• Economic and Environmental Geology
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• v.41 no.2
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• pp.183-199
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• 2008

This study is focused on characterization of the physio-chemical and mineralogical properties, investigation of their vertical changes in the tailing profile of the Guryoung mining area, classification of the profile into distinct zones, and condition conceptual model of physio-chemical conditions and phases-water relationships controlling the element behaviors in the tailings. The upper part of the groundwater is characterized by the high contents of $Fe_2O_3$ and $SO_3$ for whole rock analysis, low pH, and the occurrence of jarosite, schwertmannite and Fe-oxyhydroxide as the secondary mineral phases. The tailing profile can be divided into the covering soil, jarosite zone, Fe-sulfate zone, Fe-oxyhydroxide and gypsum-bearing pyrite zone, calcite-bearing pyrite zone, soil zone, and weathered zone on the based of the geochemical and mineralogical characteristics. The profile can be sampled into the oxidized zone and the carbonate-rich primary zone with the dramatic changes in pH and the secondary mineral phases. The conceptual model proposed for the tailing profile can be summarized that the oxidation of pyrite is the most important reaction controlling the changes in pH, the dissolution of the primary silicates and carbonates, the precipitation of secondary mineral phases, acid-neutralizing, and heavy metal behaviors through the profile.

• Fire Science and Engineering
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• v.24 no.2
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• pp.67-75
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• 2010

The fuel moisture changes accompanying with the elapsed days after a rainfall is very important to predict the risk of forest fire and make a good use of forest fire guard. So, to investigate the conditions for the risk of forest fire, it was studied the risk of forest fire for fallen leaves level, rotten level, and soil level after more-than-5 mm-rainfall according to the different forest density of pine forests which were located in Yeong-dong region in the Spring of 2007. The result of the study showed that the around 17% of fuel moisture which was the risky level for forest fire was reached after three days of a rainfall in the coarse dense forest region and after five days in the medium or highly dense forest region. However, for the rotten level represents more than 30% of fuel moisture even after six days after the rainfall, and the lower and upper level of the soil represented a slight or almost no changes. Based on the result, the prediction model ($R^2$=0.56~0.87) for the change of fuel moisture was developed, and it was examined by applying to actual meteorological measurements in the same period of 2008. It showed a meaningful result of 1% level of distinction.

• Journal of the Korean Geotechnical Society
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• v.15 no.3
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• pp.83-97
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• 1999

This paper presents the results of a parametric study on the interaction between buried pipes and surface load using the finite element method of analysis. A series of laboratory model tests were also performed in order to validate the adopted finite element model and to capture essential features of the physical behavior of buried pipes subjected to surface load. In the parametric study, a wide range of boundary conditions were analyzed with emphasis on the response of the buried pipes to surface load. The results of analysis such as contact stress distribution at the soil/pipe interface and axial thrust of the pipe were thoroughly analyzed, and a database on the response of buried pipe under surface load was established for future development of a semi-empirical design/analysis method. The results indicated that the degree of interaction between buried pipes and surface load significantly varies with the vertical and lateral location of pipe with respect to surface load, and that the current design method, which does not consider soil-structure interaction, cannot correctly capture the pipe response to surface loading. Furthermore, based on the results of analysis, a semi-empirical equation was suggested, which estimates the maximum pipe thrust due to surface load for flexible buried pipes.

• Journal of the Korean Association of Geographic Information Studies
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• v.18 no.1
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• pp.156-169
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• 2015

This study was to evaluate the RCP climate change impact on hydrological components in the Imha-Dam watershed using SWAT(Soil and Water Assessment Tool) Model. The model was calibrated for six year(2002~2007) and validated for six year(2008~2013) using daily observed streamflow data at three watershed stations. The overall simulation results for the total released volume at this point appear reasonable by showing that coefficient of determination($R^2$) were 0.70~0.85 and Nash-Sutcliffe model efficiency(NSE) were 0.67-0.82 for streamflow, respectively. For future hydrologic evaluation, the HadGEM3-RA climate data by scenarios of Representative Concentration Pathway(RCP) 4.5 and 8.5 of the Korea Meteorological Administration were adopted. The biased future data were corrected using 34 years(1980~2013, baseline period) of weather data. Precipitation and temperature showed increase of 10.8% and 4.9%, respectively based on the baseline data. The impacts of future climate change on the evapotranspiration, soil moisture, surface runoff, lateral flow, return flow and streamflow showed changes of +11.2%, +1.9%, +10.0%, +12.1%, +18.2%, and +11.2%, respectively.

• Journal of the Korean Geotechnical Society
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• v.21 no.8
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• pp.37-43
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• 2005

Hoek-Brown model, which was developed in order to predict the behavior of rock mass, has widely been utilized and revised by many researchers to solve various problems encountered in tunnelling and slope stability analysis. However, there is no schematic investigation on the application of the Hoek-Brown model to numerical analysis including finite element simulations. In this paper the Hoek-Brown model was formulated as a constitutive model according to the procedure of generalized plasticity theory, and a Rounded Hoek-Brown model, which could overcome the numerical difficulties by modifying the edge part of the yield surface as a curve shape, was newly proposed. The new model could satisfy the requirements as an elasto-plastic constitutive soil model and follow the yield surface of the original Hoek-Brown model in the compression mode. The constitutive equation for the proposed model herein was established and presented to be applicable to the generalized nonlinear finite element analysis.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.4
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• pp.221-233
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• 2000

