• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2023년도 학술발표회
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• pp.287-287
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• 2023

Surface water-groundwater interaction (SWGI) is an important hydrological process that influences both the quantity and quality of water resources. However, regional scale SWGI model calibration and uncertainty analysis have been a challenge because integrated models inherently carry a vast number of parameters, modeling assumptions, and inputs, potentially leaving little time and budget to explore questions related to model performance and forecasting. In this study, we have proposed the application of iterative ensemble smoother (IES) for uncertainty analysis and calibration of the widely used integrated surface-subsurface model, SWAT-MODFLOW. SWAT-MODFLOW integrates Soil and Water Assessment Tool (SWAT) and a three-dimensional finite difference model (MODFLOW). The model was calibrated using a parameter estimation tool (PEST). The major advantage of the employed IES is that the number of model runs required for the calibration of an ensemble is independent of the number of adjustable parameters. The pilot point approach was followed to calibrate the aquifer parameters, namely hydraulic conductivity, specific storage, and specific yield. The parameter estimation process for the SWAT model focused primarily on surface-related parameters. The uncertainties both in the streamflow and groundwater level were assessed. The work presented provides valuable insights for future endeavors in coupled surface-subsurface modeling, data collection, model development, and informed decision-making.

• 지질공학
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• 제18권4호
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• pp.471-482
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• 2008

이 연구는 충남 연기군 원성리에 소재하고 있는 안티몬공장에서 산업폐기물로 발생된 안티몬 폐기물을 매립지의 토양수, 인접하천수, 인근마을 지하수에서 안티몬을 포함한 일부 중금속에 의한 오염특성을 밝히고자 수행되었다. 하지만 현재 매립지는 수년전에 폐기물은 수거하여 다른 지역으로 옮긴 후 복토된 상태이다. 본 연구를 위하여 조사지역에서 지하수, 하천수, 토양수 총 35점을 채취하였고 대조마을에서 2점의 지하수를 채취하였다. 연구결과 매립지 농지의 토양수에는 안티몬의 농도가 대조마을 지하수보다 훨씬 높은 $48.75{\sim}74.81\;ppb$의 범위를 보여, 이는 주요 선진국 음용수 수질 기준치를 최고 수 십 배 상회한다. 매립지와 접한 하천수 3지점, 마을지하수의 1곳, 안티몬공장내 지하수 1점에서도 안티몬의 농도가 비교적 높게 검출되었다. 철, 망간 등의 중금속이 토양수 및 하천수에서 최고 6.5 ppm, 7.3 ppm으로 매우 높은 값을 보인다. 그러나 그 외 중금속은 일부 토양수, 하천수, 지하수에서 대조마을 지하수보다 높은 값을 보이지만 수질기준치에 비해 상당히 낮은 같을 보인다. 모든 물 시료의 화학적 유형은 Ca-$HCO_3$ 유형에서 Ca-($Cl+SO_4+NO_3$) 유형까지 넓게 분포한다. 토양수가 Ca - $SO_4$의 유형을 보이는 것은 안티몬이 매립되었던 폐기물의 환산화물의 함유에 기인하는 것으로 보인다. 일부지하수는 칼륨과 질산염 성분의 높은 값을 보여 비료와 생활오염물질에 의한 오염을 보인다. 결론적으로 폐기물을 매립지의 복토층 아래 토양내 아직도 상당량 안티몬 등 중금속이 존재하며, 이들이 인근 하천 및 지하수를 오염시키고 농작물까지 영향을 미칠 수 있으므로 적절한 방재 대책을 세워야 할 것이다. 본 연구는 국내 안티몬 폐기물에 의한 수질오염사례에 대한 최초의 연구결과로 환경부에서도 국가적 수질관리 차원에서 안티몬에 대한 대책을 세워야 할 것이다.

