• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 추계학술발표대회 논문집
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• pp.191-194
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• 2001

A partially coupled thermo-piezoelectric-mechanical triangular finite element model of composite laminates with surface bonded piezoelectric actuators, subjected to externally applied mechanical load, temperature change load, electric field load is developed. The governing differential equations are obtained by applying the principle of free energy and variational techniques. A higher order zigzag theory displacement field is employed to accurately capture the transverse shear and normal effects in laminated composite plates of arbitrary thickness. Nonconforming shape functions by Specht are employed in the transverse displacement variables. Numerical examples demonstrate the accuracy and efficiency of the proposed triangular plate element.

• 한국소음진동공학회논문집
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• 제24권10호
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• pp.788-794
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• 2014

In this paper, the transient response analysis of the trapezoidal corrugated plate subjected to the pulse load is investigated by the theoretical method. Three types of pulse loads are considered: stepped, isosceles triangular and right triangular pulse loads. The corrugated plates can be represented as an orthotropic plate. Both the effective extensional and flexural stiffness of this equivalent orthotropic plate are considered in the analysis. The plate is stiffened by concentric stiffeners perpendicular to the corrugation direction. The stiffening effect is represented by the discrete stiffener theory. This theoretical results are validated by those obtained from 3D finite element analysis based on shell elements. Some numerical results are presented to check the effect of the geometric properties.

• 전자공학회논문지A
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• 제33A권10호
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• pp.144-151
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• 1996

In this paper, the theoretical analysis and the computer simulation of a new modified cochran's triangular interferometer as an incoherent holography, which can eliminate bias and conjugate image problems of the conventional cochran's triangular interferometer, are spresented. In other words, it is theoretically derived by using jones matrix operation that bias and conjugate image can be removed by adding simple optical components including a polarizing beam splitter, wave plates, and linear polarizers to the conventional with a point source, we demonstrated the validity of the suggested method by comparing the modified cocharan's triangular interferometer with the conventional one.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 가을 학술발표회 논문집
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• pp.39-44
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• 2002

A three node triangular element with drilling rotations incorporating Improved Layerwise Zig-zag Theory(HZZT) is developed to analyze the vibration of spinning pretwisted composite blades with embedded damping layer. Matching conditions at the interfaces between the damping material and the border material are enforced by setting the shear forces matched and different shear strains along the interfaces. The natural frequencies and modal loss factors of cantilevered pretwisted composite blade with damping core are calculated with the present triangular element enforcing the matching conditions and compared to experimental results and MSC/NASTRAN results using a layered combination of plate and solid elements.

• Journal of the Optical Society of Korea
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• 제8권4호
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• pp.182-187
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• 2004

We synthesized and analyzed the optical transfer function(OTF) of the modified triangular interferometer (MTI) using two-pupil synthesis method. Also, we presented the optimal MTI, which can obtain any bipolar function by combining two wave plates and a linear polarizer. By using the proposed MTI, we can obtain the complex hologram without bias and conjugate image.

• Journal of Mechanical Science and Technology
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• 제17권1호
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• pp.64-76
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• 2003

In this work, a new penalty formulation is proposed for the analysis of Mindlin-Reissner plates by using the element-free Galerkin method. A penalized weak form for the Mindlin-Reissner Plates is constructed through the exterior penalty method to enforce the essential boundary conditions of rotations as well as transverse displacements. In the numerical examples, some typical problems of Mindlin-Reissner plates are analyzed, and parametric studies on the order of integration and the size of influence domain are also carried out. The effect of the types of background cells on the accuracy of numerical solutions is observed and a proper type of background cell for obtaining optimal accuracy is suggested. Further, optimal order of integration and basis order of Moving Least Squares approximation are suggested to efficiently handle the irregularly distributed nodes through the triangular type of background cells. From the numerical tests, it is identified that unlike the finite element method, the proposed element-free Galerkin method with penalty technique gives highly accurate solution without shear locking in dealing with Mindlin-Reissner plates.

