• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.590-595
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• 1998

This study was performed to obtain a numerical model for a viscous fluid damper from an experimental testing. The input signals for displacement were chosen as two type : a triangular and a sinusoidal forms. The performing test parameters were the area of the resistant plate and the oil film thickness of the viscous fluid and the temperature effect was neglected. The numerical model was established by assuming to behavior as an non-Newtonian fluid. The test results were summarized by the equation of F = 0.0308A(V/d)$^{0.51}$25/. Using the obtainal formula, the procedure to apply the viscous damper for a real structure design was introduced..

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.207-211
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• 2009

To investigate the vibration characteristics of compact disc player(CDP) due to excited vibration and disturbances, it is necessary to consider the transmissibility of the CDP. The disturbances as well as the temperature in the vehicle are the one of the important factors when CDP is designed. In this study, the effect on the temperature of the oil damper, which is applied to anti-vibration system of the CDP, was investigated. When the temperature was changed from -30 to 90 and the properties of the oil damper (hardness of rubber, viscosity of oil) were changed, the transmissibility was measured.

• Journal of the Korean Society of Safety
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• v.12 no.1
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• pp.9-18
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• 1997

This paper is a study on the dynamic characteristics of truncated cone type squeeze film damper(SFD) bearing and rotor system. This model can alter the radial oil film gap which Is Important to the performance of rotor-bearing system and manufactured easily to change the shape concept of traditional circular type SFD bearing. In theoretical analysis, the oil film pressure distribution, the oil film force, the film damping coefficient and the eccentricity ratio, etc. were induced with regard to the film inertia effect. The film damping coefficients and optimum design parameters are calculated. When unbalance parameter U is greater than 0.2, the nonlinear vibration such as "Jump" phenomena appears in the vicinity of rotor critical speed. At this time, the increases of bearing parameter U, journal distance S, Reynolds number Re can control this unstable vibration. The experimental results show that SFD hearing and rotor system which are designed according to the design parameters in the stable region are operated stably in rotational speed 9,600rpm without nonsynchronous behavior.

• International Journal of Automotive Technology
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• v.8 no.1
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• pp.103-109
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• 2007

The nonlinear characteristics of a suspension is directly related to the ride quality of a passenger car. In this study, the nonlinear characteristics of a spring and a damper of a passenger car is analyzed by dynamic experiments using the MTS single-axial testing machine. Also, a mathematical nonlinear dynamic model for the suspension is devised to estimate the ride quality using the K factor. And the effect on the variation of the parameters of the suspension is examined. The results showed that the dynamic viscosity of the oil in a damper was the parameter that most influeced the ride quality of a passenger car for the ride quality of a passenger car.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.375-380
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• 2004

Vibration of railway vehicle has harmful effect to dynamic performances of railway represented to stability, safety and ride comfort. Hence reduction of vibration has been discussed as an important problem and has been widely investigated. A new technology of vibration control, energy regenerative control, is introduced. Energy regenerative damper using this new vibration control converts vibration energy into other kind of energy that we can utilize. In this paper, this energy regenerative damper is applied to the dynamic absorber and vehicle suspension. And it is evaluated whether the energy regenerative railway vehicle suspension is possible.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.2
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• pp.74-83
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• 1997

The non-periodic angular accelerations of engine are the major cause of gear rattle. This gear rattle is based on the existence of a backlash between the drive gear of input shaft and the free gear of output shaft in the gearbox. Especially, the neutral gear rattle have a very bad effect on the ride quality. Test-rig was constructed in order to evaluate the parameter influence upon the neutral gear rattle. Also, each different 4 type torsional characteristic of clutch was manufactured. Experimental conditions are the use of each different 4 type torsional characteristic of clutch and oil temperature variation in gearbox. In case of the same stiffiness of pre-damper type clutch at idling, the clutch of large hysteresis showed dam- ping effects at the 2nd input gear and the 2nd output gear. Also, the main-damper type clutch was shown to large resonance phenomenon at the 2nd input gear. Accordingly, main-damper type clutch was unapp- roriate at idling.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.955-958
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• 2005

In this study, the wind load characteristics for a transmission tower is investigated considering the effect of the transmission lines through stochastic analysis. The assemblage of the transmission line and insulator are modeled as a double pendulum system connected to the SDOF model of the tower It is observed that the background component of the overturing moment induced by the wind response of the transmission line has considerable portion in the total overturning moment. Based on this result, a rotational viscoelastic damper (VED) is proposed for the mitigation of the transmission line reactions, which act as wind load transferred to the tower. To verify the effectiveness of the proposed strategy, time history analysis is conducted for different wind velocities and VED damping constants. From the analysis, the proposed VED is proved to be effective for mitigation of the background component rather than the resonance component of the transmission line reaction.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.838-843
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• 2005

The nonlinear characteristics of a suspension is directly related to the ride quality of a passenger car. In this study, a dynamic experiment for a spring and a damper of a passenger car is performed to analyze the nonlinear characteristics using MTS 1-axial testing machine and a mathematical nonlinear dynamic suspension model based on experimental data is devised to estimate the ride quality using Billings' method. The devised nonlinear model is applied to the ride quality analysis using K factor and the effect of suspension parameters is examined. As a result, the friction between the cylinder and the piston of a damper is the most effective parameter for the ride quality of a passenger car.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.340.2-340
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• 2002

A practical implementation method of squeeze-film aeroelastic disk vibration damping and its practical design performance are presented to provide a solution method to meet the tight TMR(Track Mis-Registration) design budget of high-TPI HDDs. Most previous research results are mainly based on the component-level study in the 'open-cover state' which is far from the realistic operations HDD condition. (omitted)

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.110-115
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• 2002

In this paper, the results of an analysis of the dynamic behavior of the eddy current brake(ECB) system are presented. The measured irregularity of the track in Korean high speed line and the track irregularity given by ERRI(high level) were used for simulation. The wheel-rail profile combination were analyzed with different rail gauges. A model of the bogie with an substitute body for the carbody was implemented in the Multi-body-Simulation Program SIMPACK. The ECB frame was modelled both as flexible body and as rigid body. Four different driving conditions were analyzed. In this study dynamic behavior in general were performed to evaluate the design of eddy current brake system and specially the effect of damper was also studied. A comparison of simulations with and without damper shows that the damper have most effect for lower speed. The simulation results will be verified by comparison with measured data from on line test and also used for improving design.