• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.6
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• pp.512-519
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• 2013

It is important to understand the vibrating behavior of plate structures for its many engineering applications. In this study, the vibration characteristics of strip plates that have finite width and infinite length are investigated theoretically and numerically. The waveguide finite element(WFE) approach, which is an effective tool for studying waveguide structures, is used in this study. The WFE method requires only a cross-sectional finite element model, and uses theoretical harmonic solutions to assess wave propagation along the longitudinal direction. First, WFE results for a simple strip plate are compared with the theoretical results(i.e., dispersion diagrams and point mobilities) to validate the numerical model. Then, in the numerical analysis, different numbers of longitudinal stiffeners are included in the plate model to investigate the effects of stiffeners in terms of the dispersion curves and mobilities. Finally, the dispersion curves of a stiffened double plate are obtained to examine the characteristics of its wave propagation.

• Journal of Aerospace System Engineering
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• v.12 no.3
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• pp.26-37
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• 2018

The Korea Aerospace Research Institute has developed a 6U HiREV Nano-satellite for the observation of the earth using high resolution videos and images. Since the 6U Nano-satellite is bulky compared to the 1U/3U Nano-satellite, the first natural frequency is relatively low. Large equivalent stress and total deformation, due to structural load, can be generated. In this paper, the design of the 6U HiREV Nano-satellite is described and structure analysis, such as acceleration load analysis, modal analysis, and random vibration analysis are carried out. It is proven that the structural design of the 6U HiREV is stable. These results will be useful as reference materials for the development of additional 6U Nano-satellites, which will be applied to various future missions in KOREA.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.5
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• pp.467-475
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• 2015

In this paper, the behaviour of a cantilevered beam was predicted to examine the difference between linear and non-linear static, dynamic analysis for a structure by using CR nonlinear formulation. Then, external transverse static and dynamic loads were applied at the free tip of the beam. Classical theories were used for the present linear analysis and co-rotational dynamic FEM program was used for the present nonlinear analysis. In the static analysis, effects of the load for the beam deflection were observed in both linear and nonlinear analysis. Then, normalized displacement at the tip of the beam was predicted for different frequency ratio and a significant difference was obtained in the vicinity of the resonant frequency. In addition, effects of frequency and time for the beam deflection were investigated to find the frequency delay.

• Journal of the korean Society of Automotive Engineers
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• v.9 no.1
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• pp.23-32
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• 1987

기계,구조물의 신뢰성을 향상시키는 입장에서, 최근에 특히 진동문제가 크로즈업되고 있다. 이것 은 기계, 구조물이 고속화, 대형화, 대용량화함에 따라 종래의 기술만으로는 통용이 되지않기 때 문이라고 생각한다. 이러한 이유로 기계, 구조물의 동력학적 검토를 위해 수치해석기술과 실험해 석기술이 근년에 대단히 비약적으로 발전하고 있다. 이러한 해석기술의 진보를 뒷받침하는 것은 근년의 계산기 및 그 이용기술이다. 즉, 수치해석분야에서 Cray RAN을 시초로 하는 각종전자계 측기기, 고성능미니컴퓨터와 시계열통계해석기술 및 모우도 해석기술이다. 특히 모우드해석에 관 해서는 근년의 진보가 현저하고, 종래의 간단한 가진실험 데이터로부터의 모우도, 파라미터(고유 치, 고유감쇠비, 고유모우드)의 추출에 그치지 않고, 진동응답예측(simulation)과 유한요소법과의 결합이라고 하는 광범위한 기술내용의 포함하는 중요한 기술이 되고 있다. 여기에서는, 이 모우 드해석 특히 실험적 모우드해석기술을 기계구조물에 어떻게 응용할것인가에 대해서 설명한다.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.4
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• pp.76-86
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• 1998

Structural intensity of plates experiencing bending vibration is analytically evaluated using the modal analysis based on assumed mode method. To evaluate the convergence of structural intensity according to the number of superposition modes, the power obtained by structural intensity integration over the closed curve containing the excitation source is compared with the power injected into plates. The erect of power reduction due to the material internal loss is evaluated using the intensity around a localized damping point, In addition, the dominant component among internal forces in the power transfer by the bending vibration of plates and the change of power flow due to stiffener are also investigated.

