• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.5
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• pp.42-49
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• 2015

In this study, the multi-disk of a high-pressure drop control valve is designed and manufactured. Then, the flow rate and high-pressure drop of fluids flowing in the high-pressure drop control valve is CAE/CFD. This study involves numerical analysis for the Zambil offshore project of a high-pressure drop control valve. ANSYS used a solver for offshore structures analysis. A high-pressure drop control valve, which transforms the power transfer of a system by reducing the inlet pressure of 345bar to the outlet pressure of 112bar, is a fundamental component in the offshore process. This study not only analyzes the relation between pressure drop and fluid velocity in a trim by using fluid analysis, but also examines the possibility of cavitation in a valve in addition to the plot for the extension of lifespan. It is demonstrated that the pressure drop from 345bar to 112bar is more feasible in the presence of the trim, which can induce a continuous and diminutive pressure drop in order to prevent cavitation in a high-pressure drop control valve.

• Korean Journal of Acupuncture
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• v.38 no.4
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• pp.308-316
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• 2021

Objectives : This study aimed to develop a cupping pressure control valve for limiting maximum negative pressure while achieving clinical therapeutic outcomes to minimize side effects induced by excessive negative pressure of air extraction cupping devices. Methods : To determine the clinical necessity and suitability of the cupping pressure control valve, this study was designed to measure the change in pressure with or without the valve using both a manual and an electric suction pump. Results : While the maximum pressure was limited by the pressure control valve, the pressure did not increase above a certain level regardless of the type of manual or electric pump. Conclusions : This study will contribute to the development of a safer and more effective base technology for cupping treatment in oriental medicine.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.9
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• pp.48-55
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• 2004

This study presents a genetic algorithm-based method fur optimizing control parameters in the pressure control of electro-hydraulic pump with variable displacement. Genetic algorithms are general-purpose optimization methods based on natural evolution and genetics and search the optimal control parameters maximizing a measure that evaluates the performance of a system. Four control gains of the PI-PD cascade controller for an electro-hydraulic pressure control system are optimized using a genetic algorithm in the experiment. Optimized gains are confirmed by inspecting the fitness distribution which represents system performance in gain spaces. It is shown that genetic algorithm is an efficient scheme in optimizing control parameters of the pressure control of electro-hydraulic pump with variable displacement.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.461-464
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• 2003

A new control volume finite element method is proposed for three dimensional analysis of polymer flow. Tetrahedral finite element is employed and co-located interpolation procedure for pressure and velocity is implemented. Inclusion of pressure gradient term in the velocity shape functions prevents the checkerboard pressure field from being developed. Vectorial nature of pressure gradient is considered in the velocity shape function so that velocity profile in the limit of very small Reynolds number becomes physically meaningful. The proposed method was verified through three dimensional simulation of pipe flow problem for Newtonian and power-law fluid. Calculated pressure and velocity field showed an excellent agreement with analytic solutions for pressure and velocity. Driven-cavity problem, which is reported to yield checkerboard pressure filed when conventional finite element method is applied, could be solved without yielding checkerboard pressure field when the proposed control volume finite element method was applied. The proposed method could be successfully applied to the three dimensional mold filling problem.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.152-159
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• 2010

This paper describes the actual application of a feedback control loop as a means for minimizing turbine impulse chamber pressure variation during the turbine steam valve tests at a 1,000 MW nuclear power plant. The chamber pressure control loop was implemented in the new digital control system which was installed as a replacement for the old analog type control system. There has been about 40MW of the generator output change during the steam valve tests, especially the high pressure governing valve tests, because the old control system had not the impulse chamber pressure control so the operators had to compensate steam flow drop manually. The process of each valve test consists of a closing process and an reopening process and the operators can make sure that the valves are in their sound conditions by checking the valves movement. The control algorithm described in this paper contributed to keep the change in megawatt only to 6MW during the steam valve tests. Thereby, the disturbance to reactor control was reduced, and the overall plant control system's stability was greatly improved as well.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.7
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• pp.84-91
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• 2012

In this paper, design by magnetic analysis software and proportional control of solenoid for pressure valve for electric pressure cooker is described. The validation of design was proved by 3D finite element analysis results. Also the efficiency of an air ventilation mechanism was considered when pressure was happened by fluid analysis results. The linear proportional control system by AVR was manufactured and its validation was proved by pressure control of solenoid.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.6
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• pp.623-632
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• 2015

This study proposes a control strategy of the common rail pressure with a fuel injection limitation algorithm to reduce particulate matter (PM) emissions under transient states. The proposed control strategy consists of two parts: injection quantity limitation and rail pressure adaptation. The injection limitation algorithm determines the maximum allowable fuel injection quantity to avoid rich combustion under transient states. The fuel injection quantity is limited by predicting the burned gas rate after combustion; however, the reduced injection quantity leads to deterioration of engine torque. The common rail pressure adaptation strategy is designed to compensate for the reduced engine torque. An increase of the rail pressure under transient states contributes to enhancement of the engine torque as well as reduction of PM emissions by promoting atomization of the injected fuel. The proposed control strategy is validated through engine experiments. The rail pressure adaptation reduced the PM emission by 5-10% and enhanced the engine torque up to 2.5%.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.5
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• pp.179-187
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• 2001

In this paper, a primary pressure regulating type ratio control system is developed for a metal belt CVT, and the CVT ratio changing characteristics are investigated by simulation and experiment. The hydraulic part of the ratio control system has a simple structure with one 3-way spool valve as a main ratio control valve and one bleed type variable force solenoid as a pilot valve. The mathematical modelling of the CVT hydraulic system is derived by considering the CVT shift dynamics. Simulation results of CVT speed ratio and the primary pressure agree with the experimental results demonstrating the validity of the dynamic models. It is found from the simulation and experimental results that the response time of speed ratio and primary pressure can be shortened by increasing the ratio control valve port area, and the size of feedback orifice of ratio control valve gives a damping effect on the primary pressure oscillation.

• Journal of Korean Public Health Nursing
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• v.27 no.2
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• pp.267-279
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• 2013

Purpose: This study was conducted to identify blood pressure control rate and related factors in hypertensive patients. Methods: Data were collected using face to face survey with measuring blood pressure from 268 hypertensive patients. Results: Subjects without spouses were 2.19 times more likely to control their blood pressures (p=.002). Whenever subjects came up 1 score in the low sodium diet score, they were 1.37 times more likely to control their blood pressures (p=.044). The possibility of blood pressure control rose 1.58 times per point in the stress management score (p=.011) and the sleep and rest score (p=.002). Conclusion: It is important to develop education and intervention program of lifestyle regarding low sodium diet, stress management and sleep and rest, in order to improve the blood pressure control.

• Journal of Power System Engineering
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• v.13 no.3
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• pp.59-64
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• 2009

This study presents a new approach to pressure control of a impression cylinder for roll coater which is a kind of face pressure control between blanket roll and impression roll. Roll-to-Roll method for printing is a very useful tool for mass production such as RFID elements, smart sensors and solar cell devices. In this study, a decupling control strategy of the roll coater which is a combination of a cylinder system, a dry system and two pressure regulators with two pneumatic cylinders was discussed. Also, the characteristics of component such as a pressure regulator having a pressure reducing function and the movement of a blanket roll and a impression cylinder were analyzed using the Matlab software. From this results, the techniques of a shock and a vibration reduction were suggested.