• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.298-301
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• 2007

Magnesium alloy sheets have unique mechanical properties such as high in-plane anisotropy/asymmetry of yield stress and hardening response. The unusual mechanical behavior of magnesium alloys has been understood by the limited symmetry crystal structure of HCP metals or by deformation twinning. In the present study, the continuum plasticity models considering the unusual plastic behavior of magnesium alloy sheet were derived for a finite element analysis. A new hardening law based on two-surface model was developed to consider the general stress-strain response of metal sheets such as Bauschinger effect, transient behavior and the unusual asymmetry. Three deformation modes observed during the continuous tension/compression tests were mathematically formulated with simplified relations between the state of deformation and their histories. In terms of the anisotropy and asymmetry of the initial yield stress, the Drucker-Prager's pressure dependent yield surface was modified to include the anisotropy of magnesium alloys.

• Microbiology and Biotechnology Letters
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• v.19 no.6
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• pp.614-618
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• 1991

Antifungal compound, KRF-001, was produced by Bacillus subtilis subsp. krictiensis isolated from soil. Physico-chemical factors affecting cell growth and bioactivity were examined to improve the production yield. Nutrient composition, temperature, pH and phosphate ion concentration were proved to be important factors for the production of KRF-001. Mutation was performed to select high yielding strains. First, mutation was performed with ultra-violet light, and the second mutation process was conducted by MNNG (N-Methyl-N'-nitro-N-nitrosoguanidine) resulting in three high yielding strains.

• Toxicological Research
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• v.20 no.2
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• pp.167-172
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• 2004

Obesity is one of causes of the all adult diseases. We investigated the body weight decrease effect of the selected plants by digestive enzyme activity inhibition test. In a preliminary test, Inonotus obliquus and Rubus coreanus Miq. were found to be effective. Based on this result & previous result, we manufactured the mixture of plant extracts named as Misol$^{TM}$. Misol is applied anti-obesity beverage and rice. When we administered Miso/ sub TM/ to rats, it was found to be effective in body weight decrease. Result that is experimented during 20 weeks, is effective body weight and total cholesterol, triglyceride decrease. In case of human, anti-obesity beverage administered group showed 5.65% body weight decrease, 4% waist length decrease and 6% abdomen length decrease respectively. And anti-obesity rice administered group showed 2.3 kg body weight decrease, 2.9 cm waist length decrease and 3.74 cm abdomen length decrease respectively. This body control effect was supported by plant extracts in the Misol, anti-obesity beverage and rice - administered group. From these results, we suggest that this functional food could be helpful for body weight controlling obesity.

• Tunnel and Underground Space
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• v.25 no.2
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• pp.168-185
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• 2015

The thermal-hydrological-mechanical (T-H-M) behavior of rock mass surrounding a large-scale high-temperature cavern thermal energy storage (CTES) at a shallow depth has been investigated, and the effects of hydrological conditions such as water table and rock permeability on the behavior have been examined. The liquid saturation of ground water around a storage cavern may have a small impact on the overall heat transfer and mechanical behavior of surrounding rock mass for a relatively low rock permeability of $10^{-17}m^2$. In terms of the distributions of temperature, stress and displacement of the surrounding rock mass, the results expected from the simulation with the cavern below the water table were almost identical to that obtained from the simulation with the cavern in the unsaturated zone. The heat transfer in the rock mass with reasonable permeability ${\leq}10^{-15}m^2$ was dominated by the conduction. In the simulation with rock permeability of $10^{-12}m^2$, however, the convective heat transfer by ground-water was dominant, accompanying the upward heat flow to near-ground surface. The temperature and pressure around a storage cavern showed different distributions according to the rock permeability, as a result of the complex coupled processes such as the heat transfer by multi-phase flow and the evaporation of ground-water.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.12 no.1
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• pp.69-77
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• 2014

Unsaturated hydraulic conductivity of the bentonite-buffer was evaluated using the relative humidity data. The method for calculating unsaturated hydraulic conductivity was deduced from the general analytical equation representing the movement of water in unsaturated media, which was applied to the experimental results of water infiltration tests for identifying the behavior of unsaturated hydraulic conductivity according to the water saturation. Unlike the saturated condition, the hydraulic gradient and water flux were irregularly changed, and the unsaturated hydraulic conductivity was increased with increasing the experimental time. Swelling of bentonite grains due to the water absorption increased the volume and size of pore within bentonite, resulting in the increase of water velocity and unsaturated hydraulic conductivity. This result suggested the necessity of further investigation on the correlation between the swelling degree of bentonite-buffer and unsaturated hydraulic conductivity. The method used in this study can be useful technique for evaluating long-term hydraulic performance of bentonite-buffer in the radioactive waste disposal system.

