• Fire Science and Engineering
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• v.23 no.3
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• pp.17-22
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• 2009

Epoxy powder is being in use for insulation materials widely. Especially, in cause of coating insulation can be caused electrical fire and explosion by Joul's heat. This study has been compared and examined around breakdown, arc discharge, and V-t about insulation of Epoxy powder. Also, it has been researched about insulation which is cause of electrical fire and its basic data. According to temperature change, sample KS was stable before the Tg to be about $8{\sim}10%$ decrease in the breakdown test. In case of V-t and arc discharge, it had been kept up suitable characteristic. Also, in case of electrical characteristic, sample KS has excellent capacity.

• Journal of Korean Society for Atmospheric Environment
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• v.11 no.4
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• pp.339-349
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• 1995

The purpose on this study is to optimize the chromatographic determination method of trace aldehydes in ambient air. Carbonyl compounds in urban air were trapped at $C_{18}$ DNPH-coated cartridges, and generated hydrazone derivatives were separated by HPLC and detected by UV-vis spectroscopic detector at 360nm. Formaldehyde and acetaldehyde compounds could be isolated from urban(Seoul) air with more than 95% collection efficiency. The analytical detection limits for formaldehyde and acetaldehyde are 0.06pp $b_{v}$, 0.08pp $b_{v}$ for 108 L air samples, respectively. The precision of this method are 3 .sim. 4%(RSD) for mutiple injection of hydrazone standards. Separation of seven dinitrophenylhydrazones could be achieved in appoximately 20 minutes operation time using $C_{18}$ column with apprepriate eluent. The method was applied to the analysis of aldehydes and ketone in Seoul ambient air. The 24-h ambient levels of formaldehyde, acetaldehyde reached up to 6 .sim. 14 and 3 .sim. 8ppbv, respectively. The daily average concentration ratio were 0.60 for acetaldehyde/formaldehyde.yde.

• Journal of The Korean Astronomical Society
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• v.28 no.2
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• pp.177-196
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• 1995

We present UBV CCD photometry of the double cluster NGC 1850 located at the NW edge of the bar of the Large Magellanic Cloud. The color-magnitude diagram shows that NGC 1850 has a prominent population of massive core-He burning stars which is incomparably richer than any other known star clusters. The reddening is estimated from the (U-B) - (B-V) diagram to be E(B - V) = $0.15{\pm}0.05$. We have estimated the ages of NGC 1850 and a very compact blue star cluster (NGC 1850A) located at ${\sim}30''$ west of NGC 1850 using isochrones based on the convective overshooting models: $80{\sim}10$ Myrs and $5{\sim}2$ Myra, respectively. Several evidence suggest that it is probably the compact cluster NGC 1850A that is responsible for the arc-shaped nebulosity (Henize N 103B) surrounding the east side of NGC 1850.

• Journal of the Korean Applied Science and Technology
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• v.19 no.2
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• pp.137-144
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• 2002

Methyl glycoside oleic acid polyester was successfully prepared from methyl glycosides and methyl oleate by emulsion interesterification in the presence of methyl fructoside oleic acid polyester as an emulsifier. Emulsion interesterification process was optimized to obtain 98% yield of methyl glycoside polyester within $3{\sim}5hr$ at temperatures as relatively low as $90{\sim}150^{\circ}C$ and $20{\sim}200mmHg$ pressure with a five-fold molar ratio of oleic acid methyl ester to methyl glycoside in the presence of 2(w/w)% potassium carbonate and 2O(v/v)% methyl fructoside polyester based on oleic acid methyl ester.

• Journal of the Korean Vacuum Society
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• v.16 no.2
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• pp.134-140
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• 2007

Optical structure of $V_{2}O_{5}$ thin films were analyzed and confirmed, the films were deposited in oxygen partial pressure 0% and 10% by RF magnetron sputtering system. Measurements of the elliptic constants were made in the range of $0.75{\sim}4.0\;eV$ by using phase modulated spectroscopic ellipsometer. The elliptic constants of the thin films were analyze by Double Amorphous dispersion relation. The calculated n, k spectra of $V_{2}O_{5}$ layer were obtained over the range of $0.75{\sim}4.0\;eV$ photon energy. SEM and XRD measurements were also made to validate the ellipsometric analysis and they give good agreement with the structural properties of the films. It was found that optical structure of the $V_{2}O_{5}$ layer has a 3 phase(roughness/film/substrate) and optical absorption properties are greatly depend on the partial pressure of the oxygen.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1485-1487
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• 2002

