• Journal of the Korean Ceramic Society
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• v.49 no.6
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• pp.561-565
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• 2012

Due to their unique combination of properties, Si-based ceramics, such as silicon carbide (SiC), silicon nitride ($Si_3N_4$) and silicon oxide ($SiO_2$ as fused silica), have a range of industrial applications in fields such as the chemical industry, aluminum manufacturing, oil and gas production and solar cell production. For each materials group, examples of typical applications from various industry sectors are presented while taking into account the property fingerprint.

• Bulletin of the Korean Chemical Society
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• v.18 no.8
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• pp.886-889
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• 1997

The crystal structure and optical properties of copper nanoparticles, prepared in fused silica by ion-implantation and subsequent heat-treatment, were characterized by X-ray, TEM, linear absorption, and degenerate four-wave mixing (DFWM) technique. The X-ray data show fcc lattice structure of the nanocrystals and their size was measured as 8-20 nanometer by high resolution TEM. Using DFWM, the third-order nonlinear optical coefficient of the Cu-SiO2 thin films was measured as 0.4-1.1×10-8 esu in the surface plasmon resonance absorption region (540-570 nm).

• Korean Journal of Materials Research
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• v.18 no.11
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• pp.604-609
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• 2008

The sintering behavior of zircon with silica was investigated. Zircon with 5 vol% of sedimentation $SiO_2$ resulted in the apparent density of $4.45\;g/cm^3$, the diametral tensile strength of $12.125\;kgf/cm^2$, and the micro Vickers hardness of 1283 HV. The dissociation temperature and mechanical characteristics of the $ZrSiO_4$ were changed with different kinds of $SiO_2$. $SiO_2$ addition prevented dissociation of $ZrSiO_4$. Zircon with 5 vol% of sedimentation $SiO_2$ and with 5 vol% of fused $SiO_2$ resulted in increased diametral tensile strength and increased micro Vickers hardness by suppression of $ZrSiO_4$ dissociation and low temperature liquid $SiO_2$ formation. Zircon with fumed $SiO_2$ and quartz $SiO_2$ resulted in decreased diametral tensile strength and decreased micro Vickers hardness because of cristobalite and quartz phase formation and high temperature liquid $SiO_2$ formation. Zircon with 10 vol% of $SiO_2$ resulted in decreased diametral tensile strength and decreased micro Vickers hardness because of weak particle coupling due to excess formation of liquid $SiO_2$.

• Korean Journal of Materials Research
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• v.8 no.10
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• pp.879-883
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• 1998

In the vacuum casting process for superalloys, molten metal are poured into the heated ceramic mold up to $1000^{\circ}C~1700^{\circ}C$. The mold has to have the high temperature strength during casting and made by hlgh purity alumina. In this sturdy, the mold was made by low purity alumina and changed silica contents intended to have high strength The 7.7wt.% SiOz specimens have 10- 55% higher strength than others in room and high temp. Therefore, the cast mold has been developed in this study for single crystal vacuum cast by controlling the ratio of fused alumina and colloidal silica which are used commercially for conventional casting in industries.

• Korean Journal of Soil Science and Fertilizer
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• v.10 no.4
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• pp.245-256
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• 1978

The effects of different particle size distribution of fused phosphate on the changes of phosphorus content in soil and plant, growth and yield of paddy rice were investigated through pot and field experiments. The following results were obtained. 1. Negative correlation was found between unhulled rice yield and the composition of fused phosphate whose particle size was larger than 28 mesh, and 65 to 150 mesh, and highly significant correlation was found between unhulled rice yield and the composition of fused phosphate whose particle size was 28 to 48 mesh. But no significant correlation was found betweeen unhulled rice yield and the composition of fused phosphate whose particle size was 48 to 65 mesh. Thus the composition of 56% of 28 to 48 mesh particles and 44% of 48 to 65 mesh particles would give the best effect. 2. In the soil of the Jeonbug series rice plant in the plots treated with fine single textured fused phosphate showed poor early growth, i.e. poor tillering and short plant height. But at harvesting stage it showed rather increased number of tillers and higher plant height. Of the composite fused phosphate the more particles of 28 to 48 mesh it had, the better growth it showed. In the soil of the Yesan series rice plant in the treated plots showed much better tillering and higher plant height in contrast with that in the control plots. Of the single textured fused phosphate the finer particles showed better growth, while of the composite fused phosphate the more particles finer than 48 mesh it had, the poorer the tillering. 3. The content of available phosphorus in the soil tended to increase as the particles of both single textured and composite phosphate became finer. The soil phosphorus content decreased as the content of phosphorus absorbed by rice plant increased at each stage of growth, and the amount of soil phophorus decreased became larger as the the particles were finer. The amount of available phosphorus in the treated soils was larger in the soil of the Yesan series than in the soil of the Jeonbug series which was a long cultivated soil and contained relatively high phosphorus. 4. In the single textured fused phosphate the amount of phosphorus absorbed by rice plant tended to increase as the particles were finer, and great difference was found at heading stage, but at harvesting stage little difference was found for all the plots. In the field experiment in the soil of the Jeonbug series more phosphorus was absorbed by rice plant in the plots treated with the composite fused phosphate of higher content of 28 to 48 mesh particles. In the pot experiment the amount of phosphorus absorbed by rice plant was highest in the plots treated with the composite fused phosphate of 53.35% of particles larger than 48 mesh and 46.6% of particles smaller than 48 mesh. In the pot experiment in the Yesan series the amount of absorbed phophorus was highest in the plots treated with the fused phosphate of 47.75% of particles larger than 48 mesh and 50. 216% of particles smaller than 48 mesh. 5. A reverse relationship was found between the absorbed phosphorus and silica. In the pot experiment in the soils of both the Jeonbug and Yesan series the amount of phosphorus absorbed by rice plant increased as the particles were finer, while the amount of absorbed silica tended to decrease.

