• Journal of Power System Engineering
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• v.9 no.2
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• pp.45-49
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• 2005

Liquefied natural gas takes up six hundredths of the volume of natural gas, which makes storage and transportation much easier. To send out natural gas via a pipeline network across the nation, high-pressure LNG pumps supply highly compressed LNG to high-pressure vaporization facilities. The Number of high-pressure LNG pumps determined the send-out amount in LNG receiving terminal. So it is main equipment at LNG production process and should be maintained on best conditions. In this paper, to find out the cause of high beat vibration at cryogenic pumps, vibration and motor current signal analysis have been performed. High vibration of cryogenic pumps could be reduced due to the modification of motor rotor.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.776-779
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• 2005

Liquefied Natural Gas takes up six hundredths of the volume of natural gas, which makes storage and transportation much easier. To send out natural gas via a pipeline network across the nation, high pressure LNG pumps supply highly compressed LNG to high-pressure vaporization facilities. The Number of high Pressure LNG pumps determined the send out amount in LNG receiving terminal. So it is main equipment at LNG production process and should be maintained on best conditions. In this paper, to find out the cause of high beat vibration at cryogenic pumps, vibration and motor current analysis have been performed. And high beat vibration of cryogenic pumps could be reduced due to the modification of motor rotor.

• 한국연소학회:학술대회논문집
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• 2002.11a
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• pp.193-207
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• 2002

The present study is mainly motivated to investigate the vaporization, autoignition, and combustion of liquid fuel spray injected into high pressure environment. In order to represent these phenomena realistically, discrete droplet model (DDM) which simulates the spray using finite number of representative droplets was adopted for detailed consideration of the finite rate of uansport between liquid and gas phases. The Eulerian-Lagrangian formulation was used to analyze the two-phase interactions. The high pressure vaporization model was applied using the thermodynamic and phase equilibrium at droplet surface. The high pressure effect as well as high temperature effect was considered in the calculation of liquid and gas properties. The characteristics of spray in high pressure environment were explained by comparison with normal pressure case.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.769-772
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• 2009

Diaphragm compressors are used for a hydrogen compression because it can achieve high gas pressure with high purity. But diaphragm's lifetime may depend on the shape of the cavity and deflection from fluctuation the pressure change, which is necessary to monitored. In this study, the gas and hydraulic oil pressure in the cavity were measured as piston speed varies for diaphragm compressor. The results show pressure change quantities were reduced and maximum pressure points are delayed as the piston moves faster. And the hydraulic pressure were elevated as gas pressure elevated. And the compression period was more faster than expansion period.

• Journal of Mechanical Science and Technology
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• v.20 no.7
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• pp.1019-1029
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• 2006

The ballistic range has long been employed in a variety of engineering fields such as high-velocity impact engineering, projectile aerodynamics, creation of new materials, etc, since it can create an extremely high-pressure state in very short time. Of many different types of ballistic ranges developed to date, two-stage light gas gun is being employed most extensively. In the present study, a theoretical work has been made to develop a new type of ballistic range which can easily simulate a flying projectile. The present ballistic range consists of high-pressure tube, piston, pump tube, shock tube and launch tube. The effect of adding a shock tube in between the pump tube and launch tube is investigated. This improvement is identified as the reduction in pressures in the high pressure tube and pump tube while maintaining the projectile velocity. Equations of motions of piston and projectile are solved using Runge-Kutta methods. Dependence of projectile velocity on various design factors such as high pressure tube pressure, piston mass, projectile mass, area ratio of pump tube to launch tube and type of driver gas in the pump tube are also analyzed. Effect of various gas combinations is also investigated. Calculations show that projectile velocities of the order 8 km/sec could be achieved with the present ballistic range.

