• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.56-56
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• 2003

계류라인은 해양관측부이 혹은 해양구조물을 일정일치에 계류시키기 위해서 중요한 역할을 수행한다. 본 연구에서는 상부구조물의 거동에 의한 계류라인의 거동특성을 파악하기 위하여, 상부 윗단에서 일정주기와 진폭으르 가진되는 경우에 장력과 변위의 응답을 살펴보았다. 수평으로 가진되는 경우에 규칙적으로 가진됨에도 불구하고 맨윗단에서 장력은 가진 주파수 성분 이외에 고주파수 성분이 함께 응답하였다. 이 때 고주파수 성분은 계류라인의 길이와 장력에 따라서 다른 성분으로 나타났는데, 이 성분은 상부단에서 발생한 에너지가 전달되어 해저고정단에서 다시 반사되어 발생하는 것으로 판단되어 진다. 향후 이 성분에 대한 정량적인 연구가 필요하다. 수직으로 가진되는 경우에는 장력이 충격력 효과로 나타났는데, 이것은 지반과의 상호작용에 의한 것으로 판단된다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.627-628
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• 2009

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.6 s.52
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• pp.103-114
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• 2006

Forced vibration testing is important for correlating the mathematical model of a structure with the real one and for evaluating the performance of the real structure. There exist various techniques available for evaluating the seismic performance using dynamic and static measurements. In this paper, full scale forced vibration tests simulating earthquake response are implemented by using a hybrid mass damper. The finite element (FE) model of the structure was analytically constructed using ANSYS and the model was updated using the results experimentally measured by the forced vibration test. Pseudo-earthquake excitation tests showed that HMD induced floor responses coincided with the earthquake induced ones which were numerically calculated based on the updated FE model.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.5
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• pp.482-489
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• 2010

This paper describes the test procedure, instrumentation, verification methodology and the results of the ground vibration test(GVT) and force vibration test(FVT) of the SmartUAV aircraft to estimate experimentally dynamic characteristics of the aircraft. Bungee cords are used to emulate free-free boundary conditions of the test aircraft. The SmartUAV is excited by three shakers and one-hundred frequency response functions(FRF's) is measured. The FRF's are reduced and analyzed to identify the dynamics parameters of the SmartUAV. To extract modal parameters of the SmartUAV such as, natural frequencies and damping ratios, the poly-reference least square complex exponential method is used in the time domain. The mode shape coefficients are estimated with the least squares frequency domain method to identify the vibration modes. The FVT was performed by fixed sine frequency with three shakers on the x, y and z direction and vibration characteristics of structures and detail equipments are measured.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1991.04a
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• pp.163-166
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• 1991

현재 PWR의 동력로의 값은 대당 10억불이나 되는데, 원래 20년 수명을 예 측하고 설계된 것이나, 이를 두 배로 늘려서 40년이 수명을 가질 수 있겠는 가 하는 문제가 크게 대두되었다. 본 연구는 가장 중요한 구조물인 로심부 지지통의 수명판정조건을 제시하기 위하여 계산한 일부이다. 수명판정을 하 기 위해서는 barrel의 강제진동 응답으로부터 fluctuating stress를 구해야만 한다. 본 연구에서는 modal analysis를 이용하여 변위를 모드함수의 급수전 개의 형태로 표시하고 가진주파수가 barrel의 고유진동수와 일치하는 모드만 을 택하여 fluctuation stress를 구하였다.

• Composites Research
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• v.14 no.5
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• pp.20-25
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• 2001

This paper deals with finite element analysis for free vibration and forced sinusoidal vibration of Ka- and Ku- band antenna structures using MSC/NASTRAN. The structures are designed to satisfy minimum resonance frequency requirement in order to decouple the dynamic interaction of the satellite antenna with the spacecraft bus structure. The large mass method was utilized to analyze output acceleration according to the forced sinusoidal vibration inputs in X-, Y- and Z- directions. The analysis results can also be used thor verification experimental planning of satellite antenna.

• The Journal of the Acoustical Society of Korea
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• v.16 no.1
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• pp.16-23
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• 1997

As analysis of the forced dynamic response and vibrational mode for the cantilevered beam is described. Experimental results are compared with the natural frequencies and vibrational modes for the cantilevered beam using the theory of Bernoulli-Euler and finite element method. We have found 1st and 2nd resonance frequency of the cantilevered beam by means of the various external frequencies, $1{\sim}70Hz$, using magnetic transducer. And we have studied the vibrational displacement at obtained resonance frequency of the cantilevered beam. The experimental results for the nodes of cantilevered beam were 0 in 1st mode and 0,0.786 in 2nd mode. close agreement between the theoretically predicted results and experimental result was obtained for the vibrational mode.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.217-221
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• 2007

In this study, forced vibrations analysis was performed for main wing of small scale WIG vehicle which is equipped two-stroke pusher type propeller engine, in terms of structural. for the frequency response analysis, excitations were assumed by H-mode(Horizontal mode), X-mode(Twisted mode) which is main vibration mode of engine, and for the transient response analysis, excitations were assumed by L-mode(Longitudinal mode) with propeller thrust which is occurred when it revolution.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.2 s.95
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• pp.123-128
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• 2005

Forced vibration of a thin circular ring with a concentrated harmonic force is analyzed when the ring is free and has only the in-plane motion. Using the unit doublet function for external force, the governing equation is obtained and is solved by the use of Laplace transform. The exact solutions of displacement components and bending moment are obtained. In order to verify the solutions of analysis, finite element analysis is performed and the results shows good agreement. Then, frequency response curves for displacement and bending moment are obtained. In deriving the governing equations and the solutions, nondimensional parameter of the exciting frequency and the magnitude of exciting force are extracted. As the displacement components are obtained, the remaining bending strain, slope, curvature, shear force, etc. can also be derived. With the results of this work, the responses of a free ring excited on multiple points with different frequencies can also be obtained easily by superposition.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.5
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• pp.742-750
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• 1986

The lateral vibrating motion of a railway vehicle over a certain critical speed is a well known problem in the field of train dynamics. It is known that the train equations of motion are strongly coupled and highly nonlinear with the motion and causing that it is very difficult to solve the equations simultaneously. In this paper, a 8 degree of feedom model of a railway vehicle was suggested to solve the rail vehicle lateral motion. In stead of solving the nonlinear equation simultaneously, statistical linearization technique was adopted to solve those equations. The analysis results from the statistical linearization method were directly compared with those from direct nonlinear equations and found that the linearization technique can be very effective and economical for railroad vehicle analysis. By the way, it was found that the analysis results can analytically explain the intermittent hunting phenomena which has been frequently observed in experiments.