• Journal of Drive and Control
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• v.12 no.4
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• pp.35-40
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• 2015

A gas spring provides support force for lifting, positioning, lowering, and counterbalancing weights. It offers a wide range of reaction force with a flat force characteristic, simple mounting, compact size, speed controlled damping, and cushioned end motion. The most common usage is as a support on a horizontally hinged automotive tail gate. However, its versatility and ease of use has been applied in many other industrial applications ranging from office equipment to off-road vehicles. The cylinder of a gas spring is filled with compressed nitrogen gas, which is applied with equal pressure on both sides of the piston. The surface area of the rod side of the piston is smaller than the opposite side, producing a pushing force. The magnitude of the reaction force is determined by the cross-sectional area of the piston rod and the internal pressure inside the cylinder. The reaction force is influenced by many design parameters such as initial chamber volume, diameter ratio, etc. In this paper, we investigated the reaction force characteristics and carried out parameter sensitivity analysis for the design parameters of a gas spring.

• Journal of the Korea Safety Management & Science
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• v.12 no.4
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• pp.93-98
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• 2010

본 연구에서는, 반도체, LCD 공정에서 금속막을 증착하기 위하여 PECVD장비에 화재, 폭발 위험성과 독성을 가진 Silane가스를 사용하게 되는 장비인 gas cabinet, pipeline, VMB(Valve manifold box), MFC(mass flow controller)장비 등, 전반적인 시스템에 대하여 영국 HES의 ALARP개념을 도입하여 위험성 평가를 실시하여 문제점을 도출하고 대책을 강구 하는데 목적이 있고, 여러 가지 문제점중 절대적으로 수용 할 수 없는 Critical Risk로는 Gas Cylinder를 사용하여 Silane을 공급하고자 할 때에는 필히 Gas Cabinet을 사용하여 공급하여야 하고, Tube Trailer를 사용하여 공급하고자 할 때에는 필수적으로 Purge System을 갖추어 공급하여야 한다. 선택적으로 수용할 수 있는 High, Medium Risk로는 Gas Cylinder 또는 Tube Trailer를 사용하여 Silane을 공급하고자 할 때는 Inlet 부분에 RFO(Resticted Flow Orifice)를 설치하여 사용하고 Gas Supply Room에는 CO2소화설비를 적용하지 말고 Water Mist등 물 분무설비를 적용하여야한다.

• Journal of the Korean Institute of Gas
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• v.20 no.6
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• pp.80-88
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• 2016

A fire station and scuba have operated filling facilities for respiratory high-pressure cylinder without getting authority or reporting according to High-Pressure Gas Safety Control Act. They need facility improvement and special management to make provision for the time of accident during filling process. The Government have strived to correct illegal operations and suggested an alternative, establishing and operating the safety cabinet. It insures a safety being distance from danger caused by overpressure and a safety provoked by the protective wall equals or superiors. The safety cabinet is required to have an internal structure that smoothly distribute overpressure at the time of rupture. Plus, it needs to minimize fragments. It is also equipped with the performance of protective wall that makes overpressure to outside vent on the place where there is no person (top or bottom). This study calculated the consequence of physical explosion damage and built a prototype of safety cabinet. In addition, through the gas burst test, it derives for the ways to mitigate the physical explosion damage.

• Advances in materials Research
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• v.9 no.1
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• pp.15-32
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• 2020

In this article, an analytical solution is presented for the steady-state axisymmetric thermal stress distributions in a composite hollow cylinder. The cylinder is composed of two isotropic and anisotropic materials which is subjected to the thermal boundary conditions of convective as well as radiative heating and cooling on the inner and outer surfaces, respectively. The solution of the temperature is obtained by means of Bessel functions and the thermal stresses are developed using Potential functions of displacement. Numerical results are derived for a cylinder which is similar to a gas turbine combustor and showed that the maximum temperature and thermal stresses (radial, hoop, axial) occurred in the middle point of cylinder and the values of thermal stresses in anisotropic cylinder are more than the isotropic cylinder. It is worthy to note that the values of the thermal conditions which estimated in this research, not to be presented in any other papers but these values are very accurate in calculation.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.411-412
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• 2002