• 물과 미래
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• 제16권4호
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• pp.245-252
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• 1983

근년에 이르러 국내 지표수의 오염 현상은 사회적으로 매우 심각한 문제를 야기시키고 있어 수자원의 보호문제가 매우 중요한 시점에 이르렀다. 한강유역내에 발달 분포된 천층의 충적 퇴적층과 결정질암내에 저유된 지하수에 대해 동위원소를 이용한 환경 조사를 시행하였으며 결과를 분석한 바 다음과 같은 가정을 확인하였다. 1) 천층지하수의 함양원은 서울 도심지역은 하천수였고, 교외 외각의 농촌 지역은 강우의 직접 지하 침투에 의해 일어나고 있으며, 2) 충적 퇴적층으로 피복된 결정질 암은 상부충적퇴적층내에 저유된 천층 지하수가 충진원의 역할을 한다. 한강하류부의 해안 가까운 곳에 분포된 일부 충적층과 그 하부의 결정질암내에 저유된 지하수는 $H^3$의 함량이 매우 낮은치를 나타내는데 이는 핵실험이전의 기상수가 상당히 먼곳에서 충진되었기 때문으로 시료된다. 안정동위원소 조사에 의하면 한강상류에 분포된 석회암 대수층의 함양지역은 하류부의 충적층과는 달리 비교적 고지대였으며 석회암 대수층내에서 지하수의 체제 시간은 수개월 정도였다. 지하수의 포함된 극소량의 Pb, Mn, Zn 량과 충진메카니즘을 대비하려고 시도하였으나 명확한 관계가 나타나지 않았다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제18권1호
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• pp.94-101
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• 2013

It is well known that uncertainty associated with soil sampling is bigger than that with analysis. In this research, uncertainties for soil sampling when assessing TPH and BTEX concentration in soils were quantified based on actual field data. It is almost impossible to assess exact contamination of the site regardless how carefully devised for sampling. Uncertainties associated with sample reduction for further chemical analysis were quantified approximately 10 times larger than those associated with core sampling on site. Bigger uncertainties occur when contamination level is low, sample quantity is small, and soil particle is coarse. To minimize the uncertainties on field, homogenization of soil sample is necessary and its procedures are proposed in this research as well.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.404-408
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• 2003

In this study, we examined the influences of pH and total concentration on the speciation of heavy metals (Cd, Cu, Zn) in acid mine drainage. Their labile concentrations were analyzed by Anodic Stripping Voltammetry (ASV) at both natural pH and adjusted pHs (from 2 to 8). We obtained regression equations for predicting labile concentrations as a function of the water pH and contamination level (total dissolved metal concentration). Our data show that labile Cu depends on both the total concentration and pH, while labile Cd and Zn concentrations are controlled mainly by their total concentration rather than pH. Therefore, the pH variation of AMD may significantly change the toxicity and bioavailability especially of Cu, owing to its speciation change.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.497-500
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• 2003

If ground water levels of a confined fractured rock aquifer fluctuate with sea tides, individual values of hydrogeologic parameters can be determined. Tidal efficiency and time lag are first calculated from the water level data recorded at an observation device situated inland from the sea. The tidal efficiency factor of the aquifer at the seacoast is then determined from the observation in monitoring wells and used to calculate storage coefficient. Tidal efficiency factor and the tidal time lag are utilized to calculate storage coefficient and the results are compared. This method is tested in the southeastern coastal area of Busan, Korea. This is a simple and inexpensive way to test confined aquifer but the analysis should be performed according to the coastal environment.

• Nuclear Engineering and Technology
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• 제40권7호
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• pp.593-606
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• 2008

In this study, data on radionuclide migration and retardation processes in the engineered and natural barriers of High-Level Radioactive Waste (HLW) repository have been reviewed and compiled for use in the performance assessment of a HLW disposal system in Korea. The status of the database on radionuclide migration and retardation that is being developed in Korea is investigated and summarized in this study. The solubilities of major actinides such as D, Th, Am, Np, and Pu both in Korean bentonite porewater and in deep Korean groundwater are calculated by using the geochemical code PHREEQC (Ver. 2.0) based on the KAERI-TDB(Korea Atomic Energy Research Institute-Thermochemical Database), which is under development. Databases for the diffusion coefficients ($D^b_e$ values) and distribution coefficients ($K^b_d$ values) of some radionuclides in the compacted Korean Ca-bentonite are developed based upon domestic experimental results. Databases for the rock matrix diffusion coefficients ($D^r_e$ values) and distribution coefficients ($K^r_d$ values) of some radionuclides for Korean granite rock and deep groundwater are also developed based upon domestic experimental results. Finally, data related to colloids such as the characteristics of natural groundwater colloids and the pseudo-colloid formation constants ($K_{pc}$ values) are provided for the consideration of colloid effects in the performance assessment.

