• 한국지반공학회논문집
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• 제23권11호
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• pp.77-85
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• 2007

본 연구에서는 준설토 및 Bottom ash를 동시에 재활용하기 위하여 개발된 복합지반재료의 역학적 특성을 고찰하였다. 본 실험에서 제작된 복합지반재료는 부산 신항 건설현장에서 채취한 준설토, 시멘트, 기포 및 삼천포 화력발전소에 서 발생한 Bottom ash로 구성되어졌다. 다양한 배합비로 제작된 복합지반재료의 역학적 특성을 고찰하고, 특히 Bottom ash 혼합에 의한 역학적 거동 특성을 조사하기 위하여 다양한 실내실험이 수행되어졌다. 복합지반재료에 대한 실험결과 응력-변형 관계와 일축압축강도는 배합조건에 크게 의존하는 것으로 나타났고, 특히 Bottom ash 혼합시 압축강도 및 응력-변형 곡선의 기울기가 증가하는 Bottom ash 보강효과를 확인하였다. 복합지반재료의 압축강도는 양생기간이 증가할수록 증가하며, 28일 강도는 7일 강도의 약 $1.7{\sim}1.8$배 증가하는 것으로 나타났다. 복합지반재료의 단위중량은 기포함량에 크게 의존하였다. 복합지반재료의 변형계수($E_{50}$)은 Bottom ash의 혼합으로 인해 강도가 증가함에 따라 증가되었다.

• 대한지리학회지
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• 제38권2호
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• pp.275-291
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• 2003

ICT(Information & Communication Technology) 활용 지리수업을 위해서는 데이터베이스(database, 이하, ‘DB' 라 칭함)형 교수-학습 자료를 개발하는 것이 필수적이다. 이러한 DB형 교수-학습자료는 WBI(Web Based Instruction. 웹기반수업)에서의 지리이미지자료 사용상의 문제점을 극복해 줄 대안으로 간주된다. 이를 위하여 본 구에서는 우선 지리이미지 데이터베이스 프로그램(이하. '지리이미지 DB 프로그램' 이라 칭함)을 기반으로 CD-ROM 형태의 지리이미지 전자사전(이하, 'GEO-DB' 라 칭함)을 제작했다. GEO-DB에는 3,060개의 지리이미지가 원자료로 수록되어 있는데, 이러한 자료들은 온라인과 오프라인 상에서 교사와 학습자가 공동으로 수집한 것이다. GEO-DB에는 교사와 학습자 모두 지리이미지 자료를 단순하게 활용함은 물론. 임의적으로 자료의 가공이 가능하도록 포트폴리오 기능을 첨부했는데, 이러한 포트폴리오 기능은, 특히 학습자의 자기주도적 학습능력의 신장에 기여하고자 한 것이다 GEO-DB는 사용의 수월성, 검색의 신속성 및 확장의 무한성을 갖고 있어서, 지리 교수-학습에서 ICT의 활용 가능성을 극대화시켜 줄 수 있고. 학습자의 지리학습능력의 신장과 지리학습태도의 변화에 크게 기여할 수 있는 것으로 교사와 학습자에 의해 평가되었다.

• Advanced Composite Materials
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• 제17권3호
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• pp.247-258
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• 2008

This paper is concerned with the long-term performance of geo-textile (GT) composites in terms of creep deformation and frictional properties. Composites of PVA GT and HDPE GM were made to investigate the advanced properties of long-term performance related to waste landfill applications. The same experiments were also performed for typical polypropylene and polyester GT and compared to PVA GT/HDPE GM composites. We also develop high performance GT composites with GM by using PVA GT, which is capable of improving the frictional properties and thus enhances long-term performance of GT composites. Experimental study reveals that the friction coefficient of GT composites is relatively large compared with those of polyester and polypropylene non-woven GT as long as the friction media has similar size to the particles of domestic standard earth. In addition, the geo-composites bonded with geo-grid by a chemical process were investigated experimentally in terms of strain evaluation and creep response values. Geo-grid plays an important role as a reinforcing material. Three kinds of geo-grid were prepared as strong yarn polyester and they were woven type, non-woven type, and wrap knitted type. The sample geo-grids were then coated with PVC. The rib tensile strength tests were conducted to evaluate geo-grid products in terms of tensile strength with regard to single rib. The test was performed according to GRI-GGI. It was concluded again from the experiments that the tensile and creep strains of the geo-grid showed such stable values that the geo-grid prepared in this study could protect geo-textile partially in practical structures.

• Geomechanics and Engineering
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• 제9권4호
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• pp.531-545
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• 2015

Two fundamental issues exist in the damage theory of geo-material based on the concept of thermodynamics: existence or nonexistence of the dissipation potential, and whether the dissipation potential could be decoupled into a damage potential and a plastic one or not. Thermodynamics theory of elastoplastic damage assumes the existence of dissipation potential, but the presence of dissipation potential is conditional. Based on the dissipation inequality in accord with the second law of thermodynamics, the sufficient and necessary conditions are given for the existence of the dissipation potential separately in total and incremental forms firstly, and proved strictly in theory. With taking advantage of the basic mechanical properties of geo-materials, the nonexistence of the dissipative potential is verified. The sufficient and necessary conditions are also given and proved for the decoupling of the dissipation potential of geo-materials in total and incremental forms. Similarly, the non-decoupling of the dissipation potential has also been proved, which indicates the dissipation potential of geo-materials in total or incremental forms could not be decoupled into a dissipative potential for plasticity and that for damage respectively. The research results for the fundamental issues in the thermodynamics theory of damage will help establish and improve the theoretic basis of elastoplastic damage constitutive model for geo-materials.

