• Bulletin of the Korean Chemical Society
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• v.16 no.3
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• pp.293-296
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• 1995

• Journal of Environmental Science International
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• v.7 no.5
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• pp.669-677
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• 1998

A porous $\alpha$-alumina tube of 2.5 mm O.D. and 1.9 mm I.D. was used as the support of an inorganic membrane. Macropores of the tube, about 150 nm in size, were plugged with silica formed by thermal decomposition of tetraethylorthosilicate at $600^{\circ}C$. The forced cross-flow CVD method that reactant was evacuated through the porous wall of the support was very effective in plugging macropores. The H$_2$ permeance of the prepared membrane was of the order of $10^{-8}/ molㆍs^{-1}/ㆍm^{-2}/. Pa{-1}$/, while the $N_2$ permeance was below $10^{-11}/ molㆍs^{-1}/ㆍm^{-2}/ㆍPa^{-1}$/ at $600^{\circ}C$. This was comparable to that of silica-modified Vycor glass whose size was 4 nm.

• Journal of the Korean Ceramic Society
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• v.54 no.2
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• pp.102-107
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• 2017

The dependence of the IR optical properties of PMMA/$Al_2O_3$ nanocomposite on the alumina content was investigated in the wavelength range of $3500-2800cm^{-1}$. The samples were prepared via emulsion polymerization technique using oleic acid as a coupling agent. Grafting density calculations were carried out by means of elemental analysis CHN to yield the best coupling agent content. FTIR analysis confirmed the existence of a chemical bond between aluminum oxide and oleic acid. The outcomes of XRD analyses showed the presence of cubic gamma aluminum oxide in the nanocomposite, in contrast to the amorphous nature of PMMA. TEM images showed the core-shell morphology of the particles other than pristine PMMA. Optical constants of the nanocomposite were calculated based on FTIR spectra and the Kramers-Kronig equations. The presence of nano alumina modified some of the optical indexes in IR region.

• Analytical Science and Technology
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• v.35 no.3
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• pp.129-135
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• 2022

We tested the pre-treatment of alumina, leucine, alumina mixed with leucine at ratios of 9:1 (Al-Leu (9:1)) and 5:1 (Al-Leu (5:1)), and alumina mixed with sodium lactate at a ratio of 5:1 (Al-Lac (5:1)) on aged fingerprints (1, 7, 14, and 30 days after natural fingerprinting) before cyanoacrylate (CA) fuming to improve the development efficacy. As a result of the experiment, fingerprints with pre-treatment of alumina, leucine, Al-Leu (9:1), Al-Leu (5:1), and Al-Lac (5:1) showed better development efficacy (area and minutiae) than fingerprints without pre-treatment. Therefore, this modified CA fuming method improved the development efficacy with five pretreatments.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.6
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• pp.756-766
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• 1999

This study was performed to evaluate effect on color and opacity of 3 different copy-milled In-Ceram cores by glass infiltration and porcelain veneering. Color was evaluated by the $CIEL^*a^*b^*$ readings were recorded with a Colorimeter, Color difference value(${\Delta}E^*_{ab}$) was calculated and opacity was represented by the contrast ratio. The variance of each color parameter ($L^*,\;a^*,\;b^*$), color difference value, and opacity change after glass-infiltrated and after veneered with porcelain was compared. Three experimental groups were fabricated as follows. Group 1 (Alumina core) 15 Alumina blanks was infiltrated with originally marketed glass (A1) and veneered with porcelain(A1) Group 2 (modified Alumina core) : 15 Alumina blanks was infiltrated with its associated glass(S11) and veneered with porcelain(A1) Group 3 (Spinell core) : 15 Spinell blanks was infiltrated with originally developed glass(S11) and veneered with porcelain(A1). The results were as follows: 1. After glass infiltration, $L^*$ value showed decrease, $a^*$ value showed decrease only group 1(p<0.001) and $b^*$ value showed increase on group 1, increase on group 2, 3(p<0.001). 2. After porcelain veneering, $L^*$ value showed decrease(p<0.001), $a^*$ value showed increase on group 1, decrease on group 2(p<0.05) and $b^*$ value showed decrease on group 1, increase on group 2, 3 (p<0.001). 3. ${\Delta}E^*_{ab}$ between before and after glass infiltration was more than 13.77, and between after glass infiltration and after porcelain veneering more than 19.63. 4. After glass infiltration and porcelain veneering, Alumina showed the lowest $L^*,\;a^*$ value and highest $b^*$ value among 3 different groups (p<0.05). ${\Delta}E^*_{ab}$ between group 1-2, 1-3 was higher than that of group 2-3. 5. After glass infiltration, opacity showed decrease, Group 1 had the highest opacity(p<0.05), but no significant differences between group 2 and 3. Above results suggest that glass infiltration and porcelain veneering effects on color and opacity of In-Ceram core, and that modified In-Ceram Alumina uses single crowns or bridges like In-Ceram Spinell.

