• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.890-893
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• 2002

Since 1970s, varistors using metal-oxide resistors have been applied to Gapless surge arresters for power system. In the paper, the structure of metal-oxide surge arresters without gaps for 362kV GIS which is developed the first in korea has been introduced. And the main evaluation items for the metal-oxide resistors which are reference voltage test, residual voltage test, long duration current impulse withstand test and operating duty test is tested and evaluated.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.516-521
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• 1993

In order to hold a underwater vehicle at a depth, we can modulate buoyancy that acts on the underwater vehicle. In this research, by using a ballon, we was able to generate buoyancy that could control depth in which vehicle was operate. And in order to control flux of air that was flowed in balloon, we used solenoid valve, relief valve and so on. We derived differential equations of volume of balloon, pressure of inside of balloon, dynamic of underwater vehicle, and air flux for the simulation and linearized these differential equation. So we designed LQG/LTR controller, and applied the controller to nonlinear system. Through the simulation, we compares the nonlinear system with the linear system and investigated the operation of solenoid valve.

• Transactions of The Korea Fluid Power Systems Society
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• v.2 no.3
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• pp.12-17
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• 2005

This paper presents a theoretical study of the delivery flow ripple produced by a swash plate type hydraulic piston pump for the purpose of developing a computer simulation program capable of predicting the pump source flow ripple accurately at the design stage. Particular attention has been paid to the development of the theoretical model by clarifying quantitatively the design influences of key parts of valve plate such as relief groove and pre-compression/expansion.

• Transactions of The Korea Fluid Power Systems Society
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• v.7 no.2
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• pp.19-26
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• 2010

The typical trunk lid system for vehicle is composed of a hinge having 4-bar link and gas lifter. Here, the energy regenerative brake of hydraulic driven systems is applied to the tail gate system for vehicle and removed the gas lifter. The new tail gate system is composed of a hydraulic pump by electric motor, a hydraulic motor, four check valves, an accumulator, a relief valve and a directional control valve. The dynamic characteristics of the hydraulic motor system, such as the surge pressure and response time, are investigated in both brake action and acceleration action. The capacity selection method of accumulator by mathematical model is based upon trial and error approach and computer simulation by AMEsim software is carried out.

• Journal of Korean Society of Water and Wastewater
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• v.13 no.2
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• pp.95-104
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• 1999

A simulation of water hammer, introduced by abruptly varied motion of a pumping machine, was performed at a one of typical pumping station in Korea. Impact of hydraulic structure such as check valve, pressure relief valve and air valve in mitigating water hammer effect was estimated gradually. Method of characteristic was employed for the effective calculation of discharge and head. The relationship between various hydraulic structures and flow was properly integrated on the base of the method of characteristic. The methodology in this approach can provide significant contribution in decision making procedure for the design of hydraulic structure at a typical pumping station in Korea.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.445-446
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• 2015

본 논문은 지중송전 케이블 접속함의 이종 절연물에 대한 계면압력 측정에 대하여 기술하였다. 일반적으로 지중 송전케이블의 접속함의 경우, 운전 및 외부조건에 따라 절연물간의 계면압력은 변화하게 되고, 특히 저온에서 계면의 절연성능이 저하되면 고장발생 가능성이 높아진다. 이러한 계면압력 변화 경향을 파악하기 위하여 본 논문에서는 유압 시험을 통해 접속함 조립 시의 초기 계면압력을 측정하였고 그 결과를 기술하였다. 또한 응력 시뮬레이션과 유압 측정값을 비교하여 이론 및 실측값에 대한 신뢰성을 확보하였다.

• CELLMED
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• v.3 no.1
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• pp.2.1-2.5
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• 2013

Ephedra and ephedra alkaloids are sympathomimetic compounds extracted from the genus Ephedra. They have been used to treat colds and provide cough relief for centuries in oriental medicine. Recently, it has been reported that Ephedra plays a crucial role in weight loss and the enhancement of athletic performances. However, the overuse of Ephedra causes cardiovascular side effects such as increases in blood pressure, heart rate, and palpitations. Ephedra's adverse effects also were mentioned in Shan Han Lun, a famous formulary in traditional Chinese medicine. The present study demonstrated Ephedra's effects and the deficiency of Yang due to the overuse of Ephedra.

• The KSFM Journal of Fluid Machinery
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• v.14 no.6
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• pp.11-17
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• 2011

The cause of waterhammer phenomenon due to valve closing which is installed on pipeline is clarified in this study. Also if waterhammer phenomenon occurs on simple pipeline, expensive facilities like pressure relief valve is adapted to protect pipeline from waterhammer so far. But this study shows that waterhammer phenomenon can be suppressed by just simple modification of valve control sequence, and this technique is verified by simulation and site experiment.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.25-34
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• 1999

In this study, the sliding wear in spur gears, using Archard's wear model, is analyzed. Formulas of tooth sliding wear depth along the line of action are derived. The tooth profile is modified Id make a smooth transmission of the normal loads and the cylinder profile for reducing the pressure spike is suggested. The sliding wear rate is calculated with these profiling results. We expect these modification methods to contribute to the reduction of sliding wear in the root and the tip of tooth and tooth edge.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.267-272
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• 1995

The paper describes an approach for measuring flow ripple generated by oil hydraulic axial piston pumps. Flow ripple has periodic waveforms due to the cyclic nature of a pump's operation, and interacts with the connected hydraulic systems such as pipes and components to produce a pressure ripple, also known as fluid-borne noise. It is indispensable to measure a flow ripple because increasing of vibration and noise caused by a flow ripple has become a point to be considered and has need of solving these problems. The measurement of flow ripple with high frequencies from oil hydraulic axial piston pumps is msde by using the remote instantaneous flow rate measurement method. As a result, the reverse flow through the relief groove in valve plate has an important effect upon a flow ripple generated by a pumps.