• Tunnel and Underground Space
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• v.34 no.1
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• pp.28-53
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• 2024

In general, high-level radioactive waste (HLW) generated as a result of nuclear power generation should be disposed within the country. Determination of the disposal site and host rock for HLW deep geological repository is an important issue not only scientifically but also politically, economically, and socially. Considered host rock types worldwide for geological disposal include crystalline rocks, sedimentary rocks, volcanic rocks, and salt dome. However, South Korea consists of various rock types except salt dome. This paper not only analyzed the geological and rock mechanical characteristics on a nationwide scale with the preliminary results on various rock type studies for the disposal host rock, but also reviewed the characteristics and possibility of various rock types as a host rock through deep drilling surveys. Based on the nationwide screening for host rock types resulted from literature review, rock distributions, and detailed case studies, Jurassic granites and Cretaceous sedimentary rocks (Jinju and Jindong formations) were derived as a possible candidate host rock types for the geological disposal. However, since the analyzed data for candidate rock types from this study is not enough, it is suggested that the disposal rock type should be carefully determined from additional and detailed analysis on disposal depth, regional characteristics, multidisciplinary investigations, etc.

• Journal of Conservation Science
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• v.19
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• pp.85-98
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• 2006

Rock property of the Seosan Maaesamjonbulsang is composed of biotite granite with medium grained texture. The triad Buddha is highly deteriorated by the joint, fracture, break-out, exfoliation, dew condensation of the surface and discoloration of the secondary pollutant. Host rock of the triad Buddha is divided dozens of rock blocks with various shape, and developed irregular discontinuity planes. Besides, the host rock is promoted biological pollution due to the surrounding crowded vegetation and high humidity environment. As the results of structural stability, it is confirmed that developed discontinuity system in the host rock is exposed instability sloping environment. Therefore, the host rock and surroundings are required maintenance, and required preservation by continuance monitoring for understand behavior of discontinuity system.

• Journal of Soil and Groundwater Environment
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• v.22 no.4
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• pp.33-48
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• 2017

An optimum disposal plan of disused sealed radioactive sources (DSRSs) should be established to ensure long-term disposal safety at the low- and intermediate-level radioactive waste (LILW) disposal facility in Gyeongju. In this study, an optimum disposal system was suggested and preliminary post-closure safety assessment was performed. The DSRSs disposal system was composed of a rock cavern and near surface disposal facilities at the Gyeongju LILW disposal facility. The assessment was conducted using GoldSim program, and probabilistic assessment and sensitivity analysis were implemented to evaluate the uncertainties in the input parameters of natural barriers. Deterministic and probabilistic calculations indicated that the maximum dose was below the regulatory limits ($0.1mSvyr^{-1}$ for the normal scenario, $1mSvyr^{-1}$ for the well scenario). It was concluded that the DSRSs disposal system would maintain environmental safety over a long-time. Moreover, the partition coefficient of Np in host rock, Darcy velocity in host rock, and density of the host rock were the most sensitive parameters in predicting exposure dose in the safety assessment.

• Economic and Environmental Geology
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• v.13 no.3
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• pp.159-166
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• 1980

A model study was conducted for the investigation of apparent resistivity variation along with electric resistivity variation of host rock and dip variation of bed. Experiments were carried out for the cases of horizontal and dipping beds in a water tank by using Wenner and Schlumberger arrays and by changing salinity of water. The ratios of resistivity values of the bed to that of brine were 1 : 10, 1 : 50, 1 : 100 and 1 : 500. Natural coally-shale of $55cm{\times}35cm{\times}3.5cm$ was used as a bed for experimental model, and brine as a host rock. Equi-resistivity curves and characteristic curves were obtained for each case of the experiment. The equi-resistivity curve was drawn both on the cross section parallel to strike of bed and longitudinal section perpendicular to it. The characteristic curve was drawn on the cross section. In the case of dipping bed of different dips, the curves are parallel to the boundary of the bed in the upper part of the bed, and are inclined to the opposite direction with the same angle of the dip of bed in the lower part. We can deduce, from the equi-resistivity curves, the location, shape and dip of the bed. It is shown in the characteristic curves that when the ratio of resistivity value of bed to that of host rock increases, the slope of curves becomes steeper, location of low-resistivity zone lower, and the width of it narrower. The slope of curves also becomes steeper when dip of bed increases. We can deduce, from the characteristic curves, the ratio of resistivity values between adjacent beds. It was found out from the experiments that electric resistivity method could be applicable to prospecting for underground geology with an electric resistivity contrast of 1 : 10. This fact strongly suggests that distinction of coal from coally-shale could be possible in a certain field condition.

• Journal of Korea Soil Environment Society
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• v.2 no.1
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• pp.35-44
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• 1997

A column study using artificial acid rain was conducted to evaluate the buffering capacities in soil layer and host rock. In an effort to compare the effect of composition of host root two valleys of which compositions of host rock are different were chosen within the study area and the pHs of the water flowing in the valleys were measured from May, 1996 to October, 1996. The pHs of the artificial acid rain prepared by adding appropriate amounts of both sulfuric and nitric acids to distilled water were 3, 4, and 5, and the column effluents were analyzed for major cations and anions. The cation exchange capacities(CECs) of A Horizon and the B Horizon were 9.68 and 6.16 meq/100g, respectively, Compared to the B Horizon, the pH in the column effluent of A Horizon with larger CEC was higher. The sums of $Ca^{2+}$, $Mg^{2+}$, $Na^{+}$in the column effluents gradually decreased, indicating the loss of CEC by acid rain. The field study showed that pHs of the surface water in the valleys increased as the water flows downwards. The magnitude of this buffering capacity was greater for the valley in which smectite in addition to kaolinite and illite was a weathered product of host rocks. This also indicates that host rock as well as soil layer retains the buffering capacity.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.2
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• pp.99-105
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• 2011