• 한국압력기기공학회 논문집
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• 제15권1호
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• pp.8-17
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• 2019

Perforated plates are used for the steam generator tube-sheet and the Reactor Vessel Closure Head in the Nuclear Power Plant. The ASME code, Section III Appendix A-8000, addresses the analysis of perforated plates, however, this analysis is only limited to the flat plate with a triangular perforation pattern. Based on the concept of the effective elastic constants, simulation of flat and spherical perforated plates and their equivalent solid plates were carried out using Finite Element Analysis (FEA). The isotropic material properties of the perforated plate were replaced with anisotropic material properties of the equivalent solid plate and subjected to the same loading conditions. The generated curves of effective elastic constants vs ligament efficiency for the flat perforated plate were in agreement with the design curve provided by ASME code. With this result, a plate with spherical curvature having perforations can be conveniently analyzed with equivalent elastic modulus and equivalent Poisson's ratio.

• 한국광학회지
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• 제8권2호
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• pp.99-106
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• 1997

본 논문에서는 변형된 삼각 간섭계를 이용하여 인코히어런트(incoherent) 홀로그래피의 근본적인 문제인 바이어스와 공액영상을 제거할 수 있다는 것을 실험과 수치복원을 통해 입증하였다. 기존의 삼각 간섭계에 간단한 수동소자를 추가하여 구성된 변형된 삼각 간섭계의 출력면쪽에 위치한 wave plates를 이용하여, 변형된 삼각 간섭계내에서 시계방향과 반시계방향으로 진행하는 두 빛의 상대적인 위상차를 조절함으로써 4가지의 빛의 세기를 얻고, 이를 이용하여 바이어스와 공액영상이 제거된 복소홀로그램을 얻었다. 또한 이를 수치적으로 복원한 결과와 기존의 삼각 간섭계를 이용하여 얻은 홀로그램을 수치적으로 복원한 결과를 비교분석함으로써, 변형된 삼각 간섭계를 이용하여 바이어스와 공액영상이 제거되는 것을 실험적으로 증명하였다.

• Structural Engineering and Mechanics
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• 제55권3호
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• pp.583-603
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• 2015

There are so many applications of perforated pates with various penetration patterns. If they are penetrated regularly, it can be represented by solid plate with equivalent material properties, which has a benefit of finite element modelling and reducing computation time for the analysis. Because the equivalent material properties suggested already are not proper to be applicable for the dynamic analysis, it is necessary to extract the equivalent material properties for the dynamic analysis. Therefore, in this study, the equivalent modulus of elasticity are obtained for the perforated plate with a triangular penetration pattern by comparing the natural frequencies of the perforated plate with those of solid plate, which are represented with respect to the ligament efficacy. Using the equivalent material properties suggested, the modal analyses of the partially perforated rectangular plate with a triangular penetration pattern are performed and its applicability is shown by comparing natural frequencies of perforated and homogeneous solid plates from finite element method and analytical method.

• 항공우주기술
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• 제3권1호
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• pp.257-266
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• 2004

고차 지그재그이론을 이용하여 면내회전 자유도를 갖는 3절점 삼각형요소를 개발하여 복합재 적층판의 층간 응력분포를 정확히 계산하였고 점탄성물질이 심어진 비틀린 복합재료 판의 진동을 해석하였다. 평면상에서 점탄성물질과 가장자리에서 박리현상을 방지하기 위하여 사용된 경계물질사이의 경계면상에서 전단력 적합조건이 사용되었다. 본 연구에서 개발된 지그재그 삼각형요소를 이용하여 점탄성물질이 심어진 비틀린 외팔보 복합재료판의 고유진동수와 감쇠계수를 계산하고 실험치 및 판과 고체요소를 혼합한 MSC/NASTRAN 결과치와 비교하였다.