• 대한기계학회논문집A
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• 제29권4호
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• pp.606-613
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• 2005

Effects of circumferentially local wall thinning on the fracture behavior of pipes were investigated by monotonic four-point bending. Local wall thinning was machined on the pipes in order to simulate erosion/corrosion metal loss. The configurations of the eroded area included an eroded ratio of d/t= 0.2, 0.5, 0.6, and 0.8, and an eroded length of ${\ell}\;=10mm,$ 25mm, and 120mm. Fracture type could be classified into ovalization, local buckling, and crack initiation depending on the eroded length and eroded ratio. Three-dimensional elasto-plastic analyses were also carried out using the finite element method, which is able to accurately simulate fracture behaviors excepting failure due to cracking. It was possible to predict the crack initiation point by estimating true fracture ductility under multi-axial stress conditions at the center of the thinned area.

• 한국정밀공학회지
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• 제33권1호
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• pp.53-61
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• 2016

Angular misalignment has a significant effect on the characteristics of angular contact ball bearings (ACBBs). This paper presents an analysis of fatigue life for ACBBs subjected to angular misalignment. A simulation model is developed with de Mul's bearing model and the ISO basic reference rating life model. Simulation is performed to calculate the life of the ACBBs subjected to angular misalignment. The numerical results show that angular misalignment influences the load distribution significantly, thus reducing the bearing rating life. The fatigue life of ACBBs is decreased by angular misalignment regardless of axial preload, external radial load and rotational speed. The results show that angular misalignment should be maintained at less than 1mrad for ACBBs.

• 콘크리트학회논문집
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• 제12권4호
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• pp.3-14
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• 2000

Structural performance of the walls subjected to lateral load reversals depends on various parameters such as loading history, sectional shape, reinforcement, lateral confinement, aspect ratio, axial compression, etc. Thus, the performance of the shearwall for wall-type apartment should be evaluated properly considering above parameters. This study investigates the effect of sectional shape on the structural performance of the wall. Sectional shape of the specimen is rectangular, barbell and T. Based on this experimental results, all specimens behaved as ductile fashion and failed by concrete crushing of the compression zone. Deformation index of those specimens evaluated better than 3 of ductility ratio, and 1.5% of deformability specified by seismic provision. Moreover, the performance of the rectangular shaped specimen, whose compression zone was confined with U-bar and cross tie, was as good as the barbell shaped specimen. Therefore, if we considered construction practice such as workmanship and detailing, shearwall with rectangular section may be more economical lateral load resisting system.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.396-404
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• 2009

This paper presents the results of numerical investigation on support mechanism of geogrid-encased stone columns for use in soft ground. A number of cases were analyzed using a axial- and 3D stress-pore pressure coupled model that can effectively model construction sequence and drainage as well as reinforcing effects of geogrid-encased stone columns. The results indicated that the geogrid encasement tends to significantly improve the load carrying of a stone column. Also revealed was that such a confinement effect depends on encasement length and stiffness of geogrid. It is also shown that there exist critical encasement length and stiffness of geogrid for a given condition.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 가을 학술발표회 논문집
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• pp.541-548
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• 2002

Membrane, cable structure and membrane-cable structural system are more lighter than another common structural system, and these are able to be effectively build Lip spatial structures using axial stiffness. However when the load reach at critical load level, it might be happened snap-through or bifurcation according to the structure's shape, and these collapse mechanism should be very important in the design of structures. So, In this paper we study static instability of Zetlin-type cable dome, one of the hybrid cable dome. Moreover, as the unstable behavior of shell structures are very sensitive to the initial condition, we seek to find the effect of initial condition.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.117-120
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• 2007

This study deals with the free vibrations and buckling loads of column with clamped-spring ends and constant volume. The column has the regular polygon cross-section whose depth is varied with the linear functional fashion. The differential equation governing the free vibration of such column is derived in which the effect of axial load is included. The differential equation is solved numerically for calculating frequencies. By using the relationship between loads and frequencies, the buckling loads are also obtained.

