• Korean Journal of Crystallography
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• v.14 no.1
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• pp.16-23
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• 2003

The electronic structure and chemical bonding of β-MnO₂ were theoretically investigated by DV-X/sub α/ (the discrete variation X/sub α/) method. which is a sort of the first principle molecular orbital method using Hatre-Fock-Slater approximation. The calculations on several cluster models having different sizes were carried out for the determination of a model suited for analyzing bulk state. The Mn/sub 15/O/sub 56/ model was selected as a sufficiently suitable model for the calculation of electronic state and chemical bonding by the comparison of the calculated XPS (X-ray photo-electron spectrum) and experimentally measured XPS. By using this model, the electron energy level, the density of state, the bond overlap population, the charge density distribution, and the net ionic transfer between cations and anions were calculated and discussed.

• Microbiology and Biotechnology Letters
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• v.22 no.3
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• pp.283-289
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• 1994

The production of maltose utilizing swollen extrusion starch seems to have many technical advantages, such as, high reaction rate and high yield, production of high purity concentrated maltose, and low energy consumption, over the conventional method utilizing liquefied starch. The characteristics of maltose formation in heterogeneous enzyme reaction system comtaining swollen extrusion starch was investigated using fungal $\alpha $-amylase. The influence of extrusion conditions on structure of extruded starch, such as, degree of gelatinization, water absorption index, and water solubility index was analyzed. The relationship between the structural features and maltose forming reaction was investigated, and the result was analyzed in terms of surface reaction of insoluble extruded swollen starch. The characteristics of maltose formation from swollen sxtrusion starch was compared using endo-type fungal $\alpha $-amylase and exo-type $\beta $anylase, and the structural trasformation of extruded starch was also observed to clarify the reaction mechanism.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.3
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• pp.44-50
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• 2019

HNIW is a high energy material and has four crystalline phases, it is known that the thermal properties of the material depend on the crystal phase. In this sturdy, the viscosity, mechanical and burning properties of a solid propellant with nitrate ester polyester(NEPE) system with respect to the crystal phases of HNIW. According to the crystal phase of HNIW, the mechanical properties of the cured propellant did not change considerably, however differences were observed in the burning properties. Considering both a high density and stable burning properties, the optimum crystal phase of HNIW can be identified as the main factor influencing to the NEPE system propellant.

• Korean Journal of Materials Research
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• v.7 no.2
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• pp.129-135
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• 1997

This study has investigated the effects of aging treatment on thc nlechanical propcrries of blg-iiAl-x%nix - 0.1.2) alloys fabricated by the squeeze castmg process. The microstructurcs of as-squeeze cast were composed of pro eurectic $\alpha$ magnesium solid solution, super saturated $\alpha$ solid solution and $\beta(Mg_{17}AI_{12}$) compund. Agcd at both $200^{\circ}C$ and $240^{\circ}C$, Mg--6AixZn alloys showed the peak hardness due to the formation of $\beta(Mg_{17}AI_{12}$) precipitates. The tiiscontinuous precipitates of the lamella r\.pe are predominant at $200^{\circ}C$ aging tredrment. tvhilc. the finely dispersed continu ous precipitates were major type at $240^{\circ}C$ treatment. Mg-- GAI-xZn a1loi.s fabricated hy the squeeze casting process had the hetter combination of tensile strength and elongation compared to the conventionally cast alloys. As increascci zinc: contents. the tensile strength was increased 11y the soiid solutirin strengthening effect of zinc,.

