• Journal of the Korean GEO-environmental Society
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• v.6 no.2
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• pp.39-49
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• 2005

In this study, the fifteen month behavior of two geosynthetic reinforced walls which was constructed on the shallow weak ground was measured and analyzed. The walls were backfilled with clayey soil obtained from the construction site nearby, and the safety factors obtained from general limit equilibrium analysis were less than 1.3 in both wall. The measured and analyzed data were horizontal earth pressures, strain of reinforcements, and excess pore water pressures. The used reinforcements were nonwoven geotextile, woven geotextile and geogrid. Although the length of reinforcement was only 30% of wall height and the safety factors of the walls were less than 1.3, the walls were constructed without any problems on the such weak ground. The analysis results showed that the maximum strain of reinforcements were negligible and the strain was between 2.3 and 6.0% according to tensile characteristic of the reinforcements. The excess pore water pressure was not changed due to the rainfall and the horizontal earth pressures in upper and lower part of the walls were larger than the active and the rest pressure.

• Agricultural and Biosystems Engineering
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• v.4 no.1
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• pp.34-38
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• 2003

A mathematical model was developed for estimating the mechanical interrelation between characteristics of soil and main design factors of a tracked vehicle, and predicting the tractive performance of the tracked vehicle. Based on the mathematical model, a computer simulation program (TPPMTV) was developed in the study. The model considered the continuous change in tension for the whole track of a tracked vehicle, the analysis of shape and tension of the track segment between sprocket and first roadwheel, and the side thrust on both sides of grouser by the active earth pressure theory in predicting the tractive performance of a tracked vehicle. Also, the model contained not only sinkage depth of the track but the pressure distribution under the track in analyzing the side thrust. The effectiveness of the developed model was verified by performing the draw bar pull tests with a tracked vehicle reconstructed for test in loam soil with moisture content of 18.92％. The predicted drawbar pulls by the model were well matched to the measured ones. Such results implied that the model developed in the study could estimate the drawbar pulls well at various soil conditions, and would be very useful as a simulation tool for designing a tracked vehicle and predicting its tractive performance.

• Journal of The Korean Astronomical Society
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• v.36 no.3
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• pp.105-110
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• 2003

Recent observations of galaxy clusters in radio and X-ray indicate that cosmic rays and magnetic fields may be energetically important in the intracluster medium. According to the estimates based on theses observational studies, the combined pressure of these two components of the intracluster medium may range between $10\%{\~}100\%$ of gas pressure, although their total energy is probably time dependent. Hence, these non-thermal components may have influenced the formation and evolution of cosmic structures, and may provide unique and vital diagnostic information through various radiations emitted via their interactions with surrounding matter and cosmic background photons. We suggest that shock waves associated with cosmic structures, along with individual sources such as active galactic nuclei and radio galaxies, supply the cosmic rays and magnetic fields to the intracluster medium and to surrounding large scale structures. In order to study 1) the properties of cosmic shock waves emerging during the large scale structure formation of the universe, and 2) the dynamical influence of cosmic rays, which were ejected by AGN-like sources into the intracluster medium, on structure formation, we have performed two sets of N-body /hydrodynamic simulations of cosmic structure formation. In this contribution, we report the preliminary results of these simulations.

• Journal of the Korean Society for Railway
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• v.9 no.3 s.34
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• pp.298-304
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• 2006

An active application of concrete track is being expected for the future constructions of Korean railroad. For the successful concrete track construction and design in earthwork areas, the roadbed behavior should be reasonably estimated using the proper analysis method. In this paper, behaviors of concrete track on the reinforced roadbed constructed with the standard stiffness and depth were estimated thorough numerical analyses and field measurements. A three dimensional finite difference method was employed to model the concrete tracks and subground. The settlement and vertical pressures caused by train load were estimated by the numerical method and compared with the field measurement results. The bearing characteristics of roadbed were presented and the proper method for the analysis of concrete track was proposed.

• International Journal of Aeronautical and Space Sciences
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• v.9 no.1
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• pp.42-47
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• 2008

One of the main cases of the desertification impact is the negative contribution of human activities that worsen environment. There are historical facts of inability and excessive activities which destroyed the civilizations. The basic difference is only in the tempo and scales of civilization collapse. Human pressure was accumulated within the centuries and millennia due to the extremely active economic activities. But today it covers only the decades. Presently the process of desertification has a global scale. There are huge factors of Earth aridization as an increase of the quantity of C02 and atmospheric dust and bloom. This process related not only to the arid areas. Obviously a comprehensive approach of development of territories, particularly arid areas is very important. The use of the satellite information and technologies of remote sensing data processing can take a significant place for decision-makers for calculation and estimation of the environment impacts.

