• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.248-253
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• 2009

The propulsion system which apply the diesel engine with reduction gear as prime mover, generally installs the elastic coupling between engine and intermediate shaft, This coupling can isolate the vibratory torque excited by diesel engine, or the excess transient torque and moment occurring by external impact. So, diesel engine and reduction gear can safely operate by elastic coupling. Unfortunately, the elastic coupling for skimmer vessel was repeatedly broken by unknown vibration during the sea trial In this paper, the authors are searching for the possibilities and causes of the elastic coupling failure, via the global vibration measurement and the past incident investigation.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.3
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• pp.211-216
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• 2013

A wind generator system model includes wind model, rotor dynamics, synchronous generator, power converter, distribution line and infinite bus. This paper investigates the low-Voltage Ride-Through capability of PMSG wind turbine in a variable speed. The drive train of a wind turbine on 2-mass modeling can observe the shaft torsional vibration when the low-voltage occur. To reduce the torsional vibration when the low-voltage occur, this paper designs suppression control algorithm of the torsional vibration and implements simulation. The simulation based on MATLAB/SIMULINK has validated at the transient state of the PMSG and an experiment using 3kW simulator has validated the LVRT control.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.8 s.101
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• pp.975-979
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• 2005

The analysis of a mechanical system, body traveling along the elastic structure, has been a topic of interest. The establishment of analytical method for the development and control of this system is required in the fields of many machine operations such as modern weapons and high-speed feed drive system for a machine tool. The dynamic equations are derived on the torsion of a cantilever hollow shaft induced by the spin-up of a moving mass and the displacement of the mass. Influences of design parameters such as the inertia ratio, the mass moving speed and the friction coefficient are discussed on the transient response of the system.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.242-244
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• 2011

A wind generator system model includes wind model, rotor dynamics, synchronous generator, power converter, distribution line and infinite bus. This paper investigates the low-Voltage Ride-Through capability of PMSG wind turbine in a variable speed. The drive train of a wind turbine on 2-mass modeling can observe the shaft torsional vibration when the low-voltage occur. To reduce the torsional vibration when the low-voltage occur, this paper designs suppression control algorithm of the torsional vibration and implements simulation. A Matlab/Simulink is used to investigate the response during the transient state.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.993-999
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• 2007

반도체나 TFT-LCD등을 생산하는 정밀산업 공장구조물에는 진동에 민감한 수많은 정밀장비(검사 및 생산용 장비)가 청정실(Clean Room)에 설치되어 운용된다. 정밀장비는 정상운용을 위하여 주변에 각종 유틸리티 설비가 설치된다. 이러한 수많은 유틸리티 설비들과 그 밖의 많은 장비들로 인하여 공장 내 청정실에는 각종 수 많은 소음/진동원들이 산재해 있다. 이러한 소음/진동원으로 인하여 청정실 내에는 소음/진동의 환경을 저하시킨다. 이에, 본 연구에서는 정밀장비 주변에 설치 된 유틸리티의 가동으로 인하여 발생하는 진동으로 인하여 간헐적으로 정밀장비에 영향을 미치는 과도진동의 현상을 확인하고, 과도진동 현상에 대하여 정밀장비에서 제시한 진동허용규제치와 비교/평가하고, 진동허용규제치의 유효성에 대하여 확인하였다.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.107-109
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• 2007

This paper presents a dynamic force analysis of switched reluctance motor using 2D-transient finite element method. The main exciting of the vibration is the electiromagnetic force in the stator that is calculated Maxwell stress method. The advantage for elimation of vibration of 12/8 SRM was explained by comparing the radial force of 12/8 and 6/4 SRM in both time and frequency domain. In order to effective mitigate the vibration during turning off process, effects of different commutation method were investigated.

• Structural Engineering and Mechanics
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• v.31 no.6
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• pp.663-678
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• 2009

An exact solution is obtained for forced torsional vibration of a finite class 622 piezoelectric hollow cylinder with free-free ends subjected to dynamic shearing stress and time dependent electric potential at both internal and external surfaces. The solution is first expanded in axial direction with trigonometric series and the governing equations for the new variables about radial coordinate r and time t are derived with the aid of Fourier series expansion technique. By means of the superposition method and the separation of variables technique, the solution for torsional vibration is finally obtained. Natural frequencies and the transient torsional responses for finite class 622 piezoelectric hollow cylinder with free-free ends are computed and illustrated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.290-293
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• 2008

This paper proposes a criterion to select the modes for modal truncated model of flexible rotor only supported by active magnetic bearings. The proposed approach relies on the concepts of minimum control input and output energy assuming that the system is subjected to transient disturbances. Accurate large order model for the levitated rotor is taken by finite element analysis and transformed to the modal equation. By proposed methodology, which modal states should be retained in the truncated model are investigated over the whole operational speed range by the calculation. Finally, the effectiveness is verified by checking the model error between original model and reduced model.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.413-415
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• 2008

In this paper, the new algorithm which eliminates structural noise and extracts the impact signature from the measured vibration signal is developed. We studied how the transient vibration signal due to the impact is distorted while propagating through the structure. Also the characteristics of noise generated by flow and the mechanical components are analyzed. The developed method is verified in the model plenum and the flow system in the laboratory. Results show the significant improvement in the sensitivity and accuracy.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.1
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• pp.82-88
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• 2002

This paper deals with the free vibrations of horizontally curved beams with transition curve. Based on the dynamic equilibrium equations of a curved beam element subjected to the stress resultants and inertia forces, the governing differential equations are derived for the out-of-plane vibration of curved beam wish variable curvature. This equations are applied to the beam having transition curve in which the third parabolic curve is chosen in this study. The differential equations are solved by the numerical procedures for calculating the natural frequencies. As the numerical results, the various parametric studies effecting on natural frequencies are investigated and its results are presented in tables and figures. Also the laboratory scaled experiments were conducted for verifying the theories developed herein.