• 한국위성정보통신학회논문지
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• 제5권1호
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• pp.63-68
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• 2010

인공위성 구조체는 발사환경과 궤도환경하에서 탑재체 및 여러 구동기 등을 안전하게 지지할 수 있도록 설계되어야 한다. 위성체의 형상설계가 이루어지면 상세설계를 위하여 발사체에서 공급하는 규격에 의한 준정적하중을 사용하여 구조해석을 수행한다. 이 때 준정적하중을 이용하여 설계된 위성체의 구조 건정성을 확인하기 위하여 발사체 업체는 위성체와 발사체를 연성한 후 연성하중해석을 수행한다. 현재 개발중인 위성체의 경우, 연성하중해석을 수행하기 위하여 위성체 모델을 Craig-Bampton 모델로 축약한 후, 발사체 제작업체로 전달하였다. 발사체 제작업체에서는 위성체 모델과 발사체 모델을 이용하여 연성하중해석을 수행하였으며, 가속도 결과와 변위결과를 계산하여 이를 전달하였다. 전달받은 가속도 결과와 변위결과로부터 위성체는 안전하게 설계되었으며, 위성체 내/외부에서 간섭이나 충돌의 위험성이 없다는 것을 확인하였다.

• 한국공간구조학회:학술대회논문집
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• 한국공간구조학회 2008년도 춘계 학술발표회 논문집
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• pp.127-132
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• 2008

최근, 지진하중에 대한 대공간구조무의 응답특성에 관한 연구가 다수 수행되었으며, 라이즈/스팬비가 큰 지붕구조에 대하여서는, 수평지진입력에 대한 역대칭모드의 증폭이 지배적으로 됨이 지적되었다. 본 연구에서 제안하는 정적지진하중평가법에서는, 라이즈가 있는 지붕구조의 내진설계를 수행함에 있어, 허용응력도설계법을 따르며, 그림1과 같이 설계용전단력를 지붕면에 따라 부가하는 정적평가법을 채용하고 이를 정적지진하중평가법이라 부르기로 한다. 본 논문의 구성으로서는, 정적평가법의 개념 및 정적설계식의 유도과정을 나타내고, 라이즈/스팬비가 서로 다른 지붕구조물을 대상으로 하여, 본 평가법에 의한 결과와 정적응답해석을 수행한 결과를 비교하고, 정적평가법의 타당성에 대하여 검토한다.

• 한국구조물진단유지관리공학회 논문집
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• 제9권2호
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• pp.129-136
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• 2005

교량의 안전진단 과정에서 안전성 평가를 위해 전면교통통제 하에 차량재하시험이 일반적으로 실시된다. 교통통제의 단점을 개선시킨 최근에 제안된 의사정적재하시험에서는 계측된 시간이력 데이터 중 자유진동 부분을 퓨리에변환시켜 고유진동수를 구한다. 이렇게 구해진 고유진동수에는 분석기법에 따른 오차가 포함되며, 자유진동 데이터의 획득에도 다소 애로사항이 따른다. 이 연구에서는 Morlet wavelet를 모웨이블렛으로 하는 웨이블렛변환을 의사정적재하시험으로 계측한 데이터에 적용하여 구한 고유진동수와 감쇠율이 신뢰성을 가지며, 이 분석기법이 의사정적재하시험에 의한 차량재하시험의 자료 분석에 적용 가능하고 타당성이 있음을 보인다.

• Structural Engineering and Mechanics
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• 제32권3호
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• pp.407-427
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• 2009

A fundamental solution for the transient, quasi-static, plane problems of linear viscoelasticity is introduced for a specific material. An integral equation has been found for any problem as a result of dynamic reciprocal identity which is written between this fundamental solution and the problem to be solved. The formulation is valid for the first, second and mixed boundary-value problems. This integral equation has been solved by BEM and algorithm of the BEM solution is explained on a sample, mixed boundary-value problem. The forms of time-displacement curves coincide with literature while time-surface traction curves being quite different in the results. The formulation does not have any singularity. Generalized functions and the integrals of them are used in a different form.

