• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2002.08a
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• pp.298-301
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• 2002

경계요소법은 Laplace 방정식을 지배방정식으로 하는 지하수 흐름이나 해안공학 문제의 해석에 있어 매우 정확한 해를 제공하는 수치 기법이다. 특히, 경계요소법은 유한차분법이나 유한요소법과 같은 다른 수치기법과 달리 계산시간이나 기억용량의 절감 등에서 매우 효율적이다. 또한, 임의의 형태를 갖는 지형에도 큰 문제없이 쉽게 적용할 수 있고 요소의 크기를 자유롭게 조절할 수 있는 장점이 있다. (중략)

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.51-54
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• 2009

본 논문에서는 MLS기반 유한요소에 대한 개략적인 현재 개발상황과 향후 예상할 수 있는 응용분야에 대한 제안을 하였다. 이동최소제곱근사를 이용하여 형상함수를 생성하는 MLS기반 유한요소는, 요소의 경계에서 기존 유한요소의 성질-크로네커 델타 조건-을 가지면서도 기존 요소가 갖지 못했던 임의의 절점추가가 자유롭다는 장점이 있어 다양한 변절점요소로의 개발이 이루어져왔다. 선형 또는 이차형상함수를 갖는 2차원 변절점요소 뿐 아니라, 균열선단과 균열면을 포함하고 있는 2차원 균열요소와 3차원에서의 제한적인 변절점요소 등이 개발되어 다양한 불연속성 문제에 적용 가능함이 입증되었다. 이러한 MLS기반 유한요소는 향후 2차원 변절점 3각요소, 2차원 삼각균열요소, 변절점 쉘요소, 균열 쉘요소, 마칭큐브알고리즘에 적합한 3차원 변절점요소로의 개발이 가능할 것으로 예상되며, 본 논문에서는 3차원 변절점요소를 이용한 복잡한 요소망 생성에 대한 예제로 대퇴골의 요소망 생성을 보였다.

• Geotechnical Engineering
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• v.8 no.1
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• pp.7-18
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• 1992

This paper is a basic study of three by finite element method. Plate and medium. Plate is discretized 4 node p melt. At the interface between plate a melt is adopted for considering plate Measured vertical displacement out by plate foundation interaction finite zion is followed as ; 1. as being interface element adopts dation interaction finite element 2. As being interface element and platefoundation interaction finite 3. As being interface element adopte Therefore, post processing that as.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.2
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• pp.322-330
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• 1987

Isotropic linear viscoelasticity problems are analyzed numerically in time domain by Boundary Element Method with quadratic isoparametric boundary elements. Viscoelastic fundamental solutions are newly derived by using the elastic-viscoelastic correspondence principle and corresponding boundary integral equations are also presented. Numerical results of two examples are compared with the derived exact solutions to verify the accuracy and validity of the method. A detailed study on the accuracy of displacement and stress in terms of time integration step is given.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.05a
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• pp.307-312
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• 1999

A piezoelectric flextentional sonar transducer has been simulated using a coupled FE-BEM. The dynamics of the sonar transducer is modelled in three dimensions and is analyzed with external electrical excitation conditions. Different results are available such as steady-state displacement modes, underwater directivity patterns. It is shown that the present barrel-stave sonar transducer of the piezoelectric material produces flextentional displacements which could be related with higher output power, lower quality factor and more omnidirectional beam pattern than other types of sonar transducers.

• Journal of Sensor Science and Technology
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• v.7 no.1
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• pp.9-16
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• 1998

This paper describes how the directivity pattern of the scattered sound pressure is distributed when a plane acoustic wave is incident on a rigid or soft spherical shell underwater. A coupled Finite Element-Boundary Element method is developed as a numerical technique. The result of the coupled FE-BE method is agreed with theoretical solution for algorithmic confirmation.

• Nuclear Engineering and Technology
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• v.14 no.4
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• pp.178-185
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• 1982

Albedo-type boundary condition is incorporated into the finite element formulation of the cubic Hermite polynomials for the two-dimensional solution of the two-group diffusion problem. Two modifications are introduced with respect to the conventional expression for the weak form of the group diffusion equation with the zero flux or zero current boundary condition and the cubic element functions over the boundary nodes. The finite element formulations obtained from those modifications are tested with the two-dimensional ZION problem. The numerical effectiveness of the modifications are examined.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.756-759
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• 2011

일반적으로 컴퓨터를 이용한 수치 해석에는 격자 수치 해석 방법인 유한요소법 또는 유한차분법이 주로 사용되어 왔다. 그러나 이러한 방법들은 해석하고자 하는 영역을 요소나 격자 등으로 분할해야 하기 때문에 복잡한 현상들을 다루는 데 어려움을 갖게 된다. 이를 극복하기 위해 개발된 방법이 무요소법(Meshfree Method)이며 본 논문에서는 다양한 무요소법들 중 SPH(Smoothed Particle Hydrodynamics)가 고려되어진다. SPH는 라그랑지안 수치 근사 기법을 사용하는 입자법(Particle Method)으로 SPH를 정확하게 실행하기 위해서는 적절한 경계 처리법이 요구된다. 그러나 기존의 경계 처리법은 유체 입자의 침투현상 및 커널(Kernel) 끊김 현상이 발생하기 때문에 적합하지 않다. 따라서 지금까지 SPH의 경계 처리법을 향상시키기 위해 다양한 접근법들이 제안되었으며 본 논문에서는 이러한 접근법들 중 정반사(Specular Reflection), 재회복(Bounce-back), 재도입(Reintroduce) 방법 및 경계 반발력(Repulsive Force)과 가상 입자(Ghost Particle)의 적용이 분석되고 현상 접목을 통해 적절한 경계 처리법이 제안되어진다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.7
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• pp.789-796
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• 2012

Radiated noise analysis from a ship structure is a challenging topic owing to difficulties in the accurate calculation of the fluid-structure interaction as well as owing to a massive degree of freedom of the problem. To reduce the severity of the problem, a new fluid-structure interaction formulation is proposed in this paper. The complex frequency-dependent added mass and damping matrices are calculated using the high-order Burton-Miller boundary integral equation formulation to obtain accurate values over all frequency bands. The calculated fluid-structure interaction effects are added to the structural matrices calculated by commercial finite element software, MSC/NASTRAN. Then, the impedance and underwater radiation noise due to an excitation of structure are calculated. The present formulation is applied to a ship to calculate the underwater radiated noise.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.2
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• pp.95-102
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• 2014

In this paper, a coupling scheme for applying finite element analysis(FEA) programs, such as, LS-DYNA and MIDAS/Civil, to a nonlinear soil structure interaction analysis by the boundary reaction method(BRM) is presented. With the FEA programs, the structure and soil media are discretized by linear or nonlinear finite elements. To absorb the outgoing elastic waves to unbounded soil region as much as possible, the PML elements and viscous-spring elements are used at the outer FE boundary, in the LS-DYNA model and in MIDAS/Civil model, respectively. It is also assumed that all the nonlinear elements in the problem are limited to structural region. In this study, the boundary reaction forces for the use in the BRM are calculated using the KIESSI-3D program by solving soil-foundation interaction problem subjected to incident seismic waves. The effectiveness of the proposed approach is demonstrated with a linear SSI seismic analysis problem by comparing the BRM solution with the conventional SSI solution. Numerical comparison indicates that the BRM can effectively be applied to a nonlinear soil-structure analysis if motions at the foundation obtained by the BRM for a linear SSI problem excluding the nonlinear structure is conservative.