• Tunnel and Underground Space
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• v.27 no.2
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• pp.89-99
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• 2017

For a successful performance of Carbon Capture Sequestration (CCS) projects, appropriate injection conditions should be designed to be optimized for site specific geological conditions. In this study, we built a simple 2-dimensional analysis model, based on the geology of Jang-gi basin which is one of the potential sites of domestic CCS projects. We evaluated the impact of initial stress conditions and injection rate through coupled TOUGH-FLAC simulator. From the preliminary analysis, we constructed risk scenarios with the higher potential of shear slip and performed scenario analysis. Our analysis showed that normal stress regime produced the highest potential of shear slip and stepwise increasing injection rate scenario resulted in much larger pore pressure build up and consequent higher potential of the shear slip, which was evaluated using a mobilized friction coefficient.

• Tunnel and Underground Space
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• v.14 no.4
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• pp.295-303
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• 2004

For the deep underground excavation site with the geological complexity of soft seam and hard rock, the numerical analysis and in-situ measurement on the behaviors of roadway and surrounding rock according to stepwise excavation of the steep soft seam are carried out. The strata behavior is modeled using elasto-plastic FEM considering the empirical failure criteria of Hoek ＆ Brown and the strain-softening model. Hydraulic pressure capsule, MPBX and tape extensometer are installed around the roadway for the in-situ measurement of rock stress and deformation. Despite the complexity of geology and excavation procedure, the elasto-plastic analysis considering the empirical failure criteria of Hoek ＆ Brown and the strain-softening model shows good agreement with the in-situ measurement. Comparison of numerical modeling with in-situ measurement enables to predict the behaviors of the roadway and to obtain design parameters for the excavation and support at depth.

• Korean Journal of Food Science and Technology
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• v.25 no.6
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• pp.787-793
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• 1993

A mold producing large amounts of lipid were isolated from leaves, arable soils, rice straw, cow feces, compost heaps and fermented soybeans. Among various sources, the microbes from leaves produced the large amount lipids, which were identified as Aspergillus sydowi SW 4-1. This study was focused mainly on the optimization of cultural conditions for lipid production by A. sydowi SW 4-1 and the characterization of the produced lipids. A. sydowi SW 4-1 was cultivated in a medium containing 27% sucrose for 17 days at $27^{\circ}C$. Biomass was 4.99g/100ml of the cultural medium and lipid content was 41.4% on a dry biomass basis. The major fatty acids were palmitic acid, stearic acid, oleic acid, and linoleic acid.

• The Journal of Engineering Geology
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• v.20 no.2
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• pp.169-181
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• 2010

This study aimed at simulating several responses to stresses caused by the ground water level variations around the K-1 oil stockpile. For this simulation, we considered the characteristic hydrogeological condition including the special occurrence of long and thick acidic dyke, which is regarded as the main geological structure dominating the ground water flow system at this study area. We activated twenty-four imaginary wells which are located in northern and southern area around central K-1 site. Each neighboring distance is altogether 300 m and whole distance between K-1 site and remote wells is 1,200 m. Through the modeling, we operated the long-term and continuous pumping tests and finally categorized five zones based on maximum pumping rates for the imaginary wells; zone I within 300 meter distance from K-1 site with a pumping rate of 50 $m^3/day$; zone II between 300 to 600 meter distance from K-1 site with a pumping rate of 75 $m^3/day$; zone III between 600 to 900 meter distance from K-1 site with 150 $m^3/day$; zone IV between 900 to 1,200 meter distance from K-1 site with 300 $m^3/day$; and zone V of acidic dyke area. At zone V, especially because of their possibility of high transmissivity for groundwater flow, it is necessary to control and restrict groundwater discharge.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 1996.06a
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• pp.216-219
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• 1996

• Proceedings of the Korean Society of Crop Science Conference
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• 1982.10a
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• pp.10-10
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• 1982

• Tunnel and Underground Space
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• v.30 no.6
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• pp.559-572
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• 2020

This paper performs laboratory experiments for borehole stability considering temperature and true triaxial stress condition, and observes a thermo-mechanical behavior of the rock under stress and temperature conditions of deep underground. China yellow sandstone and Hwangdeung granite specimens were used to perform a true triaxial compression test. Mechanical tests were carried out under nine confining pressure conditions, and thermo-mechanical tests using granite samples were carried out under six confining pressure conditions at 60-100℃. In the mechanical tests, maximum principal stress at borehole breakout was proportional to intermediate principal stress. In the thermo-mechanical tests, it was confirmed that thermal stress is added to the stress field of the borehole with the increase in temperature, resulting in additional breakout progress. To analyze the results of the laboratory experiment, Mogi-Coulomb failure criterion was used. The results of traditional triaxial compression test on cylindrical specimens and borehole breakout under true triaxial compressions matched well with Mogi-Coulomb failure criterion.

• Journal of the Korean earth science society
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• v.42 no.2
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• pp.164-174
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• 2021

The study examines the shearing and crushing characteristics of land-derived subaqueous granular materials in a gravel-bed river. A series of large-sized ring shear tests were performed to examine the effect of shear time and shear velocity on the shear stress characteristics of aquarium gravels with a 6-mm mean grain size. Three different shear velocities (i.e., 0.01, 0.1, and 1 mm/sec) were applied to measure the shear stress under the drained (long-term shearing) and undrained (short-term shearing) conditions. Different initial shear velocities, i.e., 0.01→0.1→1 mm/sec and 0.1→0.01→1 mm/sec, were considered in this study. The test results show that the grain crushing effect is significant regardless of drainage conditions. The shear stress of coarse-grained materials is influenced by initial shear velocities, regardless of the drainage conditions. In particular, particle breakage increases as grain size increases. The shearing time and initial shear velocity are the primary influencing factors determining the shear stress of gravels. The granular materials may be broken easily into particles through frictional resistance, such as abrasion, interlocking and fracture due to the particle-particle interaction, resulting in the high mobility of granular materials in a subaqueous environment.

• The Journal of Engineering Geology
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• v.17 no.4
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• pp.555-566
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• 2007

In general, RMR classification system is used for the support design of a tunnel. Face mapping during excavation and RMR-based rock classifications are conducted in order to provide information for complementary changes to preliminary survey plans and for continuous geological estimations in direction of tunnel route. Although they are ever so important, there are not enough time for survey in general and sometimes even face mapping is not available. Linear regression analysis for the estimation of mediating RQD and condition of discontinuities, which require longer time and more detailed observation in RMR, was performed and optimum regression equations are suggest as the result. The geological data collected from tunnels were analyzed in accordance with three rock types as sedimentary rock, phyllite and granite to see geological effects, generally not been considered in previous researches. Parameters for the regression analysis were set another RMR factor.

• Journal of the Korean Geosynthetics Society
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• v.9 no.1
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• pp.1-11
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• 2010

The soil mechanical characteristics according to geologic conditions were investigated in the study area. The geology of study area was consisted of Ingok Tuff, Yuchi Conglomerate and Dado Tuff. Yuchi Tuff covered about 80% of the study area. The disturbed and undisturbed soils were sampled from the conglomerate area, Tuff area and Shale area, and then a series of the laboratory soil tests was performed. The soils sampled from the conglomerate area have a large dry unit weight and a low permeability relatively, while the soils sampled from tuff and shale areas have a small dry unit weight and a high permeability. It is proven that the soil permeability is highly affected by the effective grain size and the silt and clay content. That is, the soil permeability is increased with increasing the effective grain size, and the soil permeability is decreased with increasing the silt and clay content.