• Journal of the Korean Society for Precision Engineering
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• v.32 no.7
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• pp.591-595
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• 2015

The roller rig tester for safety performance evaluation of wheel derailment is a test facility which can give the test load condition to the test wheel, similar to the actual dynamic condition in actual running condition. This study describes the evaluation result on the durability of the resilient wheel equipped with the ring damper and the damping material, and installed in the half part of a full scaled bogie in combination with the primary spring when it rotates under the dynamic condition. The evaluation result on durability of resilient wheel after load test of 2 million cycles shows that the safety of wheel is not affected by the applied load in visual inspection and nondestructive test, however, in the bolt used for fastening the ring damper to the wheel the loosening was found. Accordingly the use of self-locking nut and washer is recommended.

• The KSFM Journal of Fluid Machinery
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• v.7 no.4 s.25
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• pp.24-31
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• 2004

The aim of this study is to provide fundamental information for the development of Semi-Active Damper Using Magnetic fluid. To achieve the aim, the damping effect of magnetic fluid is investigated by experiments that the diameter of inner circular bar and the input amplitude were varied in the magnetic field generated by the permanent magnet and the electromagnet coil. From the study, the following conclusive remarks can be made. As the diameter of inner circular bar and input amplitude increase, the damping effect is improved. This is explained by the fact that as the contact area between inner circular bar and magnetic fluid increases, the increase of friction lowers kinematic energy. If the magnetic field is generated, the damping effect is improved. This is explained the assumption that as the intensity of magnetic fluid particle increases, there is virtual mass phenomenon.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.281-286
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• 2003

A Suspension system of a car is composed of dampers and springs. The dampers and springs usually have nonlinear characteristics. However, the nonlinear characteristics of the springs and dampers through analytical model cannot agree with the experimental results. Therefore, the nonlinearity of the suing and damper should be known from the experimental results. In this study, the methods of system identification for nonlinear dynamic system in time domain are discussed and the nonlinear parameter estimation lot experimental data of an EF-SONATA car was done. The results show that a cubic and a coupled term should be considered to model the suspension system.

• Structural Engineering and Mechanics
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• v.51 no.5
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• pp.743-754
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• 2014

Investigations of regular and chaotic vibrations of the autoparametric pendulum absorber suspended on a nonlinear coil spring and a magnetorheological damper are presented in the paper. Application of a semi-active damper allows controlling the dangerous motion without stooping of system and additionally gives new possibilities for designers. The investigations are curried out close to the main parametric resonance. Obtained numerical and experimental results show that the semi-active suspension may reduce dangerous motion and it also allows to maintain the pendulum at a given attractor or to jump to another one. Moreover, the results show that, for some parameters, MR damping may transit to chaotic motions.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.733-734
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• 2006

In this parer, characteristics of the flexible rail in levitation control system are analysed. The magnetic levitation system is an electromagnet type and is full-scaled vehicles. The system consists of electromagnet, chopper, flexible rail, secondary suspension system and levitation controller. The mathematical modelling for the whole system is carried out. Especially, the flexible rail is modelled using second-order mass-spring-damper system. Using the derived model, the dynamic characteristics for the system are presented with different vehicle speed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.130-135
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• 1998

The Reciprocating compressor are widely used in the refrigeration field for its simplicity in principle and high efficiency. In this work, we developed a mathematical model of a reciprocating compressor. The suction and discharge valves are modeled by the spring-mass-damper systems. The working fluid flow is derived from unsteady Bernoulli's equation. With the design parameters, the valve motions and pressure fluctuations are studied numerically and experimentally.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.139-142
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• 1996

This paper presents a method of controlling contact force for deburring tasks. The cope with the nonlinearities and time-varying properties of the robot and the environment, a neural network control theory is applied to design the contact force control system. We show that the contact force between the hand and the contacting surface can be controlled by adjusting the command velocity of a robot hand, which is accomplished by the modeling of a robot and the environment as Mass-Spring-Damper system. Simulation results are shown.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.289-293
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• 1996

Vibration absorber is used to protect the primary system from steady-state harmonic disturbance. By attaching the absorber to the primary system which is modeled as a SDOF system, the new system becomes two DOF system. Depending on the driving frequency on the original system, the absorber needs to be carefully tuned, that is, to choose adequate value of the absorber mass and stiffness, so that the motion of the original mass is a minimum. This paper presents the effects of resonance frequency ratio and of vibration absorber with oil damper and coil spring for linear damped primary systems.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1609-1614
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• 2000

This paper presents the modeling, theoretical formulation, and stability analysis for a combined system of a spinning disk and a head that contacts the disk. In the analytical model, head interface is considered by a rotating mass-spring-damper system together with a frictional follower force on the damped annular disks. The method of multiple scales is utilized to perform the stability analysis that shows the existence of instability associated with parametric resonances. This instability can be effectively stabilized by increasing the damping ratio of a disk.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.675-676
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• 2011