
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• 제29권1호
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• pp.97-106
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• 2013

The temporal and spatial variations of water quality in a stratified reservoir are fully dependent on the characteristics of inflow loading from its watershed and the transport regimes of pollutants after entering the reservoir. Because of the meteorological and hydrological conditions in Korea, the pollutants loading to reservoirs are mostly occur during rainfall events. Therefore it is important to understand the characteristics of pollutants loading from upstream rivers and their spatial propagation through the stratified reservoir during the rainfall events. The objectives of this study were to characterize the water quality variations in upstream rivers of Imha Reservoir during a rainfall event, and the transport and spatial variations of pollutants in the reservoir through extensive field monitoring and laboratory analysis. The results showed that the event mean concentration (EMC) of SS, BOD, $COD_{Mn}$, T-N, T-P, $PO_4-P$ are 8.6 ~ 362.1, 2.5 ~ 5.1, 1.5 ~ 5.1, 1.1 ~ 1.9, 8.3 ~ 57.1, 5.6 ~ 25.7 times greater than the mean concentrations of these parameters during non-rainfall period. The turbidity and SS data showed good linear correlations, but the relationships between flow and SS showed large variations because of hysteresis effect during rising and falling periods of the flood. The ratio of POC to TOC were 12.6 ~ 14.7% during the non-rainfall periods, but increased up to 28.2 ~ 41.7% during the flood event. The turbid flood flow formed underflow and interflow after entering the reservoir, and delivered a great amount of non-point pollutants such as labile and refractory organic matters and nutrients to the metalimnion layer of reservoir, which is just above the thermocline. Spatially, the lateral variations of most water quality parameters were marginal but the vertical variations were significant.

• 한국수자원학회논문집
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• 제45권8호
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• pp.839-851
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• 2012

일반적으로 수계의 용수공급능력을 평가하기 위해서는 수요량을 단계적으로 증가시키며 용수부족 여부를 검토하고 그 결과에 따라 수요량을 조정하는 시행착오법을 사용한다. 이것은 시뮬레이션 모형 뿐 아니라 최적화모형의 경우에서도 마찬가지다. 그러나 이 같은 시행착오법은 수차례의 최적화를 반복하는 번거로움을 수반한다. 이에 본 연구에서는 물 부족이 발생하지 않은 최대 용수공급능력을 보다 쉽게 찾을 수 있도록 2단계의 목표계획기반 최적화 모형을 제시하였다. 즉, 제1단계에서는 제시된 모형을 유입량 정보가 정확하다는 가정아래 최대 용수공급능력을 산정한다. 그리고 제2단계에서는 실제 용수공급상황에서는 미래 유입량에 대한 정보가 없는 점을 고려하여 최대 갈수기간에 한해 실시간 모의운영을 통하여 용수공급능력을 산정한다. 이 방법을 다기능 보가 신설되어 기존 수문환경과 차이점을 보이는 금강수계에 적용하고, 완전한 정보가 있는 경우와 그렇지 않은 경우의 결과를 비교함으로써 유입량 정보가 용수공급능력에 미치는 영향을 이해하고 평가할 수 있었다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회(1)
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• pp.63-64
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• 2005

• 한국물환경학회지
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• 제28권1호
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• pp.26-37
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• 2012

Multi-dimensional hydrodynamic and water quality models are widely used to simulate the physical and biogeochemical processes in the surface water systems such as reservoirs and estuaries. Most of the models have adopted the Eulerian grid modeling framework, mainly because it can reasonably simulate physical dynamics and chemical species concentrations throughout the entire model domain. Determining the optimum grid cell size is important when using the Eulerian grid-based three-dimensional water quality models because the characteristics of species are assumed uniform in each of the grid cells and chemical species are represented by concentration (mass per volume). The objective of this study was to examine the effect of grid-size of a three dimensional hydrodynamic and water quality model (EFDC) on hydrodynamics and mass transport in the Saemangeum Reservoir. Three grid resolutions, respectively representing coarse (CG), medium (MG), and fine (FG) grid cell sizes, were used for a sensitivity analysis. The simulation results of numerical tracer showed that the grid resolution affects on the flow path, mass transport, and mixing zone of upstream inflow, and results in a bias of temporal and spatial distribution of the tracer. With the CG, in particular, the model overestimates diffusion in the mixing zone, and fails to identify the gradient of concentrations between the inflow and the ambient water.

• 상하수도학회지
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• 제9권4호
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• pp.73-86
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• 1995

The propriety of the numerical model application was examined on Paldang resevoir and its inflow tributaries located in the center of the Korean peninsula and the long term water quality forecast of the oxygen profile was carried out in this syduy. The input data of the model was the capacity of the reservoir, catchment area, percolation, diffusion rate, vertical mixing rate, dissolution rate from the bottom of the reservoir, outflow of the resevoir, water quality measurement and meteorology data of the drainage basin, and the output result was the annual estimation value of the dissolved oxygen concentration and the biochemical oxygen demand. The modeling method is based on the measured or calculated boundary condition dividing the water area into several blocks from the macorscopic aspect and considering the mass balance in these blocks. As the result of the water quality forecast, it was expected that the water quality in Northern Han River and Paldang reservoir would maintain the recent level, but that the water quality in the Southern Han River and its inflow tributary would worsen below the grade 4 of the life environmental standard from around 2000 owing to the decrease of DO concentration and the increase of BOD concentration.

