• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.5
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• pp.83-88
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• 2003

Measurements on the combustion characteristics of dimethyl ether(DME:$CH_3$O$CH_3$) as compared with LPC in constant volume combustion chamber have been conducted. The DME is a good alternative fuel having oxygen component in fuel. To elucidate the combustion characteristics of dimethyl ether as a fuel, the combustion pressures, combustion durations, and pollutants(NOx, $CO_2$, CO) are measured with equivalence ratios(Ø), and initial Pressures of fuel-air mixture. In the case of DME, the NOx concentration peaks in leu flame Ø = 0.85~0.9, and $CO_2$ concentration peaks at Ø=1.1, while the CO concentration abruptly rises at the condition of fuel-rich mixtures.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.4
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• pp.178-185
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• 2007

A study is improvement of power and emission in a inline-pump Dr diesel engine by using Dimethyl ether Fuel. Dimethyl ether (DME) is an oxygenated fuel with a cetane number higher than that of diesel oil. It meets the ULEV emission regulation and reduces the smoke to almost zero when used in a diesel engine. But NOx emission is almost same and CO, THC emissions are lower than that of diesel engine. The emissions aren't satisfied the stronger emission regulation in the further. Generally DOC (Diesel Oxidation Catalyst) is used to reduce CO & THC emissions and EGR (Exhaust Gas Recirculation) system is used to reduce NOx emission. Test results showed that the torque and the power with DME were almost same as those of pure diesel oil, but the brake thermal efficiency increased a little. also the BSEC (Brake Specific Energy Consumption) with DME was similar that of diesel. The test results showed that the DOC was the vary effective method to reduce the CO emission in case of Dimethyl Ether Fuel in diesel engine. But, THC emission is showed a little reduction rates. Also EGR system was the very effective method to reduce the NOx emission in case of Dimethyl Ether Fuel in diesel engine.

• Natural Product Sciences
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• v.6 no.4
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• pp.193-198
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• 2000

Phytochemical study of the constitutive polyphenolics of the flower aqueous alcohol extract of Tamarix tetragyna was carried out. The new sulphated flavonol, quercetin 3',4'-dimethyl ether $3-O-KSO_3$ as well as the new natural galloyl glucose, $2-O-galloyl-({\alpha}/{\beta})-^4C_1-glucopyranose$ were isolated and characterized. The known sulphated flavonols, kaempferol 7,4-dimethyl ether $3,5-di-O-KSO_3$, quercetin 7-methyl ether $3,3',4'-tri-O-KSO_3$, quercetin 7,4'-dimethyl ether $3-O-KSO_3$ and quercetin $3-O-KSO_3$ and the known sulphated phenolics, isoferulic acid $3-O-KSO_3$ and ellagic acid 4,4'-dimethyl ether $3-O-KSO_3$ were also separated and identified. The structures were established by conventional methods of analysis and confirmed by $^1H-,\;^{13}C-NMR$ and negative ESI-mass spectrometry. 2D-homonuclear chemical shift correlation NMR experiment was applied for the new natural galloylglucose.

• Journal of the Korean Chemical Society
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• v.40 no.9
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• pp.635-639
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• 1996

New bis-crown ether containing siloxane chain was synthesized. 1,3-Bis(trimethylsiloxy)-1,3-dimethyl-1,3-di(4'-ethylbenzo-18-crown-6) disiloxane (1) was synthesized by reaction of 4'-vinylbenzo-18-crown-6 with 1,3-bis(trimethylsiloxy)-1,3-dimethyl-1,3-disiloxane in the presence of Pt catalyst. 4'-Vinylbenzo-18-crown-6 was prepared through five-step reaction which started from the reaction of catechol and acetic anhydride.