• Weed & Turfgrass Science
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• v.2 no.1
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• pp.30-37
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• 2013

The objective of this research was to understand herbicidal activity of essential oils isolated from leaves of pine (Pinus densiflora), nut pine (Pinus koraiensis), larch (Larix kaempferi) and khingan fir (Abies nephrolepsis) in Korea. In a seed bioassay, essential oils of nut pine, larch and khingan fir inhibited the growth of rapeseed (Brassica napus) seedlings by 50% at 4,766, 1,865, $5,934{\mu}g\;ml^{-1}$, respectively, however, that of pine did not show any herbicidal effect. In a green house experiment, fall panicum, Southern crabgrass, sorghum, barnyardgrass, quackgrass, black nightshade, Indian jointvetch, velvet leaf, and Japanese morningglory were controlled in 24 hours by the foliar application of 10% essential oils from pine, nut pine, larch and khingan fir. The treated plant parts showed burndown effect, however, new shoots appeared 3 days after treatment. Results of GC-MS analysis showed that essential oils from pine, nut pine, larch and khingan fir contained 16, 25, 25, and 16 compounds, respectively, with hydrocarbons, alcohols, ketones, and esters. The major compounds of the essential oils were 3-carene, bornyl acetate, camphene, limonene, ${\alpha}$-pinene, ${\beta}$-pinene and ${\beta}$-phellandrene.

• The Korean Journal of Food And Nutrition
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• v.19 no.1
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• pp.38-46
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• 2006

The purpose of this study was to analyze the flavors of four fresh herbs(rosemary, basil, applemint, and majoram) and when they are fried, boiled, baked, and microwaved. Among the 18 flavors in rosemary, 37.40% was composed of ${\alpha}$-pinene(flavor of refreshing pine). The next highest composition of rosemary was 1,8-ci-neole(fresh, cool, sweet flavor) with 23.34%. In basil, 1,8-cineol had the most composition with 32.9%, and next was 3-hexen-1-ol(delicate floral fragrance) with 20.6%. When it was boiled, it barely had loss and when it was fired, only 10% of its flavor was left. Trans-${\beta}$-ocimene(camphoraceous and pine-like flavor) composed applemint with 16.66% and ${\beta}$-pinene(dry-woody and resinous-piney flavor) with 12.99%. Majoram was composed with 21 differrent flavors, 18.80% was composed of sabinene(spicy, woody-herbaceous flavor) and ${\gamma}$-terpine(citrusy flavor) composed 15.61% of majoram. Majoram had more flavor left when cooked compared to other herbs. In conclusion, rosemary and majoram had the most stability than other herbs, and boiling and baking left more flavor than frying them.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.2
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• pp.351-357
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• 1997

The cyclodextrin glycosyltransferase(EC 3.2.1.19) from Bacillus firmus was purified by precipitating with ammonium sulfate followed by, DEAE-Sephadex A-50 column chromatography and Sephadex G-100 column chromatography. In this way, we were able to obtain the single band protein on SDS-PAGE with a yield of 12%, whose purity was 49 fold. The purified CGTase was identified as a protein having molecular weight of approximately 80,000 dalton and isoelectric point of 9.6. The optimum pH and temperature for the enzyme activity were 8.0 and $65^{\circ}C$, respectively. The enzyme was stable at between pH 5.5 and 9.0 and up to $50^{\circ}C$. After 24hr of enzyme reaction using soluble starch as substrate, the ratio of ${\alpha}-$, ${\beta}-$ and ${\gamma}-cyclodextrin$ production was 0.01 : 2.90 : 1.00, respectively. And this CGTase pro-duced mainly ${\beta}-$ and ${\gamma}-cyclodextrin$.

• Korean Journal of Microbiology
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• v.43 no.4
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• pp.292-297
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• 2007

