• 한국자동차공학회논문집
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• 제19권1호
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• pp.133-138
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• 2011

Compression pressure of individual cylinder and valve timing have big influence on combustion pressure, indicated mean effective pressure (IMEP), emission, vibration, combustion noise and many other combustion parameters. Therefore, uniformity of compression pressure and valve timing became one of most important engine design and production standard. Conventional method to evaluate compression pressure uniformity is to measure each cylinder pressure by mechanical pressure gage during cranking. This conventional method causes inaccuracy of cylinder pressure measurement because of different cranking speed results from battery status and also causes high manhour and cost. To check valve timing, related FEAD parts should be disassembled and timing mark should be checked manually. This study describes and suggests new methodology to measure compression pressure by analysis of start motor current and to check valve timing by cylinder pressure with high accuracy. With this new methodology, possibility to detect leaky cylinder and wrong valve timing was observed.

• 한국자동차공학회논문집
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• 제8권6호
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• pp.111-121
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• 2000

Generally, the hydraulic pressures are used for transmitting the force. Therefore, a highly reliable and inexpensive control system has been required for a passenger car. The control-ability of active suspension system is strongly affected by the performance of pressure control valve in the view of dynamic response and energy consumption. In this study, we suggested main design parameters for the optimum design of proportional pressure control valve. The mathematical simulation model was derived from the quarter type model which consisted a valve and hydraulic damper for the purpose of analyzing the valve characteristics. Experiments were performed to confirm the performance of the valve and computations were carried out to ascertain the usefulness of the developed program. The results from computations fairly coincide with those from experiments. This has been achieved by developing the servomechanism valve which comprises the simple combination of a solenoid, a spool valve and a poppet valve. The results from experiments and computations show the development process of optimum proportional pressure control valve in the hydraulics system.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.321-324
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• 2002

Hydraulic valve control the pressure and the How of fluid by the hydraulic oil transfered from pump but the ER fluid consists of solid particles of micrometer in size and insulating oil so in the general hydraulic valve. We invented ER-Valve using ER fluid as working fluid. The ER fluid, working fluid of ER-Valve is a functional fluid to represent the feature of fluid according to strength of electric field. In this research we made our own 4 types of plate type ER-Valve which has same surface but different width and length and then we conducted performance test. We measured flow rate and pressure drop of fluid which is flowing in the ER-Valve according to the electric field strength to conduct this test. We modeling ER-Valve relating to ER-Valve system and yield shear stress according to the strength of electric field. We used the pressure drop according to the strength of electric field by differential pressure gauge in the our own made ER-Valve. This test reviewed experimental the special changes of ER-Fluid in the steady flow condition.

• 한국기계기술학회지
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• 제13권1호
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• pp.81-88
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• 2011

The triple eccentric butterfly valve has metal sheet and this study about butterfly valve ceiling is an innovative approach. But it is affected by the static pressure as well as cross-current. The damage at the valve on the pipe resulted from the reflux is due to valve leakage. This study is investigated on the triple eccentric disk and it is applied with angle and the static pressure in all cases to develop cross-current triple eccentric butterfly valves. The disc with the diameter of 300A is valve against flow velocity. The entrance pressure by flow characteristics is performed with numerical analysis. As the result, valve torque production is reduced more than the conventional triple eccentric valve and entrance pressure is decreased on the increase of valve open angle. And flow coefficient can be known to be increased.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.630-635
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• 2001

The stem thrust required to unwedging a gate valve is influenced by the pressure and temperature when the valve is closed and by the changes in these conditions between closure and opening. "Pressure Locking" and "Thennal Binding" refer to situations where pressure and temperature effects cause the unwedging load to be much higher than normal. A model of these phenomena has been developed. The effects of pressure and temperature are analyzed to determine the change in this disk-to-seat "interference". Flexibilities or Stiffness of the disk and body strongly influence the unwedging thrust. Calculation and limited comparison to data have been performed for the RHR motor operated valve designs and scenario. Pressure changes can increase the unwedging thrust when bonnet pressure exceeds the pressure in the adjacent piping and temperature changes can increase the unwedging thrust when a temperature change after closure produces an increase in the disk-to-seat interference.

