• Journal of environmental and Sanitary engineering
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• v.22 no.4
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• pp.23-32
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• 2007

Changes in the characteristics of dissolved organic matter was studied at selected stations in the Nakdong river basin using physical and chemical methods. Characteristics of dissolved organic matters were analysed and assessed. Production of disinfection byproducts were also investigated. Distribution of the organic compounds according to the Molecular weight(MW) indicate that MWs higher than 100K were highest with cattle excrement wastewater and MW between 100-10K were highest with waters from forest streams. Low MW compounds (Jess than 1K) were highest with the effluents from environmental facilities. Results of resin fractionation study show that acidic hydrophobic substances(AHS) were dominant in many stations. The values were higher in the samples from mainstreams and sidestreams where the influence of organic matter is higher than the water from environmental facilities. Hydrophilic neutral substances(HoN) such as hydrocarbon, pesticides and detergents were higher in the wastewater treatment facilities. HoN values of water from the forest streams were 4.7% indicating there is no synthetic pollutant.

• Korean Journal of Weed Science
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• v.17 no.2
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• pp.135-138
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• 1997

Sulfonylureas are highly active herbicides which can be applied at very low rate(10-50g/ha) to control broadleaf weeds. The nature of this category of compound is, however, very unstable toward hydrolysis. Therefore, the preparation of these compounds as liquid formulation was not possible. Most of the current formulations of sulfonylurea are in dry forms such as water dispersible granule or wettable powder. Even in these dry forms, the active ingredients also encounter significant chemical decomposition. This study involves the preparation of the sulfonylurea salts by reacting the parent compound with base such as sodium hydroxide. The salt becomes stable toward hydrolysis and it turns soluble when diluted with water. This discovery makes the preparation for liquid formulation or soluble granule of sulfonylurea possible. The stoichiometry of base added to the neutral sulfonylurea is controlled quite precisely. The base has to be added enough to quench the acidic impurities in the technical material and to convert the active ingredient into salt. However, the base should not be overused to cause further saponification of the sulfonylurea salts. The chemical nature of these compounds is presented and the chemical reaction is described. New soluble liquid formulation and solid granule formulation of sulfonylurea are suggested.

• Journal of Korean Society of Water and Wastewater
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• v.8 no.1
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• pp.27-33
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• 1994

With the rapid industrialization, an ever-increasing quantity and kind of new organic compounds pose environmental problems due to their toxicity and physiological effect. However, research on the biodegradation of these compounds under anaerobic condition is very limited inspite of its efficiency and economical advantage. In this research, the pH effect on the ring cleavage of phenol under anaerobic condition was investigated, and the theory of phase separation was applied to the degradation of phenol for investigating the role of acidogenic bacteria. Results, obtained from biochemical methane potential(BMP) assay for 15.5 days of incubation, showed that acidic condition was more desirable for phenol degradation than alkaline condition. By both unacclimated methanogenic granular sludge and two mixed cultures, phenol was completely removed within six weeks of incubation with a gas conversion rate of over 86% of theoretical one. However, phenol was not degraded by unacclimated acidogenic culture, and thus it is considered as a syntrophic substrate. In case of phase separated biochemical methane potential(PSBMP) assay, in which acidogenic and methanogenic culture were seeded separately and consecutively, those that had been subjected to normal acidogens for 3 to 4 weeks showed higher gas production than those seeded with sterile or frozen culture.

• Bulletin of the Korean Chemical Society
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• v.32 no.9
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• pp.3377-3381
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• 2011

In this work, the amine grafting treated activated carbons were studied for carbon dioxide adsorbent. The surfaces of activated carbon were functionalized by 3-chloropropyltrimethoxysilane, which was subsequently grafted with amine compounds tris-(2-aminoethyl)amine and tri-ethylenetetramine and subjected to comparison. The surface functional groups of the amine grafted activated carbons were characterized using XPS. The textural properties of the amine grafted activated carbons were analyzed by $N_2$/77 K isotherms. Carbon dioxide adsorption behaviors of the amine grafted activated carbons were examined via the amounts of carbon dioxide adsorption at 298 K and 1.0 atm. From the results, tris-(2-aminoethyl)amine grafted activated carbons showed 43.8 $cm^3$/g of carbon dioxide adsorption while non-treated activated carbons and triethylenetetramine grafted activated carbons showed less carbon dioxide adsorption. These results were thought to be due to the presence of isolated amine groups in the amine compounds. Tris-(2-aminoethyl)amine grafted activated carbons have basic features that result in the enhancement of adsorption capacity of the carbon dioxide molecules, which have an acidic feature.

• Journal of Ginseng Research
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• v.20 no.1
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• pp.54-59
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• 1996

Red Ginseng extracts sol'n was sterilized at 85f for 20 mins and/or stored at 4$0^{\circ}C$ for 6 months and centrifuged for 20 mins at 8,500xg in order to investigate the changes in chemical components of supernatants and the properties of precipitates. Contents of crude saponin and ginsenoside-$Rb_1$, -$Rg_1$, -Re were partially decreased during heating and storage. Starch contents were decreased from 26.81% in red ginseng extracts to 17.50-8.81% in supernatants, whereas free sugar contents were increased from 15.50% to 20.29~21.35% by heating and storage. The contents of protein and minerals in supernatants were decreased, but acidic polysaccharides and polyphenol compounds were not changed. pH values of supernatants and precipitates were decreased. The absorbances of brown color precursor and brown pigment in precipitates, detected at 285 nm and 440 nm were remarkably increased. The Overa11 data suggest that precipitates in red ginseng extracts sol'n formed during steilization and storage are provably the brown pigments resulting from Maillard reaction of amino compounds with reducing sugar which could be released from starch and protein matrix and $Cu^+$, $Ca^{2+}$ and $Fe^{3+}$ ions are implicated with the reaction incorporated.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.6
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• pp.606-613
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• 2010

