• Tunnel and Underground Space
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• v.19 no.3
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• pp.248-260
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• 2009

With regard to oversea mineral resources development, recent trend has been changed from a simple capital investment to a direct development of the resources. In relation to the stability of a slope in large open-pit coal mine, groundwater system was investigated and the validity of horizontal drainage hole was evaluated in Pasir coal mine, Indonesia. In this work, various field tests were carried out for a characterization of groundwater system, which included in-situ permeability measurement, tracer test and monitoring of groundwater levels. Especially, the influence of SM river on the characteristics of the groundwater flow system was mainly inspected. For the permeability measurement, Guelph permeameter was employed, and was found that sandstone was more permeable than mudstone and coal seam. From a comparison of lithological structure and the results of groundwater level monitoring, sandstone and thin coal seam with fractures were found to be a main channel for groundwater flow. In the results of tracer tests, the effect of SM river on the groundwater system depends on the geological structure of its base. To identify the effect of horizontal drainage holes, 2-D groundwater modeling was performed. Four different cases were tested, which are different from the length of drainage hole and the existence of pond on top of the slope. To enhance the drainage effect and slope stability, the drainage hole should be drilled to the depth of coal seam layer, which provides a main pathway of groundwater flow and embedded by sandstone. For this purpose, correct identification of surrounding geology should be preceded.

• The Journal of Engineering Geology
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• v.26 no.1
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• pp.87-99
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• 2016

We present the results of two-dimensional numerical simulations predicting the flow of groundwater in a fractured unsaturated zone. We applied the k-field distribution of permeability derived from discrete fracture network (DFN) modeling as the hydraulic properties of a model domain. To model an unsaturated zone, we set the depth from the ground surface to the underground aquifer. The rate of water infiltration into the unsaturated zone was divided into two parts, an artificial structure surface and unsaturated soil zone. The movement of groundwater through the unsaturated zone was simulated with particular emphasis on contaminant transport. It was clearly observed that the contaminants dissolved in groundwater transported vertically from the ground surface to the saturated zone.

• Tunnel and Underground Space
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• v.11 no.1
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• pp.42-58
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• 2001

In order to protect the environment from waste disposal activities, the prediction of the flux and flow paths of the contaminants from underground facilities should be assessed as accurately as possible. Especially, the prediction of the pathways and travel times of the nuclides from high level radioactive wastes in a deep repository to biosphere is one of the primary tasks for assessing the ultimate safety and performance of the repository. Since the contaminants are mainly transported with groundwater along the discontinuities developed within rock mass, the characteristics of groundwater flow through discontinuities is important for the prediction of contaminant fates as well as safety assessment of a repository. In this study, the actual fracture network could be effectively generated based on in situ data by separating geometric parameter and hydraulic parameter. The calculated anisotropic hydraulic conductivity was applied to a 3D porous medium model to calculate the path flow and travel time of the large studied area with the consideration of the complex topology in the area. Using the model, the pathways and travel times for groundwater were analyzed. From this study, it was concluded that the suggested techniques and procedures for predicting the pathways and travel times of groundwater from underground facilities to biosphere is acceptable and those can be applied to the safety assessment of a repository for radioactive wastes.

• Tunnel and Underground Space
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• v.13 no.6
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• pp.465-475
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• 2003

Groundwater inflow into the caverns constructed in fractured rock mass was simulated by numerical modeling, NAPSAC (DFN, discrete fracture network model) and NAMMU (CPM, continuous porous media model), a finite-element software package for groundwater flow in 3D fractured media developed by AEA Technology, UK. The input parameters for modeling were determined on surface fracture survey, core logging and single hole hydraulic test data. In order to predict the groundwater inflow more accurately, the anisotropic hydraulic conductivity was considered. The anisotropic hydraulic conductivities were calculated from the fracture network properties. With a minor adjustment during model calibration, the numerical modeling is able to reproduce reasonably groundwater inflows into cavern and the travel length and times to the ground surface along the flow paths in the normal, dry and rainy seasons.

