• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.648-651
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• 2003

Fine $LaAlO_3$ powders were successfully synthesized from $La_2O_3$ and ${\gamma}-Al_2O_3$ powders milling for $10{\sim}50hrs$ via the high energy milling technique (mechanochemical methode) in room temperature and air. The particle size of $LaAlO_3$ powder were estimated from XRD patterns and SEM images to be $160{\sim}180nm$. The $LaAlO_3$ ceramics are derived for the synthesized powders (milling for 10, 30 and 50hrs) by sintering at $1400^{\circ}C$. The micrographs of grains showed a agglomeration and the degree of agglomeration increased with the milling time. The $LaAlO_3$ made from synthesized powders milling for 30hrs can be sintered to 98% of theoretical density at $1,400^{\circ}C$ for 4hrs.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.1
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• pp.61-68
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• 2007

Interfacial fracture energy(${\Gamma}$) between $Al_2O_3$ thin film deposited by Atomic Layer Deposition(ALD) and sputter deposited Cu electrode for embedded PCB applications is measured from a $90^{\circ}$ peel test. While the interfacial fracture energy of $Cu/Al_2O_3$ is very poor, Cr adhesion layer increases the interfacial fracture energy to $39.8{\pm}3.2g/mm\;for\;Ar^+$ RF plasma power density of $0.123W/cm^2$, which seems to come from the enhancement of the mechanical interlocking and Cr-O chemical bonding effects.

• Journal of the Korean Ceramic Society
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• v.42 no.4
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• pp.237-244
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• 2005

We prepared the cylindrical $\gamma-alumina$ pellets of 5 mm in diameter and 10 mm in average length using amorphous alumina and pore generating agent. The pellets were immersed in an aqueous solution of the mixture of $Fe(NO_{3})_{3}{\cdot}9H_{2}O$ and $CH_{3}COOH$. They were then hydrothermally treated at $200^{\circ}C$ for 3 h in autoclave, dried and calcined. For the application as an environmental catalyst, we investigated the decomposition characteristics of aniline and the initiation characteristics of $OH^{\cdot}$ conversion action in $O_{3}$ environment with or without the $Fe_{2}O_{3}$ supported y-alumina catalyst and $O_{3}$ molecule.

• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.125-132
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• 2018

The direct synthesis of $C_2$ chemical directly from methane was studied by employing catalysts with ordered mesopores in a dielectric barrier discharge plasma reactor. The reaction was carried out using MgO/OMA (ordered mesoporous alumina), $MgO/{\gamma}-Al_2O_3$ and $MgO/{\alpha}-Al_2O_3$ as catalysts. When MgO/OMA was applied, it showed excellent performance in the plasma reactor using pulse-type power supply and the selectivity of $C_2$ chemicals was measured as 67%. The effects of metal oxide type, textural property of support, alumina phase and power supply type on catalytic performance were investigated especially in terms of $C_2$ chemical formation. BET (Brunauer, Emmett, Teller), X-ray diffraction, transmission electron microscope and thermogravimetric analysis were used to investigate the characterization of the catalyst before and after the reaction.

• Proceedings of the Membrane Society of Korea Conference
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• 1994.04a
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• pp.58-58
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• 1994

슬립캐스팅법으로 제조한 튜브형 $\alpha$-알루미나 담체 (평균기공크기 = $0.1 \mum$)에 졸-겔 침지코팅(dipcoating) 또는 가압코팅 (pressurized coating) 법에 의하여 극미세입자 $\gamma$-AlOOH, $TiO_2, SiO_2$, 및 aluminosilicate diphasic 졸을 코팅한 후 300 ~ 500$\circ$C 에서 열처리하여 세라믹 복합막을 제조하였다. 복합막 전체에 대한 균열유무는 $N_2$ 기체투과율의 평균압력에 대한 의존성으로부터 평가하였으며, 한외여과 (ultrafiltration)에의 응용성을 규명하기 위하여 막의 재질 및 제조조건에 따른 polyethylene glycol (PEG) 수용액의 분획분자량 변화를 측정하였다. 합성 세라믹 복합막의 분획분자량 측정 결과 $SiO_2$의 경우 2,000 정도로 매우 우수하였으며 $\gamma-Al_2O_3, TiO_2$, 그리고 aluminosilcate 막들은 6,000 ~ 10,000 범위 값을 갖고 있었다. 또한 막의 기공크기 및 분획분자량을 제어하기 위한 방법으로서 $TiO_2$ 복합막을 300 ~ 700$\circ$C 에서 열처리하였으며 이들에 대한 분획분자량 변화를 비교 분석하였다.

• Journal of the Korean Ceramic Society
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• v.26 no.1
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• pp.132-138
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• 1989

High purity(99.99%) spherical particles of hydrated Basic Aluminum Salts(BAS) were prepared by a homogeneous precipitation process utilizing the urea decomposition reaction and characterized by XRD, SEM, TG-DTA, IR and PSA methods. Amorphous hydrated BAS was precipitated in the range of pH 4~6. The molar ratio [Al3+]/[SO42-] for the precipitate particles was about 3.7. With increasing the concentration of aluminum sulfate the precipitation of the hydrated BAS occurred slowly and the precipitate particles with a narrow size distribution were fine(1-2${\mu}{\textrm}{m}$ in diameter). At temperatures in the range 400$^{\circ}$to 95$0^{\circ}C$, desulfurization and dehydroxylization resulted in weight loss with 22%. When the precipitate particles were thermally treated, the crystlline ${\gamma}$-Al2O3 was identifited by XRD at 50$0^{\circ}C$ and ${\gamma}$-Al2O3 particles were transformed into $\alpha$-Al2O3 at 100$0^{\circ}C$. A vermicular network was produced by calcining at 125$0^{\circ}C$ for 30min.