• Journal of Ginseng Research
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• v.13 no.2
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• pp.198-201
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• 1989

The amounts of panaxynol and panaxydol, which are major polyacetylone compounds In white ginseng were determined by capillary-GC (FID), and the extraction efficiencies when using varictus extraction solvents (petroleum ether, dichloromethane, ether, ethyl acetate, acetone, acetonitrilr and methanol) and various extraction methods (shaking, Soxhlet and reflux) were compared . The GC column was SPB-1 fused silica capillary (0.25 mm id x30 m, Supelco), and the column oven temperature was programmed to rise from $200^{\circ}C$ to $300^{\circ}C$ at the rate of $4^{\circ}C$ per minute. The extraction efficiencies for panaxynol and panaxydol according to extraction souvtints were the highest in methanol and decreased in the order of dichloromethane, acetone, ether, ethyl acetate, acetonitrile and petroleum ether. The extracttion efficiencies for panaxynol and panaxydol according to extraction methods were the highest for reflux and the lowest for shaking, and those with Soxhlet were almost equal to those for reflux. The analytical amounts of panaxynol and panaxydol obtained by reflux with methanol %mere 4.2 and 6.4 mg/g, respectittely in white ginseng.

• Journal of Ginseng Research
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• v.13 no.2
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• pp.183-188
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• 1989

A gas chromatographic method was developed for determination of the concentration of three major polyacetylene compounds in ginseng roots---panaxynol, panaxydol and panaxytriol. The column and the detector used were an SPB-1 fused silica capillary (0.2mm i.d.$\times$30m, Supelco) and a flame ionization detector (FID). The column oven temperature was kept at $250^{\circ}C$ isothermally The retention times of panaxynol, panaxydol and panaxytriol peaks were 4.2,5.1 and 6.9 min before TMS-derivatitration and 4.5,5.4 and 7.4 min after TMS-derivatization, respectively. The minimum determinable concentrations of panaxynol, panaxydol and panaxytriol before TMS-derivatiEation were at the 20, 50 and 100 ppm levels, while the concentrations of panaxydol and panaxytriol as well as panaxynol after TMS- derivatisation could be towered to the 5 ppm level. The panaxynol, panaxydol and panaxytriol contents in red ginseng were determined by use of this method after TMS-derivatization : the amounts obtained were 724, 721 and 71$\mu\textrm{g}$/g, respectively.

• Applied Biological Chemistry
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• v.32 no.4
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• pp.344-349
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• 1989

Eleven lignan compounds in fruits of Schisandra chinensis BAILLON were identified by gas chromatography/mass spectrometry(GC/MS). The GC/MS conditions were as followed: the GC column used was SPB-1 fused silica capillary $(0.25mm\;id{\times}30m,Supelco)$ and the column oven temperature was programmed from $200^{\circ}C$ to $300^{\circ}C$ at the rate of $4^{\circ}C$ per minute; the MS ionization voltage was 70eV (EI mode). The compounds identified were gomisin J $(M^+;\;388)$, deoxyschizandrin$(M^+;\;416)$, gomisin N $(M^+;\;400)$, schizandrin$(M^+;\;432)$, wuweizisu C $(M^+;\;384)$, gomisin A $(M^+;\;416)$, angeloylgomisin H $(M^+;\;500)$, tigloylgomisin H $(M^+;\;500)$, angeloylgomisin Q $(M^+;\;530)$, gomisin B $(M^+;\;514)$ and benzoylgomisin H $(M^+;\;522)$, peaks of which were separated well on the GC chromatogram.

• Journal of the Korean Ceramic Society
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• v.41 no.9
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• pp.663-669
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• 2004

Mullite and cordierite, which were stable oxides having excellent thermal and chemical characteristics, were widely used as an engineering and electronic materials. However, thermal shock resistance of the mullite was detriorated, and strength of the cordierite was also reduced at high temperatures. The mullite-cordierite composite powders were synthesized for solving these problems in this study. The mullite-cordierite composite powders were manufactured by the solution-polymerization method using mixtures of fused silica, aluminium nitrate, magnesium nitrate, and PVA. Crystallinity, phase formation, density, and surface area of the synthesis powders were characteristics. Fine mullite-cordlerite composite powders were successfully synthesized at 1300$^{\circ}C$ and their surface areas were about 20㎡/g after planetary milling for 1h. With increasing the milling time, surface area increased to 23 ㎡/g for 4h ana 24㎡/g for 8h.

• Korean Journal of Optics and Photonics
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• v.14 no.1
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• pp.1-7
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• 2003

We determined the optical constants of organic light emitting material of Alq$_3$ in a spectral range between 1.5 and 6 eV using the physical model introduced by Forouhi and Bloomer［Phys. Rev. B 34, pp. 7018-7026, 1986.］. The initial parameters of $A_i,\;B_i,\;C_i$ of Forouhi-Bloomer dispersion relations were determined from the absorption peaks and widths of absorption spectra of the Alq$_3$ film. The refractive index of substrate, a fused silica, is derived from the Sellmeier equation with the measured transmittance and reflectance spectra. Then, the complex refractive index and thickness of the Alq$_3$ film were calculated by use of a nonlinear least square fitting program with the Forouhi-Bloomer dispersion relation and the measured transmittance and reflectance spectra.