• JSTS:Journal of Semiconductor Technology and Science
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• v.9 no.2
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• pp.117-123
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• 2009

$Pb_{x}Cd_{1-x}S$ films are prepared in the composition range of 0.05${\leq}x{\leq}$0.25, using a chemical bath deposition growth technique under optimum conditions amide at realizing good photo response. The x-ray diffraction results show that the films are of PbS-CdS composite with individual CdS and PbS planes. The films exhibit two direct band gaps, 2.4 eV attributed to CdS, while the other varies continuously from 2.4 eV to 1.3 eV. The films surface morphology is smooth with crystallite, whose grain size increases with increasing mole fraction (x). The decrease in band gap with increase in lead concentration suggests inter-metallic compound of PbS (Eg=0.41 eV) with CdS (Eg=2.4 eV)

• KSBB Journal
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• v.19 no.6 s.89
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• pp.421-426
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• 2004

The extraction and separation of isoflavones from Korean soybean were peformed by various mechanical and chemical extraction methods. They included solvent extraction, stirring, supersonification and sub/supercritical water extraction. From the experimental results of the variation of solvent extraction by change in composition, the increase in extraction of a specific compound by stirring or supersonic energy, and the application of supercritical fluid with superior solvating power over solvents, the sonification was the most desirable extraction method in extracting aglycone isoflavones, daidzein and genistein from Korean soybean.

• Bulletin of the Korean Chemical Society
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• v.20 no.5
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• pp.517-524
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• 1999

By heating the magnesiumsilicate (Mg2SiO4:forsterite) xerogel in carbon dioxide, carbonaceous component was intentionally introduced into the amorphous solid precursor. Carbon was introduced homogeneously as unidentate carbonate. Upon being heated at 800 。C in carbon dioxide, the xerogel which had homogeneously distributed carbonaceous component in it crystallized into a single phase product of a new crystalline material, which had approximate composition of Mg8Si4Ol8C. The powder X-ray diffraction pattern of the new crystalline material did not match with any known crystalline compound registered in the powder diffraction file. Crystallization from amorphous xeroget to the new crystalline phase occurred in a very narrow range of temperature, from 750 。C to 850 。C in carbon dioxide, or in dty oxygen. Upon being heated above 850 。C, carbonaceous component was expelled from the product, accompanied by irreversible transition from the new crystalline material to forsterite.

• Bulletin of the Korean Chemical Society
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• v.27 no.6
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• pp.853-856
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• 2006

Dion-Jacobson phases $CsCa_2Nb_2FeO_9$ and $CsCa_2Nb_2AlO_9$ were reinvestigated by the Rietveld analysis of powder X-ray diffraction (XRD) method, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). These nominal compounds, previously known as the oxygen-deficient layered perovskites with the sequences of $NbO_6-MO_4-NbO_6$ in tripled slab, in fact, were mixed phases of n = 3 Dion-Jacobson phases and impurities such as $Ca_2NbFeO_6$ and $Ca_3Al_2O_6$. The difference of morphology and chemical in-homogeneity between Dion-Jacobson phases and impurities could be clearly identified by scanning electron microscopy with energy-dispersive X-ray spectroscopy. The chemical composition of $CsCa_2Nb_2FeO_9$ was calculated into $Cs_{0.59}Ca_{2.64}Nb_{2.92}Fe_{0.81}$ in small agglomerate crystals and $Cs_{0.95}Ca_{1.97}Nb_{3.08}Fe_{0.15}$ in long plate-like crystals.

• Journal of the Korean Applied Science and Technology
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• v.18 no.3
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• pp.241-247
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• 2001

Aqueous urethane dispersion resin begins to assume commercial importance due to increasing environmental awareness of VOC in coating industry. Moreover there have been strong industrial needs for the development of reactive-type polyurethane flame retardant coatings. In this study, chlorinated polyester polyols were synthesized by two step polycondensation reaction using mono chloroacetic acid, adipic acid, trimethylol propane, and 1,4-butanediol. In the next step polyurethane dispersion was prepared using these chlorinated polyester polyols and isophorone diisocyanate with dimethylol propionic acid(DMPA) and trimethylamine. The structure of chlorinated polyol was characterized by GPC, FT-IR and NMR. Particle size and its distribution were examined in terms of various dispersion parameters including molecular weight and composition of polyol, amount of DMPA, and NCO/OH ratio, etc. The effect of chlorinated polyols on flammability was also evaluated.

• Applied Chemistry for Engineering
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• v.8 no.3
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• pp.430-437
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• 1997

Uranyl-peroxide compound was prepared by the reaction of excess hydrogen peroxide solution and trace uranium in filtrate from nuclear fuel conversion plant. The $CO_3{^{2-}}$ in filtrate was removed first by heating more than $98^{\circ}C$, because uranyl-peroxide compound could not be precipitated by $CO_3{^{2-}}$ remaining in filtrate. The optimum condition for uranyl-peroxide compound was ageing for 1 hr after controling the pH with $NH_3$ gas and adding the excess $H_2O_2$ of 10ml/lit.-filtrate. Uranium concentration in the filtrate was appeared to 3 ppm after the precipitation of uranyl-peroxide compound, and the chemical composition of this compound was analyzed to $UO_4{\cdot}2NH_4F$ with FT-IR, X-ray diffractometry, TG and chemical analysis. Also, this fine particle, about $1{\sim}2{\mu}m$, could be grown up to $4{\mu}m$ at pH 9.5 and $60^{\circ}C$. The separation efficiency of precipitate from mother liquor was increased with increase of pH and reaction temperature. Otherwise, the crystal form of this particle showed octahedral by SEM and XRD, and $U_3O_8$ powder was obtained by thermal decomposition at $650^{\circ}C$ in air atmosphere.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.3
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• pp.505-510
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• 1999

