• Journal of Advanced Marine Engineering and Technology
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• v.30 no.4
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• pp.455-462
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• 2006

Natural gas is a promising alternative fuel to meet strict engine emission regulations in many countries. Natural gas engines can operate at lean burn and stoichiometric burn conditions with different combustion and emission characteristics. In this paper, the fuel economy, emissions, misfire, knock and cycle-to-cycle variations in indicated mean effective pressure of lean burn natural gas engines are highlighted. Stoichiometric burn natural gas engines are briefly reviewed. To keep the output power and torque of natural gas engines comparable to that of gasoline engines, high boosting pressure should be used. High activity catalyst for methane oxidation and lean deNOx system or three way catalyst with precisely control strategies should be developed to meet stringent emission standards.

• Journal of the Korean Institute of Gas
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• v.26 no.4
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• pp.1-8
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• 2022

DME, a clean fuel that is being studied as an alternative fuel for diesel engines, can reduce exhaust gas, which is the one of the crucial problems of diesel engines, and has a very high cetane number and high oxygen content. DME is a fuel has properties similar with LPG and can use the infrastructure of LPG. In this study, The target was to build a database of basic data on the mass flow rate discharged for the performance evaluation of the plunger-type high pressure pump. In this study, the mass flow rate of the DME plunger type high pressure pump was analyzed by changing the common rail pressure and the motor rotation speed. The experimental conditions were the common rail pressure was changed from 300 to 500 bar and the motor rotation speed was changed from 300 to 1000 rpm. In addition, basic mass flow data were constructed to high-pressure pumps for DME. As a result of the experiment, in both cases the mass flow rate was increased.

• 한국연소학회:학술대회논문집
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• 2001.11a
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• pp.73-82
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• 2001

The characteristics of the catalytically supported thermal combustion with Pd-based catalyst using the bench scale high pressure combustor has been investigated up to 7 atm. The emission of $NO_{\chi}$ depends on the preheating temperature and the excess air ratio. Most $NO_{\chi}$ emission seems to come from the pre-burner for the preheating of the inlet gas. Decreasing excess air ratio in the inlet gas below 1.5 results in the stable catalytically supported thermal combustion in the post combustion region while the $NO_{\chi}$ emission increased up to 15 ppm. Further, the increase of the pressure shows the dramatic increase of the emission CO and THC. However, the $NO_{\chi}$ emission decreased slightly due to the lower combustion temperature at the high pressure.

• The KSFM Journal of Fluid Machinery
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• v.9 no.6 s.39
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• pp.35-44
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• 2006

Operation conditions of a reheat cycle gas turbine for a combined cycle power plant was analyzed. Based on measured performance parameters of the gas turbine, a performance analysis program predicted component characteristic parameters such as compressor air flow, compressor efficiency, efficiencies of both the high and low pressure turbines, and coolant flows. The predicted air flow and its variation with the inlet guide vane setting were sufficiently accurate. The compressor running characteristic in terms of the relations between air flow, pressure ratio and efficiency was presented. The variations of the efficiencies of both the high and low pressure turbines were also presented. Almost constant flow functions of both turbines were predicted. The current methodology and obtained data can be utilized for performance diagnosis.

• Journal of the Korean Chemical Society
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• v.48 no.3
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• pp.243-248
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• 2004

Brake theory of viscosity, which can sucessfully calculate the viscosity of real gases, dense gases and liquids, is extended to the binary gas mixture. Adjustable parameters are not involved, but the calculated results are good agreements with the experimental values at high pressure as well as low pressure. Corresponding state equation for viscosity can be obtained by using the Redlich-Kwong equation, so that we hope this equation may be useful for the supercritical fluid in engineering applications at high pressure around the critcal point.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.787-790
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• 2009

There are several types of compressors which are appropriate for hydrogen gas station. Metal diaphragm type of hydrogen compressor is the one of them, a use in which satisfies the requirements of maintaining gas purity and producing high pressure over 700 bar. The objective of this study is to investigate an characteristics of compression as bulk modulus of oil varies. Three cases of bulk modulus ranging from $2{\times}10^9$, $4.52{\times}10^9$ and $7{\times}10^9$ were studied through FSI (Fluid Structure Interaction) analysis. Gas pressure, oil pressure and deflection degree of diaphragm were analysed during a certain period of compression process. Highest pressure and deflection were found in the condition of high bulk modulus of $7{\times}10^9$.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.73-74
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• 2015

Synthesis gas such as hydrogen and carbon monoxide was produced from $CH_4/oxygen$ mixture using insulated pressurized porous media combustor. Experimentally, two cylindrical SiC foams with the different pore density were piled up in a quartz tube and fully premixed mixture was supplied in the axial direction. After stabilizing fuel-rich flame at the interface of the two foams at several pressure conditions, mole fractions of synthesis gases were measured by gas chromatography. Heat recirculation through the inner foam structure could extend the flow velocity of stable region over the laminar burning velocity. As the pressure increased, the rich flammability limit, $H_2/CO$ ratio, and module M increased.

• 한국전산유체공학회:학술대회논문집
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• 1997.10a
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• pp.113-119
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• 1997

This paper addresses to the injection pressure effect on the diesel spray. The injection pressure is varied from 10MPa, in general system, upto 200MPa, in high pressured system in order to understand the effect. The gas phase is modelled in terms of the Eulerian continuum conservation equations of mass, momentum, energy and fuel vapour fraction. The liquid phase is modelled following the discrete droplet model approach in Lagrangian form. The droplet distributions, vapor fractions and gas flows are analyzed in various injection pressure cases.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.2
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• pp.54-63
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• 1994

Mg thin films were prepared on SPCC(cold-rolled steel) substrates by vasuum evapoaration and ion-plating. The influence of argon gas pressure and substrates bias voltage on the crystal orientation and morphology of the film was determined by using X-ray diffraction and scanning electron micrography (SEM), respectively. And the effect of crystal orientation and morphology of the Mg thin films on corrosion behavior was estimated by measuring the anodic polarization curves in deaerated 3% NaCl solution. The crystal orientation of the Mg films deposited at high argon gas pressure exhibited a (002) preferred orientation, regardless of the substrate bias voltage. Film morphology changed from a columnar to a granular structure with the increase of argon gas pressure. The morphology of the films depended not only on argon gas pressure but also bias voltage ; i.e., the effect of increasing bias voltage was similar to that of decreasing argon gas pressure. The influences of argon gas pressure and bias voltage were explained by applying the adsorption inhibitor theory and the sputter theory. And also, this showed that the corrosion resistance of the Mg thin films can be changed by controlling the crystal orientaton and morphology.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.491-494
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• 2015

We present 12CO (2-1) data for four spiral galaxies (NGC 4330, NGC 4402, NGC 4522, NGC 4569) in the Virgo cluster that are undergoing different ram pressure stages. The goal is to probe the detailed molecular gas properties under strong intra-cluster medium (ICM) pressure using high-resolution millimeter data taken with the Submillimeter Array (SMA). Combining this with Institut de RadioAstronomie $Millim{\acute{e}}trique$ (IRAM) data, we also study spatially resolved temperature and density distributions of the molecular gas. Comparing with multi-wavelength data (optical, $H\small{I}$, UV, $H{\alpha}$), we discuss how molecular gas properties and star formation activity change when a galaxy experiences $H\small{I}$ stripping. This study suggests that ICM pressure can modify the physical and chemical properties of the molecular gas significantly even if stripping does not take place. We discuss how this affects the star formation rate and galaxy evolution in the cluster environment.