• Computational Structural Engineering
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• v.11 no.3
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• pp.155-164
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• 1998

이 논문은 변단면을 고려한 수평 곡선보의 자유진동에 관한 연구이다. 진동시 곡선보 요소에 작용하는 합응력과 관성력의 동적평형방정식을 이용하여 변단면 원호형 수평 곡선보의 자유진동을 지배하는 상미분방정식을 유도하였다. 이 미분방정식을 원형 단면을 갖는 선형변변단면에 적용하여 고유진동수, 진동형 및 합응력을 산출하였다. 수치 해석예에서는 양단고정 및 양단회전 곡선보를 채택하였으며, 수치해석 결과로서 고유진동수와 단면비, 세장비 및 중심각 사이의 관계를 그림에 나타내었다. 또한 실험실 규모의 실험을 통하여 본 연구결과의 타당성을 보였다.

• Journal of the Earthquake Engineering Society of Korea
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• v.1 no.1
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• pp.31-39
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• 1997

This paper is on the vibration control of access floor on the frames of reinforced structure. In this study, the horizontal anti-vibration system using precise spring damper was developed and modeling and vibration analysis of the RC structure was performed for the control of horizontal vibration coused by machinery and worker's moving. Experiment was done in three cases, no damper at the RC structures, dampers connecting pedestal to pedestal and pedestal to the structure, for the investigation of the effect of the system on disigned RC structure. For each experiment, the occeleration responses on slab and access floor after giving impact wave and external vibration were measured. It was shown that the magnitude of resonance response of the system with dampers are smaller than without damper and the resonance peak also partly moved to low-frequency range. Furthermore. It was shown that the acceleration components of the system with domoers decreased greatly in high-frequency range and the system was very much effective especially for external vibration. In order to verify the anti-vibration effect of the developed system, the vibration analysis was also done for the system by using the finite element modelling. The analysis results was in good agreement with experimental results. Thus, It is concluded that this study is useful for the design of precise anti-vibration system and micro-vibration control of concrete structures.

• Air Cleaning Technology
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• v.9 no.2 s.33
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• pp.19-42
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• 1996

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.4
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• pp.63-72
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• 1998

This study is to develop a technique for micro-vibration analysis and control of concrete slabs to fulfil the vibration criteria for working environments. The proposed technique is for determining the unknown forces from accelerance of two concerned points and the micro-vibration analysis and control of concrete slabs are then validated by numerical model and structural tests. And it is recommended that the natural frequency of structures for micro-vibration control design should be above 25 Hz~30 Hz, and 1.5 times forcing frequency in case of 3~5% structural damping ratio of concrete structures.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1994.04a
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• pp.167-171
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• 1994

본 연구에서는 차폐구조 내부에 위치한 소음원의 체적이 비교적 큰 근접 음향 차폐구조로 취급하여, 구조 내부의 공간적 음장분포해석(spatial sound distribution analysis)은 하지 않고 단지 소음원의 표면과 차폐 벽면 간의 공기층에 의한 간섭 영향을 고려하면서, 차폐로 인한 음압의 상승(build up)효과를 고려하여, 직육면체의 형상을 가지는 차폐구조에 부착되는 각각의 벽면들의 음향 삽입손실(Insertion Loss, IL) 특성을 전달매트릭스 기법(Transfer Matrix Analysis, TMA)을 이용하여 해석하였으며, 이러한 벽면들에 대한 이론 해석의 결과로 제작된 벽면들의 음향차폐특성을 시험을 통해 나타내었다.