• Journal of Ocean Engineering and Technology
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• v.6 no.1
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• pp.62-68
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• 1992

In this study, a system coupled with the nonlinear dynamic vibration absorber was modelled, and its equation of motion was analized by the harmonic balance method to obtain the amplitude ratio. And also, the stability analysis was done by the Routh Hurwitz method. In the vibration systems coupled with the nonlinear dynamic vibration absorber, the unstable region and the jump phenomenon can be ramarkably affected by the damping ratio. The stable and unstable region that obtained to differential method excellently agreed to the result of the stability analysis of Routh Hurwitz.

• Journal of KSNVE
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• v.7 no.6
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• pp.1039-1048
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• 1997

This paper describes the effects of dual dynamic vibration absorbers attached to a primary vibration system with damping. The efficiency of dual dynamic vibration absorbers was investigated with the height of amplitude ratio at the resonance frequency ratio of the damped vibration system according to mass ratio, natural frequency ratio and damping ratio. The variation of amplitude ratio related to frequency ratio of primary vibration system is verified experimentally and theoretically according to dual dynamic vibration systems using computer program designed to find mutual relationship between two absorbers.

• Journal of KSNVE
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• v.10 no.2
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• pp.325-330
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• 2000

A dynamic absorber is used to protect the primary vibration system under the steady-state harmonic disturbance. In a number of cases it appears expedient to install several absorbers of smaller masses instead of one. This may be due to the need of distribute the absorber's response along the construction, restrictions on the absorber's installation. So, we studied characteristics of the primary vibration system for the optimal natural frequency ratio and the optimal damping ratio of serial multi-dynamic absorber. Also we obtained the optimum values of the serial multi-dynamic absorber parameters using computer simulation for the damped primary vibration system. In designing multi-dynamic absorber, we presented for the optimal natural frequency and the optimal damping ratio of multi-dynamic absorbers.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.12
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• pp.129-135
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• 1996

This paper presents the effectiveness of the dynamic vibration absorber consisting of a single mass, coil springs and oil damper on the resonance freauency ratio and amplitude ratio for damped linear systems, that is, primary vibration system with damping. The effects of the dynamic vibration absorber are investigated numerically and experimentally for values of mass ratio, natural frequency ratio, and damping ratio. The experimental results show good agreement with calculated ones. As a result, the characteristics shown by the present work are useful in optimal tuning the dynamic vibration absorber in practice.

• Journal of the Korea Computer Industry Society
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• v.7 no.1
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• pp.33-38
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• 2006

The motions of suspension bridge as well as hanging cable are governed by nonlinear partial differential equations. Nonlinearity gives rise to a large amplitude oscillation. We use finite difference methods to compute periodic solutions to the torsional partial differential equations. We use the one-noded forcing term and a slight perturbation in the forcing term.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.5
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• pp.706-712
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• 1986

The unsteay heat transfer from an isothermal circular cylinder in fluctuating cross flow is simulated numerically, for the case where the amplitude of the oscillating velocity is small compared with the mean velocity. By solving the linear perturbation equations derived from the unsteady full Navier-Stokes and the energy equations, the amplitude and the phase of heat transfer response are obtained in the range of Reynolds number R$_{3}$ < 40. The effects of the velocity, the cylinder radius and the frequency on the response are expressed graphically in terms of the normalized velocity and the cylinder radius.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.3
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• pp.755-760
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• 1990

VAXIMA is a computer software which gives us results in terms of parameters. We use VAXIMA to analyze quantitatively a conservative dynamical system with cubic and quintic nonlinear terms. The system is described by a nonlinear second-order autonomous ordinary differential equation. Using the Lindstedt-Poincare method, we obtain period-amplitude characteristics. In order to check the validity of the approximate solution, we integrate numerically the equation of motion.

• Journal of KSNVE
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• v.7 no.1
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• pp.20-29
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• 1997

내부공진은 2자유도계 이상의 다양한 비선형 시스템에 존재할 수 있으며 모드 사이의 진동에너지의 교환의 원인이 된다. 위에서 설명한 흡진기의 경우처럼 그 시스템의 동작에 필수적인 요소가 되기도 하며 직사각형 평판의 경우처럼 선형이론 으로는 예측불가능한 진폭변조된 진동을 유발하기도 한다. 이론적인 해석의 결과 다양한 분기와 여러가지 형태의 해를 가지며, 특히 주기적 정상해와 혼돈적인 해를 갖는 것이 밝혀졌다. 이러한 주기적 정상해는 구조물에 따라 여러 가지 형태로 나타 나며 평판의 경우는 진폭변조된 움직이는 파형으로, 본문에서는 언급하지 않았지만 현의 경우는 타원의 퀘적의 크기와 주축의 방향의 변화로 나타난다. 이러한 다양한 해들은 구조물의 종류와 형상에 따라 다른 형태로 나타나며 향후 연구의 대상이라 생각되어진다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1994.10a
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• pp.144-147
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• 1994

본 연구에서는 진도우파수 성분과 진동진폭에 대한 이상진동의 멤버쉽함수(membership function)를 고려하여, 멤버쉽정도(membership grade)를 구하고, 퍼지연산에 의하여 회전동기와 비동기진동을 구별하는 1차 진단을 한후, 각각에 대한 진동진폭의 멤버쉽함수와 인과매트릭스(decision table)를 이용하여 보다 세분된 2차 진단을 수행하는 2단계의 진단수법을 제안한다. 그리고 실험장치에서 여러가지의 결함을 인위적으로 만들고, 이 계측자료와 관련자료를 이용하여 본 진단법의 유용성을 검토하였다.

• Proceedings of the Korea Contents Association Conference
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• 2010.05a
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• pp.347-349
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• 2010

탄성표면파 필터에 관한 여러 가지 모델링이 연구된 이후, 다양한 필터와 공진기가 신호처리용으로 사용되어, 많은 다른 모델들이 이를 분석하고 통합하기위해 유도되어 왔다. 탄성표면파 필터는 크기가 소형이고 제작이 간편하며, 주변의 전자회로와 조합하기 쉬운 장점이 있다. 비대칭의 진폭특성과 비선형 위상특성을 갖는 필터를 설계하고, 설계된 필터의 설계오차를 보정하기 위해서는 임의의 진폭 및 위상특성을 갖는 필터의 설계방법을 연구한다.