• Spatial Information Research
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• v.7 no.1
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• pp.103-117
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• 1999

During the last several years, the geographic information system(GIS) technology has emerged as a very effective tool for analyzing complicated groundwater system Linking GIS to spatially distributed hydrogeological data and groundwater models offers many advantages in the analysis of urban groundwater system. This paper describes the urban hydrogeological application of GIS in Seoul area. This study constructs an urban hydrogeological database via pre- and post-processing of various types of urban hydrogeological data, such as groundwater-level fluctuation, topogaphic data, water chemistry data, subway pimping station data, tidal effect of the Han River, and hydrogeological parameters. A hydrogeological model has been designed to enable importing data from the database and providing the model output for the repetitive manipulation and display in GIS.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.85-89
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• 2005

Lineament maps are the important tools that may reveal points of groundwater recharge, flow and development. In particular, groundwater flows and yields in mountainous area, composed of crystalline rocks with many fractures, are governed mainly by the lineaments corresponding to fractures, joints and faults. Lineaments may give important information on the best distribution of wells and their management. For two districts; Pohang and Cheonan, the relationship between lineament and groundwater factors was analyzed. To compare groundwater productivity, storativity, and transmissivity of a well site along the distance to lineament, the distances to lineament was regrouped into five groups with an equal range, 100m, for the Pohang district and they are also divided into five groups with an equal range, 150m, for the Cheonan district. From the results of the Spearman Rank Correlation Analysis and Kendall Analysis for each group, the means of SPC and T of wells which are located near lineaments generally have large values. The means of SPC and T show a reverse linear relationship with a lineament distance, but the means of S shows a disperse distribution and no distinct linear relation. Result of the linear regression model between SPC and lineament length density shows that it will be effective to use the lineament length density map when finding the optimal well site on a regional scale.

• Journal of Environmental Science International
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• v.26 no.10
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• pp.1135-1146
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• 2017

At riverbank filtration sites, groundwater levels of alluvial aquifers near rivers are sensitive to variation in river discharge and pumping quantities. In this study, the groundwater level fluctuation, pumping quantity, and streamflow rate at the site of a riverbank filtration plant, which produces drinking water, in the lower Nakdong River basin, South Korea were interrelated. The relationship between drawdown ratio and river discharge was very strong with a correlation coefficient of 0.96, showing a greater drawdown ratio in the wet season than in the dry season. Autocorrelation and cross-correlation were carried out to characterize groundwater level fluctuation. Autoregressive model analysis of groundwater water level fluctuation led to efficient estimation and prediction of pumping for riverbank filtration in relation to river discharge rates, using simple inputs of river discharge and pumping data, without the need for numerical models that require data regarding several aquifer properties and hydrologic parameters.

• Journal of Soil and Groundwater Environment
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• v.6 no.3
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• pp.107-117
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• 2001

The characteristics of groundwater movement under the heavy rainfall at Nan-ji waste landfill site are studied using HELP(Hydraulic Evaluation of Landfill Performance) program, which calculates the daily leachate in the Nan-ji waste landfill site. In this study, instead of the average recharge value, which is used in the past study, the real reacharge value is used to calculate the daily leachater. It is found about 70 times greater than thor average recharge value under the condition of heavy rainfall in the rainy season. The flow characteristics of groundwater for water level fluctuation is simulated using the ground water flow model MODFLOW(A Modular 3-D Finite Different Groundwater Flow Model) program, and the slurry layer is newly added. The result of the study is different from that of the ordinary simulation, which shows much higher ground water level than from the ordinary simulation.

• Journal of Soil and Groundwater Environment
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• v.21 no.6
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• pp.67-79
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• 2016

Gaussian process regression (GPR) is proposed as a tool of long-term groundwater quality predictions. The major advantage of GPR is that both prediction and the prediction related uncertainty are provided simultaneously. To demonstrate the applicability of the proposed tool, GPR and a conventional non-parametric trend analysis tool are comparatively applied to synthetic examples. From the application, it has been found that GPR shows better performance compared to the conventional method, especially when the groundwater quality data shows typical non-linear trend. The GPR model is further employed to the long-term groundwater quality predictions based on the data from two domestically operated groundwater monitoring stations. From the applications, it has been shown that the model can make reasonable predictions for the majority of the linear trend cases with a few exceptions of severely non-Gaussian data. Furthermore, for the data shows non-linear trend, GPR with mean of second order equation is successfully applied.