• The Journal of Engineering Geology
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• v.5 no.2
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• pp.155-165
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• 1995

Fluid flow studies of fractured rocks require three-dimensional modeling of the fracture system. The stochastic discrete fracture models constructed by Monte Carlo simulation technique were applied to the analysis of groundwater flow and mass transport in fractured rock for the assessment of tightness criteria of underground LPG storage cavern. The parameters that most affect the conceptual discrete fracture modeling proved either fracture orientation or size and on the fract'lre flow interpretation proved conductive fracture intensity. The fracture transmissivity played important role in solute transport in fractured rock simulated by particle tracking approach. It was partly recognized that the calibrated stochastic discrete fracture model can be used for the tightness criteria of underground LPG storage cavern.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.153-154
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• 2003

라돈은 바위나 토양 속에 존재하는 우라늄이 붕괴하면서 자연발생하므로 사실상 지구 어느 곳에서나 존재한다. 최근 국내에서는 대덕연구단지 지역주민이 애용하는 샘물에서 라돈과 우라늄등 방사성핵종의 농도가 미국환경보호청(USEPA)의 음용수 수질 기준치를 훨씬 상회하여 인체에 유해성이 우려된다는 보도가 있었다.[1] 본 연구는 지하수내에 존재하는 라돈이 인체건강에 영향을 주는 두 가지 인체노출경로를 파악하고 이들 경로에 대해 각각 수학적 모델들을 개발하여 인체노출량을 정량적으로 평가하여 보았다. 본 연구의 결과는 추후 라돈의 정량적인 인체위해도를 평가하는데 도움을 주리라고 판단된다. (중략)

• KSCE Journal of Civil and Environmental Engineering Research
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• v.9 no.4
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• pp.103-112
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• 1989

A numerical model for Steady state groundwater flow has been established to understand the groundwater flow phenomena near a radioactive waste repository. The integrated finite difference method based on a network composed of nodes and members was applied to investigate groundwater flow in homogeneous, heterogeneous and layered media. Its numerical solution was in good agreement with analytic solution. Physical phenomena associated in the groundwater flow depending on both hydraulic characteristics and effects of fractured zone were also investigated. A method by which feasible groundwater flow paths can be identified was developed. This method used the composite network for the geologic media near a repository and the direction of computed groudwater velocity. Groundwater velocity and travel time were predicted for the possible pathway form a repository to a biosphere.

• Proceedings of the KSEG Conference
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• 2004.03a
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• pp.16001-16125
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• 2004

물리검층은 주로 석유탐사 분야에서 개발·이용되어왔으나 소구경 시추공을 이용하는 지반조사. 자원평가, 지하수조사 또는 환경오염조사 등에서 물리검층의 수요가 증가하고 있다. 국내에서 수행된 물리검층은 우라늄 탐사 목적으로 1980년 전후로 많이 수행되었으며 1990년 중반에는 지하수 조사에 일부 활용되어 왔다. 현재 물리검층의 활용도가 증가하고 있는 분야는 지반조사 분야로 원위치 물성측정, 시추공과 교차하는 암반의 균열파악 등 터널, 교량과 같은 각종 토목분야의 지반조사에 많이 활용되고 있다. 이외에도 지하수 유동특성 규명이나 환경오염조사, 자원평가(지열, 온천, 석·골재, 금속광상 등)에도 활용되고 있다. (중략)

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.442-446
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• 2003

이 연구는 제주도 한림 지역에서 지하수의 수질과 오염의 특성을 규명하고자 시행되었다. 2002년 8월과 11월에 걸쳐 34개 지점에서 지하수 시료를 채취하였고, 이를 분석하여 지하수의 수질을 유형별로 분류하였다. 연구지역은 주로 (Na,Mg)-HCO$_3$ 유형이 나타나며, 일부 지점에서는 Mg-(HCO$_3$+Cl), (Ca,Mg)-HCO$_3$ 유형 등이 나타난다. 이는 지하수의 유동 경로를 따라 서로 다른 수리지화학적 반응이 일어나며, 지표 오염물질의 유입 등이 지하수의 수질에 영향을 미치고 있음을 지시한다. 질산성 질소의 경우, 국내 먹는물 수질기준치 10 mg/L를 초과한 시료는 전체 시료의 8월 조사에서 약 32%, 11월 조사에서 약 27% 이었고, 공간적 분포 특성은 비교적 낮은 고도 150m 이하의 저지대에서 채취한 시료에서 주로 나타났다. 인위적인 오염물질의 유입 가능성이 있는 지점은 전체 시료의 79.4% 이었다.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2010.10a
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• pp.179-180
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• 2010