• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.10
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• pp.647-651
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• 2016

The power relay can easily control high voltage and high current through metallic contacts. In addition, it has the advantage in reasonable price. So it has been used in many applications. But the power relay has a weak point by mechanical movements. These mechanical movements cause the bouncing phenomenon. Arc and bouncing phenomenon are the main causes of electric abrasion and material erosion. In this study, mechanical repetitive experiments and repetitive experiments in electrically connected state are conducted. Then these two experimental results in terms of bouncing phenomenon and changes in the contact surface are compared. In all number of repetitions, contacts in an electrically connected state cause smaller number of bounce. Also, It has lower contents of silver on eroded surface than the other. The experimental results would be helpful to the further study of contacts life span.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1850-1852
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• 1997

In this paper, the behavior and effect of conducting particles in a $SF_6$ insulated electrode system, are presented. It is shown that the bouncing voltage of the particle is independent of particle length, and that the breakdown voltages are affected by the particle length. The longer the particle, the lower the breakdown voltages. The bouncing-off, the lift off and breakdown voltages increase as the particle diameter increase. The breakdown voltage of free particle is lower than fixed particle on the enclosure.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.4
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• pp.164-168
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• 2002

The main hazard leading to breakdown in GIS(Gas Insulated Switchgear) comes from free conducting particles, which can cross between tee electrodes and cause dielectric failure under the influence of the electric field. Bouncing height of the particle can be an important factor to evaluate the possibility of breakdown occurrence. In this paper, how to estimate, outside a GIS, the bouncing height of the particle was newly suggested when GIS is in service. Both experimental results using 362 kV test chamber and computer simulation results on estimating the height were presented and compared with each other.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.8
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• pp.520-524
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• 2017

Electrical relay in an essential part of smart grids, electrical vehicles, and LED lightning systems. Therefore, studying relay reliability is important. Relays using permanent magnet actuators (PMAs), which are energy efficient, are also in the spotlight. However, most of the permanent magnets used in PMAs have a characteristic wherein the magnetic flux decreases as the temperature increases. When the magnetic flux is reduced, the force acting on the actuator is reduced. Therefore, in this study, we measured the decrease in the relay operating speed with permanent magnet reduction due to temperature rise. In addition, changes in the bouncing phenomena due to magnetic flux reduction were analyzed. As a result, the operating speed of the relay has decreased and the bouncing phenomenon has not significantly changed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.5
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• pp.407-412
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• 2019

In this paper, the changes in the electrical characteristics (arc energy, contact resistance, and bouncing phenomenon) due to the deterioration of the contact are analyzed. The results are generally consistent and can be analyzed for contact deterioration. The results of the experiment demonstrate that the arc energy is linearly related to the current when the contact samples and the voltage conditions are the same. The contact resistance varies due to multiple factors, but is generally within a certain range, and the contact deterioration can be determined. Contact stabilization can be detected by the decrease in the bouncing phenomenon due to deterioration (the change of the shape of the contact).

• Transactions of Materials Processing
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• v.25 no.1
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• pp.49-55
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• 2016

Electrohydraulic forming (EHF) is a high-speed forming process that uses an electric arc discharge in water. Shock waves resulting from the electric arc discharge are propagated to the blank through water and the blank moves toward the die. Advantages of EHF include improved formability due to the high-speed process and reduction of the bouncing effect. In the current study, a numerical simulation of EHF was developed using LS-DYNA. In the simulation, the model for the electric arc was assumed as an adiabatic gas expansion and an Arbitrary Lagrange-Eulerian (ALE) multi material formulation was used to describe the interaction between the electric arc and the water. In order to model the Fluid-Structure Interaction (FSI), a coupling mechanism was used. The blank of Al 1100-O was simulated using shell elements. The results of the simulation showed that the blank was deformed due to the pressure propagation of water and the bouncing effect did not affect the formability of blank.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.4
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• pp.149-157
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• 2000

Computer simulations of the mechanical behavior of a three point bend specimen with a quarter notch under impact load are performed. The case with a load application point at the side is considered. An elastic-plastic von Mises material model is chosen. Three phases such as impact bouncing and bending phases are found to be identified during the period from the moment of impact to the estimated time for crack initiation. It is clearly shown that no plastic deformation near the crack tip is appeared at the impact phase. However it is confirmed that the plastic zone near the crack tip emerges in the second phase and the plastic hinge has been formed in the third phase. Gap opening displacement crack tip opening displacement and strain rate are compared with rate dependent material(visco-plastic material). The stability during various dynamic load can be seen by using the simulation of this study.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.275-278
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• 2003

The pantograph contact can be disrupted due to irregularities in the motion. The pantograph detachment prohibits the current flow and makes the system uncontrollable. During the pantograph detachment period, the control error are accumulated by the integral property of the controller. The output of the controller, therefore, can be induced to be an extremely large value. When the pantograph is reattached, the extremely large output of the controllers causes a very high overshoot (or under-shoot) of the line current and the DC-link voltage. This work proposes a new method for detecting the pantograph bouncing conditions and designs a controller considering such conditions based on the pantograph bouncing detector.

• Journal of Biosystems Engineering
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• v.21 no.3
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• pp.293-305
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• 1996

Effects on the tractor vibrations of tread, wheelbase and axle load distribution were analyzed by using mathematical models of tractor and random road surface. A 4 degrees of freedom tractor model was developed to predict the bounce, pitch and roll motions of tractor. The front axle which is constrained to roll with respect to tractor body was also included in the model. A random road profile was generated and used as an excitation input to the tractor. Output vibrations of the model were predicted and analyzed by a computer simulation method. In general, longer tread tends to reduce rolling and longer wheelbase does bouncing and pitching motions. Tractor vibrations were minimum when the ratio of front to rear axle loads was in the range of 30:70-35:65. Sensitivity analysis showed that rolling and pitching motions most sensitively varied with changes in tread and wheelbase while bouncing motion did with the location of mass center.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.2
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• pp.73-82
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• 1994

Low-band type active suspension system is implemented on a passenger car. Level. roll, pitch and bouncing motion of body are controlled by a digital controller. Sky-hook damper is applied to control bouncing motion. This paper describes overall construction of the system, design of hydraulic system, sensor system, controller, and control scheme. Performance of prototype car has been evaluated on a test track and reported in the second paper.