• Structural Engineering and Mechanics
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• 제2권2호
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• pp.211-225
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• 1994

Responses of asymmetrical multistorey buildings to earthquakes are obtained by quasi-static code approach and real time dynamic analysis, using two different structural models. In the first model, all vertical members are assumed to be restrained at the slab levels and hence their end rotations, about horizontal axes, are taken as zero. In the second model this restriction is removed and the rotation is assumed to be proportional to the lateral stiffness of the member. A simple microcomputer based procedure is used in the analyses, by both models. Numerical examples are presented where results obtained from both the models are given. Effects of modelling on the response of three buildings, each with a different type and degree of asymmetry, are studied. Results for deflections and shear forces are presented and the effects of the type of model on the response are discussed.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표대회 논문집(III)
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• pp.615-620
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• 1998

The objective of this experimental study is to investigate the hysteretic behavior of reinforced concrete piers subjected to quasi-static cyclic loads, which have been used in large numbers for railway and urban transportation facilities. Important test parameters are hoop ratio, axial load, loading type, and the behaviors f members have been evaluated through limit states of crack occurrence, yielding and ultimate state of member, ductility and load-deflection loop can be secured by considering the influence of hoop reinforcement ratio and axial load, and that plastic hinge length and ductility ar determined by the combination of the quantities of hoop reinforcement and axial load.

• Steel and Composite Structures
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• 제27권6호
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• pp.789-801
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• 2018

A weak-form formulation of finite annular prism methods (FAPM) based on Reissner's mixed variational theorem (RMVT), is developed for the quasi three-dimensional (3D) static analysis of two-directional functionally graded (FG) circular plates with various boundary conditions and under mechanical loads. The material properties of the circular plate are assumed to obey either a two-directional power-law distribution of the volume fractions of the constituents through the radial-thickness surface or an exponential function distribution varying doubly exponentially through it. These FAPM solutions of the loaded FG circular plates with both simply-supported and clamped edges are in excellent agreement with the solutions obtained using the 3D analytical approach and two-dimensional advanced plate theories available in the literature.

• Wind and Structures
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• 제5권6호
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• pp.543-562
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• 2002

The main purpose of this study is to discuss the design wind loads for the structural frames of single-layer latticed domes with long spans. First, wind pressures are measured simultaneously at many points on dome models in a wind tunnel. Then, the dynamic response of several models is analyzed in the time domain, using the pressure data obtained from the wind tunnel experiment. The nodal displacements and the resultant member stresses are computed at each time step. The results indicate that the dome's dynamic response is generally dominated by such vibration modes that contribute to the static response significantly. Furthermore, the dynamic response is found to be almost quasi-static. Then, a series of quasi-static analyses, in which the inertia and damping terms are neglected, is made for a wide range of the dome's geometry. Based on the results, a discussion is made of the design wind load. It is found that a gust effect factor approach can be used for the load estimation. Finally, an empirical formula for the gust effect factor and a simple model of the pressure coefficient distribution are provided.

• Advances in nano research
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• 제7권1호
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• pp.63-75
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• 2019

This article represents a quasi-3D theory for the buckling investigation of magneto-electro-elastic functionally graded (MEE-FG) nanoplates. All the effects of shear deformation and thickness stretching are considered within the presented theory. Magneto-electro-elastic material properties are considered to be graded in thickness direction employing power-law distribution. Eringen's nonlocal elasticity theory is exploited to describe the size dependency of such nanoplates. Using Hamilton's principle, the nonlocal governing equations based on quasi-3D plate theory are obtained for the buckling analysis of MEE-FG nanoplates including size effect and they are solved applying analytical solution. It is found that magnetic potential, electric voltage, boundary conditions, nonlocal parameter, power-law index and plate geometrical parameters have significant effects on critical buckling loads of MEE-FG nanoscale plates.

• 연구논문집
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• 통권27호
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• pp.57-73
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• 1997

The bogie between the track and the railway vehicle body, is one of the most important component in railroad vehicle. Its effects on the safety of both passengers and vehicle itself, and on the overall performance of the vehicle such as riding quality, noise and vibration are critical. The bogie is mainly consisted of the bogie frame, suspensions, wheels and axles, braking system, and transmission system. The complex shapes of the bogie frame and the complicate loading condition (both static and dynamic) induced in real operation make it difficult to design the bogie frame fulfilling all the requirements. The complicated loads applied to the bogie frame are i) static load due to the weight of the vehicle and passengers, ii) quasi-static load due to the rolling in curves iii) dynamic load due to the relative motion between the track, bogie, and vehicle body. In designing the real bogie frame, fatigue analysis based on the above complicated loading conditions is a must. In this study, stress analysis of the bogie frame has been performed for the various loading conditions according to the UIC Code 6 15-4. Magnitudes of the stress amplitude and mean stress were estimated based on the stress analysis results to simulate the operating loads encountered in service. Fatigue strength of the bogie frame was evaluated by using the constant life diagram of the material. 3-D surface modelling, finite element meshing, and finite element analysis were performed by Pro-Engineer, MSC/PATRAN, and MSC/NASTRAN, respectively.