• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.970-973
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• 1995

The proposal of this paper is the constructing of knowledge database with manufacturing information. This database contains characteristics of workpiece materials, cutting tools, NC machines, manufacturing processes, and work conditions. And all shape in the system are feature models such base plate, step, hole, pocket, boss, and slot. These information generate a final decision for machining process by the expert system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.486-491
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• 1998

본 연구에서는 충돌면의 형상에 따른 고속 원형 충돌제트의 불안정 모드를 밝히기 위하여 우선 충돌면의 형상에 따른 주파수 특성을 비교하고자 하였다. 이를 위해 충돌면이 제트의 직경보다 작은 원판(small plate)과 제트의 직경보다 큰 구멍(hole)의 2가지 경우에 대하여 실험을 하였고, 평판 충돌음에 대한 연구결과와 비교 검토하였다.

• Bulletin of the Society of Naval Architects of Korea
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• v.23 no.4
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• pp.11-18
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• 1986

The fundamental theory and application of boundary element method for two-dimensional problem are introduced in this paper. Based on this boundary element procedure, several numerical calculations such as circular cavity problem, a thin plate with hole under tension and a long thick-walled cylinder under internal pressure are performed. The numerical results show fairly good agreement with exact solutions or results of finite element method.

• Structural Engineering and Mechanics
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• v.7 no.5
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• pp.503-512
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• 1999

Practicing a hole or an orifice through a plate or a slab constitutes a very frequent engineering situation due to operational reasons imposed on the structural system. From a designer's viewpoint it is important to know the effect of this modification of the mechanical system upon its elastodynamic characteristics. The present study deals with the determination of the lower natural frequencies of the structural element described in the title of the paper using a variational approach and expressing the displacement amplitude of the plate in terms of the double Fourier series which constitutes the classical, exact solution when the structure is simply supported at its four edges.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.665-670
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• 2002

Pleasantness or quietness becomes one of the most important factors for residential designs recently. Especially for apartments, the noise generated by falling objects becomes a sensitive issue these days. To overcome the problem of the impact noise in apartments, the floor design has been changed. To reduce the transmissibility of the noise, composite floor structures are devised and implemented for the construction of apartments. In this paper, the noise reduction performance of a composite floor plate with holes is analyzed. Computational modelings for the structures are developed and its performance is evaluated by using the finite element method. The results show that the noise can be well reduced with the multi-layer composite floor plates with holes.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.4
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• pp.283-292
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• 2009

Laser-based ultrasonic sensing requires the probe with fixed fecal length, but this requirement is not essential in laser-based ultrasonic generation. Based on this fact, we designed a pulsed laser-based ultrasonic wave propagation imaging (UWPI) system with a tilting mirror system for rapid scanning of target, and an in-line band-pass filtering capable of ultrasoaic mode selection. 1D-temporal averaging, 2D-spatial averaging, and 3D-data structure building algorithms were developed far clearer results allowing fur higher damage detectability. The imaging results on a flat stainless steel plate were presented in movie and snapshot formats which showed the propagation of ultrasound visible as a concentric wavefield emerging from the location of an ultrasonic sensor. A hole in the plate with a diameter of 1 mm was indicated by the scattering wavefields. The results showed that this robust UWPI system is independent of focal length and reference data requirements.

• Structural Engineering and Mechanics
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• v.26 no.5
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• pp.591-615
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• 2007

An improvement is introduced to solve the plane problems of linear elasticity by reciprocal theorem for orthotropic materials. This method gives an integral equation with complex kernels which will be solved numerically. An artificial boundary is defined to eliminate the singularities and also an algorithm is introduced to calculate multi-valued complex functions which belonged to the kernels of the integral equation. The chosen sample problem is a plate, having a circular or elliptical hole, stretched by the forces parallel to one of the principal directions of the material. Results are compatible with the solutions given by Lekhnitskii for an infinite plane. Five different orthotropic materials are considered. Stress distributions have been calculated inside and on the boundary. There is no boundary layer effect. For comparison, some sample problems are also solved by finite element method and to check the accuracy of the presented method, two sample problems are also solved for infinite plate.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.8 s.179
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• pp.1978-1990
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• 2000

In this study, the free vibrations of the cantilever plate, which is one of the most frequently used elements in various machine structures, are analyzed and further the results are utilized to develop the methodology to predict and control the natural frequencies for designing stabilized systems. The proposed method has three major steps. The first step is the frequency response test to investigate the natural frequencies of some plates, then the database is constituted from experiments and the FEM, and finally the natural frequencies are predicted using the database to be cross-checked by the identification test. The result of this study will help design many different stable structures without any complicated calculations.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.345.1-345
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• 2002

This paper dealt with an experimental study on the hydroelastic vibration of clamped perforated rectangular plates submerged in water. The penetration of holes in the plates had a triangular pattern with P/D (pitch to diameter) 1.750, 2.125, 2.500, 3.000 and 3.750. The natural frequencies of the perforated plates in air were obtained by the analytical method based on the relation between the reference kinetic and maximum potential energies and compared with the experimental results. (omitted)

• Journal of the Korea Institute of Military Science and Technology
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• v.8 no.4 s.23
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• pp.136-145
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• 2005

특이응력해석을 위한 일반화된 가역상반일 경계적분식이 섬유강화복합재를 모형화한 직교 이방성 크랙평판의 수치해를 위하여 발전시켰다. 이 적분방정식은 평판경계에서의 탄성변위와 트랙션의 변수로 구성된 경계적분식의 형태로 하중이 없다는 두 크랙면의 경계조건과 유한의 탄성변형에너지의 개념에서 경계적분식에 필요한 특성해를 규정하고 대응되는 보조해를 계산하였다. 대칭모우드 I형의 중앙원공크랙평판 및 복합모우드형의 반원편측크랙 일단고정평판의 응력확대계수가 임의의 섬유방향각에 따라서 계산되었다.