• 동력기계공학회지
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• 제18권2호
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• pp.31-36
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• 2014

In this paper, pneumatic valve which consists of valve body, valve controller, nozzle and a multi-bender PZT actuator was suggested and fabricated. The fabricated pneumatic valve was experimented for performance evaluation. From the experimental results, we know that the flow rate of the suggested valve is 23 lpm at the pressure difference of 1bar and the maximum flow rate is 30 lpm at the pressure difference of 4 bar. The flow rates after endurance test of 9.8 million were 22.57 lpm and 28.62 lpm at the pressure difference of 1bar and 4bar, respectably. Finally, it was verified that the B10 life of the suggested pneumatic valve is over 50 million.

• 대한기계학회논문집B
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• 제31권2호
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• pp.151-158
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• 2007

The mechanism of power transmission from motor torque to stem thrust and the operation characteristic of each stroke position are analyzed using the diagnostic signal, and effects of differential pressure on the performance of motor operated flexible wedge gate valve are investigated. Test facility consists of 76 mm motor operated valve(flexible wedge type), pump and pipe system. Static and dynamic test are performed separately, and two differential pressure conditions are applied in the dynamic test. To evaluate the performance of valve, test signals for the torque, thrust, current, voltage and stroke length are acquired by using UDS which is diagnosis device for motor operated valve, and each diagnostic signal is analyzed and compared. The characteristic of valve performance factors such as stem factor, rate of loading, valve factor, are evaluated, and these factors are found to be severely influenced by the fluid differential pressure.

• 한국수소및신에너지학회논문집
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• 제33권5호
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• pp.525-533
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• 2022

In this study, in order to numerically analyze the heat flow characteristics in the valve according to the opening rate for the solenoid valve for hydrogen supply applied to the hydrogen storage tank, flow characteristics were comparatively analyzed. Through the analysis of pressure and temperature distributions within the valve according to the high-pressure supply condition of 70 MPa or more, the heat flow characteristics in the valve, inlet and outlet passage according to the opening rate of the valve were identified. As a result a sudden change in the fluid behavior appears in the neck region of the valve, and it is understood that the flow separation caused by the flow path shape of the expanded tube has a dominant influence on the flow characteristics. And, it was confirmed that the shape of the valve seat is a factor significantly affecting the improvement of flow rate and differential pressure performance.

• 한국생산제조학회지
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• 제23권2호
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• pp.103-108
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• 2014

Growing concerns about environmental pollution have led to an increase in the demand for compressed natural gas (CNG) vehicles in recent years. CNG vehicles are equipped with a cylinder valve installed in a high-pressure vessel to control the CNG flow. The cylinder valve must meet high quality safety standards because the pressure vessel stores high-pressure CNG. Therefore, safety evaluation of the cylinder valve is necessary to ensure the safety of CNG vehicles. In this study, fluid-structure interaction analysis for the structural integrity of the cylinder valve were conducted using a commercial finite element analysis code(ANSYS WORKBENCH V14). The CFD analysis was performed using a steady-state technique according to the inlet and outlet pressures in order to predict the pressure distribution. Structural analysis was performed by a static structure technique at the maximum working pressure to evaluate the structural integrity of the cylinder valve. From the results, the safety factor of the valve component is between 1.57 and 21.5.

• 한국유체기계학회 논문집
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• 제2권4호
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• pp.24-30
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• 1999

An analytical study has been carried out to investigate the effects of the check valve installation on the volumetric and adiabatic efficiencies in a scroll compressor. Both the valve displacement limit and the valve stiffness affected the valve motion, the pressure upstream of the valve, and the pattern of the mass flow through the valve to the discharge plenum. Nonetheless, the presence of the check valve did not cause any noticeable change in the volumetric efficiency. Only a slight increase in the compression work was needed to overcome the pressure increase in front of the valve. The pressure build-up upstream of the valve can be alleviated with the larger limit of the valve lift and a smaller valve stiffness.