• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1000-1005
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• 2010

Ride comfort is an important factor for the development of a high-speed train. The aerodynamic force to a high speed train inside tunnels increases the car-body vibration and makes its ride comfort worse. In this study, the aerodynamic force is estimated through a CFD analysis using ADINA, and its car-body vibration and ride comfort are calculated for the aerodynamic force which acts on the side of the train. The numerical results show that the vibration is a lateral mode of the car-body and decreases the ride comfort. On the basis of this numerical simulation, more accurate simulation is necessary for the shape of tunnel and the lateral suspension system of a high speed train.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.840-843
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• 2006

The determination of firing order is very significant procedure in initial stage of design for medium speed diesel engine. Generally, the selection of firing order has been accomplished in view of minimum excitation forces condition. In this paper all possible firing orders under the given number of cylinder were considered to decide the optimum. Meanwhile torsional vibration characteristics using the phase vector sum method and minimum excitation force concept were applied. From these results, some superior cases were selected. And then, the torsional vibration response analysis and the resonance characteristics of engine structure were investigated for the final decision.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.895_896
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• 2009

this paper presents a rotor shape optimization of interior type permanent magnet (IPM) motor for vibration minimization. the vibration of permanent magnet motor is generated by cogging torque, radial force and commutation torque ripple which are electromagnetic source of vibration. In order to minimize the vibration, the optimal notches are put on the rotor pole face and the arc type pole face is applied. The variations of cogging torque and radial force of each model vibration frequency are computation by finite element method (FEM) and the validity of the analysis and rotor shape design is confirmed by vibration experiments.

• Journal of KSNVE
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• v.9 no.4
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• pp.828-834
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• 1999

The paper describes the vibration and the stability of nonuniform tapered beams resting on two-layered elastic foundations. The two-layered elastic foundations are constructed by discributed Winkler springs and shearing layers as ofen used in oil models. Governing equations are derived from energy experssions using Hamilton's Principle. The associated eigenvalue problems are solved to obtain the free vibration frequencies or the buckling loads. Numerical results for the vibration and the stability of beams under an axial force are presented and compared with other available solutions. Finally, vibration frequencies and critical forces are investigated for various thickness ratios, shear foundation parameters, Winkler foundation parameters, and boundary conditions of tapered beams.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.228-230
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• 2005

In this paper, we address an active vibration control system, which suppresses the vibration engaged by magnetically levitated stage. The stage system consists of a levitating platen with four permanent magnetic linear synchronous motors in parallel. Each motor generates vertical force for suspension against gravity and propulsion force horizontally as well. This stage can generate six degrees of freedom motion via the vertical and horizontal forces. In the stage system, which represents the settling-time critical system, the motion of the platen vibrates mechanically. We designed an active vibration control system for suppressing vibration due to the stage moving. The command feedforward with inertial feedback algorithm is used for solving stage system's critical problems. The components of the active vibration control system are accelerometers for detecting stage tables's vibrations, a digital controller with high precise signal converters. and electromagnetic actuators.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.1049-1054
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• 2002

Fluid Pulsation in pipe usually cause several forces and these forces make mechanical vibration and noise. Protecting pipe from mechanical vibration is very important problem because vibration make pipe damage and break. To analyze pipe, we must formulate both the fluid pulsation force and vibration of pipe. In this paper fluid force from pulsation is modeled by Fluid Dynamics and solved by FEM(finite element method). The discharge pipe is also modeled by the FEM with use of 6 dof beam model. The acceleration of discharge pipe is estimated by the suggested method in this paper. The comparision of estimated results with experimental results show good agreement, which verified the validation of this method

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.11
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• pp.1106-1112
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• 2012

This paper deal with a technique for monitoring machining conditions by measuring the vibration of cutting forces at milling machining. The vibrations of cutting forces in milling process were measured and analyzed to be related with processing parameters. The magnitude of cutting force is linearly proportional to the feed rate and cutting depth, and frequency of cutting force is linearly proportional to the rotating speed. Wired and wireless communication methods were applied in transmitting the measured vibration signals and the two methods were compared. The magnitude of the vibration signals transmitted by the wireless communication method was similar to that transmitted by the wired communication method.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.12
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• pp.956-963
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• 2002

In a recent construction industry, cable supported structures such as a cable-stayed bridge or space stadium have been increasingly constructed according to rapidly upgrade their related technologies. Generally stay cables as a critical member need to be rearranged for being satisfied with design tension forces. In this purpose, a vibration method has been applied to estimate the tension forces exerted on existing stay cables. In this study, cable vibration tests were tarried out to evaluate the cable tension forces comparing with theoretical and practical formulas. Using the measured frequencies obtained from free vibration and Impulsive tests, an accuracy of the estimated tension forces is confirmed according to use the first single mode only or higher multiple modes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.247-252
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• 2008

This paper presents an active vibration control of cantilever beams under disturbances by a primary force. A direct velocity feedback control using a pair of PZT actuator and a velocity sensor is considered. Variation of the stability and performance with the locations of the sensor/actuator pair is investigated. It is found that the maximum gain varies with the locations of the sensor/actuator pair significantly. The maximum gain shows a symmetric distribution along the beam length with respect to the center point, although the boundary condition of the beam is unsymmetric. The control performance is affected by the location of the primary force as well as the location of the sensor/actuator pair. The active control system can more effectively reduce the vibration when the primary force is located close to the fixed boundary.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.9
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• pp.920-929
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• 2008

The main noise and vibration source of the BLDC rotary compressor for air conditioner was analyzed by using the measurement of noise and vibration, noise contour, and experimental modal analysis. The source is presumed to the mechanical resonance excited by the electromagnetic attractive force of the BLDC motor. To reduce the excessive noise of the BLDC rotary compressor due to the mechanical resonance, air-gap enlargement and structural dynamic modification were applied in this paper. Its validations were conducted by the analysis of the electromagnetic attractive force which is generated by the BLDC motor and by the measurement of noise and vibration of the BLDC rotary compressor. By enlarging the length of air-gap and conducting the structural dynamic modification, the noise and vibration in the compressor was significantly improved by 4.5 dB(A) and 56 percent, respectively.