• Korean Journal of Construction Engineering and Management
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• v.8 no.4
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• pp.185-193
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• 2007

In order to improve the performance of succeeding superstore construction projects, it is essential to find out an effective way for applying the opportunities of improvement on their repetitive construction process based upon the analysis of various success or failure cases occurred on previous similar projects. This research study suggests a way to improve their construction process through the applications of six sigma techniques on superstore construction projects. A literature review was implemented on the basic concept of six sigma and its general performance steps, and the step by step applications of six sigma techniques were accomplished regarding to the speciality of superstore construction projects. The opportunities of improvement for superstore projects were figured out, and the result of their applications on other superstore projects was analyzed. As a result, it was found that the adoption rate of identical success or failure cases was increased. Also, there were several improvement effects on the projects such as $10{\sim}20$ days of time savings by projects, decrease of reworks by preventing failure cases, quality and safety improvement. These results indicate that the six sigma techniques are applicable and valuable for improving the repetitive process of superstore construction projects.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.29 no.4
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• pp.98-110
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• 2011

Seochon('West Village') is located in the west side of Gyeongbokgung(Gyeongbok Royal Palace) inside the old city wall of Seoul. Seochon has beautiful scenic view surrounding Mt. Inwang and has been known as the representative historical and cultural landscape region in Korea that historical and cultural resources are rich. But when the figure of Seochon which has repeated the changes with the ones of the times is considered, values of beauty of natural landscape that Seochon had and its own placeness have not been gradually recognized as it has been swept away in logic of the development on the strength of economics. This study tries to examine the original form of landscape on Seochon which can be the standard of landscape change, the causes and process of its change and possibility to conserve and restore it to recognize potential value about historical culture of Seochon landscape and conserve and protect it. For this, this study compared and analyzed literature including poems and Yusangi, paintings and names of the scenery of the seasons as the landscape texts with the current status. The study result has found that Pilwundae should rehabilitate cultural assets to secure the prospect right and protect neighboring bedrock, Suseong-dong should expand the restoration areas focusing on the projects to make parks which are now being restored, Cheonghwigak and Cheongpunggye areas should restore waterways including historicity which is connected to figures and Seshimdae and Baekun-dong green zone should set the protective area for conservation.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.2
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• pp.141-155
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• 2023

Monitoring technology based on electrical resistivity is widely used for non-destructive data collection and health analysis of underground structures and tunnels. Vulnerable sections such as fault zone generates many problems during construction of the tunnel. These problems cause displacement and stress changes of the ground. Therefore, it is necessary to predict the state of the fault zone section to ensure the mechanical stability of the underground structure. Monitoring the size of joints and the porosity of the fillings is essential for rocks. Previous studies have not considered the variety of fillings in rock joints. In this study, electrical resistivity tests were conducted according to the particle mixing state of the sandy fillings. When the size of fillings is decreased at the constant porosity, the electrical resistivity tends to increase. The results of this study are expected to be useful as basic electrical resistivity data for predicting the ground conditions and evaluation of the ground behavior that is containing sandy fillings in the rock joint for tunnels.

• Tunnel and Underground Space
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• v.33 no.5
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• pp.348-372
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• 2023

In relation to the high-level radioactive waste disposal project in deep fractured rock aquifer environments, it is essential to evaluate hydrogeological characteristics for evaluating the suitability of the site and operational stability. Such subsurface hydrogeological data is obtained through in-situ tests using boreholes excavated at the target site. The accuracy and reliability of the investigation results are directly related to the selection of appropriate test methods, the performance of the investigation system, standardization of the investigation procedure. In this report, we introduce the detailed procedures for the representative test method, the constant pressure injection test (CPIT), which is used to determine the key hydrogeological parameters of the subsurface fractured rock aquifer, namely hydraulic conductivity and storativity. This report further refines the standard test method suggested by the KSRM in 2022 and includes practical field application case conducted in volcanic rock aquifers where this investigation procedure has been applied.

• Tunnel and Underground Space
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• v.33 no.5
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• pp.399-413
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• 2023

The present study conducted a numerical modeling of CO₂ injection at the Janggi Basin using the TOUGH-FLAC simulator, and examined the hydro-mechanical stability of the aquifer and the fault. Based on the site investigations and a 3D geological model of the target area, we simulated the injection of 32,850 tons of CO₂ over a 3-year period. The analysis of CO₂ plume with different values of the aquifer permeability revealed that assuming a permeability of 10^-14 m² the CO₂ plume exhibited a radial flow and reached the fault after 2 years and 9 months. Conversely, a higher permeability of 10^-13 m² resulted in predominant westward flow along the reservoir, with negligible impact on the fault. The pressure changes around the injection well remained below 0.6 MPa over the period, and the influence on the hydro-mechanical stability of the reservoir and fault was found to be insignificant.