• 한국농공학회논문집
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• 제58권4호
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• pp.21-35
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• 2016

This study is to evaluate the applicability of SWAT (Soil and Water Assessment Tool) model for multi-purpose dams and multi-function weirs operation in Namhan river basin ($12,577km^2$) of South Korea. The SWAT was calibrated (2005 ~ 2009) and validated (2010 ~ 2014) considering of 4 multi-purpose dams and 3 multi-function weirs using daily observed dam inflow and storage, evapotranspiration, soil moisture, and groundwater level data. Firstly, the dam inflow was calibrated by the five steps; (step 1) the physical rate between total runoff and evapotranspiration was controlled by ESCO, (step 2) the peak runoff was calibrated by CN, OV_N, and CH_N, (step 3) the baseflow was calibrated by GW_DELAY, (step 4) the recession curve of baseflow was calibrated by ALPHA_BF, (step 5) the flux between lateral flow and return flow was controlled by SOL_AWC and SOL_K, and (step 6) the flux between reevaporation and return flow was controlled by REVAPMN and GW_REVAP. Secondly, for the storage water level calibration, the SWAT emergency and principle spillway were applied for water level from design flood level to restricted water level for dam and from maximum to management water level for weir respectively. Finally, the parameters for evapotranspiration (ESCO), soil water (SOL_AWC) and groundwater level fluctuation (GWQMN, ALPHA_BF) were repeatedly adjusted by trial error method. For the dam inflow, the determination coefficient $R^2$ was above 0.80. The average Nash-Sutcliffe efficiency (NSE) was from 0.59 to 0.88 and the RMSE was from 3.3 mm/day to 8.6 mm/day respectively. For the water balance performance, the PBIAS was between 9.4 and 21.4 %. For the dam storage volume, the $R^2$ was above 0.63 and the PBIAS was between 6.3 and 13.5 % respectively. The average $R^2$ for evapotranspiration and soil moisture at CM (Cheongmicheon) site was 0.72 and 0.78, and the average $R^2$ for groundwater level was 0.59 and 0.60 at 2 YP (Yangpyeong) sites.

• 한국지구과학회지
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• 제29권5호
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• pp.396-407
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• 2008

Hydrogeologic properties of a well field around middle mountainous areas in Pyosun, Jeju volcanic island were examined based on water level monitoring, geologic logging and pumping test data. Due to the alternating basaltic layers with varying permeability in the subsurface, it is difficult to analyze the hydraulic responses to artificial pumping and/or natural precipitation. The least permeable layer, detrital materials with clay, is found at a depth of 200 m below surface, but it is not an upper confining bed for lower main aquifer. Nevertheless, this layer may serve as a natural barrier to vertical percolation and to contaminant migration. Water levels of the production wells are dominantly affected by pumping frequently, while those of the remote observation wells are controlled by ambient precipitation. Results of pumping tests revealed a possible existence of horizontal anisotropy of transmissivity. However, some results of this study include inherent limitations enforced by field conditions such as the consistent of groundwater production and the set of time periods for the cessation of the pumping prior to pumping tests.

• Ecology and Resilient Infrastructure
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• 제5권3호
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• pp.125-133
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• 2018

인공신경망 (Artificial neural network, ANN)은 간편히 시계열 데이터를 예측할 수 있는 모델 중에 하나로 지하수위를 예측하는데 빈번히 사용되었으며, 많은 연구자들이 ANN으로 지하수위 예측에 있어서 높은 예측 신뢰성을 얻기 위하여 노력해 왔다. 본 연구에서는 ANN를 이용한 지하수위 예측 시 계절 효과를 반영하기 위한 input으로 사용되는 Dummy가 지하수위 예측 결과에 미치는 영향에 대하여 분석하였다. 정성적 및 정량적인 분석을 위하여 도해법과 상관계수, 에러 지수를 이용하였다. 분석결과 하천변 도심지역에서는 ANN의 input으로 사용된 Dummy가 오히려 예측 신뢰성을 떨어뜨리는 결과를 보였다.