• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.10 no.3
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• pp.161-170
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• 2012

To provide domestic values of input parameters in a safety assessment of radioactive waste disposal under domestic deep underground environments, various kinds of experiments have been carried out under KURT (KAERI Underground Research Tunnel) conditions. The input parameters were classified, and some of them were selected for this study by the criteria of importance. The domestic experimental data under KURT environments were given top priority in the data review process. Foreign data under similar conditions to KURT were also gathered. The collected data were arranged and the statistical calculations were processed. The properties and distribution of the data were explained and compared to foreign values in view of their validity. The following parameters were analysed: failure time and early time failure rate of a container, solubility of nuclides, porosity and density of the buffer, and distribution coefficients of nuclides in the geomedia, hydraulic conductivity, diffusion depth of nuclides, groundwater flow rate, fracture aperture, length of internal fracture, and width of faulted rock mass in the host rock.

• Journal of the Korean GEO-environmental Society
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• v.24 no.12
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• pp.53-60
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• 2023

Recently, along with the improvement of high-speed rail and road design speed, the proportion of tunnel construction work is increasing proportionally. In particular, the construction of long tunnels is rapidly increasing due to the mountainous terrain of our country. In this way, due to the trend of tunnels becoming longer, it is difficult to design and construct tunnels by avoiding fault zones. In the case of tunnel construction in mountainous areas, ground investigation is often difficult even during design due to the topographical conditions, making precise ground investigation difficult, and as a result, the upper part of the tunnel is damaged during tunnel construction. When fault zones, which are vulnerable to weathering, exist, the stability of the tunnel during excavation is directly affected by the fault zone distribution, strength characteristics, and groundwater distribution range. In particular, when a fault zone is distributed in the upper part of a tunnel, damage such as tunnel collapse and excessive displacement may occur, and in order to prevent this in advance, countermeasures must be established through analysis of similar cases. Therefore, in this study, when a large-scale fault zone exists in the upper part of a tunnel, the relationship and characteristics of damage to the tunnel structure were analyzed.

• Journal of Korea Soil Environment Society
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• v.2 no.3
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• pp.69-80
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• 1997

This investigation was conducted to provide information for characteristics of environmental pollution by the heavy metals from the abandoned gold mine in order to characterize the distribution patterns and environmental damages of the contaminants to the surrounding environment. Through analysis of CN, Cd, Cu, Pb, Zn, As, Cr, and Hg in a mine tailings, paddy soils, and stream sediments, the physico-chemical properties of the mine tailings and paddy soils were measured. The pH's were 5.4, 8.4 for the paddy soil and mine tailing, respectively. The maximum contents of CN, Pb, Cd, and As the in mine tailing were 99.98, 1,752.72, 31.88, and 298.50 mg/kg, respectively. The amounts of these ions were higher than the standard level of industrial area in Korea. The average content of CN and heavy metals in the paddy soils were higher than the background level of heavy metals in the unpolluted paddy soils around the mine. Especially, the contents of heavy metals in the paddy soils along the adjacent stream were higher compared to the paddy soil that was not influenced by the mine tailings. The contents of CN and heavy metals in the stream sediment close to the mine area were similar to those of the mine tailings, but decreased along the distance of the stream farther away from the tailings that was the source of these pollutants.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.8
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• pp.465-471
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• 2015

Adsorption experiments for radionuclides such as $^3H$, $^{90}Sr$ and $^{99}Tc$ were conducted using fractured rock collected in unsaturated zone. The released radionuclide through artificial barrier from the near surface repository can be transported by the flow of rainfall or pore water through fractures in unsaturated zone and reach to groundwater flow. Therefore, it is important to investigate transport behavior (retardation) of radionuclides through fractured rock for the safety assessment and long-term performance of repository. Fractured rock samples were collected and characterized by X-ray microtomography (XMT) analysis, which can be used to develop a more robust unsaturated fracture transport model. When fracture-filling materials are exist, distribution coefficient of $^{90}Sr$ is higher than without fracture-filling materials. In this study, batch sorption distribution coefficient ($K_d$) of radionuclide was determined and used to increase our understanding of radionuclide retardtion through fracture-filling materials.

• The Journal of the Petrological Society of Korea
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• v.16 no.1 s.47
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• pp.12-26
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• 2007

We have studied orientational characteristics of vertical rift and grain planes developing in 108 quarries for Mesozoic granites. Orientations of these planes vary in different localities. In general, orientations of these planes are predominantly NNE in South Korea. From the regional distribution chart, orientations of these planes show three dominant sets in terms of frequency orders: (1) $N2{\sim}10^{\circ}E(1st-order),\;(2)\;N15{\sim}25^{\circ}E(2nd-order),\;(3)\;N45{\sim}70^{\circ}E,\;N10{\sim}30^{\circ}W\;and\;N70{\sim}80^{\circ}W(3rd-order)$. These granite quarries are classified by the relative difference in the easiness of rock splitting between horizontal and vertical quarrying planes into: R-type, G-type, and H-type. The results showed that quarries for Triassic granites belong to R and G-types;those for Jurassic granites belong to R, G and H-types. In addition, quarries for Cretaceous granites belong mainly to R-type. Among these quarry types, the most diverse type was identified in the quarries for Jurassic granites. R-type (77.8%) shows a higher distribution ratio compared with G and H-types (22.2%). In general, anisotropy of physical properties is found in granitic rocks and there exists close correlation between orientations of granitic rock splitting planes and those of the open microcracks. Meanwhile, it has been reported that preferred orientations of open microcracks suggest maxinum principal stress orientations.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.6
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• pp.430-437
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• 2012

