• Journal of the Korean Geosynthetics Society
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• v.17 no.1
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• pp.75-83
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• 2018

This paper described a results of dynamic stability by using wheel tracking test and unconfined compression test, in order to evaluate behavior characteristics on the developed pocketable expansion material for emergency restoration of ground cavity. The wheel tracking test result showed that the settlement increment ratio of the recovered ground by the expansion material was decreased compared to the sandy ground in high load condition. That is, it was confirmed that the expansion material was able to restrain the settlement due to the material stiffness, and the same results were obtained for the dynamic stability evaluation results. From the results of unconfined compression test, the pocketable expansion material was found to be able to fully support load on the restored cavity.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.335-342
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• 2003

In order to analyze the deformational behavior accurately, the in-situ testing technique which provides the reliable deformational characteristics at whole strain ranges, needs to be developed. The pressuremeter is a unique method for assessing directly the in-situ shear modulus of soils with strain amplitude. This paper introduces a new alternative, the cavity strain measuring system in pressuremeter designed for whole strain ranges of $10^{-5}$%∼20%. Not only in the synthetic calibration chamber but also in the field, the pressuremeter tests were performed to determine the compliance of the new developed pressuremeter system. The variation in shear modulus with strain amplitude above $5\times 10^{-2}$% was reliably determined by the developed pressuremeter. It is concluded that the major cause of error in small cavity strain measuring is not from the cavity strain measuring system but from the friction between measuring arm and membrane during unloading-reloading loops.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.5
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• pp.19-26
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• 2011

In order to investigate the effect of fuel injection hole configuration within the scramjet combustor, experiment and quasi-one-dimensional analysis was performed. And the results were compared with experiment and analysis result which were performed in 2008 with same facility and test condition. Fuel injection hole size was decreased and quantity was increased. However the depth of fuel penetration and flow quantity of fuel were maintained. As a test result, combustion performance was increased significantly with no-cavity injector and slightly with plain-cavity. However, combustion performance with zigzag-cavity was decreased.

• Journal of the Korean GEO-environmental Society
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• v.12 no.8
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• pp.39-50
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• 2011

Nowadays, H-piles are usually used as temporary retaining walls, and sometimes buried in the ground after construction. The purpose of this study is the development of flowable fill materials that are easy to fill holes of retaining wall structure and minimize friction during pulling out H-pile. The first test was performed to decide mix proportion that is reasonable for purpose, in the second test, direct shear test was performed to get pullout resistance between flowable fills material and H-pile, and one dimensional consolidation test was performed to analyze the compressibility. In the test result, it showed that flowable fill material mix proportion is 350-450% of water, 70-100% of cement and 70-100% of sand based on the bentonite weight.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.5
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• pp.13-20
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• 2020

The effect of the relative distance between two cavity flame holders on the performance of a supersonic combustor was experimentally investigated. A rectangular cross-sectional combustor model with one cavity flame holder on each of two facing walls was used, with two difference distances between cavities of 135 mm and 220 mm. The fuel equivalence ratio was varied as 0.16 and 0.38. A direct-connected type test facility was used to provide Mach 2 flow condition. The test results revealed that the combustion pressure was higher for the shorter cavity distance case. But fuel equivalence ratio did not have large effect on the combustion pressure. It was concluded that, to get higher combustor pressure, there needs to be further combustor configuration change such as smaller cavity distance or tandem cavity installation.

• Journal of the Korean Geotechnical Society
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• v.35 no.11
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• pp.37-49
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• 2019

In order to analyze the effect of burial depth on the generation of ground cavities and cave-ins, a series of model experiments with different height of model ground were performed. Digital images of the model ground were captured to evaluate the internal deformation of the model grounds by adopting the PIV (Particle Image Velocimetry) technique. Additionally, the vertical displacement at the surface, the size of the cavity, and the weight of the discharged soil were measured in each test. The results indicate that the model ground with low burial depth, which does not satisfy the criterion, was more vulnerable to ground cavities and cave-ins than the model ground with high burial depth.

• The Magazine of the IEIE
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• v.31 no.7
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• pp.26-42
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• 2004

선도시험망(Advanced Network) 또는 연구개발망(R＆D Network： Research and Development Network)이라고 불리는 연구망은 상용망에 적용하기 이전의 장비 및 서비스에 대한 시험, 검증을 하기 위한 파일럿(pilot) 망으로서 일반 상용망에 비해 높은 대역폭이 제공되고 한정된 사용자에게 특수 목적을 위해 제공되는 첨단망을 의미한다. 특히 상용망에서 안정적으로 장기간수행하기 힘든 대규모의 정보교류나 실시간 공동참여를 가능하게 하는 연구전용 인프라(R＆D infra)라고 할 수 있다. (중략)

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.11a
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• pp.11-11
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• 2000

가스터빈엔진의 연소기는 개발 방법상 가장 시험에 의존적인 구성품 중의 하나로 성공적인 개발을 위해서는 설계자의 경험 및 수많은 시험 평가가 필수적으로 수반된다. 본 논문에서도 삼성테크윈(주)과 한국항공우주연구소에서 공동 개발중인 APU 용 연소기에 대하여 이러한 설계 및 시험 개발 연구 과정 및 결과를 중심으로 기술하였다.(중략)

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.1
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• pp.51-57
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• 2011

Irregular distributions of limestone cavity in Gang-Won province area may cause unexpected accidents from reduced serviceability or failure of structure. It is requested that an appropriate ground reinforcement method should be used to improve bearing capacity of structure, and the method should also be satisfied with environmental requirements. Among several methods used for foundation constructions in cavity area, Rod Jet Pile(RJP) method has been widely used. While the RJP method was used to improve bearing capacity for the railway bridge foundations, water pollutions of drinking water as well as fishery located adjacent to this project area were occurred. The main reason of the water pollution was cement runoff used in cement mortar during injecting material in RJP method. Laboratory tests were performed to prevent water pollution. The compaction mortar method using low movable material was selected for this project. The quality of water at a fishery adjacent to the site and the compressive strength of cores taken from the construction site were measured. Test results show that the water pollutions was minimized, and the average compressive strength of foundation material was over 5 MPa. As a result of this study, compaction mortar method can be used to ensure the bearing capacity of foundation and to prevent environment pollutions.

• The Hankook-Saengyark Bo
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• no.241
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• pp.5-5
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• 2000

민통선내 홍삼단지 조성(파주농기센터, 친환경 유기농법 재배) - 자생화 수요증가로 화훼산업 자리매김 - 붕사 이용해 더덕 수확 늘려(안동북부시험장) - 홍화, 남부지역 파종 가을이 유리 - 작약재배 깻묵 뿌리면 증수