The seasonal variations of chemical composition of jujuba leaf were studied by analyzing general composition, amino acid composition, fatty acid composition, mineral, phenol, condensed tannin, flavonoid contents. Fresh jujuba leaf contained 4.42~6.31% protein and 4.31~5.71% fat on wet basis. Jujuba leaf was rich in aspartic acid, glutamic acid and leucine, but methionine was a limiting amino acid. Four kinds of free sugar, i.e. glucose, fructose, sucrose and maltose were found in jujuba leaf. The contents of fructose and glucose increased during growth, while the contents of disaccharides, sucrose and maltose, decreased. The main fatty acids of the leaf were palmitic acid, linoleic acid, stearic acid and oleic acid. Jujuba leaf was rich in K, Na and Ca, however, the amounts of Fe, Mn and Cu were low. The contents of Ca and Na increased during growth but the content of Mg decreased. The content of total phenolic compound was 0.83~0.89% and the content of condensed tannin was 0.40~0.45%. Two major flavonoids such as rutin and isoquercitrin were detected and their contents were 103.8~125.2mg/kg and 26.2~40.0mg/kg, respectively.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.1
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• pp.126-136
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• 2019

Objective: This study was performed to compare fat content, reducing sugar contents, sensory traits, and fatty acid (FA) and volatile compound profiles in longissimus thoracis (LT) among Korean cattle (KC), Holstein (HO), and Angus (AN) steers. Methods: Twelve LT samples (about 500 g each) of KC with an average age of $31{\pm}0.42months$, an average carcass weight of $431{\pm}12.5kg$, and a quality grade (QG) of 1+ were obtained from the joint livestock products market. Twelve LT samples of HO cattle with an average age of $24{\pm}0.54months$, an average carcass weight of $402{\pm}7.81kg$, and a QG of 2 were also obtained from the same market. Twelve LT samples of AN steers with an average age of about 20 months and a QG of choice were purchased from a beef delivery company. After slaughter, samples were kept at $4^{\circ}C$ for 42 days and prepared for immediate analysis or stored at appropriate conditions. The chemical composition, color, pH, shear force, collagen content, reducing sugars, sensory evaluation, FA composition, and volatile compound content for each LT sample were analyzed. Results: The LT of KC had the highest (p<0.05) fat content, the highest reducing sugar content, and the highest scores in the sensory evaluation (flavor, tenderness, juiciness, and overall acceptance). All the sensory traits were positively correlated (p<0.001) with intramuscular fat and reducing sugar content. Several FAs and volatile compound profiles varied among the breeds. KC LT had the highest (p<0.05) concentrations of acetaldehyde, 3-methyl butanal, and 3-hydroxy-2-butanone, and these volatile compounds were positively correlated (p<0.05) with all the sensory traits. Conclusion: Variations in fat content and reducing sugar contents and FA and volatile compound profiles may contribute to differences in the sensory quality of LT among breeds.

• Journal of Mushroom
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• v.16 no.4
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• pp.311-317
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• 2018

The aim of this study was to identify chemical composition and antioxidant activity of phenolic extract of fruiting bodies of an artificially cultivated Hankyong Sanghwang mushroom, Phellinus linteus KACC 93057P (PLHS). The total phenolic content of 60% ethanolic extract of fruiting bodies of two-year-old PLHS grown on Oak wood logs was $19.05{\pm}0.32mg$ gallic acid equivalent (GAE)/g, which was 4-10 times high compared to the other species of mushrooms. 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbisthiazoline-6-sulfonic acid) (ABTS) radical scavenging activities and the ferric reducing antioxidant power (FRAP) value of PLHS were 2-10 and 5 times higher, respectively, than those of the other species of mushrooms. High performance liquid chromatography (HPLC) analysis of ethyl acetate fraction of 70% methanolic extract of the fruiting bodies of PLHS revealed the presence of styrylpyrone-class compounds, davallialactone, hispidin, hypholomine B, and caffeic acid, a compound of the phenylpropanoid pathway.

• Korean Journal of Food Science and Technology
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• v.51 no.3
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• pp.258-262
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• 2019

Although the chemical compositions and biological characteristics of some species of garlic have been investigated, data on Koara garlic are currently lacking. In order to investigate the major compounds and antimicrobial activity of Koara garlic, which was registered as a cultivar in 2012, it was cultivated in Seogwipo, Damyang, and Namhae. Analysis of the chemical composition of the cultivated garlic showed that the alliin, pyruvate contents, and antimicrobial activity were high in garlic grown in Seogwipo ($9.44{\pm}0.28mg/g$, $127.52{\pm}5.50{\mu}M/g$, and 0.31-1.25%, respectively). The total phenol content and reducing sugar contents were abundant in garlic grown in Namhae ($82.23{\pm}0.00g\;GAE/100g$ and $28.59{\pm}0.54mg\;GE/g$, respectively), and the total flavonoid content was high in garlic grown in Damyang ($22.41{\pm}0.77g\;QE/100g$). Although garlics grown in different cultivation areas had different chemical compositions, major compound contents and biological activities of Koara garlic were similar to those of other garlic varieties reported so far. These data will be useful for local farmers, distributors, and consumers.