Evaluation method of soil fertility by application of geographic information system (GIS) which includes landscape characteristics and soil map data was investigated from productivities of red pepper and tobacco grown on the fields with no fertilization. Total 131 fields experiments, 64 fields of red pepper and 67 fields of tobacco were conducted from 22 and 23 fields for red pepper and tobacco, respectively, located at Cheangweon and Eumseong counties in 1996, from 20 and 25 fields at Boeun and Goesan counties in 1997, and 22 and 19 fields at Jincheon and Chungju counties in 1998. All the experimental sites were selected on the basis of wide range of distribution in landscape and soil attributes. Dry weights and nutrients (N, P and K) uptakes by red pepper plant and tobacco leaves were considered as basic fertility of the soil (BFS). The BFS was estimated by twenty-five independent variables including 13 chemical properties and 12 GIS data. Twenty-five independent variables were classified by two groups, 15 quantitative variables and 10 qualitative variables, and were analyzed by multiple linear regression (MLR) of REG and GLM models of SAS. Dry weight of red pepper (DWRP) and dry weight of tobacco leaves (DWTL) every year showed high variations by five times in difference plots with minimum yield and maximum yield indicating the diverse soil fertility among the experimental fields. Evaluation for the BFS by the MLR including independent variables was better than that by simple regression showing gradual improvement by adding chemical properties, quantitative variables, and qualitative variables of the GIS. However the evaluation for the BFS by the MLR showed the better result for tobacco than red pepper. For example the variability in the DWTL by MLR was explained 34.2% by only chemical properties, 35.0% by adding quantitative variables, and 72.5% by adding both the quantitative and qualitative variables of the GIS compared with 21.7% by simple regression with $NO_3-N$ content in soil. Consequently, it is assumed that this approach by the MLR including both the quantitative and qualitative variables was available as an evaluation model of soil fertility for upland field.

• Journal of Korea Water Resources Association
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• v.49 no.2
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• pp.133-144
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• 2016

In this study, Frequency Domain Reflectometry (FDR) and COSMIC-ray soil moisture (SM) stations were installed at Sungkyunkwan University in Suwon, South Korea. To provide reliable information about SM, soil property test, time series analysis of measured soil moisture, and comparison of measured SM with satellite-based SM product are conducted. In 2014, six FDR stations were set up for obtaining SM. Each of the stations had four FDR sensors with soil depth from 5 cm to 40 cm at 5~10 cm different intervals. The result showed that study region had heterogeneous soil layer properties such as sand and loamy sand. The measured SM data showed strong coupling with precipitation. Furthermore, they had a high correlation coefficient and a low root mean square deviation (RMSD) as compared to the satellite-based SM products. After verifying the accuracy of the data in 2014, four FDR stations and one COSMIC-ray station were additionally installed to establish the Soil Moisture site with FDR and COSMIC-ray, called SM-FC. COSMIC-ray-based SM had a high correlation coefficient of 0.95 compared with mean SM of FDR stations. From these results, the SM-FC will give a valuable insight for researchers into investigate satellite- and model-based SM validation study in South Korea.

• Environmental Engineering Research
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• v.23 no.1
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• pp.84-91
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• 2018

The present study deals with the management of groundwater resources of an important agriculture track of north-western part of Saudi Arabia. Due to strategic importance of the area efforts have been made to estimate aquifer proneness to attenuate contamination. This includes determining hydrodynamic behavior of the groundwater system. The important parameters of any vulnerability model are geological formations in the region, depth to water levels, soil, rainfall, topography, vadose zone, the drainage network and hydraulic conductivity, land use, hydrochemical data, water discharge, etc. All these parameters have greater control and helps determining response of groundwater system to a possible contaminant threat. A widely used DRASTIC model helps integrate these data layers to estimate vulnerability indices using GIS environment. DRASTIC parameters were assigned appropriate ratings depending upon existing data range and a constant weight factor. Further, land-use pattern map of study area was integrated with vulnerability map to produce pollution risk map. A comparison of DRASTIC model was done with GOD and AVI vulnerability models. Model validation was done with $NO_3$, $SO_4$ and Cl concentrations. These maps help to assess the zones of potential risk of contamination to the groundwater resources.

• Journal of the Korean Society of Groundwater Environment
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• v.4 no.3
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• pp.161-167
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• 1997

A numerical model (SK-EST) for estimating hydraulic conductivity using monitoring data of underground LPG storage cavern was developed. The model calculates hydraulic conductivity from matrix equation which is established from the distribution of hydraulic potential. To verify the applicability of this model, an inverse analysis was performed using the monitoring data of pressure cell of an operating underground LPG storage cavern. And also using the water pressure parker test data which were obtained to look over the operation capability of pressure cell, conductivity variation with depth was estimated using the developed numerical model (SK-EST) and was compared with in situ results.

• Journal of the Korean GEO-environmental Society
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• v.2 no.3
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• pp.89-99
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• 2001

In this study, the numerical analysis of piezocone penetration and dissipation tests has been conducted using the Modified Cam-Clay model, which is generally used in soil mechanics. The Modified Cam-Clay model and related mathematical equations in finite element derivation have been formulated in the Updated Lagrangian reference frame to take the large displacement and finite strain nature of piezocone penetration into consideration. The cone tip resistance, the pore water pressure, and the dissipation curve obtained from the finite element analysis have been compared and investigated with the experimental results from piezocone penetration test performed in Yangsan site. The numerical results showed good agreement with the experimental results; however, the better numerical simulation of the continuous and deep penetration needs further research.