• Structural Engineering and Mechanics
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• 제4권3호
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• pp.209-226
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• 1996

One of the major divisions in the mathematical modelling of a tubular structure is to include the effect of the transverse shear stress and rotary inertia in vibration of members. During the past three decades, problems of vibration of tubular structures have been considered by some authors, and special attention has been devoted to the Timoshenko theory. There have been considerable efforts, also, to apply the method of spectral analysis to vibration of a structure with rectangular section beams. The purpose of this paper is to compare the results of the spectrally formulated finite element analyses for the Timoshenko theory with those derived from the conventional finite element method for a tubular structure. The spectrally formulated finite element starts at the same starting point as the conventional finite element formulation. However, it works in the frequency domain. Using a computer program, the proposed formulation has been extended to derive the dynamic response of a tubular structure under an impact load.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.441-446
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• 2004

Mechanical systems with rubber parts have been used widely in industry fields. The evaluation of the physical characteristics of rubber is important in rubber application. Rubber material is useful to machine component for excellent shock absorbing characteristics. The impact characteristics of rubber were examined by experimental and finite element method. The impact test was conducted with a free-drop type impact tester. The ABAQUS/Explicit was used for finite element analysis. The effects of thickness and diameter of the cylindrical rubber structures were investigated. The impact absorbing ratio of the rubber material was studied order to compare the peak reaction force of the specimen which only contained aluminum against the specimen with the inserted rubber part.

• International Journal of Automotive Technology
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• 제7권5호
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• pp.555-564
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• 2006

The aim of this paper is to contribute to the efficient design of traffic light poles involved in vehicle frontal collisions by developing a computer-based, finite-element model capable of capturing the impact characteristics. This is achieved by using the available non-linear dynamic analysis software "LS-DYNA3D", which can accurately predict the dynamic response of both the vehicle and the traffic light pole. The fiber reinforced polymer(FRP) as a new pole's material is proposed in this paper to increase energy absorption capabilities in the case of a traffic pole involved in a vehicle head-on collision. Numerical analyses are conducted to evaluate the effects of key parameters on the response of the pole embedded in soil when impacted by vehicles, including: soil type(clay and sand) and pole material type(FRP and steel). It is demonstrated from the numerical analysis that the FRP pole-soil system has favorable advantages over steel poles, where the FRP pole absorbed vehicle impact energy in a smoother behavior, which leads to smoother acceleration pulse and less deformation of the vehicle than those encountered with steel poles. Also, it was observed that clayey soil brings a slightly more resistance than sandy soil which helps reducing pole movement at ground level. Finally, FRP pole system provides more energy absorbing leading to protection during minor impacts and under service loading, and remain flexible enough to avoid influencing vehicle occupants, thus reducing fatalities and injuries resulting from the crash.

• 한국산학기술학회논문지
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• 제7권2호
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• pp.107-112
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• 2006

본 연구에서는 설계단계에서 소형 직류 모터의 동특성을 파악할 수 있는 유한요소 해석모델을 개발하였다. 유한요소해석 결과의 검증을 위하여 충격실험을 실시하였으며 모터의 고유진동수와 모드형상을 추출하여 비교하였다. 개발된 유한요소 해석모델을 이용하여 모터의 형상변화가 동특성에 미치는 영향을 분석할 수 있었으며 이는 향후 고품위 저진동 직류모터를 개발하는 데 효과적으로 이용될 수 있다.

• 한국항공우주학회지
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• 제34권8호
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• pp.41-46
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• 2006

충격응답함수와 조정법(regularization methods)을 이용하여 항공기 날개의 충격하중 복원 가능성을 검토하였다. 충격하중에 대한 구조의 응답을 내타낼 수 있는 충격응답함수를 날개 유한요소모델의 강성과 질량 자료로 유도하였다. 일반적으로 부적합(ill-posed) 특성을 지닌 충격응답함수의 역행렬은 반복 Tikhonov 조종법(Iterative Tikhonov Regularization Method)과 일반화 특이치 분해법(Generalized Singular Value Decomposition Method)을 사용하여 구하였다. 수치적 입증을 위하여 전투기급 주익을 사용하였다. 해당 주익의 유한요소해석을 통하여 임의의 충격하중에 대한 변위와 변형률을 계산하였으며, 이를 충격응답함수로 계산한 결과와 비교하였다. 또한, 유한요소해석에서 계산된 변형률을 사용하여 충격하중을 복원하였다. 수치적 입증 결과 항공기 구조의 충격하중 모니터링이 본 방법으로 가능할 수 있음을 보여주었다.