• 한국가스학회:학술대회논문집
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• 2004.11a
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• pp.91-96
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• 2004

• 한국가스학회:학술대회논문집
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• 2005.10a
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• pp.131-134
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• 2005

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.761-766
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• 1999

In this paper, high pressure phase behavior in the binary polyethylene/butane and polyethylene/dimethyl ether has been studied. The pressure-temperature diagrams in polyethylene/butane were shown by increasing concentration for molecular weight standards, that is, $M_w=700,\;1000$ and 2000. It is found that the temperature and the pressures go up with increasing in concentrations for each molecular weight, but the latter lower in concentrations over 16 wt % polyethylene. In addition, the phase behaviors for each molecular weights with about 5 wt % polyethylene are shown in pressure-temperature, and pressures increase with increasing in molecular weight($M_w=700,\;1000$, and 2000). The phase behaviors in polyethylene/dimethyl ether are determined according to its molecular weight, and are shown for a range of pressures of 40~280 bar and temperatures of about $120{\sim}220^{\circ}C$. It is shown that in pressure-temperature of polyethylene/dimethyl ether the pressure increases with increasing in polyethylene molecular weight, and the difference in pressure for each molecular weight shows by about 60 bar. The gap in pressure between polyethylene/butane and polyethylene/dimethyl ether system with 5 wt % polyethylene for each molecular weight standards indicates about 25(700), 90(1000), and 100 bar(2000), respectively.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.58-64
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• 2003

Dimethyl Ether(DME) has been considered as one of the most attractive alternative fuels for compression ignition engine. Its main advantage in diesel engine application is high efficiency of diesel cycle with soot free combustion though conventional fuel injection system has to be modified due to the physical properties of DME. Experimental study of DME and conventional diesel spray employing a common-rail type fuel injection system with a 5-hole sac type injector was performed in a constant volume vessel pressurized by nitrogen gas. Spray cone angles and penetrations of the DME spray were characterized and compared with those of diesel. For evaluation of the evaporating characteristics of the DME, shadowgraphy technique employing an Ar-ion laser and an ICCD camera was adopted. Tip of the DME spray was formed in mushroom-like shape at atmospheric chamber pressure, which disappeared in higher chamber pressure. Spray tip penetration and spray cone angle of the DME became similar to those of diesel under 3MPa of chamber pressure. Higher injection pressure provided wider vapor phase area while it decreased with higher chamber pressure condition.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.5
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• pp.30-37
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• 2007

Dimethyl Ether(DME) is an alternative fuel for diesel engine, it is renewable and offers potential reductions in emissions. This work was conducted to figure out the macroscopic behavior and the atomization characteristics of DME using a common-rail injection system. The macroscopic behavior was visualized with the spray visualization system composed of a Nd;YAG laser and an ICCD camera. The atomization characteristics were investigated in terms of axial mean velocity, Sauter mean diameter(SMD) and droplet distributions obtained from a phase Doppler particle analyzer(PDPA) system. In this study, it was revealed that the macroscopic behavior and the atomization characteristics of DME are similar compared with commercial diesel fuel. However, DME fuel has a shorter spray tip penetration and a small SMD due to the effect of evaporation characteristics.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.6 s.261
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• pp.514-521
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• 2007

This study focused on the effects of the $CO_2$ gas concentration in fresh charge and induction air temperature on the combustion characteristics of homogeneous charge compression ignition with dimethyl ether (DME) fuel, which was injected at the intake port. Because of adding $CO_2$ in fresh charge, start of auto-ignition was retarded and bum duration became longer. Indicated combustion efficiency and exhaust gas emission were found to be worse due to the incomplete combustion. Partial burn was observed at the high concentration of $CO_2$ in fresh charge with low temperature of induction air. However, indicated thermal efficiency was improved due to increased expansion work by late ignition and prolonged bum duration. Start of auto-ignition timing was advanced with negligible change of burn duration, as induction air temperature increased. Burn duration was mainly affected by oxygen mole concentration in induction mixture. Bum duration was increased, as oxygen mole concentration was decreased.