An integrated model for groundwater flow and radionuclide transport analyses is being developed incorporating six underground silos, an excavated damaged zone (EDZ), and fractured host rock. The model considers each silo as an engineered barrier system (EBS) consisting of a waste zone comprising waste packages and disposal container, a buffer zone, and a concrete lining zone. The EDZ is the disturbed zone adjacent to silos and construction & operation tunnels. The heterogeneity of the fractured rock is represented by a heterogeneous flow field, evaluated from discrete fractures in the fractured host rock. Radionuclide migration through the EBS in silos and the fractured host rock is simulated on the established heterogeneous flow field. The current model enables the optimization of silo design and the quantification of the safety margin in terms of radionuclide release.

• Geophysics and Geophysical Exploration
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• v.13 no.4
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• pp.378-387
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• 2010

We present the results of laboratory measurement of porosity and electrical resistivity for the samples collected near marine hydrothermal deposit to provide fundamental perspective of physical properties for future electromagnetic survey. The rock cores are sampled from the host rock, pumice, hydrothermal altered zone, and chimney. These samples are featured as easily brittle, rough surface with large pores, having components easily solvable in the water. We suggest systematic approach for measuring weights, volumes of core samples to calculate density and porosity. Measurements reveal that the resistivities of black host rock, gray host rock, pumice and chimney are 102, 39, 11, 0.1 ohm-m, respectively, when the core samples are saturated with saline water of $32,000\;{\mu}S$/cm (0.5 ohm-m) at temperature of $2.5^{\circ}C$ and these correspond to the factors of 5 for sea water, 110 for pumice and 390~1020 for host rocks with respect to the resistivity of chimney. We also confirm that resistivity of rock samples saturated with water decrease with temperature linearly over the temperature range of $20{\sim}80^{\circ}C$.

• Proceedings of the KSEEG Conference
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• 1999.04a
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• pp.344-344
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• 1999

• Geomechanics and Engineering
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• v.21 no.1
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• pp.63-71
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• 2020

Strength anisotropy is a typical feature of thin-bedded rock masses and their strength will be degraded subjected to water immersion effect. Such effect is crucial for the operation of hydropower plant because the impoundment lifts the water level of upstream reservoir and causes the rock mass of nearby slopes saturated. So far, researches regarding mechanical property of natural thin-bedded rock masses and their strength variation under water immersion based on field test method are rarely reported. This paper focuses on a thin-bedded stratified rock mass and carries out field test to investigate the mechanical property and strength variation characteristics. The field test is highlighted by samples which have a large shear dimension of 0.5 m*0.5 m, representing a more realistic in-situ situation than small size specimen. The test results confirm the anisotropic nature of the concerned rock mass, whose shear strength of host rocks is significantly larger than that of bedding planes. Further, the comparison of shear strength parameters of the thin-bedded rock mass under natural and saturated conditions show that for both host rocks and bedding planes, the decreasing extent of cohesion values are larger than friction values. The quantitative results are then adopted to analyze the influence of reservoir impoundment of a hydropower plant on the surrounding rock mass stability of diversion tunnels which are located in the nearby slope bank. It is evaluated that after reservoir impoundment, the strength degradation induced incremental deformations of surrounding rock mass of diversion tunnels are small and the stresses in lining structure are acceptable. It is therefore concluded that the influences of impoundment are small and the stability of diversion tunnels can be still achieved. The finings regarding field test method and its results, as well as the numerical evaluation conclusions are hoped to provide references for rock projects with similar concerns.

• 한국문화재보존과학회:학술대회논문집
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• 2004.10a
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• pp.81-91
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• 2004

The host rock of standing sculptured Buddha in the Yongamsa temple was macular biotite granite, which has gone through mechanical and chemical weathering. The principal rock-forming minerals are quartz, plagioclase, alkali feldspar, and biotite, the last two of which have been transformed into clay minerals and chlorite due to weathering processes. The bed rock around the Buddha statue is busily scattered with steep inclinations that are almost vertical and discontinuous planes with the strikes of $N8^{\circ}E$. The major joints have the strikes of N4 to $52^{\circ}W$ and N6 to $88^{\circ}E$ and the dips of 42 to $89^{\circ}$. Especially thee development of the joints that cross the major joints causes tile structural instability of the rock. The host rock of the Buddha image is separated into many different rock masses because of the also many different discontinuity, which group accounts for about $12{\%}$ of the rock. Thus it's estimated that the bed rock has not only plane and toppling failure but also wedge failure in all the sides. Since the earth pressure and the inclination pressure are imposed on the body of the Buddha in the basement rock, it's urgent to give a treatment of geotechnical engineering for the sake of its structural stability. The parts where serious fractures are seen should receive the hardening process using the fillers for stones. It's also necessary to introduce a landfill liner system in order to reduce the ground humidity. The rock surface of the Buddha statue are partly contaminated by lichens and bryophyte. The joints have turned into earth, which promotes the growth of weeds and plant roots. Thus biochemical treatments should also be considered to get rid of the vegetation along the discontinuous planes and prevent further biological damages.