• 한국기계가공학회지
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• 제17권3호
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• pp.109-119
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• 2018

The purpose of this study is to evaluate the structural safety of the front-end loader for the 90 kW class of agricultural tractors in impact test conditions. Deformation and stress on the loader under the impact test conditions are analyzed using the commercial finite element analysis software ANSYS. In previous research dealing with the initial design of the loader, the maximum stress occurred in the mount and exceeded the yield strength of the material. In this paper, an improved design of the mount of the loader was proposed to reduce the stress concentration in the initial design. The safety of the improved design was verified by performing rigid-body dynamics analysis, transient structural analysis, and static structural analysis under three impact test conditions: a drop and catch test, a corner pull test, a corner push test. It was found that the local stress concentration in the mount that appeared in the initial design was greatly reduced in the improved design, and that the maximum stresses occurred in the three impact test conditions are smaller than the yield strength. It is expected that the design improvement of the mount proposed in this study and the method of analysis may be effectively used to enhance structural safety in the development of new model front loaders in the future.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 춘계학술발표대회 논문집
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• pp.171-174
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• 2000

In this paper, impact sound realization of composite structures is performed to investigate the possibility of a new NDE system - Tapping Sound Analysis (TSA). TSA detects the existence of damages inside the structures by comparing tapping sound with pre-computed sound data of healthy structures. Tapping on the structures is modeled as impact problem and solved using finite element method. Calculation of sound is formulated based on the coupled finite element and boundary element method. Numerical simulation of impact sound and feature extraction scheme show that the impact sound can be used in the identification of damages of laminated composites.

• 전산구조공학
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• 제9권3호
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• pp.187-197
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• 1996

Explicit 직접적분법 알고리듬을 사용하여 Euler기둥의 동적 좌굴거동을 해석할 수 있는 수치해석법을 제시하였다. 평면뼈대 유한요소를 기하학적 비선형 거동과 전체좌굴의 영향을 고려할 수 있도록 보의 대변위 이론으로부터 유도하였고, central difference method를 바탕으로 해석 알고리듬을 개발하였다. 다양한 형상, 크기, 재하시간을 갖는 충격하중에 대하여 Euler기둥의 동적좌굴거동과 고유치 문제를 해석하였다. 수치해석 예제를 통하여 본 연구의 결과를 검증하였다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 추계학술발표대회 논문집
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• pp.170-173
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• 2001

Low-velocity impact on composite sandwich panel has been investigated. For the study, a finite element program is coded using 18-node assumed strain solid element and Newmark-beta method. Contact force is calculated from a proposed modified contact low. The finite element code is verified by solving typical example. The calculated impact behavior agreed well with experimental result.

• 콘크리트학회논문집
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• 제14권2호
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• pp.266-274
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• 2002

콘크리트 구조물 또는 조적식 구조물을 비파괴적으로 평가하는 충격반향시험은 타 기법과 비교하였을 때, 현장 적용면에서 탁월하게 우수하며, 그 신뢰성도 매우 높게 평가되고 있다 그러나 경우에 따라서 충격반향기법은 낮은 신뢰성을 나타내고 있다. 본 연구에서는 충격반향기법의 신뢰성을 수치해석에 의해 검토하였다. 유한요소해석 및 이론을 근거로 하는 동강성행렬법을 이용하여 균질한 강성구조 깊이에 따라 증가 또는 감소하는 전단강성구조, 샌드위치형 전단강성구조 등 대표적 유형의 전단강성구조를 가지는 콘크리트 터널벽체에 대해 충격반향실험의 수치 모사를 수행하였다. 이를 바탕으로 충격반향기법의 실험자료 분석 및 해석에 있어서 보다 신뢰성 있는 결과 도출을 위한 제언을 하였다.