• Ocean and Polar Research
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• 제28권2호
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• pp.153-161
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• 2006

To investigate inflow path of the East Sea Intermediate Water (ESIW) into the Ulleung Basin, hydrographic data surveyed in July 2005 were analyzed. The ESIW was characterized by the Salinity Minimum Layer (SML) within a depth range of 100 to 360 meters. Averaged potential temperature and salinity of the SML were $1.835^{\circ}C$ and 34.049 psu, respectively. Mean potential density $({\sigma}_{\theta})$ of the SML was 27.221 with a standard deviation of 0.0393. On isopycnal surfaces of 27.14 and 27.18 $({\sigma}_{\theta})$ which correspond to upper layers of the ESIW, the coastal low salinity water was separated from the offshore low salinity water by the relatively warm and saline water which might be affected by the Tsushima Warm Current Water. Relatively cold and fresh water, however, intruded into the Ulleung Basin from the region of Korean coast on isopycnal surfaces of 27.22 and 27.26 which was lower layer of the ESIW. The salinity distribution in the isopycnal layer of $27.14{\sim}27.26$ with acceleration potential on 27.22 up surface also showed clearly that the low salinity water flowed from the coastal area and intruded into the Ulleung Basin. This implies that the ESIW flows ken the north to the south along the east coasts of Korea and spreads into the Ulleung Basin in summer.

• 한국물환경학회지
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• 제31권3호
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• pp.313-318
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• 2015

To study the influence of changes in river discharge on water quality of the main stem of the Geum River, we investigated variation of inflow load from tributaries with river discharge. We also studied the mixing behavior of pollutants during mixing of waters of the main stem and Gap Stream. For this study, we collected water quality data such as suspended solids (SS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total organic carbon (TOC), total nitrogen (TN) and total phosphorus (TP) representing pre-monsoon, monsoon, and post-monsoon events of 2013 from a website of Water Information System. Based on inflow load, the Gap and Miho streams may be ones of tributaries which may largely influence water quality of main stem in upper river region. The Suksung and Nonsan Streams seemed to further affect water quality downstream. Results of modified EMMA indicated SS and TP may have another source(besides Gap Stream) at pre-monsoon, monsoon, and post-monsoon period. In contrast, TN and organic matter (BOD, COD, TOC) were conservative at pre-monsoon and post-monsoon. However, when river discharge increased, these pollutants may also came from unspecified non-point sources. Therefore, we need to attempt to find non-point sources for the pollutants in the main channel of upper Geum River region.

• 한국수자원학회논문집
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• 제30권3호
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• pp.269-278
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• 1997

저수지 운영의 기초가 되는 운영률은 대부분 과거기록 유입량중 최대 혹은 최소의 극한치 자료를 이용하거나 평균치 자료를 이용하여 도출하기 때문에 실제 운영에서 발생할 수 있는 불확실성에 대처한 기대편익 산정이나 운영방안 수립에는 적절히 이용할 수 없다. 또한 지금까지 개발된 대부분의 운영률은 유입량을 포함하여 모든 운영변수를 이미 알고 있다는 확정론적 방법에 기초하고 있어 유입량의 불확실성을 반영하지 못하는 단점이 있다. 이를 개선할 수 있는 방법으로 추계학 분석기법에 의한 운영률을 개발할 수 있는데 이는 저수지 상태방정식의 구성요소인 유입량의 추계학적 특성을 시계열상에서 이산화된 천이확률로 처리하여 모형에 적용할 수 있다. 확정론적 방법에 의한 저수지 운영방안을 개선시키기 위하여 추계학적 방법에 의한 저수지 운영률을 개발하였다. 본 연구에서는 이와같은 방법론에 따른 양해 추계학적 동적계획기법을 이용하여 충주 저수지 시스템의 최적 운영 방안을 마련하였다. 개발된 운영률을 홍수기를 제외하고는 Lag-1 Markov 모형의 기본가정을 충실히 따르고 있어 저수지 운영률로의 이용이 가능하며, 운영단계의 유입량을 적절히 예측할 수 없는 현실에서 전단계의 유입량과 적용단계의 저류량만을 이용하는 저수지 운영률의 개발이 가능하다.

• 한국수자원학회논문집
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• 제35권6호
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• pp.787-796
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• 2002

자연하천의 부정류 홍수예측을 위하여 Preissmann기법에 의한 수리학적 홍수추적을 실시하였으며, 민감도 분석을 위한 상류단과 측방유입수문곡선으로서 Log-Pearson Type-III를 사용하였다. 실제하천 적용에 있어서 유역에 대해서는 선형저수지 모형을 적용하고 하도망에 대해서는 수리학적 홍수추적을 실시하였다. 상류단과 측방유입수문곡선은 선형저수지 모형을 이용하여 산정하였으며, 하류단 경계조건으로서 Manning공식을 이용하였다. 유입수문곡선으로서 선형저수지모형이 적용된 부정류모형을 보청천유역에 적용시킨 결과 실측치와 매우 근접한 수문곡선을 예측할 수 있었으며, 본 연구는 측방유입이 있는 경우, 선형저수지 모형을 이용한 수리학적 홍수예측이 가능하고, 부정류모형을 이용하여 흐름계산을 할 경우 조도계수 산정을 위한 수단이 될 수 있을 것으로 판단된다.