• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.10
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• pp.1025-1031
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• 2011

Autoignition characteristic is an important parameter for designing diesel or PCCI engines. In particular, diesel spray flames are lifted from the nozzle and the initial flame is formed by an autoignition phenomenon. The lifted nature of diesel spray flames influences soot formation, since air will be entrained into the spray core by the entrainment of air between the nozzle region and the lifted flame base. The objective of the present study was to identify the effect of heat loss on the ignition delay time by adopting a coflow jet as a model problem. Methane ($CH_4$), ethylene ($C_2H_4$), ethane ($C_2H_6$), propene ($C_3H_6$), propane ($C_3H_8$), and normal butane (n-$C_4H_{10}$) fuels were injected into high temperature air, and the liftoff height was measured experimentally. As the result, a correlation was determined between the liftoff height of the autoignited lifted flame and the ignition delay time considering the heat loss to the atmosphere.

• Membrane Journal
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• v.29 no.2
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• pp.67-79
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• 2019

High purity propylene (propene) is an octane-enhancing chemical and also feedstock to industrially important chemicals. Purification of propylene from propane mixture is technologically and financially challenging because of their close boiling points. ZIF-8 membrane has been increasingly researched due to its great potential to separate propylene from propane effectively by molecular sieving. The increasing interest in ZIF-8 membranes lies in the so called "gate opening" effect. The gate opening effect enlarges the membrane pores and preferentially allows propylene to permeate through the membrane pores, while retaining the larger and heavier propane molecules in the feed stream in order to effect high propylene separation from propylene/propane mixture. In this paper, the widely accepted methods of ZIF-8 membrane preparation and parameters affecting propylene permeation and selectivity in ZIF-8 membrane are identified and reviewed.

• Applied Biological Chemistry
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• v.46 no.4
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• pp.361-366
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• 2003

Anti-aflatoxigenic studies on synthetic pyridione alkaloids were conducted. Seven derivatives using piperlongumine as a leading compound were prepared from 3,4,5-trimethoxycinnamic acid (TMCA). These derivatives were analyzed for their structural confrmation and purity by HPLC, GC, GC/MS and $1^H-NMR$. 1-piperidin-1-yl-3-(3,4,5-trimethoxyphenyl)propenone (1) reaction with piperidine; 1-morpholin-4-yl-3-(3,4,5-trimethoypenyl)propenone (2) with morpholine; 1-(3,5-dimethylpiperidin-1-yl)-3-(3,4,5-trimethoxyphenyl)propenone (3) with 3,5-dimethylpiperdine; 1-(2-methylpiperidine-1-yl)-3-(3,4,5-trimethoxyphenyl)propenone (4) with 2-methylpiperidine; 1-(3-hydroxypiperidin-1-yl)-3- (3,4,5-trimethoxyphenyl)propenone (5) with 3-hydroxypiperidine hydrochloride; 1-[3- (3,4,5-trimethoxyphenyl)acryloyl]piperidin-2-one (6) with ${\delta}-valerolactam;\; and\;ethyl\;1-[3-(3,4,5-trimethoxyphenyl)acyloyl]piperidine-4-carboxylate$ (7) with ethyl isonipectotate were synthesized respectively. All derivatives showed an inhibitory activity on aflatoxin $B_1$ production. In conclusion, we believe that they might be an agent for the control of mycotoxin in agricultural commodities.

• Korean Journal of Food Science and Technology
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• v.39 no.6
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• pp.614-618
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• 2007

The effect of irradiation on the quality characteristics of lyophilized kimchi powder was investigated in order to develop a commercial kimchi seasoning. Fresh and fermented kimchi powders were irradiated at 0, 1.5, 5, 10 and 30 kGy using a Linear Accelerator. By increasing the irradiation dose level, $a^*$ (redness) and $b^*$ (yellowness) values of the kimchi powders were decreased, while $L^*$ (lightness) value remained relatively unchanged as compared to the control. As the main volatile compounds, butanal, 2-butanone and acetic acid were produced in both of the kimchi powders at 30 kGy and dipropyl disulfide was detected only in the fermented kimchi. The viable counts of aerobic bacteria, yeasts, molds, and lactic acid bacteria in the kimchi powder were significantly reduced by all irradiation doses. However, aerobic and lactic acid bacteria were still observed in both of the kimchi powders at 30 kGy. No significant off-odors or off-tastes were produced in either of the kimchi powders by irradiation, while pungency decreased after irradiation. These results suggest that irradiated kimchi powder could be used as a kimchi seasoning.