• Journal of Drive and Control
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• v.12 no.4
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• pp.1-7
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• 2015

In this study, a spiral valve which is used with a cryogenic linear expander and composed of plural plate coil shapes was examined. Generally, a spiral valve is well known for having excellent efficiency and low noise characteristics. In order to determine the movement characteristics and to investigate the limit of valve displacement, the stress variations according to the changes of operating pressure, displacement and workable temperature are discussed. From this examination, it is considered that the results of this study will significantly facilitate the design and development of a spiral valve for the cryogenic linear expander.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.463-467
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• 2004

This paper presents the fabrication possibility of the micro actuator which uses a micro-thermal bubble, generated b micro-heater under pulse heating. The valve-less micropump using the diffuser/nozzle is consists of the lower plate, he middle plate, the upper plate. The lower plate includes the channel and chamber are fabricated on high processability silicon wafer by the DRIE(Deep Reactive Ion Etching) process. The middle plate includes the chamber and diaphragm d the upper plate is the micro-heater. The Micropump is fabricated by bonding process of the three layer. This paper resented the possibility of the PCR chip operation by the fabricated micropump.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.8
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• pp.91-98
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• 1999

This paper describes the air flow characteristics inside the throttle valve. Tow-dimensional steady incompressible Navier-Strokes equation are solved numerically with embedding the conceopt of the artificial compressibility and adopting the Baldwin-Lomax turbulence model. With varying the valve opening angles(the Reynolds number )such as 15$^{\circ}$(5000) , 45$^{\circ}$(3000) , 75$^{\circ}$(7000) and 90$^{\circ}$(10000), respectively. tow cases, with a valve shaft and without one, are analysed. The pressure loss between the entrance and exit is severe at 15$^{\circ}$, 100 times as larger as that of 90$^{\circ}$ case, which also depends much on the existece of the valve shaft. The counter rotating vortices are formed over the valve plate with the shaft at only 75$^{\circ}$. They are smally and very large scale in front and back of the valve shaft , respectively. The velocity profiles of 15$^{\circ}$ and 90$^{\circ}$ at the exit are almost symmetric to the horizontal center line, however, the symmetricity is no longer maintained at 45$^{\circ}$ and 75$^{\circ}$ , and in addition, the flow at 75$^{\circ}$ is enforced a lot below center line. The pressure distribution on the walls is largely changed near the valve shaft, and its magnitude becomes great as the valve angle decreases.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.5
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• pp.487-494
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• 2011

The safety valve used in LNG/LNG-FPSO ships plays an important role in maintaining a fixed level of pressure by emitting LNG gas out of the pipes in the LNG piping system. The discharge coefficient is regarded as the most important factor in the valve performance. To satisfy the ship's classification, the discharge coefficient of the safety valve must usually be over 0.8. Despite the importance of understanding the flow phenomena inside the safety valve, the valve design is usually based on experience and experiments. We carried out a computational fluid dynamics (CFD) investigation using the ANSYS-CFX software. We observed the flow phenomena inside the valve and measured the discharge coefficients according to changes in the valve lift, which is the distance between the exit of the nozzle and the lower part of the disc plate. We verified our CFD results for the discharge coefficients using available experimental data.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.320-320
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• 2000

In this paper, a temperature controller of a test plate for semiconductor is developed using LQG/LTR methodology. The liquid is heated or cooled in a tank by a heater of a cooler. The controller controls the flow of heated or cooled liquid in the plate by controling an electronic valve. The developed controller is applied to the plate designed for function test of a semiconductor under high or low temperature environment. As a result, control using the heater and the cooler together shows better control performance than using the heater or the cooler separately.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.704-709
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• 2003

The automobile air conditioning system generally consists of laminated type evaporator, swash plate type compressor, condenser, expansion valve and receiver drier. A swash plate type compressor has been used widely in automobile air conditioning system since 1955, because of wider operation range and better durability than other type compressors. In this study, the performance of an swash plate type compressor with variations of oil charging conditions has been investigated experimentally using the hot gas system. Further, the effects of varying compressor speed on the performance of the compressor has been discussed.

• Applied Chemistry for Engineering
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• v.10 no.3
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• pp.415-418
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• 1999

The characteristics of VRLA (valve regulated Iead-acid) battery with the tubular positive plate and gel type electrolyte were examined as a function of active material filling density. The filling density of positive plate was 3.2 g/mL, 3.4 g/mL, and 3.6 g/mL, respectively. These VRLA batteries were cycled with 100% DOD (depth of discharge) at the $C_5/5$ rate, followed by IU-type recharge with $I_{max}=0.2C_{10}/10$ and a final voltage V=2.40 V/cell. The test was performed in a thermostatic room at $25{\pm}1^{\circ}C$. The result indicated that the initial capacity was independent of active material filling density, i.e., the highest initial capacity was 3.4 g/mL of filling density and the lowest was 3.6 g/mL. On aspect of the cycle-life performance of the VRLA battery, the filling density of 3.6 g/mL was similar to that of 3.4 g/mL in the positive plate, and both were higher than that of 3.2 g/mL. Water-loss and degradation of the VRLA battery were decreased according to an increase of the filling density in the positive plate. The optimum filling density of the active material was 3.4~3.6 g/mL.

• Journal of Power System Engineering
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• v.7 no.4
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• pp.61-66
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• 2003

In this paper, the relation between displacement of piezoelectric material and electric field was proposed. FEA was introduced to predict the displacement and reaction force of plate spring attached in the piezoelectric material. The relation between displacement of piezoelectric material forced by plate spring and applied electric field were further verified by experimental investigation. Also, the flow rate of gas in piezoelectric valve was examined by experiment. Finally, the relation between electric field and gas flow was derived. Based on these results, these relations can be used in the design of mass flow controller.

• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.45-49
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• 2000

Vibration and noise problem in a hydraulic system became one of very important factors in evaluating the performance of a hydraulic system. It is known that vibration and noise in a hydraulic system is directly related to flow pulsation in the hydraulic pump in the system. This study investigated a modeling and simulation technique for pulsating flow in a swash plate type axial piston pump. The key design factors of the pump related to flow pulsation phenomenon of the pump are the physical parameters for notches on the valve plate of the pump. By the numerical analysis, effects of the physical parameters of the notch on the flow pulsation was elucidated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.101-102
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• 2006

The purpose of this paper is pulsation-analysis of the swash plate type axial piston pump for excavator and the method of side branch hose application, which is used normally in construction equipments. In this paper, draw the mathematical modeling for pressure pulsation mechanism of the swash plate type axial piston pump for excavator, expression the flow pulsation in the pipelines by transfer matrix method, programmed simulation for pulsation by AMEsim software, and the reliability of that was verified by the comparison with the experimental results.