Piston-cylinder system are widely used in power engineering applications. In reciprocating refrigeration compressors, where extremely low friction losses are required, ringless pistons are being used to diminish the friction between piston rings and cylinder wall. Since the ringless piston has the freedom of lateral motion there is a potential danger that it will occasionally hit the cylinder wall while moving up and down along it's axis. A good design must therefore provide a smooth and stable reciprocating motion of the piston and ensure that the fluid film separating the piston from the cylinder wall is maintained all times. And the compromise between refrigerant gas leakage through the piston-cylinder clearance and the friction losses is required utilizing a dynamic analysis of the secondary motion for the high efficiency compressor. To this end, the computer program is developed for calculating the entire piston trajectory and the lubrication characteristics as functions of crank angle under compressor running conditions. The results explored the effects of some design parameters and operating conditions on the stability of the piston, the oil leakage, and friction losses.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.790-795
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• 2001

Since the characteristics of combustion and pollutant in Diesel engines were mainly affected by the characteristics of in-cylinder gas flow and fuel spray, an understanding of those was essential to the design of the D.I. Diesel engines. The improvement of volumetric efficiency of air charging into combustion chamber is a primary requirement to obtain better mean effective pressure of an engine. Since the air resistances in intake and exhaust flow passages, valve lift and valve shape influence greatly to the volumetric efficiency, it is very important to investigate the flow characteristics of intake and exhaust port which develops air motion in the combustion chamber. This paper presents the results of an experimental investigation of steady flow through the various kinds of commercial cylinder head ports, and the development procedures of HHI's H21/32 prototype cylinder head ports.

• Journal of Power System Engineering
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• v.21 no.6
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• pp.110-116
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• 2017

Recently the global warming caused by greenhouse gas has emerged as a global environmental problem. For this reason the continued efforts to reduce greenhouse gas emission by international cooperation and each country are in progress. Climate changing has been recognized as the world economy development from fossil fuel use is the culprit. The international maritime organization marine environment protection committee of the global warming reduction emerged restrictions on air pollution have been strengthened. Therefore, the author has investigated the effects of fuel temperature on the characteristics of combustion and performance, using an four-cycle, six cylinders and direct injection diesel engine. The results of cylinder pressure, rate of pressure rise, rate of heat release and specific fuel consumption were increased by changing of fuel temperature.

• 한국전산유체공학회:학술대회논문집
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• 1998.11a
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• pp.71-77
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• 1998

In this study we calculated the flowfields around the axisymmetric bodies in the rarefied gas regime by using the DSMC. A flat-ended cylinder was selected as a representative axisymmetric body and the gas used for all calculations was nitrogen. With zero angle of attack, an increasingly rapid rise in density and the effect of shock waves near the flat-ended face were examined. And on the cylinder surface velocity slips and boundary layers could be observed in the results. Larsen-Borgnakke model was used for the energy redistribution in inelastic collisions. And by considering all internal energy modes, the distributions of translational, rotational and vibrational temperatures were plotted. The calculations were peformed for various Knudsen numbers, Especially the rotational temperatures calculated for a case were compared with the experimental results. And the simulation results show good agreements with the experimental ones.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.2
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• pp.246-259
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• 2003

For predicting the performances of the four stroke cycle spark ignition engines. the gas behavior in the engine system has been analyzed. The calculations consist of two parts. the calculation of the gas behavior in the intake and exhaust systems which was described in the first paper, and the calculation of the variations of gas properties inside the engine cylinders. In this Paper the simulations for the in-cylinder processes were described for the MPI engine, naturally aspirated and turbocharged engines with a carburettor. With the combination of the calculations of the intake and exhaust systems and the calculation of the in-cylinder processes. the predictions of the engine Performances and the exhaust emission characteristics were carried out. And the result showed good agrements with the experimental results under wide range of operating conditions.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.737-738
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• 2002

To develop and improve a GIS(Gas Insulated Switchgear), the prediction of the pressure in puffer cylinder and the flow between the nozzle and the moving electrode within GIS is very important.The leading companies in GIS business issue the results of the study of flow within GIS including arc plasma. In this study, the characteristics of the flow of the GIS developed by HHI(Hyundai Heavy Industries Co. Ltd.) was investigated. To simulate the compressible flow of GIS, the CFX, a commercial CFD code, was used. With moving grid method, the movement of piston and electrode was simulated. The moving grid method was superior to the method of varying the property of cells to move an obsticle, in stability and convergencce of solution. The calculated maximum pressure within the puffer cylinder was matched with experimental data within $5{\%}$ error. The oscilation of pressure in GIS after the movement of electrode was well predicted.