• 한국산학기술학회논문지
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• 제16권6호
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• pp.4201-4207
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• 2015

본 연구에서는 최근 뉴질랜드의 Christchurch 지역의 2011년 2월 22일의 지진규모(Mw) 6.2 지진발생 후 얻어진 데이터를 이용하여 지진에 의한 지하 상수도관 시스템의 성능에 주안점을 두고 연구를 수행하였다. 이 논문은 액상화로 인하여 발생된 영구지반변형지역과 서로 다른 재질의 상수도관에 따라 1 km 당 손상갯수로 산정되는 손상율을 액상화 지역에서의 지진발생 전후에 얻어진 높은 해상도의 라이다데이터로부터 계산된 부등침하와 횡방향 지반변형률의 관계를 통하여 산정하였다. 본 연구에서는 영구지반변형에 따른 매설된 상수도관의 지진성능을 요약하여 설명하였으며 연구결과 연성이 매우 큰 폴리에틸렌 상수도관이 매우 우수한 지진성능을 가지고 있음을 알 수 있다.

• 한국항공우주학회지
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• 제31권9호
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• pp.38-45
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• 2003

본 논문은 Strain Energy Hinge(SEH)를 갖는 다목적 2호기의 태양전지판 전개에 대한 동적 모델링과 관련이 있다. 이 연구를 위해 SEH는 단순한 비틀림 스프링으로 치환되었으며 인공위성과 태양전지판은 강체로 가정하고 운동방정식을 유도하였다. 또한 모델링에 지상 실험에 가장 큰 영향을 주고 있는 것으로 관찰된 지지줄의 영향을 고려하였다. 무중력 상태에서의 전개와 지상 전개 결과를 비교한 결과 태양전지판의 전개는 유사하나 인공위성의 운동은 지지줄의 영향으로 인해 전혀 다른 것으로 나타났다. 결론적으로 지상 전개 실험 장치를 이용해 무중력 상태의 태양전지판 전개를 어느 정도 정확하게 묘사할 수 있다. 또한 지지줄의 영향을 조사한 결과 현재 실험실의 지지줄의 길이가 적합한 것으로 나타났다. 지상실험 결과와의 비교는 다음 논문에서 다룬다.

• 한국항공우주학회지
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• 제31권9호
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• pp.82-87
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• 2003

본 논문은 변형에너지 힌지(Strain Eenergy Hinge)를 갖는 다목적 2호기의 태양전지판 전개에 대한 지상 전개실험과 이전 논문에서 다루었던 이론적인 모델링의 타당성에 관한 연구이다. 본 연구를 위해 먼저 이론적으로 설명하기 어려운 Stopper를 갖는 SEH에 대해 실험을 수행하여 비선형 좌굴 특성을 조사하였다. 이 특성은 태양전지판의 전개속도와 전개형태에 영향을 주므로 매우 중요하다. Stopper를 갖는 SEH의 실험 결과를 바탕으로 등가 모멘트-각도 선도를 도출하였으며 이 선도를 이론 모델과 결합하였다. 지상 전개 실험은 중력의 완전한 제거가 불가능하기 때문에 지지줄을 이용해 중력 보상을 시도하고 있다. 본 연구에서는 항공우주연구원에서 수행한 지상 전개 실험의 과정과 결과를 자세히 소개한다. 지상 전개실험 결과는 이론 모델에 근거한 수치 모사 결과와 잘 일치함을 볼 수 있었다. 따라서 이론 모델링의 타당성을 입증하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1991년도 추계학술발표회 논문집 지반공학에서의 컴퓨터 활용 COMPUTER UTILIZATION IN GEOTECHNICAL ENGINEERING
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• pp.216-232
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• 1991

This Finite Element Program(TAFEM) has been developed to be able to carry out the structural analsis of tunnel section and simulate the surrounding ground behaviour due to New Austrian Tunnelling Method, of which main support is the surrounding ground, itself. The Elasto-plastic theory has been applied. The used finite elements are 8-noded isoparametric element(rock & shotcrete), 2 or 3-noded rod element(rock bolt) and infinite boundary element. The load incremental method and tangential stiffness method has been used. Associated flow rule was applied to plastic flow and yield criteria inclued not only Mohr-Coulomb but also Drucker-Prager. In this paper, Drucker-Prager yield criterion has been used. The relationship between plastic strain and stress is based on the incremental strain concept and stress-strain equation on the basis of the stress path of each gauss point has been adopted. It may be rational that rock is considered to be no-tension material, so that no-tension analysis has been adopted in accordance with the brittle fracture constitutive equation.

