• Journal of Microbiology and Biotechnology
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• 제11권6호
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• pp.1106-1110
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• 2001

The parasporal biogenesis of crystal inclusion during the sporulation of Bacillus sphaericus strain 1593 was observed using transmission electron microscopy. The crystal biogenesis and sporulation process involved a sequence of events talking about 10 h. The sporulation Precesses were found to be similar to previous findings. The crystal biogenesis of B. sphaericus was initiated at the start of engulfment and nearly completed by the time of exosporium formation. The crystal formation was clearly associated with the outer forespore membrane from stages III through VI, and the crystals grew from polypeptide-like chains originated from the outer forespore membrane. These observations are different from previous findings, which report no association with the forespore membrane. The crystals were located adjacent to the outer membrane of the spore until the release stage. The axes size of the bipyramidal crystal was approximately $0.25{\mu}m{\times}42{\mu}m$. During crystal biogenesis, the crystal development could be classified into four stages; initiation stage Cl (sporulation stage . III), growth stage C2 (sporulation III to V), envelopment and maturation C3 (sporulation V to V), and finally release stage C4 (sporulation Vll).

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.847-848
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• 2004

We studied a low density 8CB liquid crystal-hydrophobic aerosil dispersions imbedded in submicron-size cylindrical pores. The nanosize spherical aerosil particles are adsorbed at the pore wall and hinder the planar anchoring. The adsorption is temperature dependent, and an axial to radial molecular configuration transition occurs within the cylindrical pores.

• 한국세라믹학회지
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• 제27권1호
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• pp.43-47
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• 1990

An attempt was made to grow Y-Ba-Cu-O single crystals by skull method(cold crucible process). Grown YBa2Cu3O7-x(YBC) single crystals were obtained from the upper part of the YBC solid mixture. There were plate-like YBC single crystals aligned with solidified flux along the crystal growth direction. Single crystal size was (5$\times$2$\times$0.2㎣) and was grown to a-b plane of YBC crystal structure which can flow super currents. Optical microscope and X-ray diffraction were employed characterize these microstructure and YBC single crystals.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1996년도 The 9th KACG Technical Annual Meeting and the 3rd Korea-Japan EMGS (Electronic Materials Growth Symposium)
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• pp.88-138
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• 1996

Electronics grew up to the largest industry in the world supported by Si wafer. In near future, the Si wafer may use 300mm in diameter for economic requirement. This size wafer may use to produce large logic chip, 256Mbit DRAM, and other large complex and high density chip. Then, the quality including flatness and crustal characters may be required very high performance. And, their price should be reasonable and high quantity may be required. These requirements should be solve lot of hard problems of crystal growth, wafering mechanical processing and their cost problems. In this presentation, I may discuss following items.

• 한국결정성장학회지
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• 제9권2호
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• pp.191-196
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• 1999

수열합성법을 이용한 $\alpha$-$SiO_2$ 단결정 분말 제조시 교반의 추가와 승온속도의 변화가 입자의 결정성, 입도분포 및 평균입경에 미치는 영향을 조사하였다. KOH를 광화제로 사용하였으며, $350^{\circ}C$에서 3시간 동안 반응을 시켜 평균입자 크기가 1~3.2$\mu\textrm{m}$인 결정 분말을 제조하였다. 실험결과 반응초기부터 교반을 한 경우에는 교반속도가 증가함에 따라 평균입경이 감소했으나, 결정성은 나빠지다가 150r/min 이상에서는 다시 좋아졌다. 또한 반응 도중에 교반을 추가하면 반응초기부터 교반을 한 경우보다 입자의 크기가 커졌다. 그러나 교반속도를 일정하게 한 후 승온속도를 느리게 하면 입자의 크기가 작아졌다.

• Bulletin of the Korean Chemical Society
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• 제29권8호
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• pp.1495-1498
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• 2008

$TiO_2$ nanopowders were synthesized by new sol-gel combustion hybrid method using acetylene black as a fuel. The dried gels exhibited autocatalytic combustion behaviour. $TiO_2$ nanopowders with an anatase structure and a narrow size distribution were obtained at 400-600 ${^{\circ}C}$. Their crystal structures were examined by powder Xray diffraction (XRD) and their morphology and crystal size were investigated by scanning electron microscopy (SEM). The crystal size of the nanopowders was found to be in the range of 15-20 nm. $TiO_2$ powders synthesized at 500 ${^{\circ}C}$ and 600 ${^{\circ}C}$ were applied to a dye solar cell. An efficiency of 5.2% for the conversion of solar energy to electricity ($J_{sc}$ = 11.79 mA/$cm^2$, $V_{oc}$ = 0.73 V, and FF = 0.58) was obtained for an AM 1.5 irradiation (100 mW/$cm^2$) using the $TiO_2$ nanopowder synthesized by the sol-gel combustion hybrid method at 500 ${^{\circ}C}$.