• Bulletin of the Korean Chemical Society
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• v.27 no.5
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• pp.789-792
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• 2006

• Archives of Pharmacal Research
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• v.15 no.1
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• pp.5-8
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• 1992

5-Alkyl-3-(1-thioxolanyl-cyclohexenyl)-resorcinol derivatives are readily prepared by boron trifluoride-on-alumina-catalyzed formation of 5-alkylresorcinols with 1-thioxolanyl-2-cyclohexenol; their formation depends on the nature of the alkylgroup. The yield is the highest with 5-(1, 1-dimethylheptyl)-resorcinol. The one with 5-pentylresorcinol is higher than 5-methylresorcinol and resorcinol apparently because of steric effects. The yields of the products increases: 3a (10%), 3b (20%) 3c (48%) and 3d (77%).

• Corrosion Science and Technology
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• v.6 no.3
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• pp.133-139
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• 2007

Nickel powder was coated with aluminum nitrate solution to increase the thermal stability of a porous nickel support and control the nickel content in the Pd-Cu-Ni ternary alloyed membrane. Raw nickel powder and alumina coated nickel powder were uniaxialy pressed by home made press with metal cylindrical mold. Though the used nickel powder prepared by pulsed wire evaporation (PWE) method has a good thermal stability, the porous nickel support was too much sintered and the pores of porous nickel support was plugged at high temperature (over $800^{\circ}C$) making it not suitable for the porous support of a palladium based composite membrane. In order to overcome this problem, the nickel powder was coated by alumina and alumina modified porous nickel support resists up to $1000^{\circ}C$ without pore destruction. Furthermore, the compositions of Pd-Cu-Ni ternary alloy membrane prepared by magnetron sputtering and Cu-reflow could be controlled by not only Cu-reflow temperature but also alumina coating amount. SEM analysis and mercury porosimeter analysis evidenced that the alumina coated on the surface of nickel powder interrupted nickel sintering.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.3
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• pp.233-239
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• 2006

Two different nanofluids were prepared by dispersing $Al_{2}O_3$ nanoparticles in transformer oil after hydrophobic surface modification. The agglomerated alumina nanoparticles with diameters from ${\mu}m$ to mm were ball-milled and then treated with surfactants such as lauric acid, stearic acid and oleic acid. The surface characteristics of modified nanoparticles were examined by FTIR spectroscopy. It showed that the hydrophobicity of nanoparticles was caused by esterification between hydroxyl groups on the particle surface and functional groups of surfactant. The shape and size distribution of ball-milled particles were analyzed by TEM and PSA. The results compared with the primary particles indicated that the size distributions of nanoparticles were dependant on milling times. The dispersion stability of modified nanoparticles dispersed in oil was highly dependent on the composition and amounts of surfactants.

• Proceedings of the Membrane Society of Korea Conference
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• 2000.11a
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• pp.112-114
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• 2000