• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.6
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• pp.1426-1435
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• 1990

Dynamic behaviour of point tracking system mounted on flying vehicle shaking in a random manner is investigated and the system dynamic is represented by nonlinear stochastic equations. 2-D.O.F. nonlinear stochastic equations are successfully transformed to linear stochastic equations via equivalent linearization procedure in stochastic sense. Newly developed hybrid technique is used to obtain response statistics of the system under non-white random excitation, which is proved to be remarkably accurate one by performing stochastic simulation.

• Proceedings of the KSLP Conference
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• 1998.11a
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• pp.183-183
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• 1998

음성이 성대진동에 의해서 생성된다는 것이 밝혀진 이래로 이것을 확인해 보기 위한 많은 노력이 있어왔다. 특히 성대의 빠른 진동을 느린 움직임으로 정확하게 관찰하기 위해서 후두스트로보스코프같은 기구가 사용되고 있지만, 이것은 실제 시간에 따른 성대움직임을 보는 것이 아니고, 또 불규칙한 진동이 나타날 경우에는 성대점막의 움직임을 관찰하는 것이 불가능한 단점이 있었다. 저자들은 초 당 8000 개의 연속된 영상을 기록할 수 있는 videokymography를 이용하여 성대점막의 실제 시간에 따른 움직임을 관찰해보고, 후두질환에서 나타나는 영상을 확인해 보기 위하여 본 연구를 시작하였다. (중략)

• Journal of KSNVE
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• v.9 no.4
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• pp.778-784
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• 1999

A method for obtaining the motion of an impact system whose primary and secondary system are composed of lumped masses, springs and dampers, and all the contacts are made through spring and damping elements is presented. The frequency response functions derived from the equations of motion and the impulse response functions obtained from the inverse Fourier transform of the derived frequency response functions are used for the calculation of the system responses. The procedure developed for the calculation of displacements and force time-histories was based on the convolution integrals of impulse response functions and forces applied to the systems. Time histories of displacements and contact forces are obtained for the case where a random excitation is applied to a point in the system. Impact statistics such as contact forces and the time between impacts calculated from those time histories is presented.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.198-203
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• 2002

A fuzzy logic controller design technique is proposed to apply for the control of flexible system under irregular disturbance. The fuzzy rules of $\ulcorner$Mode Selecting Fuzzy Controller$\lrcorner$ are constructed using displacement, velocity information and modal characteristics of the system. The frequency information of flexible system is picked up from $\ulcorner$Mode Selecting Unit$\lrcorner$ based on Fast-Fourier transform algorithm. Experiment is conducted to verify the proposed theoretical approach, Piezo ceramic and laser accelerometer are used as actuator and sensor in the experiments respectively

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.326.1-326
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• 2002

A fuzzy logic controller design technique is proposed to apply to the control of flexible system under irregular disturbance. The fuzzy rules of $\ulcorner$Mode Selecting Fuzzy Controller$\lrcorner$ are constructed using displacement, velocity information and modal characteristics of the system. The frequency information of flexible system is picked up from $\ulcorner$Mode Selecting Unit$\lrcorner$ based on Fast-Fourier transform algorithm. Experiment is conducted to verify the proposed theoretical approach. (omitted)

• Journal of KSNVE
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• v.8 no.3
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• pp.399-407
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• 1998

An investigation into the modal interaction of an autoparameteric systemunder broad-band random excitation is made. The specific system examined is a spring-pendulum system with internal resonance, which is known to be a good model for a variety of engineering systems, including ship motions with nonlinear coupling between pitching and rolling motions. By means of the Gaussian closure method the dynamic moment equations explaining the random responses of the system are reduced to a system of autonomous ordinanary differential equations of the first and second moments. In view of equilibrium solutions of this system and their stability we examine the system responses. The stabilizing effect of system damping is also examined.

• Journal of KSNVE
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• v.10 no.6
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• pp.1041-1047
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• 2000

The main objectives of this study are to examine the random response of a vibration absorber system with autoparametric coupling in the neighborhood of internal resonance by Gaussian closure and to compare the results with those obtained by Monte Carlo simulation. The numerical simulation is found to support the main features of the nonlinear modal interaction in the neighborhood of internal resonance conditions. While the Gaussian closure exhibits regions of multiple solutions in the neighborhood of internal resonance, the numerical simulation gives only one solution depending on the assigned initial conditions. The on-off intermittency phenomena of the cantilever mode is observed in the Monte Carlo simulation over a small range of parameter.

• Korean Journal of Optics and Photonics
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• v.14 no.6
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• pp.649-656
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• 2003

In this paper we confirm the relation between the phase and phase error of the beat signal at the lock-in region of the dither type ring laser gyroscope by numerical calculation. We also study the requirement of the dither noise of an amplitude modulation type for statistical zero averaging of the beat signal phase error, without accumulation. As a result, we find that the dither noise requires the increase and decrease gradients of the dither amplitude, and those gradients should be combined with similar white noise. The slope of the gradient and maximum/minimum amplitude must be changed randomly. We confirm the error accumulation characteristic related to the dither noise by comparison of the two outputs during temperature change, by operating the two kinds dither noise, one is satisfied with the requirement and the other is not.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1990.10a
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• pp.143-147
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• 1990

자동차는 주행시에 노면가진으로 인하여 진동을 받게 되는 데 이러한 진동 은 운전자의 승차감을 저하시킬 뿐만 아니라 화물과 차량 부품을 파손시키 는 원인이 되기도 한다. 노면가진력은 주로 현가장치를 통하여 차량에 전달 되어 차량의 진동을 유발하게 되므로 승차감을 향상시키려면 노면가진을 효 과적으로 차단할 수 있도록 현가장치를 설계하여야 한다. 이를 위하여 본 논 문에서는 차량을 현가장치의 형식에 따라 3가지 종류로 구분한 다음 각각을 12자유도로 모델링하여 노면이 불규칙(random)한 도로를 주행할 때의 승용 차의 진동을 해석하고, 현가스프링의 강성과 쇼크 압소바의 감쇠 값이 자체 수직 가속도 유효치(rms value)와 현가장치 유효행정(rms stroke length)에 미치는 영향을 분석하였다. 차량의 운동방정식은 현가장치의 비선형 특성을 고려하였기 때문에 미소 각 운동의 가정에도 불구하고 비선형 방정식이 된 다. 운동 방정식의 해는 4차 Runge-Kutta 적분법을 사용하여 수치해석으로 구하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.509-513
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• 2013

There are so many types of construction equipment. Excavator is one of typical construction equipment which is working under the tough and severe environments. It's important for engineers to design CE components by the vibration durability point of view. Traditionally, two typical vibration durability methods to verify the durability of components. The first is experimental method which is using the vibration durability test bench. But experimental approach on vibration durability is needed a lot of cost and time. The second is analytical method which is using the vibration durability analysis such as Dirlik, Stainberg, Lalanne and others methodologies. The one of main advantages on vibration durability analysis can reduce the cost and time. We present a vibration durability analysis process and methodology on the guardrail system in excavator.