• Journal of Environmental Science International
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• v.22 no.1
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• pp.83-89
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• 2013

Silicon carbide with aluminium oxide was used to remove the sulphur hexafluoride ($SF_6$) gas using microwave irradiation. The destruction and removal efficiencies (DREs) of $SF_6$ were studies as a function of various decomposition temperatures and microwave powers. The decomposition of $SF_6$ gas was analyzed using GC-TCD. XRD (X-ray powder diffraction) and XRF (X-ray Fluorescence Spectrometer) were used to characterize the properties of aluminum oxide. DREs of $SF_6$ were increased as the microwave powers were increased. Additive aluminium oxide on SiC increased the removal efficiencies and decreased the decomposition temperature. The XRD results show that the ${\gamma}-Al_2O_3$ was transformed to ${\alpha}-Al_2O_3$ during $SF_6$ decomposition by microwave irradiation. It was found that the best material to control $SF_6$ was SiC with $Al_2O_3$ 30 wt% in consideration of microwave energy consumption and $SF_6$ decomposition rate.

• Journal of Radiation Industry
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• v.4 no.4
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• pp.359-364
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• 2010

PVDF-HFP (binder)/silylated alumina (inorganic particle)-coated PE (polyethylene) separators were with various compositions of binder and inorganic particle were prepared by a dip-coating process with humidity control (R.H. 25% and 50%) using electron beam irradiation. The morphology of the coated PVDF-$HFP/Al_2O_3$ layer with various compositions of PVDF-HFP and $Al_2O_3$, and humidity condition was found to be an important factor in determining ionic conductivity of the prepared separators. The PVDF-$HFP/Al_2O_3$ (5/5)-coated PE separator prepared at R.H. 50% followed by electron beam irradiation at 200 kGy was applied for lithium-ion polymer battery and the cell test results showed improved high-rate discharge performance and better cyclic stability compared to the cells with the bare PE and the PVDF-HFP-coated PE separators.

• Nuclear Engineering and Technology
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• v.53 no.1
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• pp.282-293
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• 2021

This paper examines gamma-ray shielding properties of SBC-Bx glass system with the chemical composition of 40SiO₂-10B₂O₃-xBaO-(45-x)CaO- yZnO- zMgO (where x = 0, 10, 20, 30, and 35 mol% and y = z = 6 mol%). Mass attenuation coefficient (µ/ρ) which is an essential parameter to study gamma-ray shielding properties was obtained in the photon energy range of 0.015-15 MeV using PHITS Monte Carlo code for the proposed glasses. The obtained results were compared with those calculated by WinXCOM program. Both the values of PHITS code and WinXCOM program were observed in very good agreement. The (µ/ρ values were then used to derive mean free path (MFP), electron density (N_eff), effective atomic number (Z_eff), and half value layer (HVL) for all the glasses involved. Additionally, G-P method was employed to estimate exposure buildup factor (EBF) for each glass in the energy range of 0.015-15 MeV up to penetration depths of 40 mfp. The results reveal that gamma-ray shielding effectiveness of the SBC-Bx glasses evolves with increasing BaO content in the glass sample. Such that SBC-B35 glass has superior shielding capacity against gamma-rays among the studied glasses. Gamma-ray shielding properties of SBC-B35 glass were compared with different conventional shielding materials, commercial glasses, and newly developed HMO glasse. Therefore, the investigated glasses have potential uses in gamma shielding applications.

• Journal of the Korean Ceramic Society
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• v.38 no.7
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• pp.621-627
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• 2001

알루미나 졸에 평균 25nm의 TiO$_2$(Degussa P25) 광 촉매 분말을 분산하여 광촉매 코팅제를 제조하였다. 점도 약 24 cps를 가지 4.4 wt%의 알루미나 졸로부터 약 300nm 두께의 코팅막이 제조되었으며, 졸 점도의 증가에 비례하여 코팅막의 두께도 증가하였다. TiO$_2$광 촉매의 코팅용 바인더로 이용한 알루미나 졸의 결정형은 25~30$0^{\circ}C$에서 pseudo boehmite (AlOOH)이었으며, 50$0^{\circ}C$ 이상에서는 ${\gamma}$-Al$_2$O$_3$으로 전환되었다. AlOOH/TiO$_2$코팅막은 oleic acid와 humic acid에 대한 기상 및 수상 조건에서의 광 촉매 실험에서 우수한 유기물의 광분해 효능을 나타내었다. 아울러 EGI(Electro-Galvanized Iron)에 코팅된 AlOOH/TiO$_2$코팅막은 내식성 및 내지문성의 효과도 부수적으로 나타내었다.