In order to elucidate a mechanism responsible for the development of the odor characteristics of cooked, desirable-flavored shellfish, oysters were extracted using various solvents and the resulting extracts were evaluated organoleptically after cooking. The 80% aqueous methanol extract was found to produce a desirable cooked flavor. This oyster extract was fractionated using ion-exchange column chromatography and dialysis, and each of the fractions was subjected to cooking, followed by organoleptic evaluation. The outer dialysate fraction such as acidic and amphoteric water-soluble fractions produced a cooked oyster flavor. The volatile flavor compounds identified from cooked oyster included 29 hydrocarbons, 20 alcohols, 16 acids, 12 aldehydes, nine nitrogen-containing aromatic compounds, eight ketones, five furans, three esters, three phenols, and one benzene.

• Journal of Photoscience
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• v.3 no.2
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• pp.91-93
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• 1996

In connection with our interest on the photochemical properties of heteroaryl halides, which are currently the subject of heterocyclic ring formation and haloarene degradation, we have studied the photochemistry of the haloarene linked to N-heteroarene compounds. Imidazo[5,1-a]isoindole was synthesized from N-(ochlorobenzyl)imidazole or N-(o-bromobenzyl) imidazole in acidic aqueous solution or acetonitrile via the intramolgcular photocyclization (Table 1). This type of reaction provides the synthetic methods for 5- and 6-membered polyheteroatomic heterocyclic ring compounds. However, the reaction mechanism for the intramolecular photocyclization of haloarene tethered heteroarenes has not yet been established. Grimshaw et al. suggested a mechanism for homolyric carbonhalogen bond fission assisted by radical complexation to explain their results in the photocyclization of 5-(2-chlorophenyl)-1,3-diphenylpyrazole. They also reported the detection of acyclohexadienyl intermediate involved in the above reaction. Park et al. reported several transient 'intermediates involved in the laser flash photolysis of N-(o-halobenzyl) pyridinium and N-benzyl-2-halopyridinium salts. Thus we performed the laser flash photolysis study on the photocyclization reaction of N-(o-chlorobenzyl) imidazole to identify the intermediate species involved in the reaction. Here, we report on the preliminary results in the photocyclization reaction of N-(o-halobenzyl)imidazole through the detection of reaction intermediates.

• Proceedings of the Ginseng society Conference
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• 1984.09a
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• pp.185-190
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• 1984

Volatile flavor components of fresh ginseng (Panax ginseng C.A. Meyer) were studied by a combination of SE-54 fused silica capillary gas chromatography and mass spectrometry. Steam distillate of fresh ginseng roots was extracted with oxygen-free diethylether and concentrated. This aroma concentrate was separated into neutral, acidic, phenolic, and basic fractions. The neutral fraction, containing over two hundred compounds, was aromatically the closest to fresh ginseng with the key-flavor components predominantly being monoterpenes and sesquiterpenes. The sesquiterpene compounds were identified as being azulenic, menthenic, and napthalenic with a mass of 204.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.4
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• pp.195-203
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• 2006

An antagonistic strain, Burkholderia MP-1, showed antimicrobial activity against various filamentous plant pathogenic fungi, yeasts and food borne bacteria (Gram-positive and Gram-negative). The nucleotide sequence of the 16S rRNA gene (1491 pb) of strain MP-1 exhibited close similarity (99-100%) with other Burkholderia 16S rRNA genes. Isolation of the antibiotic substances from culture broth was fractionated by ethyl acetate (EtOAc) solvent and EtOAc-soluble acidic fraction. The antibiotic substances were purified through a silica gel, Sephadex LH-20, ODS column chromatography, and high performance liquid chromatography, respectively. Four active substances were identified as phenylacetic acid, hydrocinnamic acid, 4-hydroxyphenylacetic acid and 4-hydroxyphenylacetate methyl ester by gas chromatographic-mass spectrum analysis. The minimum inhibition of concentration (MIC) of each active compound inhibited the growth of the microorganisms tested at 250 to $2500{\mu}g\;ml^{-1}$. The antimicrobial activity of crude acidic fraction at 1 mg of dry weight per 6 mm paper disc was more effective than authentic standard mixture (four active substances were mixed with the same ratio as acidic fraction) over a wide range of bacterial test.

• Korean Journal of Medicinal Crop Science
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• v.4 no.1
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• pp.31-37
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• 1996

This study was conducted to know the odor characteristics and compounds in neutral, acidic and basic fraction from the essential oil of Valerliana fauriei root. Among the fraction from the essential oil of V. fauriei root, the content of neutral fraction was 92%, that of the acidic fraction, 6%, and that of basic and phenolic fractions, less than 1%, respectively. The neutral fraction was characterized by sweet-balsamic, woody, musky and medicinal odor. The acidic fraction had sweat-socks, valeric-like and cheese-like odor characters. The netural fraction of essential oil was fractionated by solvents with different polarities, resulting in 44% of ethyl ether fraction, 34% of pentane-ethyl ether fraction, 11% of pentane fraction and 11% of methanol fraction. The ethyl ether fraction was characterized by woody and medicinal odor and the pentane-ethyl ether fraction, by sweet-balsamic, woody and herb-like odor. The fractions were fractionated again by different solvents, and 12 chemical components including valeranone, 26 components including bornyl acetate, and 43 components including camphene were identified in the ethyl ether fraction, the pentane - ethyl ether fraction, and pentane fraction, respectively. In the acidic fraction, n-butanoic acid and other 44 components were identified, among which the most abundant ones were 3-methyl butanoic acid(42.1%), dimethoxy-2-propanoic acid(11.5%), and 5-­ethyldihydro-2H-furanone(5.7%).