• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.216-217
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• 2008

In recent years, scientific community has found renewed interest in hypersonic flight research. These hypersonic vehicles undergo severe aero-thermal environment during their flight regimes. During reentry and hypersonic flight of these vehicles through atmosphere real gas effects come into play. The analysis of such hypersonic flows is critical for proper aero-thermal design of these vehicles. The numerical simulation of hypersonic real gas flows is a very challenging task. The present work emphasizes numerical simulation of hypersonic flows with thermal non-equilibrium. Hyperbolic system of equations with stiff relaxation method are identified in recent literature as a novel method of predicting long time behaviour of systems such as gas at high temperature. In present work, Energy Relaxation Method (ERM) has been considered to simulate the real gas flows. Navier-Stokes equations A numerical scheme Advection Upstream Splitting Method (AUSM) has been selected. Navier-Stokes solver along with relaxation method has been used for the simulation of real flow over a circular cylinder. Pressure distribution and heat flux over the surface of cylinder has been compared with experiment results of Hannemann. Present heat flux results over the cylinder compared well with experiment. Thus, real gas effects in hypersonic flows can be modeled through energy relaxation method.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.3
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• pp.189-197
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• 2016

Green vehicles include electric vehicles, natural gas vehicles, and fuel cell vehicles (FCVs). In FCVs, pressure vessels have cylinder valves to control hydrogen flow. These valves should be of high quality in terms of safety because hydrogen is stored at ultra-high pressure in pressure vessels. Hence, safety evaluation of these valves is necessary to secure the safety of the FCV. A structural analysis of the cylinder valve was conducted in this study by using a commercial finite element analysis code. The results showed that the safety factor of valve component ranged 1.06-186.44. After categorizing, the stress components at critical points of the cylinder valve parts were evaluated using the corresponding allowable design criteria in the ASME code. The pressurization cycle test was performed as per the regulation to evaluate the safety of the valve.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.2
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• pp.177-186
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• 2002

This paper describes a research work on the development of computer-aided design system far the deep drawing & ironing of high pressure gas cylinder. An approach to the design system is based on the knowledge-based rules. Knowledge for the system is formulated from plasticity theories, handbook, experimental results and the empirical knowledge of field experts. This system has been written in AutoLISP on the AutoCAD Rl4.0 using personal computer. This system is composed of three modules which are input. process design and drawing.

• International Journal of Precision Engineering and Manufacturing
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• v.6 no.4
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• pp.31-36
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• 2005

This paper describes a research work on the die design for the deep drawing & ironing(D. D. I) of high pressure gas cylinder. D. D. I die set is large-sized die used in horizontal press, which is usually composed of a drawing, and an ironing die. Design method of D. D. I die set is very different from that of conventional cold forging die set. Outer diameter of the die set is fixed because of press specification and that of the insert should be as small as possible for saving material cost. In this study, D. D. I die set has been designed to consider those characteristics, and the feasibility of the designed die has been verified by FE-analysis. In addition, the automated system of die design has been developed in AutoCAD R14 by formulating the applied methods to the regular rules.

• Korean Chemical Engineering Research
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• v.60 no.3
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• pp.452-458
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• 2022

Three types of gas-liquid hybrid horizontal, vertical and needle-to-cylinder plasma reactors were fabricated. Through these reactors, a high-efficiency, eco-friendly cleaning concept that generates reactive active species generated in atmospheric plasma discharge and gas-liquid activation reaction of cleaning components through the potential difference within the electrode was presented. As a result of comparing the efficiency for cleaning performance, the needle-to-cylinder type reactor had the best characteristics. Through this study, it was confirmed that the gas-liquid hybrid atmospheric pressure plasma reactor has the potential to be applied to ultra-precision cleaning processes such as semiconductor processes.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.5
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• pp.61-68
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• 1992

Knock phenomenon is an abnormal combustion originated from autoignition of unburned gas in the end-gas region during the later stage of combustion process and it accompanys a high pitched metallic noise. Engine Knock is accompanied with a vibration of engine cylinder and when it is severe, it can cause major engine demage. Engine Knock is characterized in terms of knock crank angle, knock pressure, pressure jump and knock intensity. In this study, a 4-cylinder spark ignition engine was used for experiment and eighty consecutive cycles were analyzed statistically. The purpose of this study is to characterize spark ignition engine knock as a function of ignition timing and fuel research octane number. The result of this study can be summerized as follows. Knock occurrence angle approached TDC as ignition timing is advanced. Pressure and knock intensity gradually increased as spark timing is advanced. Mean knock occurence angle gradually approached TDC as fuel research octane number is decreased for identical spark timing. Knock intensity increased linearly as RON is decreased.

• Journal of the Korean Society of Safety
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• v.25 no.6
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• pp.109-114
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• 2010

Water mist fire suppression system is environmental system and needs a flange pump to jet water. In this research, high pressure Nitrogen cylinder is used as a pressurizing source instead of flange pump, and also we tried to find the possibility of using compressed Nitrogen as a fire suppression agent. As a result, it was possible to design water mist fire suppression system with Nitrogen cylinder and suppress oil fire effectively. With DK1.58 nozzle, the optimum Nitrogen pressure was 80bar and the pressure was stable during water mist spray. However, jet of Nitrogen was not effective fire suppression agent when it was dually used with water mist because water mist has blown away, and it is efficient way to use compressed Nitrogen as a pressurizing source only.

• Congress of the korean instutite of fire investigation
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• 2010.06a
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• pp.56-65
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• 2010

• Journal of Hydrogen and New Energy
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• v.22 no.4
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• pp.520-526
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• 2011

In recent years, it is very important that hydrogen storage system is safe for user in any circumstances in case of crash and fire. Because the hydrogen vehicle usually carry high pressurized cylinders, it is necessary to do safety design for fire. The Global Technical Regulation (GTR) has been enacted for localized and engulfing fire test. High pressure hydrogen storage system of fuel cell electrical vehicles are equipped with Thermal Pressure Relief Device (TPRD) installed in pressured tank cylinder to prevent the explosion of the tank during a fire. TPRDs are safety devices that perceive a fire and release gas in the pressure tank cylinder before it is exploded. In this paper, we observed the localized and engulfing behavior of tank safety, regarding the difference of size and types of the tanks in accordance with GTR.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2002.05a
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• pp.107-111
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• 2002

A complex valve dynamic analysis has been performed with a high Pressure reciprocating gas compressor. Valve dynamic equations, which take into account the flow continuity and cylinder pressure fluctuation, have been derived. Flow coefficients of valves has been analyzed, using CFD models. Results have shown that both of the suction and discharge values behave favorably without any fluttering motions.