• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.1051-1054
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• 2000

We developed the micro CSF (celebrospinal fluid) shunt valve with surface and bulk micromachining technology in polymer MEMS. This micro CSF shunt valve was formed with four micro check valves to have a membrane connected to the anchor with the four bridges. The up-down movement of the membrane made the CSF on & off and the valve characteristic such as open pressure was controlled by the thickness and shape of the bridge and the membrane. The membrane, anchor and bridge layer were made of the $O_2$ RIE (reactive ion etching) patterned Parylene thin film to be about 5~10 microns in thickness on the silicon wafer. The dimension of the rectangular nozzle is 0.2＊0.2 $\textrm{mm}^2$ and the membrane 0.45 mm in diameter. The bridge width is designed variously from 0.04 mm to 0.12 mm to control the valve characteristics. To protect the membrane and bridge in the CSF flow, we developed the packaging system for the CSF micro shunt valve with the deep RIE of the silicon wafer. Using this package, we can control the gap size between the membrane and the nozzle, and protect the bridge not to be broken in the flow. The total dimension of the assembled system is 2.5＊2.5 $\textrm{mm}^2$ in square, 0.8 mm in height. We could precisely control the burst pressure and low rate of the valve varing the design parameters, and develop the whole CSF shunt system using this polymer MEMS fabricated CSF shunt valve.

• Journal of Korean Society of Water and Wastewater
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• 제20권1호
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• pp.35-43
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• 2006

Concerns related to protecting, identifying, and isolating of subsystems of a water distribution network have led to the realization of the increased importance of valves in the system. The most important purpose of valves in water distribution systems is to isolate a subsystem due to breakage, maintenance activities, or contamination. A subsystem called segment is isolated by the closure of adjacent valves. Minimizing the pipe failure impact, an efficient algorithm is required to identify adjacent valves quickly. In this paper, an algorithm to identify adjacent valves to be closed to isolate a subsystem from the remainder of a network when a pipe failure is presented. The algorithm is operated on a matrix called the valve location matrix containing the information of valve locations. An application to an existing water distribution system demonstrates the developed algorithm efficiently locates the adjacent valves for the isolation of a broken pipe.

• The Transactions of the Korean Institute of Electrical Engineers P
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• 제53권2호
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• pp.82-88
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• 2004

In this study, an intelligent solenoid valve controller has been developed for efficient maintaining of filters in a dust collecting system. This controller has automatic controllability of solenoid valves' ON/OFF time depending on the clogging status of filters, and then it can extend the filters' lifetimes, decrease the power consumption, and make effective operation of the system possible. This controllability has been executed by the fuzzy theory that utilizes the workers' experimental knowledges, the control expert's knowledges and the differential pressures between the inlets and outlets measured by the sensors. The system's operation is under the continuous surveillance by using a current transformer, which warns the operators and lets them take necessary actions in case of abnormal operation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.861-863
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• 2003

The method of measurement for laboratory tests on noise emission from appliances and equipment used in water supply installations is specified in ISO 3822-1. This part of standard gives detailed descriptions for mounting and operating draw-off taps and mixing valves in such laboratory test. Draw-off taps and mixing valves are the most common kind of appliance used in water supply installations.

• Journal of Advanced Marine Engineering and Technology
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• 제33권5호
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• pp.696-704
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• 2009

In this paper, the flow characteristics through an industrial safety relief valve used to protect the crankcase room in a large-sized marine engine have been numerically investigated using the moving-mesh strategy. With the room pressure higher than the cracking one, the spring-loaded disc becomes open and then the air in the room blows off into the atmosphere, resulting in the reduction of the room pressure and then the shutoff of the disc. Numerical simulations are performed on the compressible air flow through the relief valve (${\phi}160mm$) with the initial room pressure (0.11 bar or 0.12bar) higher than the cracking one (0.1 bar). The numerical method has been validated by comparing the results with the empirical ones. Results show that the disc motion and flow characteristics can be successfully simulated using the moving-mesh strategy and depend strongly on the spring stiffness and the flow passage shape. With increasing spring stiffness, the maximum disc displacement decreases and thus the total disc-opening time also decreases. In addition, the flow passage shape makes a significant effect on the velocity and direction of the flow.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• 제23권5호
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• pp.1-8
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• 2009

