• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.191-203
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• 2006

The vibration characteristics of composite stiffened laminated plates with stiffener is presented using the assumed natural strain 9-node shell element. To compare with previous research, the stiffened plates are composed of carbon-epoxy composite laminate with a symmetric stacking sequence. Also, the result of the present shell model for the stiffener made of composite material is compared with that of the beam model. In the case of torsionally weak stiffener, a local buckling occurs in the stiffener. In this case, the stiffener should be idealized by using the shell elements. The current investigation concentrates upon the vibration analysis of rectangular stiffened and unstiffened composite plates when subjected to the in-plane compression and shear loads. The in-plane compression affect the natural frequencies and mode shapes of the stiffened laminated composite plates and the increase in magnitude of the in-plane compressive load reduces the natural frequencies, which will become zero when the in-plane load is equal to the critical buckling load of the plate. The natural frequencies of composite stiffened plates with shear loads exhibit the higher values than the case of without shear loads. Also, the intersection, between the curves of frequencies against in-plane loads, interchanges the sequence of some of the mode shapes as a result of the increase in the inplane compressive load. The results are compared with those available in the literature and this result shows that the present shell model for the stiffened plate gives more accurate results. Therefore, the magnitude, direction type of the in-plane shear and compressive loads in laminated composite stiffened plates should be selected properly to control the specific frequency and mode shape. The Lanczos method is employed to solve the eigenvalue problems.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.4
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• pp.65-73
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• 1985

A stochastic dynamic analysis using Mode-Acceleration Method was formulated and examined in this paper. A computer program was developed using this theory and model offshore structure was analyzed by the program. Results show that the stochastic dynamic analysis using the Mode-Acceleration Method is superior to that using Mode Displacement Method. The method using the theory developed in this paper was proved to be very reliable, economic and potential.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.4
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• pp.87-94
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• 1985

Dynamic analysis of guyed tower is presented in this paper. The scope of the study is twofold. The one is to determine an efficient analysis method to include the nonlinearity of the mooring system and the nonlinear hydrodynamic wave forces. The other is to investigate the sensitivity of two major design parameters, that is the stiffness of mooring system and the fixity condition of the tower at mud line. Time history analysis method utilizing mode superposition is mainly considered. However several other methods are also used for the purpose of comparison. Analyses are carried out using the Lena Guyed Tower, which is the first structure of this kind, as a standard structure.

• The Journal of the Acoustical Society of Korea
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• v.8 no.1
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• pp.13-22
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• 1989

This study made an analysis of the characteristics of vibration & tone color of the piano strings on which a concentrated mass was set to give variety of different variations to the gamut. Theoretical analyses in this study were based on discrete and continuous system, of which the former was transformed into a multi-degree of freedom system by dividing into a number of small parts, while the latter utilized mode summation and Laplace transformation methods. And experiments were carried out with setting concentrated masses on upright piano string.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.04a
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• pp.252-257
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• 1995

전자기력을 이용한 능동 진동제어는 1979년 Ellis 및 Mote가 원형 톱의 횡 진동의 감쇠에 관한 연구를 수행하였고, 1990년 Hong Su 및 T.S.Sankar등은 시스템의 절대 위치, 절대 속도 및 상대 위치 등의 제어 변수에 대하여 전자기 액튜에이터의 동적 특성이 진동 절연 성능에 미치는 영향에 관한 연구를 하였다. 본 연구는 상부질량과 하부질량이 스프링으로 연결된 2자유도 모델의 능동 진동제어에 대하여 이론해석과 실험해석을 수행하고 각각의 결과를 비교하였다. 실험모델은 직선운동 가이드에 설치된 2개의 질량과 하나의 전자기 액튜에이터를 이용하였다. 진동제어 방법으로서는 모우드 해석에 의한 제어, 스카이 훅 감쇠 제어, Viscous damping 제어 방법을 적용하였다. 본 연구의 목적은 이론해석 결과와 실험 결과를 비교하고 비슷한 제어효과에 대해서 에너지 소비가 작은 효율적인 제어방법을 찾는데 있다.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05a
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• pp.989-994
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• 1995

본 연구의 목적은 국내에서 개발중인 액체금속로의 면진설계를 위하여 면진층과 원자로용기 사이에 있는 내진벽의 강성이 면진시스템의 지진응답에 미치는 영향을 분석하는 것이다. 이를 위하여 내진벽강성을 고려한 모우드해석을 수행하여 내진벽의 강성변화에 따른 동특성해석을 수행하였으며 면진 및 비면진시스템의 경우에 대하여 지진해석을 수행하였다. 면진 및 비면진시스템에 대한 지진해석결과에서 비면진시스템의 경우에 내진벽강성은 지진응답에 영향을 주지만 면진시스템의 경우에는 그 영향이 매우 작은 것으로 나타났다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.20 no.6
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• pp.1-5
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• 1983

A new equation, which enables us to calculate the characteristics of coupled slot-lines on a dielectric substrate, is derived. Their calculations are based on the single slot-line analysis of S.B. Cohn, but each equation of total admittance in the even mode and the odd mode is derived by a different approach. The results agree with Knorr and Kuchler's data.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.125-129
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• 2009

본 연구에서는 동강성법을 이용하여 2자유도 진동시스템을 모델링하였다. 등가 모델을 구성한 후 Inertance의 크기에 따라 변화되는 시스템의 특성을 규명하였다. 2자유도 진동 시스템을 단일 모우드 소거에 적용할 경우 해석적인 설계 방법론을 1) 감쇠가 없는 경우 2) 1개의 감쇠기를 갖는 경우로 나누어 제시하였다.

• Journal of The Korean Digital Architecture Interior Association
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• v.4 no.2
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• pp.52-59
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• 2004

The interest about noise and vibration which occurs in buildings is increasing by a living level elevation recently. Particularly, the vibration which occurs from the elevator cage of the building is possibility of damage to the users of the building continuously. So, the purpose of this study is to suggest of measuring results to the vibration that occurs from the elevator cage and propose the countermeasure of it.

• Journal of the korean Society of Automotive Engineers
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• v.7 no.4
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• pp.67-72
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• 1985

An analytical and experimental modal analysis is carried out upon a crankshaft of a four cylinder internal combustion engine for studying dynamic characteristics of the shaft. Influence coefficient method is adopted in modelling the object and the calculated dynamic properties are directly compared with the experimentally obtained torsional and bending natural frequencies and mode shapes. It is found that the test results are well agree with the outputs from analytical model especially in low harmonics.