• Journal of the Korean Geosynthetics Society
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• v.3 no.1
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• pp.3-15
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• 2004

Geogrid reinforced soil structures with segmental block facing have been increased since 1990's, because of the convenience of installation and the flexible appearance. In this paper, the behavior of the segmental reinforced retaining wall was analysed with the results of field monitoring. The height and length of reinforced wall are 12m and 25m, respectively. The field measurement equipments are horizontal and vertical earth pressure cells, settlement plate, strain gauge, inclinometer, and displacement pin. Based on the field monitoring, the horizontal earth pressure was approximately 0.3times higher than that of the theoretical method and the maximum tensile strength of reinforcement was 26.2kN/m. The displacement of facing wall was 23mm at the point of 7.1m height of the wall and toward the wall facing. The results of the study indicate that the segmental reinforced retaining wall is in a stable condition because of good compaction & reinforcement effects, and long period of construction time. Finally, the computer program of SRWall is very useful tool to design the segmental reinforced retaining wall.

• Geotechnical Engineering
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• v.7 no.4
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• pp.35-48
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• 1991

Based on centrifuge model tests, the failure mechanism of reinforced earth retaining wall under strip load was investigated in this paper. Tests were performed by changing the materials of reinforcing strips, strip lengths, and strip arrangements. The strips were strain-gauged to measure the tensions in strips. The results were analyzed and compared with various design methosds in use to verify their feasibility. Consequently, a centrifuge model test was an effective method of investigating the behavior of reinforced earth retaining wall. The 2 : 1 stress diffusion method showed comparable results with tests in estimating the capacity of the reinforced earth wall under strip load. The superposition of tensions due to selfweight of the backfill and strip load was valid to estimate total tensions mobilized in strips. Using the elasticity theory to estimate the maximum tension mobilized in strips due to surcharge, while solutions of Boussinesq and Westergaard underestimated less tensions than the measured valises, Frohlich solution showed the comparable results with tests.

• Journal of the Korean Geosynthetics Society
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• v.19 no.4
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• pp.95-109
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• 2020

In this study, a total of six site cases were reviewed to assess the site applicability of portable dynamic cone penetration test (DCPT) by identifying the cause of damage to the damaged reinforced earth wall using portable dynamic cone penetration test. An improved dynamic concrete penetration tester was used at the site to enable ground surveys of more than 6 meters. The test results were compared with the results of the standard penetration test (SPT) and the correlation was analyzed. Through the analysis of various field application cases, it was found that portable dynamic cone penetration test was very convenient to apply at the site of the damaged reinforced earth wall, and DCPT could play a major role in identifying the cause of damage and verifying stability of the retaining wall by continuously identifying the ground strength. In addition, it was found that the results of the dynamic cone penetration test and the standard penetration test showed a correlation of N≒(1/3~2/3)·Nd in sandy soil.

• Composites Research
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• v.30 no.1
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• pp.7-14
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• 2017

In this paper, the inter-lamina shear strength (ILSS) of multi-wall carbon nanotube (MWNT) reinforced carbon fiber reinforced plastics (CFRP) and thin-ply composites were verified under low earth orbit (LEO) space environment. CFRP, MWNT reinforced CFRP, thin-ply CFRP and MWNT reinforced thin-ply CFRP were tested after aging by using accelerated ground simulation equipment. The used ground simulation equipment can simulate high vacuum ($2.5{\times}10^{-6}torr$), atomic oxygen (AO, $9.15{\times}10^{14}atoms/cm^2{\cdot}s$), ultraviolet light (UV, 200 nm wave length) and thermal cycling ($-70{\sim}100^{\circ}C$) simultaneously. The duration of aging experiment was twenty hours, which is an equivalent duration to that of STS-4 space shuttle condition. After the aging experiment, ILSS were measured at room temperature ($27^{\circ}C$), high temperature ($100^{\circ}C$) and low temperature ($-100^{\circ}C$) to verify the effect of operation temperature. The MWNT and thin-ply shows good improvement of ILSS at ground condition especially with the thin-ply. And after LEO exposure large degradation of ILSS was observed at MWNT added composite due to the thermal cycle. And the degradation rate was much higher under the high temperature condition. But, at the low temperature condition, the ILSS was largely recovered due to the matrix toughening effect.

