• Journal of Mechanical Science and Technology
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• v.19 no.12
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• pp.2253-2262
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• 2005

The focus of this work is placed on the analysis of the mixture formation mechanism under the evaporative diesel spray of impinging and free conditions. As an experimental parameter, ambient gas density was selected. Effects of density variation of ambient gas on liquid and vapor-phase inside structure of evaporation diesel spray were investigated. Ambient gas density was changed between ${\rho}a=5.0\;kg/m^3$ and $12.3\;kg/m^3$. In the case of impinging spray, the spray spreading to the radial direction is larger due to the decrease of drag force of ambient gas in the case of the low density than that of the high density. On the other hand, in the case of free spray, in accordance with the increase in the ambient gas density, the liquid-phase length is getting short due to the increase in drag force of ambient gas. In order to examine the homogeneity of mixture consisted of vapor-phase fuel and ambient gas in the spray, image analysis was conducted with statistical thermodynamics based on the non-dimensional entropy (S) method. In the case of application of entropy analysis to diesel spray, the entropy value always increases. The entropy of higher ambient density is higher than that of lower ambient gas density during initial injection period.

• 한국가스학회:학술대회논문집
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• 2003.10a
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• pp.145-148
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• 2003

• 한국가스학회:학술대회논문집
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• 1997.09a
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• pp.195-200
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• 1997

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.6
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• pp.308-312
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• 2006

Partial Discharge (PD) phenomena occurred by different nature of insulating defects has been regarded as a random process by which Phase Resolved Partial Discharge Analysis(PRPDA) has been proposed and then commercially accepted for the diagnosis of the power apparatus since more than three decades. Moreover, for the same purpose, a novel approach based on the Chaotic Analysis(CAPD) has been proposed since 2000, in which Partial Discharge(PD) phenomena is suggested to be considered as a deterministic dynamical process. In this work, for the diagnosis of Gas Insulated Transformer(GITr), four different types of specimen were fabricated as a model of the possible defects that might possibly cause its sudden failures such as turn to turn insulation, inter coil insulation, free moving particle and protrusion. For this purpose, these defects are introduced into the Gas Insulated Transformer(GITr) mock-up and experimental investigations have been carried out in order to analyze the related Partial Discharge(PD) patterns by means of both Phase Resolved Partial Discharge Analysis(PRPDA) and Chaotic Analysis(CAPD) respectively and then their comparisons are made systematically.

• Journal of the Korean Institute of Gas
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• v.17 no.1
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• pp.42-48
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• 2013

The global warming of the Korean Peninsula proceeds most rapidly in the world and its abnormal climate is more deepening. In the result of the surged electricity consumption by intense heat of summer and severe cold of winter, electricity supply and demand status is in hard situation. Currently, the supply of natural gas is increased because natural gas has the lowest greenhouse-gas emissions among the existed fossil fuel. Natural gas cooling has a lot of advantage such as decreasing electricity peak, reducing construction expenses in additional power plant, operating natural gas storage facilities efficiently, and playing a role as distributed generations. Therefore, this study analyzes the economic feasibilities of gas cooling as an alternative for electric power load management.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.2
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• pp.195-200
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• 2015

It is envisaged that the effect of increasingly stricter air emissions legislation implemented through IMO Annex VI and other local air quality controls, together with favorable financial conditions for the use of natural gas instead of liquid fuel oil as a bunker fuel, will see an increasing number of DF engine and single gas fuel engine applications to LNG carriers and other vessel types. As part of provision for the current international movements in the shipping industry to reduce GHG emission in air, new design concepts using natural gas as an alternative fuel source for propulsion of large commercial vessels, have been developed by shipyards and research institutes. In this study, an explosion analysis for a gas supply machinery room of LNG-fuelled container ship is presented. The gas fuel concept is employed for the high pressure ME-GI where a leakage in the natural gas double supply pipe to the engines is the subject of the present analysis. The consequences of a leak are simulated with computational fluid dynamics (CFD) tools to predict typical leak scenarios, gas cloud sizes and possible explosion pressures. In addition, capacity of the structure which is subject to explosion loads has been assessed.

• Journal of Energy Engineering
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• v.12 no.4
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• pp.320-327
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• 2003

A CFD (Computational fluid Dynamics) research is conducted for the investigation of the fuel alteration of MBTU (medium-Btu) gas in IGCC gas turbine combustor. The computational analysis method of the gas turbine combustor is constructed by incorporating MBTU gas reaction and fuel NOx models into commercial CFD code. With the use of the present analysis method, comparisons are made on the flow velocity, the chemical species and the temperature distributions, and on the flame shape and behavior of gas turbine combustor firing natural gas and MBTU gases (coal gas, heavy residue oil gas). Furthermore, the NOx formation characteristics and the turbine matching condition of the combustor are analyzed. Based on the computed analysis results, the present study provides the directions for the redesign and the design modification of IGCC gas turbine combustor firing MBTU gas as alternative fuel.

• Journal of the Korean Institute of Gas
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• v.18 no.5
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• pp.72-77
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• 2014

It is known that there is no demand for building the arctic environment in Korea. However, it is important to use the different energy source instead of fuel source due to global warming. It is now demanded of using gas of Alaska and Siberia for long term developing the natural gas. The design of gas pipelines in Korea is very different from the arctic region. The operation of gas in arctic region have to consider of arctic region such as permafrost and active regions. It is needed to understand of gas pipeline design with different arctic soil properties. Nowadays, the pipelines is designed with stress-based and but there is demanded for strain based design with more deformed pipeline. We study of arctic environment with different active region using Finite Element Method of thermal elasto-plastic analysis.

• Journal of the Korean Institute of Gas
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• v.7 no.4 s.21
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• pp.24-29
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• 2003

Numerical analysis was conducted to predict the damage of indoor gas explosion for the propagation of explosion flame. Indoor gas diffusion distribution due to gas leakage was obtained by diffusion equation that adopted initial conditions from reference. Enthalpy of each gas-mixture ratio and reduced mechanism was applied to calculate flame temperature, and laminar combustion velocities with the variant of each gas concentration from reference were applied to the gas mixture. Turbulent combustion velocity was modeled by coupling of turbulent energy and laminar combustion velocity in k-$\epsilon$ model. For the analysis of flame propagation cartesian and cylindrical coordinate were used to indoor position and flame propagation respectively. The study analyzes the cause of pressure rising with the variation of flame propagation by glass damage, and the result shows that indoor pressure rising with ignition position varies window dimension.

• Geomechanics and Engineering
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• v.13 no.5
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• pp.861-879
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• 2017

Coal and gas outburst is a serious dynamic disaster that occurs during coal mining and threatens the lives of coal miners. Currently, coal and gas outburst is commonly predicted using single indicator and its critical value. However, single indicator is unable to fully reflect all of the factors impacting outburst risk and has poor prediction accuracy. Therefore, a more accurate prediction method is necessary. In this work, we first analyzed on-site impacting factors and precursors of coal and gas outburst; then, we constructed a Fisher discriminant analysis (FDA) index system using the gas adsorption index of drilling cutting ${\Delta}h_2$, the drilling cutting weight S, the initial velocity of gas emission from borehole q, the thickness of soft coal h, and the maximum ratio of post-blasting gas emission peak to pre-blasting gas emission $B_{max}$; finally, we studied an FDA-based multiple indicators discriminant model of coal and gas outburst, and applied the discriminant model to predict coal and gas outburst. The results showed that the discriminant model has 100% prediction accuracy, even when some conventional indexes are lower than the warning criteria. The FDA method has a broad application prospects in coal and gas outburst prediction.