• Journal of Ocean Engineering and Technology
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• 제2권1호
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• pp.163-169
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• 1988

A beach nourishment method can be used as one of the beach. The beach nourishment is affected br a natural condition and an artificial condition; a natural condtion include conditions of bottom slope, diameter of bottom materials and wave, and an artificial condition include deposit position, method, diameter and quantity of the nourishing sand. To obtain and the best diameter of the nourishing sand a two-dimensional hydraulic model test, which simulates the erosional beach, has been accmplished. In this study the protection of the beach erosion can be maximized when the nourishing sand of 0.84mm in diameter, which is about 2.5-3.5 times of the natural bottom materials in diameter.

• Proceedings of the Korean Geotechical Society Conference
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• 한국지반공학회 2001년도 토목섬유기술위원회 학술세미나 논문집
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• pp.67-78
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• 2001

지금까지의 하천 사면보호공법은 돌망태, 사석, 호안블럭(Con'c Block), 재래형 섬유대공(Ordinary Fabric Form) 등을 주로 사용하여 왔다. 그러나, 이들 공법은 자연재료인 돌이나 사석 등이 이미 고갈되어 취득이 매우 어렵고, 콘크리트 제품은 인공구조물 일색의 보호공으로서 자연환경에 어울리지 않거나 인력을 이용한 고가의 공사비가 요구되므로 이를 개량하여 본 환경친화형 섬유대공을 개발하기에 이르렀다. 본 공법은 홍수나 수해로부터 토사제방의 침식 및 세굴방지는 물론 중간에 자연환경 적인 잔디나 조경식재를 하여 환경친화적 호안공을 형성하는 공법으로서 침식방지와 환경친화 효과를 동시에 만족시키기 공법이다.

• Proceedings of the KIEE Conference
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• 대한전기학회 2004년도 추계학술대회 논문집 전력기술부문
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• pp.217-219
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• 2004

The second harmonic component could be decreased by magnetizing inrush when there have been changes to the material of the iron core or its design methodology. The higher the capacitance of the high voltage status and underground distribution, the more the differential current includes the second harmonic during the occurrence of an internal fault. Therefore, the conventional second harmonic-restrained RDR needs modification. This paper describes an advanced numerical algorithm that utilizes terminal voltage, differential current harmonics, harmonic ratio, and flux-differential current slope. Based on the results of testing with WatATP99 simulation data, the proposed algorithm was proven to be faster and more reliable.

• Journal of the Korean Institute of Landscape Architecture
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• 제42권5호
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• pp.101-109
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• 2014

In order to save costs and enhance quality in construction without damaging the environment, the VE/LCC analysis method is increasingly used. This study was carried out to conduct a value analysis for the ecological restoration of a slope considering life cycle cost and performance. The construction conditions were classified into three types(A, B, C) according to the condition of each base. Three construction methods for slope ecological restoration were selected by each condition. Eventually, a value analysis was conducted for total nine conditions by analyzing the life cycle cost and performance. The gradient of slope and base of Condition 1 were below 1:1.2 and general soil, while condition 2 and 3 were below 1:1.0(reaping rock) and below 1:0.7(soft rock, blasted rock), respectively. A value analysis was conducted based on the value estimated via life cycle cost and performance analysis. The result showed that the B construction method had the highest value in Condition 1 as it showed 108.4, while A and C showed 90.3 and 45.8, respectively. When it comes to Condition 2, Construction Method A indicated the highest value as it showed 89.1(B: 47.5, C: 47.0). In Condition 3, Construction Method A(89.1) was the highest, while B and C showed 55.4 and 40.2, respectively. Based on the result of this study, in order to make a reasonable decision that can enhance quality and reduce costs in slope ecological restoration, the slope ecological restoration method must be reviewed in consideration of life cycle cost and performance.

• Journal of the Korea Institute of Building Construction
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• 제15권5호
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• pp.483-489
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• 2015

The Purpose of this study was to establish the basic data on the mechanical properties of PCM in the high temperature range. To this end, an experiment was conducted on the characteristics of the residual compressive strength by temperature (100, 200, 400 and $600^{\circ}C$) with a fixed temperature heating. An after heating test was performed to investigate the properties after fire damage. The result showed that the residual compressive strength of PCM had a tendency to decrease, regardless of the type of polymer. It was also found that when the contents were low, the residual compressive strength started to greatly decrease from the high temperature range of $400^{\circ}C$, and that the specimen containing PAE showed a steeper slope than the specimen containing EVA. However, since little studies have been conducted on the mechanical properties of PCM with the high temperature, it is considered that, in addition to this study, basic studies must be preceded, including studies on the repairing methods.

