• YAKHAK HOEJI
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• v.31 no.6
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• pp.394-398
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• 1987

The present paper describes the serum cholesterol level lowering effect of the underground parts of Rosa rugosa(Rosaceae) which have been used in a folkloric medicine for treating diabetics. The methanol extract was shown to lower the serum lipid level against the normal and 1% cholesterol and 0.5% cholic acid diet feeding to rats, respectively. When various fractions prepared from the above methanol extract was administered, the ethyl acetate-soluble fractions lowered the serum cholesterol level most remarkably. And when (+)-catechin from the ethyl acetate-soluble fractions was only administered to them, the serum cholesterol level was significantly lowered to 260$\pm$9.3mg/dl, the decrease of 17% for the control group. Therefore, it is suggested that (+)-catechin is one of the active principles of this plant.

• Proceedings of the PSK Conference
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• 2000.04a
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• pp.180.1-180.1
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• 2000

• Journal of the Korean Society of Safety
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• v.18 no.3
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• pp.69-74
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• 2003

To investigate the partial discharge and electric field distribution in cable joint parts, we measured the partial discharge and electric field in specimen. The specimens which cross-linked polyethylene(XLPE) and ethylene propylene diene ethylene(EPDM) are used to insulating material for underground cable md cable jointing parts. The polymers are used to insulating material in switchgear which is a kind of transformer equipment and in ultra-high voltage cable. Its using is increasing gradually, the electrical insulation properties are not only excellent but also mechanical property is excellent. And because it is possible to be made void of several type in insulator while it is produced, which the electrical field distribution is changed by void, it has a critical influence to insulator performance. The underground cable is connecting by the jointing material, insulating breakdown and the electric ageing which are caused by several mixing impurity and the damage of cable insulator layer, which reduced the life of cable while intermediate joint kit is connected. Therefore, the computer simulation is used to estimating insulator performance, XLPE is used to the insulating material of ultra-high voltage cable and EPDM is used to insulator layer in joint material kit, and which are produced as specimen. And it is analyzed the electric field concentrating distribution and partial discharge by modeling of computer simulation in void and cable joint kit.

• Journal of the Korea Institute of Building Construction
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• v.9 no.6
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• pp.91-98
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• 2009

One role of waterproofing work is to block external moisture and water. Defects in waterproofing work in building construction brings on huge repair costs for related construction work as well as for the waterproofing layer itself. However, we don't have a quantitative probabilistic management method for waterproofing work to successfully anticipate and prevent defects. From an analysis of the literature and prior research, defects in the waterproofing work in the underground parts of buildings occur frequently. We selected Fluid-Applied Membrane waterproofing work as representing waterproofing work in the underground parts of a building, and researched the general types and causes of defects. In this study, we developed the Relative-FMEA (Failure Mode and Effect Analysis) approach that merges the Matrix method and FMEA. From a survey of experts, we deduced the most important management factors for Fluid-Applied Membrane waterproofing work for the underground parts of buildings.

• Journal of the Korea Safety Management & Science
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• v.14 no.1
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• pp.65-73
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• 2012

We studied the risk analysis of fire and explosion caused by gas leak in underground-parking of gas vehicle. However, an entrance regulation of gas vehicles (H2/LPG/CNG etc.) to underground garages has not been enacted in Korea. Incase, a gas explodes in an underground parking garage placed in overcrowded residential area, such as an apartment, the scale of the damage would cause tremendous disaster. Faults of vehicle parts and management problems were evaluated by using the Failure mode and effect analysis (FMEA), which is a qualitative analysis method. The range of the damaged area by the explosion and the damage scale by the explosion pressure were analyzed by using the process hazard analysis software tool (PHAST). The study is expected to facilitate enactment of the regulation for the underground parking to restrict the gas vehicle.

• Geomechanics and Engineering
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• v.30 no.2
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• pp.107-121
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• 2022

Coal pillar assessment is of broad importance to underground engineering structure, as the pillar failure can lead to enormous disasters. Because of the highly non-linear correlation between the pillar failure and its influential attributes, conventional forecasting techniques cannot generate accurate outcomes. To approximate the complex behavior of coal pillar, this paper elucidates a new idea to forecast the underground coal pillar stability using combined unsupervised-supervised learning. In order to build a database of the study, a total of 90 patterns of pillar cases were collected from authentic engineering structures. A state-of-the art feature depletion method, t-distribution symmetric neighbor embedding (t-SNE) has been employed to reduce significance of actual data features. Consequently, an unsupervised machine learning technique K-mean clustering was followed to reassign the t-SNE dimensionality reduced data in order to compute the relative class of coal pillar cases. Following that, the reassign dataset was divided into two parts: 70 percent for training dataset and 30 percent for testing dataset, respectively. The accuracy of the predicted data was then examined using support vector classifier (SVC) model performance measures such as precision, recall, and f₁-score. As a result, the proposed model can be employed for properly predicting the pillar failure class in a variety of underground rock engineering projects.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.117-124
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• 2002

The major purpose of this study is to determine the dynamic behavior of soil-pile-structure interaction system considering the underground cavity. For the analysis, a numerical method fur ground response analysis using FE-BE coupling method is developed. The total system is divided into two parts so called far field and near field. The far field is modeled by boundary element formulation using the multi-layered dynamic fundamental solution that satisfied radiational condition of wave. And this is coupled with near field modeled by finite elements. For the verification of dynamic analysis in the frequency domain, both forced vibration analysis and free-field response analysis are performed. The behavior of soil non-linearity is considered using the equivalent linear approximation method. As a result, it is shown that the developed method can be an efficient numerical method to solve the seismic response analysis considering the underground cavity in 2D problem.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.192-197
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• 2003

It can be said that rock mass properties are characterized not by a mean value but by values with variation due to its characteristic uncertainty. This characteristic is one of the most important parts for the design of underground structures, but yet to be fully examined. Stochastic finite element method (SFEM) has been developed in order to take the randomness of structural systems into account. Using SFEM, the response variability of structural system can be obtained and it leads probabilistic stability of structure to be analyzed. In this study, displacements response variability of circular opening with hydrostatic stress field are analyzed in terms of rock mass properties having a certain mean and a standard deviation using the SFEM. The analyzed response variability shows that the necessity of probabilistic stability analysis of underground structures using reliable mean value and standard deviation of deformation modulus.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.196-197
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• 2021

The underground method can be divided into Top-Down, Semi-Top-Down, Up-Up and Down-Up methods according to the construction order of the upper and lower structures. Among them, the Down-Up method proceeds with the construction of the first floor and its lower floors, and when the foundation is completed, the vertical members of the basement are sequentially completed from the foundation and the above-ground floor is constructed. In this paper, the crack reduction method around the open section of the Down-Up method affected by earth pressure was analyzed and divided into design and construction parts.

• Korean Journal of Organic Agriculture
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• v.3 no.1
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• pp.87-97
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• 1994

In the edible parts of chinese cabbage, the NO-3 accumulation was higher in the outer leaves than in the inner leaves and it was higher in the leaf midrib than in the leaf blade. In Radish, it was higher in the aerial part of the root than in the underground part of root. NO-3 accumulation in edible parts of chinese cabbage of organic farming fertilized with compost 8t/10a was about 4 times higher than those of conventional farming with recommended mineral nitrogen; and was similar to those of conventional farming fertilized with twice the mineral nitrogen rate. But, NO-3 accumulation in radish of organic farming with 8t/10a compost was lower than those of conventional farming with recommended mineral nitrogen. It showed NO-3 content in the edible parts of vegetables should be considered one of several parpmeters to judge a real safety vegetable to be certified by government.