• Korean Journal of Hydrosciences
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• v.3
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• pp.1-9
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• 1992

The effects of fractures in rock masses on the groundwater flow and the groundwater flow system in the volcanic rocks are analyzed by GFFP-WT model, which allows more realistic analysis of groundwater system by considering the fractures in rock masses. The evaluation of the effects of fractures in rock masses on the groundwater flow has been carried out in the 2nd Yeonwha and resulted in that the fractures mostly influence flow time because of hydraulic head distribution change. The results of the groundwater flow system analysis in the volcanic rocks are as follows. Most of groundwater once flowed in Lapilli tuff flowed out through Lappilli tuff layer. But only a small fraction of water flowed out through crystal tuff layer.

• Journal of the Korean Geotechnical Society
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• v.29 no.7
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• pp.75-89
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• 2013

This paper describes a GIS-based geohydrologic methodology, called YSGWF (YonSei GroundWater Flow) for predicting the rainfall infiltration-groundwater flow of slopes. This physical-based model was developed by the combination of modified Green-Ampt model that considers the unsaturated soil parameters and GIS-based raster model using Darcy's law that reflects the groundwater flow. In the model, raster data are used to simulate the three dimensional inclination of bedrock surface as actual topographic data, and the groundwater flow is governed by the slope. Also, soil profile is ideally subdivided into three zones, i.e., the wetting band zone, partially saturated zone, and fully saturated zone. In the wetting band and partially saturated zones the vertical infiltration of water (rainfall) from surface into ground is modeled. When the infiltrated water recharges into the fully saturated zone, the horizontal flow of groundwater is introduced. A comparison between the numerical calculation and real landslide data shows a reasonable agreement, which indicate that the model can be used to simulate real rainfall infiltration-groundwater flow.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.5
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• pp.321-326
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• 2011

Recently, ground source heat pump (GSHP) systems have been introduced in many modem buildings which use the annually stable characteristic of underground temperature as one of the renewable energy uses. However, all of GSHP systems cannot achieve high level of energy efficiency and energy-saving, because their performance significantly depends on thermal properties of soil, the condition of groundwater, building loads, etc. In this research, the effect of thermal properties of soil on the performance of GSHP systems has been estimated by a numerical simulation which is coupled with ground heat and water transfer model, ground heat exchanger model and surface heat balance model. The thermal conductivity of soil, the type of soil and the velocity of groundwater flow were used as the calculation parameter in the simulation. A numerical model with a ground heat exchanger was used in the calculation and, their effect on the system performance was estimated through the sensitivity analysis with the developed simulation tool. In the result of simulation, it founds that the faster groundwater flow and the higher heat conductivity the ground has, the more heat exchange rate the system in the site can achieve.

• Journal of Soil and Groundwater Environment
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• v.16 no.6
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• pp.27-33
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• 2011

Infiltration plays an important role in the urban water cycle. Infiltration has a potential to contribute to groundwater recharge in addition to runoff reduction. However, infiltration in urban areas has been considered only as a means of runoff reduction. Conventional design methods for infiltration facilities assume soils to be fully-saturated for the sake of simplicity. The amount of groundwater recharge can not be estimated properly with this scheme. Hence, the characteristics of the unsaturated soil condition need to be considered. The finite element model using SEEP/W to estimate infiltration under the unsaturated condition is presented. Infiltration tests for Joomonjin sand are performed and the infiltration behavior of Joomoonjin sand under the unsaturated condition is measured experimentally to verify the validity of the finite element model. The results from comparing infiltrated volume between the saturated and the unsaturated conditions under the same soil and rainfall conditions show that the infiltrated volume in the unsaturated condition is two times bigger than that in the saturated condition.

• The Journal of Engineering Geology
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• v.4 no.2
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• pp.219-229
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• 1994

Since groundwater flow in fractured rocks is controlled by the distribution of fractures irregu1arly developed in space, it is not possible to understand the hydraulic characteristics of fractured aquifers using Theis equation which is applicable only to homogeneous isotropic confined aquifer. This study deals with the theoretical background of the fractal groundwater flow model with leakage, the methodology of calculation of the hydraulic parameters, and the application of the developed model to field data. From the result of the application of the fractal model to two field data in Hongcheon and Yusung areas, we obtained a good match between theoretical curves and observed curves, with the same hydraulic parameters at the pumping well and the observation well. In the two pumping test analyses, we have determined 1.9 of the fractal dimension. This means that the dimension of groundwater flow at these two sites is slightly smaller than radial flow.