• KSCE Journal of Civil and Environmental Engineering Research
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• 제39권6호
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• pp.769-777
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• 2019

Low crested coastal structures such as detached breakwaters and submerged breakwaters (artificial reefs) have been commonly used as coastal protection measures. The armour units of these structures are unstable than those in non-overtopped structure cases. The stability of low crested structures armoured by rock has been suggested in existing studies. In this study, the stability of Tetrapods armour units on theses structures has been investigated using two-dimensional hydraulic model tests. The effect of wave steepness and freeboard on the armour stability on crest, front, and the rear slope has been investigated. Armour units were mostly damaged near the upper part of the seaward slope and the crest of the seaward side. From the experimental data, the new empirical formula for the stability coefficients of the Tetrapods was proposed.

• Journal of the Korean Geotechnical Society
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• 제18권1호
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• pp.79-89
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• 2002

Various geosynthetics used as liners or protection layers are installed in the solid waste landfills. The interface shear strength between geosynthetics installed at the slope of the landfill is a very important variable for the safe design of the bottom and cover systems in the solid waste landfills. The interface shear strength between Geomembrane and Geotexile is estimated by a large direct shear test in this study, The effects of normal stress, water existing between geosynthetics and surface condition of Geomembrae, i.e. smooth or textured, were investigated. The test results show that the effect varied depending on the level of normal stress and the type of geosynthetic combinations. The shear strength was evaluated by the Mohr-Coulomb failure criterion in this research. The shear strength parameters obtained from tests considering the site specific conditions such as normal stress, dry or wet, and surface condition of geosynthetic should be applied to the design of geosynthetics installed at the slope of the landfill to construct a safe solid waste landfill.

• Journal of the Korean Geotechnical Society
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• 제19권6호
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• pp.285-298
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• 2003

Shear properies of geosynthetic/geosynthetic and geosynthetic/soil interfaces which are widely met in landfill sites were evaluated from the inclined board tests. The inclined board testing apparatus is known to reproduce the shear behavior on the low normal stress most accurately. In this study, the friction angle of each interface was estimated and the tensile force mobilized at the geosynthetic was measured as well. The test results showed that the friction angle of each interface and the tensile force of the geosynthetics depended on the amount of normal stress, the type of the geosynthetics used, and the combinations of geosynthetics and soils. In addition, the sand/geotextile/geomembrane interface system was simulated in this study, and it was observed that the tensile force developed at the geomembrane decreased due to the protection effect of the geotextile located above the geomembrane. The test results of this research was compared with those of direct shear tests published, too. Finally, by comparing the measured tensile force of the geosynthetics when the initial displacement of the box occurs, when the slope is called as the critical slope, with suggested analytic solution, the accuracy of analytic solution and the applicability to design were identified.

• Journal of the Korean Society of Environmental Restoration Technology
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• 제11권1호
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• pp.72-84
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• 2008

Since enactment of the Baekdu-Mountain Range protection law in Dec. 31st 2003, great interest arose in recovery of the natural environment in the Baekdu-Mountain Range. Since the Baekdu-Mountain Range has formed boundaries between different regions and it is the mountain that crosses our country from East to West, there are so many roads that penetrate this area. Slopes made by the construction of roads have poor foundation for the growth of vegetation and it takes a long period to restore only with natural restoration force. For this reason, various methods of revegetation to restore the damages are implemented but until now, revegetation of domestic soil cutting slopes are mainly covered by foreign import grasses to stabilize and cover grounds early. As we depended upon foreign import grasses for slopes revegetation, the landscape did not match in harmony with surrounding vegetation and therefore, we could see that these foreign grasses are withered in 2~3 years after the revegetation works and slopes become barren again. However, currently, there are no applicable standards for designs of green hill, desirable revegetation methods for the hill areas, roads and recovery models. Therefore, in this study, we investigated the status of revegetation plants and revegetation methods for the hill areas of the Baekdu-Mountain Range (azimuth, degree of tilt, and tilted places). Based on this, we attempted to find the desirable recovery models for the hill areas of the Baekdu-Mountain Range.

• Journal of the Korean Geotechnical Society
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• 제35권11호
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• pp.25-36
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• 2019

The safety barrier is installed on road embankment to prevent vehicles from falling into road side slope. Among the safety barrier, flexible guardrails are usually installed. The flexible guardrail generally consists of a protection cross-beam and supporting in-line piles. These guardrail piles are installed nearby slope edge of road embankment because the side area of the road is much narrow. The protection cross-beam absorbs impact energy caused by vehicle collision. The pile-soil interaction also absorbs the rest of the impact energy and then, finally, the flexible guardrail system resists the impact load. This paper aims to investigate the pile-soil interaction subjected to impact load using centrifuge model tests. In this study, a single pile was installed in compacted residual soil and loaded under lateral impact load. An impact loading system was designed and developed available on centrifuge tests. Using this loading system, a parametric study was performed and the parameters include types of loading and ground. Finally, the ultimate bearing capacity of supporting pile under impact load was analyzed using load-displacement curve and soil reaction pressure distributions at ultimate were evaluated and compared with previous studies.