• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.246.2-246
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• 2001

• Proceedings of the Korean Nuclear Society Conference
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• 2001.10a
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• pp.79.2-79
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• 2001

• Proceedings of the Korean Nuclear Society Conference
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• 2001.10a
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• pp.185.1-185
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• 2001

• Proceedings of the Korean Nuclear Society Conference
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• 2002.10a
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• pp.91.2-91
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• 2002

• Proceedings of the Korean Nuclear Society Conference
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• 2003.10a
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• pp.97.2-97.2
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• 2003

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.718-723
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• 2001

PPM (Performance Prediction Methodology) developed by EPRI was introduced and applied to calculate the stem thrust of 3 and 4 inches flexible-wedge gate valves. The calculated stem thrusts of open and close strokes including cracking were compared with the results measured at in-situ differential pressure tests. The comparison has shown that PPM is an extremely conservative method to predict the minimum required stem thrust to operate motor-operated valves in a design basis accident condition of nuclear power plants.

• Transactions of The Korea Fluid Power Systems Society
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• v.2 no.2
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• pp.8-13
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• 2005

This paper investigates a fast, accurate and inexpensive hydraulic motor speed control system using high speed on-off solenoid valves. In order to retain the advantages of the two position valve and obtain better performance, the valves are operated by pulse width modulation(PWM) control. PWM signal is generated from a LabWIEW program in microcomputer in order to set up various duty ratio and frequency of carrier wave in PWM signal with varying system parameters. As the results of experiments, the speed control of a hydraulic motor was successfully implemented using on-off solenoid valves. In order to attenuate the pressure ripple and speed variation due to discontinuously controlled flow through the on-off valves, a resonator hose fabricated for automobile power steering system was connected between the valve and a hydraulic motor. From experimental results obtained in the hydraulic motor system with a resonator hose, it was ascertained that the resonator hose showed excellent performances in reducing pressure ripple and motor speed variation.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.549-554
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• 2003

EPRI PPM (Performance Prediction Methodology), a method used for the prediction of required thrust of valves, can not be applied to unbalanced-disk globe valves operated in the fluid when the fluid temperature is above $150^{\circ}F$ because the thrust increase caused by the friction between the valve disk and body is not considered in the PPM. In order to apply PPM to the valves, EPRI suggested new friction prediction method to be added in the code. This paper analyzes the applicability of the prediction method comparing the disk-to-body friction load predicted from the method with the measured friction load from the field tests. The maximum values from the prediction method and those obtained from the test were 268lbs and about 1500lbs, respectively. It is included that the prediction method should be improved for the realistic prediction of disk-to-body friction load.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.1
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• pp.195-201
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• 2010

In this paper, a cooling system of high-power propulsion motor with Energy Saving System(ESS) is described. Normally, the cooling system for ship consists of fresh water pump, sea water pump, 3-way valve and cooler. In the cooling system, F.W(Fresh Water) and S.W(Sea Water) pump is operated on rated rpm, and the 3-way valve is controlled for preventing over-cooling. So, the consumption power of pump's motor is changed according to a sea water temperature. In the proposed cooling system, F.W. pump and S.W pump is controlled by inverter, and it is can be reduced the consumption power. Also, it is proved with simulation.

• Transactions of The Korea Fluid Power Systems Society
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• v.6 no.2
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• pp.14-21
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• 2009

The typical hydraulic hoisting system of the rack-bar type sluice gate is composed of a hydraulic supply unit using an uni-directional pump, a direction control valve, a hydraulic motor, a counter balance valve, and flow control valves. Here, the hydrostatic transmission is applied to the hoisting system of rack-bar type sluice gate to simplify the operation of gate such that the upward and downward direction of gate is simply controlled by the direction of pump rotation. The new hydraulic hoisting system is composed of a bi-directional pump, a hydraulic motor, two counter balance valves, two check valves, two pilot-operated check valves, two relief valves and a shuttle valve. The characteristics of a suggested system are analyzed by computer simulations.