• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.06a
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• pp.285-290
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• 1999

This paper describes that the leaf spring damper(LSD) developed by authors can be controled by side clearance between side cover and leaf spring. The test rig and two prototype dampers with different side clearance were manufactured. Experiments were performed to investigate the effects of side clearance on the damping of leaf spring damper. The stiffness and damping coefficients are obtained from the displacements and the reaction forces generated by rotating the eccentric shaft. All dynamic coeffficients are plotted with the excitation frequency which is adjusted by rotating speed of shaft.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.12
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• pp.1192-1198
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• 2011

Design routines of a torsional spring-viscous damper for a 1800 kW four cycle diesel engine-generator system are described. Modal techniques for system normalization and optimal equations for damper design are used to obtain proper design parameters of the damper. A prototype damper is manufactured according to the described design process and its two design parameters, stiffness and damping, are evaluated experimentally by torsional actuator test and free decay test. Experimentally obtained values of stiffness and damping coefficients showed good agreements with the designed values of the prototype damper.

• Journal of Ocean Engineering and Technology
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• v.25 no.1
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• pp.8-13
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• 2011

A compact array system of small buoys is used for wave energy extraction. To evaluate the performance of this system, hydrodynamic analysis is carried out in regular waves using the higher order boundary element method. The motion response of each buoy is calculated considering hydrodynamic interactions caused by other buoys. The effect of energy extraction device is modeled as a linear damping load. The efficiencies of energy conversion are compared using the various sizes and arrangements of the array system and the damping coefficients for energy extraction. The increase in size or the packing ratio of the system gives better efficiency. However, the wave condition and the cost for the system should be considered to optimize performance from the perspective of engineering and economics. The proposed nondimensionalized damping coefficient for energy extraction is 0.1~0.5.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.143-148
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• 2004

The numerical analysis of the hard disk drive slider is presented. The pressure distribution was calculated using the finite element method. The generalized Reynolds equation was applied in order to include the gas rarefaction effect. The balance of the air bearing force and preload force was considered. The characteristics of the small vibrations near the equilibrium were studied using the perturbation method. Triangular mesh with variable element size was employed to model the two-rail slider. The flying height, pitching angle, rolling angle, stiffness and damping of the two-rail slider were calculated for radial position changing from the inner radius to the outer radius and for a wide range of the slider crown values. It was found that the flying height, pitching angle and rolling angle were increased with radial position while the stiffness and damping coefficients were decreased. The higher values of crown resulted in increased flying height, pitching angle and damping and decreased stiffness.

• Journal of the korean Society of Automotive Engineers
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• v.3 no.2
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• pp.34-42
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• 1981

The feasibility of using fluidic components for improving certain performance characteristics of the suspension systems for tracked vehicle is investigated. This study describes three variable damping systems for which the damping coefficients are function of relative velocity and absolute a of the vehicle body. Through the comparison analysis between constant damping coefficient damper and each of variable dampers. the followings were found: (1)Fluidic Diode Damper gave less accelerations, (2)Both Fluidic Diode Damper and Relative Velocity Damper gave the less time for which the wheel is off the ground, (3) At low vehicle velocity Fluidic Diode Damper gave low energy dissipation rate, while at high vehicle velocity Turbulence Accelerometer Damper gave low energy dissipation rate.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.5
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• pp.156-162
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• 2003

The shock absorber is a part having a direct influence on the ride comfort, stability and dynamic load prediction of a vehicle. Thus, a rationally modeled shock absorber should be required in the dynamic analysis of vehicles. This thesis presents a modified model, based on Worden's hyperbolic tangent function, in order to fit experimental data on the velocity-damping force of a shock absorber. The hyperbolic tangent function correctly indicates the characteristics of a shock absorber, and has the advantage of containing physical causality. To evaluate the method, comparative evaluations of the linear model, the 5th polynomial model and Worden's model were carried out. The function presented in this paper is not only simple but also makes it possible to estimate the function coefficients easily and visually. In addition, it has the advantage of containing physical causality. Lastly, it effectively models the damping force of a shock absorber.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.9
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• pp.2477-2485
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• 1994

Air damper has a great advantage that is independent of temperature change. This paper presents an analysis approach and an application for designing nonviscous air damper with a piston and a cylinder. The objective functions for optimum design is damping coefficient and is maximized by changing two design variables that are length between piston and cylinder and orifice diameter. A digital computer program was developed which determines optimal air damper configuration for maximum damping coefficients. The results were applied to the automatic washer and are confirmed to be valid for the range of operating conditions.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.251-256
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• 2000

This paper presents dynamic modeling and controller design of a tracked vehicle installed with the double-rod type ERSU(electro-rheological suspension unit). A 16 DOF(degree-of-freedom) model for the tracked vehicle is established by Lagrangian method. After showing the spring and damping characteristics of the proposed ERSU, equivalent 2 DOF 1/12 tracked vehicle model is then formulated by regarding the spring and viscous damping coefficients under the static state as constant values. A robust LSDP(loop-shaping design procedure) $H_{\infty}$ controller compensating spring and damping parameter variations is then designed in order to suppress unwanted vibration of the vehicle. The control responses such as vertical and pitch acceleration are presented in time domain.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.3
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• pp.150-156
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• 1998

In this paper, a 3-DOF(Degree Of Freedom) rigid body model is developed for dynamic analysis of a hydrostatic table. The dynamic coefficients, stiffness and damping constant of each pad are calculated from the mass flow continuity condition. The validity of this model is examined in theoretical and experimental method. The dynamic behavior when mass unbalances and local variations of stiffness and damping of pads present is analyzed for real applications of hydrostatic table. Since the theoretical and experimental results show goof agreement. it can be said that the 3-DOF rigid body model is useful for the dynamic model of the table. The analysis reveals that the pitching motion is the dominant mode of vibration, It also reveals that unbalanced loads can increase amplitude of tilting motion and reduce natural frequencies and damping capacity of the hydrostatic table.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.8
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• pp.2501-2507
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• 1996

In this paper actively controlled air bearing is investigated to overcome the defects of air bearing such as low stiffness and damping coefficients. The actively controlled air beairng is composed of an air bearing, a gap sensor, a controller, and a piezo actuator. By controlling the position of air bearing with piezo actuator, the position of floating object is controlled. In this study the proportional-Integral-Derivative controller is employed. Active air bearing is investigated numerically and experimentally. There is good agreement between the simulation and the experimental results. It is shown that the stiffness and damping characteristics and positioning experimental results. It is shown that the stiffness and damping characteristics and positioning accuracy of air bearing can be improved by means of adopting actively controlled air bearing.