• Transactions of the Korean hydrogen and new energy society
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• v.19 no.5
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• pp.439-444
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• 2008

The heat capacity and pressure drop of $CO_2$ and coolant in a multi-tube type gas cooler were investigated experimentally. The main components of the refrigerant loop are a receiver, a $CO_2$ compressor, a mass flow meter, an evaporator and a multi-tube type gas cooler as a test section. The mass flowrate of $CO_2$ and coolant were varied from 0.06 to 0.075 [kg/s], respectively and the cooling pressure of gas cooler were from 8 to 10 [MPa]. The heat capacity of $CO_2$ in the test section is increased with the increment in mass flowrate of coolant, the cooling pressure and mass flowrate of $CO_2$. The pressure drop of $CO_2$ is decreased with the decrease in mass flowrate of coolant and $CO_2$, but decreased with increase in cooling pressure of $CO_2$. The heat capacity of $CO_2$ per unit heat transfer area of gas cooler is greatly high. Therefore, in case of the application of $CO_2$ at the multi-tube type gas cooler, it is expected to carry out the high-efficiency, high-performance and compactness of gas cooler.

• Journal of the Korean Institute of Gas
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• v.11 no.4
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• pp.12-16
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• 2007

The fuel pressure regulator mounted on CNG vehicles is used to maintain a constant pressure in the fuel injection system. It needs precise fuel pressure control to obtain benefits of high efficiency and low emissions in CNG vehicles. In this study, a high pressure test rig for the performance evaluation of CNG regulators was introduced. Two different CNG regulators were tested and compared each other at various test conditions. Results showed that dynamic response and creep characteristics are directly effected by the valve assembly design. Gas temperature was dramatically dropped at hish supply pressure conditions, so that effective design for coolant bowl is needed to prevent icing problem.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.41-44
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• 2015

Experimental study was conducted to investigate the effect of ultra-high injection pressure on combustion and emission characteristics in a single-cylinder diesel engine. Electronically controlled ultra-high pressure fuel injection system consistently supplied the fuel of ultra-high pressure up to 250 MPa. Various injection pressures, 40 to 250 MPa, were applied and compared. A injector with eight identical nozzle holes which have diameter of $105{\mu}m$ was used. The results showed high potential to improve the nitrogen oxide (NOx) and particulate matter (PM) trade-off relationship with an ultra-high injection pressure and the exhaust gas recirculation (EGR).

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.774-778
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• 2004

The atomization process of a circular $SF_{6}$ liquid jet issued into an otherwise quiescent, high-pressure $N_2$ gas was observed to explore the breakup mechanism of liquid ligaments involved in turbulent atomization. Both liquid and gas temperatures were fixed at a room temperature but the gas pressure was elevated to more than twice the critical pressure of $SF_{6}$. Therefore, the liquid surface was in a thermodynamic state close to a critical mixing condition with suppressed vaporization. Since the surface tension and the surface gas density approach zero and the surface liquid density, respectively, phenomena equivalent to those which would appear when a very high speed laminar flow of water were injected into the atmospheric-pressure air can be observed by issuing $SF_{6}$ liquid at low speeds in micro-gravity environment which avoid disturbances due to gravity forces. The instability ob near-critical mixing surface jet was quantitatively characterized using a newly developed device, which could issue a very small amount of $SF_{6}$ liquid at small constant velocity into a very high-pressure $N_2$ gas.

• Journal of the Korean Institute of Gas
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• v.9 no.1 s.26
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• pp.26-32
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• 2005

This paper presents the design safety of metal seals in pressure vessels. For a high-pressure vessel, a metal seal is usually used as a primary sealing, and an elastomeric rubber O-ring is adopted as a secondary sealing unit. The FEM computed results show that an aluminium material for sealing a gas leakage is superior to a steel one because of the thermal expansion rate. The deformation and stress distributions on the metal seal and pressure vessel structures are mainly dominated by transferred temperature compared to those of the gas pressure in which is supplied by an external pump. Thus, the temperature of a metal seal material should be restricted to under $200^{\circ}C$.