• 한국결정성장학회지
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• 제25권6호
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• pp.280-284
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• 2015

Au doped $TiO_2$ nanoparticles have been synthesized using a reverse micelle technique combined with metal alkoxide hydrolysis and condensation. Au doped $TiO_2$ was coated with glass substrate. The size of the particles and thickness of the coating can be controlled by manipulating the relative rates of the hydrolysis and condensation reaction of TTIP within the micro-emulsion. The average size of synthesized Au doped $TiO_2$ nanoparticle was about in the size range of 15 to 25 nm and the Au particles formed mainly the range of 2 to 10 nm in diameter. The effect of synthesis parameters, such as the molar ratio of water to TTIP and the molar ratio of water to surfactant, are discussed. The synthesized nanopaticles were coated on glass substrate by a spin coating process. The thickness of thin film was about 80 nm. The degradation of MB on a $TiO_2$ thin film was enhanced over 20 % efficiency by the incorporation of Au.

• 한국세라믹학회지
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• 제55권6호
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• pp.618-624
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• 2018

We developed a mass production method that simultaneously controls the phase transformation and crystal size of $TiO_2$ coatings on multiwalled carbon nanotubes (MWCNTs). Initially, MWCNTs were successfully coated with amorphous 15-20-nm-thick $TiO_2$ by an in-situ sol-gel method. As the calcination temperature increased in both air and argon atmospheres, the amorphous $TiO_2$ was gradually transformed into the fully anatase phase at approximately $600^{\circ}C$, a mixture of the anatase and rutile phases at approximately $700^{\circ}C$, and the fully rutile phase above approximately $800^{\circ}C$. The crystal size increased with increasing calcination temperature. Moreover, above $600^{\circ}C$, the size of crystals formed in air was approximately twice that of crystals formed in argon. The reason is thought to be that MWCNTs, which continuously supported the stresses associated with the reconstructive phase transformation, disappeared owing to complete oxidation in air at these high temperatures.

• 한국결정성장학회지
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• 제8권4호
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• pp.563-566
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• 1998

BaTiO3 분말은 티타늄 수산화물 용액과 비륨수산화물 용액을 혼합하여 적당한 온도와 압력하에서 합성되었다. 미분말이 얻어진 온도는 160~$185^{\circ}C$, 압력은 5~10kg/$\textrm{cm}^2$이였다. 분말의 모양과 크기는 주사전자현미경, 결정 상은 X-선 회절로 분석하였다. 분말합성온도, 반응시간 및 농도변화에 따르는 분말의 물성을 조사하였다. $BaTiO_3$ 분말의 평균입자크기는 반응온도 및 시간이 증가함에 따라 증가하였다. $170^{\circ}C$에서 8시간 반응시킨 경우의 평균입자크기는 약 30nm이고, 입도 분포는 균일하였다.

• 한국염색가공학회지
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• 제12권2호
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• pp.103-110
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• 2000

To examine the physical properties of POY through the microstructure control, the crystal structure such as the crystallinity, the crystallite size, the orientation, the shrinkage, the tensile properties, and the thermal stress of POY(80/48, SD) were examined at different draw ratios and annealing temperatures. From the examination following conclusions were obtained : 1. The crystallinity was more effected by the heat setting temperature than by the draw ratio. The increasing rate was greatest at the heat setting temperature range of $170~190^\circ{C}$. 2. The crystallite size perpendicular to the fiber axis was more effected by the annealing temperature at lower draw ratios. On the other hand, the crystal and amorphous orientations were more effected by the heat setting at higher draw ratios. 3. The boiling shrinkage did not change significantly, but the total shrinkage showed 13% at the draw ratio 1.9 and the heat setting temperature $170^\circ{C}$. 4. The maximum thermal stress increased with increasing the draw ratio and decreasing the heat setting temperature in the temperature range of $170~210^\circ{C}$. At the draw ratio 1.9 and the heat setting temperature $170^\circ{C}$, the maximum thermal stress found was 1.1gf/d. 5. In the heat setting temperature above $170^\circ{C}$ after the drawing, the crystallinity, the crystallite size, the orientation, and the strength increased with increasing temperature, but the shrinkage and the maximum thermal stress decreased with increasing temperature.