• International Journal of Automotive Technology
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• v.7 no.4
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• pp.501-508
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• 2006

The effect of chemical additives, such as dimethyl ether(DME), ethanol, carbon disulfide on the soot formation were examined numerically. ill this study, the Frenklach soot mechanism was used as a base mechanism to predict the soot formation in the ethane flame. The combination of Westbrook's DME mechanism, Marinov's ethanol mechanism, and chemical kinetic mechanism for hydrogen sulfide and carbon disulfide flames was made with the base mechanism because the DME, ethanol, $CS_2$ additives are added into the ethane fuel. CHEMKIN code was used as a numerical analysis software to simulate the effect of chemical additives on reduction of the polycyclic aromatic hydrocarbons(PAH's) which are soot precursors. From the numerical results it is observed that addition of DME, ethanol and $CS_2$ into ethane fuel can reduce PAH species significantly. That means theses additives can reduce soot formation significantly. Results also strongly suggest suppression of soot formation by these additives to be mainly a chemical effect. Hand OH radicals may be the key species to the reduction of PAH species for additives.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.4
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• pp.563-567
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• 1998

Volatile flavor components of edible portion of leek(Allium tuberosum R.) were extracted by SDE(simultaneous steam distillation and extraction) method using the mixture of n-pentane and diethylether (1 : 1, v/v) as an extract solvent and analyzed by GC-FID and GC/MS. Identification of the volatile flavor components was mostly based on the RI of GC and mass spectrum of GC/MS. A total of sixty-five components from leek extract were classified as 28 sulfur-containing compounds, 12 aldehydes, 9 alcohols, 4 lactones and esters, 3 acids and hydrocarbons, and 2 miscellaneous compouds. The sulfur-containing compounds were predominant in leek extract. Dimethyl disulfide(19.47%) and dimethyl trisulfide(17.38%) were the main compounds and trans-1-propenyl methyl disulfide, trans-2-hexenal and methyl allyl disulfide were also detected large amounts in leek.

• Journal of the Korean Applied Science and Technology
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• v.24 no.3
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• pp.296-300
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• 2007

This paper presents applicability of photocatalytic decomposition of methyl mercaptan using $TiO_2$. A quartz reactor was used in order to elucidate reaction pathway in photocatalytic decomposition of methyl mercaptan. Experimental results showed that more than 99.9% of methyl mercaptan was decomposed within 30 minutes. It was found that the photocatalytic decomposition of methyl mercaptan followed pseudo first order and its reaction coefficient was $0.05min^{-1}$ During 30 minutes in the photocatalytic reaction, the concentration of methyl mercaptan, dimethyl disulfide, $SO_2$, $H_2SO_4$, COS, $H_2S$ were determined. These results showed that 64% of methyl mercaptan were compensated for the increase in sulfur after 30 minutes through the mineralization. The proposed main photocatalytic decomposition pathway of methyl mercaptan was methyl $mercaptan{\rightarrow}dimethyl$ $disulfide{\rightarrow}SO_2{\rightarrow}H_2SO_4$.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.E3
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• pp.153-163
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• 2002

A laboratory- scale dual-column biofilter system was used to study the biofiltration of dimethyl disulfide (DMDS). The gas flow rate and DMDS concentration to the biofilter were varied to study their effect on the remov-al of dimethyl disulfide. Operating parameters such as pH, temperature, and water content were monitored during the biofilter operation and necessary precautions were taken to keep these parameters within the acceptable limits. It was observed that the removal efficiency of DMDS was optimal at neutral pH values. After five month op-eration, the neutralization of the filter beds with sodium carbonate became necessary for the optimum operation of the biofilters. The microbial population already present in the compost mixtures was found to be adequate in treat-ing DMDS. The compost mixtures were found to be similar in terms of biofiltration efficiency of DMDS. However, pressure drops observed in the first column compost mixture (compost/ peat mulch) was extremely high, making this compost economically not feasible. The second mixture (compost/bark) provided pressure drops within accept-able limits. A minimum residence time of 30 seconds at the optimal operating conditions appeared to be adequate for achieving high removal efficiencies (>90%).

• Korean Journal of Microbiology
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• v.40 no.2
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• pp.127-132
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• 2004

We isolated 50 strains from sludge of wastewater treatment aeration tank using selective medium for Thio-bacillus sp. by membrane filtration method. They were identified as Thiobacillus neapolitanus (7), T. tepidarius (4), T. dientrificans (5), T. versutus (23), T. intermedius (2) and T. perometabolis (9). We selected Thiobacillus versutus strain KT51, which had the highest removal efficiency (100％) of hydrogen sulfide and the highest removal efficiency (85％) of dimethyl sulfide for 30 min in screen test. Also Thiobacillus versutus strain KT81 had the highest removal efficiency (26％) of dimethyl disulfide for 30 min in screen test. In applification of lab-scale reactor (closed-biological treatment) using Thiobacillus versutus strain KT51, results were 99.8％ (＜0.02 ppm) removal efficiency of hydrogen sulfide for 15 min.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.2
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• pp.230-235
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• 2005