The 0.96Mg$TiO_3$-0.04Sr$TiO_3$ ceramics with $V_2O_5$(5wt%) were prepared by the conventional mixed oxide method. The structural properties were investigated with sintering temperature by XRD and SEM. According to the X-ray diffraction patterns of the 0.96Mg$TiO_3$-0.04Sr$TiO_3$ceramics with $V_2O_5$(5wt%), the ilmenite $MgTiO_3$ and perovskite $SrTiO_3$ structures were coexisted and secondary phase $MgTi_2O_5$ were appeared. Increasing the sintering temperature, the grain size was increased and three types of grains were exhibited: larger circular grain, small square grain and lapth-shaped grain. In the case of 0.96Mg$TiO_3$-0.04Sr$TiO_3$ ceramics with $V_2O_5$(10wt%), dielectric constant, quality factor and temperature coefficient of resonant frequency were $15.24{\sim}18.55$, $22,890{\sim}42,100$GHz, -24.5${\sim}$+2.414ppm/$^{\circ}C$, respectively.

• Journal of Internet Computing and Services
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• v.8 no.1
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• pp.47-55
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• 2007

In this paper, we propose and observe a system that adopts Common-MCS (Modulation and Coding Scheme) level over all layer and Independent-MCS level for each layer in the combined AMC-V-BLAST (Adaptive Modulation and Coding-Vertical-Bell-lab Layered Space-Time) system. Also, comparing with the combined system using Common-MCS level, we observe throughput performance improvement in case of Independent-MCS level. As a result of simulation, Independent-MCS level case adapts modulation and coding scheme for maximum throughput to each channel condition in separate layer, resulting in improved throughput compared to Common-MCS level case. Especially, the results show that the combined AMC-V-BLAST system with Independent-MCS level achieves a gain of 700kbps in $7{\sim}9dB$ SNR (Signal-to-Noise Ratio) range against using Common-MCS level. In addition, the combined AMC-V-BLAST system using MMSEnulling method with receive diversity is verified that the difference of throughput between Independent MCS level system and common MCS level system in $7dB{\sim}9dB$ SNR is about 350kbps more or less.

• Korean Journal of Environmental Agriculture
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• v.16 no.4
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• pp.347-355
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• 1997

For the selection of plants contained pesticidal active conpounds, 31 families 59 species of native plants were collected and biological activites of their crude extracts against brown planthopper (Nilaparvata lugens), Xanthomonas oryzae pv. oryzae and allelopathy were examined. Among the screened plants, the crude extracts from the leaves of Ricinus communis and Sophora angustifolia showed 100% and 82% of mortality on brown planthopper at the concentration of 1% (w/v) respectively. Mixed crude extracts of Sophora angustifolia root and Melia azedarach seed exhibited 128${\sim}$155% of synergistic effects on the mortality of brown planthopper. In case of fungicidal activity, the crude extracts from the leaves of 8 plants including Chrysanthemum indicum were inhibitory of the growth of Xanthomonas oryzae pv. oryzae at 1%(w/v) soluction. Seed germination of radish (Raphanus sativas) and barnyardgrass (Echinochloa crus-galli) was inhibited by 0.5%(w/v) leaf extracts of Pinus densiflora and Quercus acutissima. MeOH extracts of Pinus denislora leaves gave 100% inhibition in seed germintion of radish at 2%(w/v) soluction and showed a complete inhibition in seedling growth of barnyardgrass as well as radish at 5% solution.

• YAKHAK HOEJI
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• v.38 no.3
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• pp.274-280
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• 1994

A strain of actinomycetes producing extracellular adenosine deaminase inhibitor, strain V-8, was isolated from soil. Strain V-8 was gam positive and its cell wall chemotype was decided as cell wall chemotype I from analysis of diaminopimelic acid isomers and sugar pattern. This strain had a wide range of sugar utilization as carbon sources. The optimal pH and temperature for growth were $6.8{\sim}7.0$ and $28{\sim}30^{\circ}C$, respectively. From the morphological, chemotaxonomical characteristics and analysis of various physiological characteristics, the strain V-8 was identified Streptomyces sp.

• Journal of The Korean Astronomical Society
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• v.28 no.2
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• pp.119-137
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• 1995

The $UBVI_{KC}$ CCD photometry was performed in the central region(${\sim}20'{\times}20'$) of the extremely young open cluster IC1805. Member stars were selected in the (B-V)-(U-B) and (V-I)-(B-V) color-color planes. Applying recent stellar evolutionary models, we derived the age, age-spread, and initial mass function(IMF) of the cluster. IC1805 was found to be an extremely young($t_{age}{\sim}1.5Myr$) and has a flat IMF with the slope of ${\Gamma}=-1.0{\pm}0.2$.