• Proceedings of the Korean Geotechical Society Conference
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• 2007.09a
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• pp.514-527
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• 2007

Earth reinforcement techniques are used worldwide and offer proven solutions to a wide range of geotechnical engineering problems. Here in this paper, recent developments of three major reinforced soil retaining wall methods in Japan were introduced in order to show how the current situation of this technique in Japan is. And the statistical data for the volume of the use was also shown, such as the total volume of the use, the scales of the structures, layout of the earth reinforcement, fill materials, and foundation conditions. Some of the case histories were also introduced with photographs and figures. And then, as one of recent research activity by the author, the study on the application of X-ray CT for the problem of earth reinforcement method combined with other method such as piling and soil improvement was introduced. In this study, a series of model test for several reinforced ground with geogrids was conducted using a newly developed test apparatus. Then, the behavior in the soil box was scanned after settlement using X-ray CT scanner. Based on these test results, the reinforcing effect by the geogrids and the soil arching effect over the pile heads was discussed precisely and those are done in 3-D with nondestructive condition. Finally, the effectiveness of the use of X-ray CT scanner in geotechnical engineering was promised.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.54-58
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• 2006

This paper deals with primary consideration in down-conductor system and earth-termination system design of apartments. For down-conductor system, steelworks within reinforced concrete apartment structures have the electrical continuity, however, lashing is not suitable for lightning-current-carrying connections. So this paper suggest that the additional dedicated conductors should be installed and they are should be lashed to the reinforcement steel. Also this paper suggested the foundation earth electrode and global earth system as the earth-termination system of the apartments. But perfect bonding system is essential in lightning protection system to avoid life hazard and to protect electronic equipments.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.380-387
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• 2004

Recently the geosynthetics reinforced retaining wall has been widely used instead of the steel reinforced retaining wall. The geosynthetics reinforced retaining wall is a very dangerous structure if the geosynthetics lose their strength about tension or if it lose their pullout resistence, but it was known that the geosynthetics reinforced wall had a great resistence and was a very safe structure against a earthquake or a dynamic load. It can be said that most important factors in the stability of the geosynthetics reinforced wall are the horizontal length of reinforcement and the vertical distance between two reinforcements. That is to say, as the length of reinforcement is longer, the structure is more stable and as the vertical distance between two reinforcements is shorter, it is more stable. In this study, in order to get the critical condition with a safety rate of 1, various kinds of model tests about geosynthetics reinforced wall has been performed. Photos by B-shutter method has been taken during tests and from photos, which show us the failure state, the critical condition about failure has been conformed. Accordingly the equation, which says the limit of stability in geosynthetics reinforced wall., has been proposed.

• Journal of the Korean Geosynthetics Society
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• v.4 no.2
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• pp.47-56
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• 2005

Recently, geosynthetic reinforced earth walls are gradually replacing conventional concrete retaining walls for reasons of economy, expediency of construction, and aesthetics. A number of reinforced soil walls having more than 10m heights have been constructed to make more effective development in the country. However, mistakes in design and construction of reinforced earth walls have resulted in many troubles such as failure of reinforced earth walls, horizontal deformationor breakdown of facings, and so forth during or after construction. In this paper, a case study on global sliding failure of a geogrid-reinforced tiered wall is carried out to investigate the causes of the failure and suggest the proper countermeasures. From the subsurface investigation and field instrumentation, It is found that the cause of the global sliding failure was occurred by decreasing of bearing capacity of foundation ground induced by infiltration of rainwater.

• Journal of the Korean Geosynthetics Society
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• v.7 no.1
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• pp.1-6
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• 2008

In this study, the deformation and strength characteristics for non-woven geotextile-reinforced decomposed granite soil on the triaxial compression test under the same condition as the underground. The specimen of reinforced earth was made of the decomposed granite soil imbedded horizontal in a given space with non-woven geotextile. Four different type of specimen was used in this experimental programme; UR for unreinforced, R-1 for a single non-woven geotextile sheet, R-2 for two sheets, and R-3 for three sheets. According to the testing results, it was found that the strength of the reinforced soil increased when the non-woven geotextile sheets were more used. These results would be applied to the design of reinforced earth structure through the theoretical interpretation method.

• Journal of the Korean Geosynthetics Society
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• v.13 no.4
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• pp.143-151
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• 2014

This paper describes external and internal stability of reinforced earth wall using large-scale modular block and geogrid reinforcement. The evaluation for external and internal stability was conducted to analyze effect of wall height, reinforced soil (or backfill soils) and reinforcement strength. The external stability showed that the analysis cases were satisfied with design criteria, when the required minimum length and vertical spacing of reinforcement were 0.7H and 1m, respectively. The internal stability conformed that some cases were satisfied with design criteria in $25^{\circ}$ of internal friction angle of reinforced soil. Expecially, it will be applicable as wall structure considering a structural stability and economic efficiency based on evaluation of internal stability.