In order to obtain information on the design parameters of the horizontal laterals in floodplain filtration, laboratory-scale sand-box experiments were performed where the head distributions on the laterals and the groundwater profiles were measured according to the change in parameters including lateral diameter, hydraulic conductivity of the sand, water level at the well and raw-water supply rate. Measured data were analyzed using a numerical code in order to identify the discharge intensity distribution along the laterals. It was observed from the result that the lowering of the water level at the well had minimal adverse effect on the performance of the floodplain filtration. Results also elucidated that the low conveyance of the laterals to transmit the filtrate was compensated and supplemented by a natural augmentation in horizontal conveyance through the aquifer when the raw-water supply rate exceeded the adequate recovery rate. With this mechanism, the water quality is expected to improve further since the travel distance through the aquifer is amplified. Based on these findings it can be suggested that the diameter of the lateral used in the floodplain filtration may be smaller than those in riverbank/bed filtration. It was also found that the ratio between the head loss occurring in a lateral and the total head loss in the floodplain filtration was proportional to the exit velocities of the laterals, which may be used to design and/or evaluate the lateral in floodplain filtration.

• The Journal of Engineering Geology
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• v.29 no.3
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• pp.223-236
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• 2019

Resistivity surveys can identify the distribution of geological units and structures (including fragmented fault zones), the extent of weathered and modified geological strata, and the characteristics of groundwater. This study aims to analyze the underground sedimentary layers and geological structures near the Nari and Albong Basins of Ulleung-do, Korea, focusing on six survey lines to identify the spatial trends in subsurface resistivity. A modified dipole array method (D method) was employed, combining resistivity results obtained by existing dipole array methods (A and C methods). The modified method provides optimal analysis of the cross-section of underground resistivity, and shows a clear boundary between a low-resistivity zone (${\leq}500{\Omega}{\cdot}m$) of sedimentary layers and weak zones, and a high-resistivity zone (${\geq}5,000{\Omega}{\cdot}m$) of volcanic rock (trachyandesite). The estimated average thickness of the sedimentary layers is 50~100 m for the Albong Basin and 100~200 m for the Nari Basin. An anomaly zone, different from the weak zone in the bedrock, is identified as a caldera fault, and the low-resistivity zone extends from the surface down to the lowest survey depths.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.05a
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• pp.273-280
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• 2005

Robust magneto-telluric (MT) response function estimators are now in standard use in electromagnetic induction research. Properly devised and applied, these methods can reduce the influence of unusual data (outlier) in the response (electric field) variable, but often not sensitive to exceptional predictor (magnetic field) data, which are termed leverage points. A bounded influence estimator is described which simultaneously limits the influence of both outlier and leverage point, and has proven to consistently yield more reliable MT response function estimates than conventional robust approach. The bounded influence estimator combines a standard robust M-estimator with leverage weighting based on the statistics of the hat matrix diagonal, which is a standard statistical measure of unusual predictors. Further extensions to MT data analysis are proposed, including a establishment of data rejection criterion which minimize the influence of both electric and magnetic outlier in frequency domain based on statistical distribution of electromagnetic field. The rejection scheme made in this study seems to have an effective performance on eliminating extreme data, which is even not removed by BI estimator, in frequency domain. The effectiveness and advantage of these developments are illustrated using real MT data.

• The Journal of Engineering Geology
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• v.18 no.2
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• pp.127-136
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• 2008

Geophysical survey for establishing a wide site for the distribution of water content, wetting front infiltration due to the rainfall, and distribution of groundwater level has been performed by using 8round penetration radar (GPR) method, electrical resistivity method, and so on. On the other hand, a narrow area survey was performed to use a permittivity method such as time domain reflectometry, frequency domain reflectometry, and amplitude domain reflectometry methods for estimating volumetric water content, soil density, and concentration of contaminant in surface and subsurface. The permittivity methods establish more corrective physical parameters than different found survey technologies mentioned above. In this study for establishment of infiltration behaviors for wetting front in the unsaturated soil caused by an artificial rainfall, soil physical parameters for volumetric water content, pore water pressure, and pore air pressure were measured by FDR measurement device and pore water pressure meter which are installed in the unsaturated weathered granite soil with different depths. Consequently, the authors were proposed to a new establishment method for analyzing the variations of volumetric water content and wetting front infiltration from the responses of infiltrating pore water in the unsaturated soil.

• Geophysics and Geophysical Exploration
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• v.10 no.4
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• pp.383-392
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• 2007

Karstic features and mining-related cavities not only lead to severe restrictions in land utilizations, but also constitute serious concern about geohazard and groundwater contamination. A microgravity survey was applied for detecting, mapping and monitoring karstic cavities in the test site at Muan prepared by KIGAM. The gravity data were collected using an AutoGrav CG-3 gravimeter at about 800 stations by 5 m interval along paddy paths. The density distribution beneath the profiles was drawn by two dimensional inversion based on the minimum support stabilizing functional, which generated better focused images of density discontinuities. We also imaged three dimensional density distribution by growing body inversion with solution from Euler deconvolution as a priori information. The density image showed that the cavities were dissolved, enlarged and connected into a cavity network system, which was supported by drill hole logs. A time-lapse microgravity was executed on the road in the test site for monitoring the change of the subsurface density distribution before and after grouting. The data were adjusted for reducing the effects due to the different condition of each survey, and inverted to density distributions. They show the change of density structure during the lapsed time, which implies the effects of grouting. This case history at the Muan test site showed that the microgravity with accuracy and precision of ${\mu}Gal$ is an effective and practical tool for detecting, mapping and monitoring the subsurface cavities.