• Structural Engineering and Mechanics
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• 제24권2호
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• pp.247-268
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• 2006

The parts of pile, above the soil and embedded in the soil are called the first region and second region, respectively. The forth order differential equations of both region for critical buckling load of partially embedded pile with shear deformation are obtained using the small-displacement theory and Winkler hypothesis. It is assumed that the behavior of material of the pile is linear-elastic and that axial force along the pile length and modulus of subgrade reaction for the second region to be constant. Shear effect is included in the differential equations by considering shear deformation in the second derivative of the elastic curve function. Critical buckling loads of the pile are calculated for by differential transform method (DTM) and analytical method, results are given in tables and variation of critical buckling loads corresponding to relative stiffness of the pile are presented in graphs.

• Structural Engineering and Mechanics
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• 제27권3호
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• pp.263-276
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• 2007

This paper presents a fuzzy finite element model for the analysis of structures in the presence of multiple uncertainties. A new methodology to evaluate the cumulative effect of multiple uncertainties on structural response is developed in the present work. This is done by modifying Muhanna's approach for handling single uncertainty. Uncertainty in load and material properties is defined by triangular membership functions with equal spread about the crisp value. Structural response is obtained in terms of fuzzy interval displacements and rotations. The results are further post-processed to obtain interval values of bending moment, shear force and axial forces. Membership functions are constructed to depict the uncertainty in structural response. Sensitivity analysis is performed to evaluate the relative sensitivity of displacements and forces to uncertainty in structural parameters. The present work demonstrates the effectiveness of fuzzy finite element model in establishing sharp bounds to the uncertain structural response in the presence of multiple uncertainties.

• 대한토목학회논문집
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• 제30권1A호
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• pp.1-13
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• 2010

본 연구에서는 사장교의 기하학적 비선형 거동을 기하학적 비선형 유한요소 해석을 통해 분석한다. 사장교의 주탑 및 거더는 휨 모멘트 뿐만 아니라 케이블의 장력에 의해 축력이 작용한다. 즉, 거더와 주탑은 보-기둥 부재와 같이 휨모멘트와 축력의 상호작용에 의한 대변위 거동을 일으킬 수 있다. 본 연구에서는 기하학적 비선형 해석을 통해 완성계 사장교의 대변위 효과, 주탑 및 거더의 보-기둥 효과 그리고 케이블의 새그효과가 모두 고려된 비선형 거동을 검토하였다. 거더 및 주탑은 6자유도 프레임 요소로 모사하고 사장교 케이블은 새그효과를 효율적으로 고려하기 위해 3자유도 등가 트러스 요소를 사용하여 모사하였다. 해석은 먼저 사하중에 대한 초기 형상 해석을 통해 사하중을 고려하고, 이 후 각기 다른 형태의 활하중에 대한 기하학적 비선형 해석을 수행하였다. 해석 후 각 모델의 변형형상, 각 주요 지점의 하중-변위곡선, 케이블 장력의 변화등의 정량적 수치를 분석하여 고려한 활하중 형태 및 사장교 형식에 대한 주요 기하학적 비선형 거동을 규명하였다.

• 한국지반공학회논문집
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• 제33권5호
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• pp.37-44
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• 2017

본 연구에서는 특정 암반에 근입된 강관말뚝의 거동특성을 분석하기 위하여, 강관말뚝의 직경, 두께 및 길이 조건에 따른 인발, 압축 및 수평재하 시의 시험결과 예측을 위한 3차원 수치해석 연구를 수행하였다. 먼저, 인발재하에 대한 거동특성을 분석한 결과, 동일한 말뚝길이 및 두께와 인발하중 크기를 기준으로 말뚝직경에 반비례하는 인발변위가 나타나는 것으로 확인되었다. 또한 압축재하에 따른 하중-침하 관계를 통하여, 말뚝 직경에 비하여 말뚝의 두께가 하중저항에 대한 효과에 더욱 큰 영향을 미치는 것으로 분석되었으며, 수평하중 재하에 따른 수평변위 관계를 바탕으로 수평하중의 저항효과는 말뚝직경에 의한 영향이 큰 것으로 분석되었다. 따라서 강관말뚝을 이용하여 기초구조물 설계에 따른 재하시험을 위해서는 예비설계 단계에서 말뚝 조건이 거동특성에 미치는 영향을 분석할 필요가 있는 것으로 확인되었다.