Volatile organic components from fresh and freeze-dried onions were extracted by SDE apparatus and analyzed by GC/MS. Components of 40 and 31 were identified in fresh and freeze-dried onions respectively. These components included esters, aldehydes, ketones, alcohols and S-containing compounds. Major compounds of S-containing compounds such as 1-propanethiol, dipropyl trisulfide, and methyl propyl trisulfide in fresh onions were clearly decreased in freeze-dried onions. Then, S-containing compounds such as methyl allyl sulfide, propyl ally sulfide, dially disulfide and 3,5-diethyl-l,2,4-trithiolane and alcohols such as pentanol, hexanol and propanol were disappeared by freeze-drying. Exceptionally, ethyl acetate, dimethyl disulfide and 2-methyl-2-pentenal were increased as different trend with major S-containing compounds. (Z)-Propenyl methyl disulfide and (E)-propenyl methyl disulfide were also changed by freeze-drying in the similar pattern as mentioned above compounds.

• Korean Journal of Food Science and Technology
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• v.54 no.2
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• pp.126-133
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• 2022

The objective of this study was to analyze volatile and aroma-active compounds in Korean wild chive (Allium monanthum Maxim.) cultivated in open-fields or greenhouse systems using solvent-assisted flavor evaporation-gas chromatography (GC)-mass spectrometry and GC-olfactometry. Aroma-active compounds were evaluated using aroma extract dilution analysis (AEDA). Twenty-two aroma-active compounds with log₂ flavor dilutions (FD) of 1-10 were detected in Korean wild chive, which was cultivated in an open-field or a greenhouse. 2-Isopropyl-3-methoxypyrazine ("earthy"), 2-sec-butyl-3-methoxypyrazine ("earthy", "musty"), and dipropyl disulfide ("sulfurous") were the most predominant aroma-active compounds with log₂FD of 9-10; this was followed by dimethyl trisulfide ("onion-like") and (E)-1-propenyl propyl disulfide ("fresh onion-like"). The "sulfurous", "earthy", "pungent", and "cabbage-like" aroma notes were strong in Korean wild chive. More intense "pungent" odors were detected in Korean wild chive cultivated in an open-field, whereas more intense "cabbage-like" odors were detected in Korean wild chive cultivated in a greenhouse.

• Journal of Environmental Science International
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• v.16 no.1
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• pp.33-38
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• 2007

The concentrations of offensive odorous compounds emitted from the two chemical plants in Chongju and Yeosu industrial complex in Korea were determined by uv/vis spectroscopy, gas chromatography, and high performance liquid chromatography. The odorous compounds examined in this study are ammonia, trimethyl amine, formaldehyde, acetaldehyde, propion aldehyde, butyl aldehyde, n-valeric aldehyde, iso-valeric aldehyde, hydrogen sulfide, methyl mercaptan, dimethyl sulfide and dimethyl disulfide. The concentrations of those were determined from the 10 sampling points of the two plants, respectively. The emission concentrations of all odorous com-pounds examined in the two plants were lower than those of the regulation standard levels of industrial complex in Korea, respectively. The propion aldehyde, n-valeric aldehyde, methyl mercaptan and dimethyl disulfide in Chongju and Yeosu plants, and butyl aldehyde and iso-valeric aldehyde in Yeosu plant were not detected at any sampling points examined.

• Journal of Food Hygiene and Safety
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• v.15 no.3
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• pp.235-240
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• 2000

Various separation techniques of antimicrobial compounds from food materials have proven to be ineffective, involving liquid-liquid extraction and chromatography. We established efficient separation procedure for partially purifying antimicrobial compounds from Korean leek. Separation procedures consisted of ultrafiltration, liquid-liquid extraction, TLC and HPLC. Molecular weight of antimicrobial compounds were less than 5,000 dalton. Major compounds were propenyl methyl disulfide, S-methyl methylthiosulphonate and dimethyl disulfide.

• Journal of the East Asian Society of Dietary Life
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• v.16 no.3
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• pp.299-307
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• 2006

Raw whole garlic was pickled in two different ways, in soy sauce and in brine, to test the change of flavor compounds with aging period. The changes of pH, acidity, hardness and flavors were measured, accompanied with sensory evaluation. The pH of whole garlic in soy sauce and in brine was decreased as the aging period increased. The acidity was increased as pH decreased. Hardness tended to decrease as the aging time increased. For whole garlic in soy sauce and in brine, trans propenyl methyl disulfide, allyl methyl trisulfide, diallyl trisulfide, dimethyl trisulfide, allyl- 2,3-epoxypropyl sulfide, and 2-methyl-l,3-dithiane were increased as the aging proceeded but allyl methyl disulfide and diallyl disulfide tended to decrease. Hardness through the sensory evaluation decreased as the aging time increased. When the overall quality was compared between whole garlic in soy sauce and in brine after 60 days, the latter could be better estimated. Pickled garlic increased the flavor compounds such as trans propenyl methyl disulfide, allyl methyl trisulfide, diallyl trisulfide, dimethyl trisulfide, allyl-2,3-epoxypropyl sulfide, and 2-methyl-l,3-dithiane as the aging proceeded. Therefore, the above flavor compounds are considered as the major ingredients of the characterized flavor of pickled garlic.