• Geomechanics and Engineering
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• v.10 no.5
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• pp.565-575
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• 2016

Geosynthetics reinforced soil (GRS) walls constructed on weak grounds may change in both the horizontal earth pressure and deformation on wall facing. However, only few studies were done in the literature to measure and analyze the horizontal external deformation behavior of GRS walls constructed on soft grounds for a long period of time. The present study describes the external deformation behavior of GRS walls observed for 12-year long-term performance. The horizontal deformation of the geosynthetics-wrapped-facing GRS walls shows a passive behavior along one third of the wall height, from top going downwards, and active behavior for the rest of the wall height. Even if the geogrid and nonwoven geotextiles are exposed directly to sunlight and rainfalls in a span of 12 years, they have functioned well as wall facing. Therefore, the geosynthetic reinforcement material is strong enough to resist ultraviolet rays.

• Journal of the Korean Home Economics Association
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• v.34 no.3
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• pp.1-8
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• 1996

These days, Home Economics in Korea is confronted with the inner argument about its identity and the outer pressure of re-organization caused by educational reformation. Fundamentally, these internal and external challenges to Home Economics arise from that Home Economics has not been fulfilling the needs of individuals and families due to weakening of integrate perspective, insufficient practice and conservative tendency of study. To get over the current problems and construct a new paradigm of Home Economics contributing to the requirements of new era, the following prerequisites might be fulfilled; \circled1 More active concern about surmounting the alienation that threatening the modern family life and self-actualization of individuals. \circled2 An endeavor to find a new family philosophy and patterns of family culture as the basis of community restoration that harmonize the traditions with changes. \circled3 An Effort to find a highter values that contribute to symbiosis and development of global community including all human beings, creatures and eco-system on the earth.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.5
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• pp.533-541
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• 2021

Retaining walls have been used to prevent slope failure through resistance of earth pressure in railway, road, nuclear power plant, dam, and river infrastructure. To calculate dynamic earth pressure and determine the characteristics for seismic behavior, many researchers have analyzed the nonlinear response of ground and structure based on various numerical analyses (FLAC, PLAXIS, ABAQUS etc). In addition, seismic fragility evaluation is performed to ensure safety against earthquakes for structures. In this study, we used the FLAC2D program to understand the seismic response of the inverted T-type wall with a backfill slope, and evaluated seismic fragility based on relative horizontal displacements of the wall. Nonlinear site response analysis was performed for each site (S2 and S4) using the seven ground motions to calculate various seismic loadings reflecting site characteristics. The numerical model was validated based on other numerical models, experiment results, and generalized formula for dynamic active earth pressure. We also determined the damage state and damage index based on the height of retaining wall, and developed the seismic fragility curves. The damage probabilities of the retaining wall for the S4 site were computed to be larger than those for the S2 site.

• Journal of the Korean Geosynthetics Society
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• v.22 no.3
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• pp.11-25
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• 2023

In this study, the design and numerical analysis method of the inclined self-supported wall using cement treated soil were studied. In the case of the inclined self-supported wall, the active earth pressure decreased due to the decrease in the coefficient, Ka according to the slope (angle) and the weight decreasing effect, thereby increasing the overall stability. The wall with the slope caused a change in failure mode from overturning to sliding on the excavation side, and the optimal slope was evaluated to be about 10°. Compared to the strength reduction method, the overall stability in numerical analysis results in conservative results in limit equilibrium analysis, so it was found that this method should be attended when designing. As a result of the parameteric study, the stability on bearing capacity and compression failure did not significantly increase above the slope of 10° when the surcharge was small (about 20kPa or less). In the case of cohesion of the backfill, The results similar to numerical analysis were found to consider cohesion. It was evaluated that stability on sliding, oveturning, shear, and tension failure increases in proportion to the thickness of the wall, but there is no significant change in the stability on the bearing capacity and compressive failure regardless of the thickness of the wall above a certain angle (about 10°).

• Geotechnical Engineering
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• v.2 no.3
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• pp.27-36
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• 1986

To investigate the seepage effect on the compacted backfill of retaining walls, an expriment and an analytical study were carried out First, the expriment was performed with a two-way permeameter newly designed for the do- termination on the degree of permeability anisotropy of compacted soils. As a result, e-log(kz/ky) plot showed a linear relationship, where kz and ky were permeability coefficients for the normal and the parallel directions to the compaction. The degree of permeability anisotropy, kz/ky was 2 to 4 at Dr>90% for sands, regardless of the methods of compaction. The kz/ky of the fine sand was greater than that of the coarse sand. Second, the exprimental results were applied to the extention of Gray's theory for the investigation of the active thrust affected by the seepage of permeability anisotropy. The active thrust was decreased with the increase in the degree of permeability anisotropy, and it It.as a little effect on wall friction.