Solenoid valve cleaner is used for clean the solenoid valve in automatic transmission for a car when it is clogged with transmission oil sludge. Nevertheless when the solenoid is turned off, the residual current in the solenoid coil makes slow motion of the plunger in the solenoid which makes lower in cleansing performance and speed. In this paper, the method of performance Improvement for solenoid valve cleaner is proposed. The residual current in the solenoid coil is eliminated rapidly by the proposed method and it improves the cleansing performance and speed. The experimental results show the validity of the reposed method.

• Aerospace Engineering and Technology
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• 제12권2호
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• pp.108-117
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• 2013

The oxidizer shutoff valve of a gas generator controls the mass flow rate of the propellant of a rocket engine using pilot pressure and spring the force of the valve. The developing oxidizer shutoff valve can be shut off if the pilot pressure is removed from the actuator. Therefore, force balancing is necessary to analyze the characteristics of the forces with respect to the opening and closing of the valve in order to evaluate its performance. In light of this, the valve has been designed to adjust the control pressure required to open the poppet and to determine the working fluid pressure at which the valve starts to close. Under cryogenic flow test as a tests level of C.R.T(Control Random Test), the chattering phenomena occurred due to much leakage of a metal seat section. The pressure for chattering of the oxidizer valve is predicted at about 11 bar using force balancing analysis.

• Aerospace Engineering and Technology
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• 제8권2호
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• pp.140-148
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• 2009

MOV(Main Oxidizer shut-off Valves) control the combustion of launch vehicle systems by the supply and the isolation of liquid oxygen to a main combustion chamber in launch vehicle systems. Moreover, in the steady operational state, the MOV should secure a constant flow rate of liquid oxygen for combustion instability in the combustion chamber. Concerning the development of MOV, TM(Technology Model) has been manufactured and normal operations of the valve have been verified. However, the Cv of TM has been proved to be too low as compared with a design specification value. Therefore, CFD analysis have been performed by modification of the configurations of TM in order to increase sufficiently Cv of EM(Engineering Model), which is the following model of TM. The modifications of TM configurations such as partial scale-up of valve, increase of stroke length, and outlet angle of 120o would result in a considerable augmentation of Cv. It has been verified by flow capacity tests that the improved Cv of EM is min. 212, which is higher than Cv of TM, 161 by about 32%.

• Proceedings of the KIPE Conference
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.200-203
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• 1997

This paper describes an study electric injection system for diesel engines. It is needed effective fuel injection which controls the solenoid valve of fuel pump. To solve this, this paper proposes DCC-PWM method which can realize fast reply and low holding current for solenoid valve on/off. For the proposed design method, simulation tools of ACSL are used to analyze the system. And the single-chip microcomputer is used to reduce the size of controller and to improve flexibility. And the system's validity can be verified through the experimental results.

• Journal of Biosystems Engineering
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• 제17권3호
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• pp.223-228
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• 1992

This study was conducted to develop an electro-hydraulic three-point hitch control system using an electro-hydraulic servo valve and microcomputer and to investigate the performance of the three-point hitch control system through indoor and field experiments. 1. The results from indoor experiments coincided with those from computer simulation reported in the previous paper. However, the draft control with the value 4 of Kd showed a slight sustained oscillation after it reached the draft set. 2. From the field experiments, it appeared that the RMS errors increased with the ground speed of tractor. In position control, the three-point hitch control system with electro-hydraulic servo valve showed better performance than that with on-off electro-magnetic valve in the ground speed less than 1.6 m/s. In draft control, however, there was no significant differece in performance between those two systems. 3. In depth control, the both types of electro-hydraulic three-point hitch control system showed better performance than the conventional mechanical-hydraulic three-point hitch control system.