• Geomechanics and Engineering
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• 제9권5호
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• pp.569-583
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• 2015

Two fundamental issues exist in the damage theory of geo-material based on the concept of thermodynamics: existence or nonexistence of the dissipation potential, and whether the dissipation potential could be decoupled into a damage potential and a plastic one or not. Thermodynamics theory of elastoplastic damage assumes the existence of dissipation potential, but the presence of dissipation potential is conditional. Based on the dissipation inequality in accord with the second law of thermodynamics, the sufficient and necessary conditions are given for the existence of the dissipation potential separately in total and incremental forms firstly, and proved strictly in theory. With taking advantage of the basic mechanical properties of geo-materials, the nonexistence of the dissipative potential is verified. The sufficient and necessary conditions are also given and proved for the decoupling of the dissipation potential of geo-materials in total and incremental forms. Similarly, the non-decoupling of the dissipation potential has also been proved, which indicates the dissipation potential of geo-materials in total or incremental forms could not be decoupled into a dissipative potential for plasticity and that for damage respectively. The research results for the fundamental issues in the thermodynamics theory of damage will help establish and improve the theoretic basis of elastoplastic damage constitutive model for geo-materials.

• Geomechanics and Engineering
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• 제27권6호
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• pp.583-594
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• 2021

The gas permeability behavior of unsaturated bentonite-based materials is of major importance for ensuring effective sealing of high-level radwaste repositories. This study investigated this by taking a sample of Granular Bentonite Material (GBM) at the end of the Engineered Barrier Emplacement (EB) experiment in the Opalinus Clay, placing it under different humidity conditions until it achieved equilibration, and testing the change in the gas permeability under loading and unloading. Environmental humidity is shown to have a significant effect on the water content, saturation, porosity and dry density of GBM and to affect its gas permeability. Higher sensitivity to confining pressure is exhibited by samples equilibrated at higher relative humidity (RH). It should be noted that for the sample at RH=98%, when the confining pressure is raised from 1 MPa to 6 MPa, gas permeability can be reduced from 10^-16 m² to 10^-19 m², which is close to the requirements of gas tightness. Due to higher water content and easier compressibility, samples equilibrated under higher RH show greater irreversibility during the loading and unloading process. The effective gas permeability of highly saturated samples can be increased by 2-3 orders of magnitude after 105℃ drying. In addition, cracks possibly occurred during the dehydration and drying process will become the main channel for gas migration, which will greatly affect the sealing performance of GBM.

• Structural Engineering and Mechanics
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• 제13권6호
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• pp.639-652
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• 2002

The present study aims to improve an existing model for the prediction of deceleration time history, penetration depth and forces on ogive and conical nose shaped missiles under normal impact into geo-material targets. The actual ogive nose shaped missile has been considered in the analysis and the results thus obtained have been compared with the existing model and significant improvements are found. A close proximity in the results has also been observed with the experimental values. The results of ogive nose shaped missile have also been compared with equivalent conical nose shaped missile. Variation of radial stresses along nose length and radial direction has been studied. Effect of CRH on missile penetrating performance has been investigated.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1063-1068
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• 2008

When construction of high pressure jet-grouting is to be performed, it has been reported that applied cement slurry which hasn't got dried out can cause severe environmental pollution, and can flow into near streams and fish farms. Several laboratory tests were performed in this study in order to verify safety of paste-like grouting material that was developed newly to be applied to void in the ground. According to experimental test results, it is proved to be so safe that application of the newly developed flowable grouting material can prevent the materials from spilling into surrounding areas and is not harmful to fishes.

• 한국지반환경공학회 논문집
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• 제9권2호
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• pp.15-22
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• 2008

최근 황토를 건설재료로 많이 사용하지만 황토의 공학적 특성을 고려하지 않고 일반 흙으로 취급하여 설계, 시공되어져 여러 가지 문제점이 발생되고 있는 실정이다. 황토는 그 자체적인 성질로는 토목공사에 효율적으로 활용하는데 있어 한계가 있기 때문에 효용성을 증대시키기 위하여 서 남해 청정해역에서 양식업 중 패류의 생산에서 부수적으로 발생하는 굴패각을 황토와 효율적으로 혼합 이용하여 건설재료의 대체 재료로 활용성을 연구하고자 한다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.476-478
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• 2003

Capability of material fixation in forest was noticed since COP3, but now it was difficult to understand material fixation in wide area. In this study, we attempted to estimate and test the amount of carbon, nitrogen, and phosphorus fixed by forest from satellite images. First, we classified into tree species and estimated the number of trees in the forest by species, area, and digital numbers. We inspected to apply it in wide area. Next, we compared the amount of carbon, nitrogen, and phosphorus with NDVI and each band of satellite images.