This study was performed to compare in vitro immune enhancing effects of polysaccharides extracted from cultivated mycelia of Agaricus blazei Murill. Carbohydrate contents of semi-purified polysaccharides were 85.6% and 95.3%, while ${\beta}$-glucan conents were 67.9% and 88.1% for intracellular and extracellular polysaccharide, respectively. Samples were adjusted to the same in their carbohydrate contents before efficacy tests. Both intracellular and extracellular polysaccharide increased nitric oxide (NO) synthesis of macrophage RAW 264.7 in dose dependent manner, and the maximum increase rate was 53.9 and 53.1% in intracellular and extraceltular polysaccharide, respectively. The polysaccharides also increased synthesis of cytokines such as interleukin (IL)-$1{\beta}$, IL-6 and tumor necrosis factor (TNF)-${\alpha}$ in RAW 264.7. For all the 3 cytokines, the increase rate of synthesis was much higher in extracellular polysaccharide compared to intracellular polysaccharide, especially at low concentration. Both polysaccarides increased the proliferation of splenocytes in vitro, intracellular polysaccharide showed increase in dose dependent manner while extraceltular polysaccharide showed increase untill medium concentration ($250\;{\mu}g/ml$). They did not show direct cytotoxicity against cancer cells such as B16F0 melanoma. As results, it was regarded that the both intracellular and extracellular polysaccharide from A. blazei showed immune enhancing effects in vitro, but the activity is higher in extracellular polysaccharide compared to intracellular polysaccharide.

• Korean Journal of Food Science and Technology
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• v.31 no.5
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• pp.1178-1183
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• 1999

Essential oils were isolated from the peel of mandarin (Citrus unshiu Marc. Var. Okitsu) cultivated in Cheju Island. Among three different isolation methods investigated, simultaneous distillation gave higher yield 1.14%(w/w) than solvent extraction or cold pressing. The densities of essential oils were between 0.8409 and 0.8530, which showed no significant effect of the isolation methods. Some variations in the number of constituents detected and the content of d-limonene in the peel oils were observed depending upon the isolation methods. The citrus fruit was collected seasonally from the field and used as a sample for analysis. The peel thickness and the peel content of citrus fruit were around 2 mm and about 17% on wet weight basis, respectively, in harvest season. The maximum yield of essential oils was obtained in September from citrus peels just prior to ripeness and thereafter the yield had a tendency of decrease but remained over 1%(w/w). The relative content of d-limonene, the major constituent of citrus peel oils. increased gradually with ripening up to 68.69%(relative peak area, RPA). The other minor constituents were ${\gamma}-terpinene,\;{\beta}-elemene$, farnesene, hexadecanoic acid, ${\alpha}-pinene,\; {\beta}-myrcene$ and linalool in the decreasing order of their own contents of 7.75, 2.96, 2.29, 1.76, 1.63, 1.56 and 1.46%(RPA).

• Journal of the Korean Society of Food Culture
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• v.17 no.5
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• pp.535-542
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• 2002

The volatile compounds of Myungtae (Alaska pollack) sikhae obtained by simultaneous steam distillation and extraction(SDE) apparatus were separated by gas chromatography(GC) and gas chromatography mass spectrometry(GC/MS). The totals of 155 volatile flavor components was identified in traditional Kyungsangdo Myungtae (Alaska pollack) sikhae, respectively. ${\alpha}$-Zingihirene(11.03%) (E)-di-2-propenyl disulfide(7.95%) ${\beta}$-cironellol(6.02%), methyl allyl disulfide(3.58%), cryptone(3.39%), camphene(3.23%), pentanol(3.21%), penadecanal(2.66%) and ${\beta}$-phellandrene(2.06%) were contained as the main compounds of Myungtae shikae. The fraction obtained from sikhae were tested for electron donating ability, angiotensin converting enzyme and xanthine oxidase inhibitory activity. There was no electron donating abilities$(SC_{50})$ of hexane and water fraction. On the other hand, the abilities of ethylacetate fraction and butanol fraction showed $310.64\;{\mu}g/mL,\;1096.49\;{\mu}g/mL$, respectively. Angiotensin converting enzyme inhibitory activities$(IC_{50})$ of ethylacetate fraction and butanol fraction were 1.623 mg/mL, 1.303 mg/mL, respectively. Xanthine oxidase inhibitory activities$(IC_{50})$ of ethylacetate fraction and butanol fraction were 3.591 mg/mL, 2.083 mg/mL, respectively.