• 산업기술연구
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• 제21권A호
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• pp.317-327
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• 2001

For soils with high void ratios, the inverse method of utilizing results obtained from centrifuge model test was used to find the constitutive relation of effective stress - void ratio - permeability whereas conventional oedometer test and constant rate of strain consolidation test were also used to fine its relation at ranges of relatively low void ratio. Results of column test about settlement of interface and pore pressure and distribution with time were compared with numerically estimated values to confirm such a constitutive relation as obtained from the inverse method. Consolidational settlement in dredged and reclaimed ground, where the consolidation was in progress, was predicted by using the numerical technique implemented with the finite strain consolidation theory.

• 한국지반공학회논문집
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• 제24권11호
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• pp.143-155
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• 2008

지반앵커는 그라우트가 힘을 받는 형태에 따라 분류되는데 앵커의 인발시 그라우트가 인장을 받으면 인장형 앵커로 압축을 받으면 압축형 앵커로 분류된다. 본 연구에서는 인장과 압축을 동시에 받는 기구를 가진 복합형 앵커를 개발하였다. 현장시험을 위해 연약지반내의 앵커체 내부에 변형률게이지를 설치하였고, 측정된 시험결과를 통해 인장과 압축변형률이 동시에 발생하는 인발저항기구를 관찰할 수 있었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.561-568
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• 2003

The protection of adjacent structures in urban excavation has been an important issue. But the research on the interaction between ground movements and adjacent structure has been scarce, therefore this study was necessitated. Current design practice for the prediction of excavation-induced ground movements heavily rely on empirical method. In this study, damage levels of brick building are examined closely by means of angular distortion, deflection ratio, horizontal strain. The results of numerical analysis indicated that the movement of actual building was 60∼65% of the ground movement, while angular distortion was 45∼65%. Also numerical analysis for the assessment of brick building can be applied to the building protection at various construction stages.

• Geomechanics and Engineering
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• 제11권4호
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• pp.587-605
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• 2016

This study aimed to develop upper and lower bounds to predict the tunnel support pressure under the pile tip during the circular tunnel excavation. Most previous studies on the upper and lower bound methods were carried out for the single ground structures, e.g., retaining wall, foundation, ground anchor and tunnel, in the homogeneous ground conditions, since the pile-soil-tunnel interaction problem is very complicated and sophisticated to solve using those bound methods. Therefore, in the lower bound approach two appropriate stress fields were proposed for single pile and tunnel respectively, and then they were superimposed. In addition, based on the superimposition several failure mechanisms were proposed for the upper bound solution. Finally, these upper bound mechanisms were examined by shear strain data from the laboratory model test and numerical analysis using finite element method.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.571-576
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• 2010

In this study, an application method of critical strains concept for tunnels' safety by using the values of measured displacements which are obtained in the field is discussed. The aim is to: (1) study on the engineering meanings of critical strains concept by reviewing the previous researches and application examples with measured displacement values; (2) study on the engineering reasonability of critical strains concept with the view point of a tunnel engineering and a geotechnical engineering; (3) study on the features of ground deformation due to tunneling and reciprocal relation between total displacement and measured displacement; (4) evaluate a tunnel safety by using domestic measurements collected in the field; and (5) re-evaluate the control criteria which were previously used in the field, with the view point of critical strains concept. Consequently, it was confirmed that critical strains in the ground has a reasonability and a possibility of unified or common concept with the view point of a tunnel engineering.

• 오토저널
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• 제13권6호
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• pp.109-118
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• 1991

In this study, it is intended to investigate the effect of the grinding conditions such as table feed, down feed, cross feed of residual stress distribution. And this distribution is investigated upon the grinding direction and the its orthogonal direction at ground layers. The material is used carbon steel (SM20C) which usually used to motor axis. And in order to be considered as Bernoulli-Euler beam, the dimension of the specimen is appropriately designed. According as corroiding the ground surface, the residual stress layers are removed and strain which occured on account of unbalance of internal stress is detected by rosette-gate. Through A/D converter and computer, these values are saved and evaluated residual stress by stress-strain relation formula. Finally, these results are diagrammatized with Auto Cad. The results obtained are as follows. As the depth from the ground surface increases in grinding direction and its orthogonal direction, tensile residual stress exists in the surface, and subsequently it becomes compressive residual stress as it goes downward. As the table feed, the cross feed and the down feed increase, maximum residual stress is transformed form the tensile to the compressive.