• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.12
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• pp.822-827
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• 2017

Mg/Al layered double hydroxide with two-dimensional (2D) nanostructures was synthesized by a hydrothermal technique. The morphology and aspect ratio of $Mg_4Al_2(OH)_{14}3H_2O$ were controlled by the concentration and kinds of the hydrolysis agent, and temperature. The aspect ratio of $Mg_4Al_2(OH)_{14}3H_2O$ layered double hydroxides with the 2D hexagonal crystal structure was tailored from about 12.6 to about 45.7. The intercalated $CO{_3}^{2-}$ anions of the synthesized 2D $Mg_4Al_2(OH)_{14}3H_2O$ layered double hydroxides were exchanged to $NO_3{^-}$ anions. The bulk 2D $Mg_4Al_2(OH)_{14}3H_2O$ layered double hydroxides with the increased space between two layers due to the anion exchange were exfoliated in a formamide solution. The aspect ratio of the exfoliated 2D $Mg_4Al_2(OH)_{14}3H_2O$ layered double hydroxides increased to 570.3.

• Journal of the Korean Ceramic Society
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• v.37 no.5
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• pp.459-465
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• 2000

3CaO.3Al2O3.CaSO4(C4A3)clinker was prepared by solid state reaction and then its hydration property was investigated. C4A3 clinker was fired at various temperatures in the range of 700~135$0^{\circ}C$. The hydration of it was studied by XRD, DSC, Solid-state 27Al MAS NMR and SEM. According to the results, the Ca4A3 clinker was produced by reacting calcium aluminates with CaSO4 and Al2O3 and C4A3 was formed as a main phase after calcining at 120$0^{\circ}C$. The hydration products were mainly calcium monosulfoaluminate hydrate and Al(OH)3, and they were produced after 2hrs of hydration. However the hydration rate was about 74% at 3days.

• Journal of the Korean Ceramic Society
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• v.26 no.2
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• pp.210-220
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• 1989

The properties of the powder of Al2O3-15v/o ZrO2(＋3m/o Y2O3) system prepared by co-precipitation method at the pH values of 7, 9, 10 and 11 were investigated. Al2(SO4)3.18H2O, ZrOCl2.8H2O and YCl3.6H2O were used as starting materials and NH4OH as a precipitation agent. Zirconium hydroxide decreased the specific surface area of aluminum hydroxide of AlOOH type, while increased the specific surface area of aluminum hydroxide of Al(OH)3 type, and formed co-network structure of Al-O-Zr type with the aluminum hydroxides. The rate of transition to $\alpha$-Al2O3 from co-precipitated materials occurred in the order of 7≒10, 9 and 11 of pH values. Al2O3 and ZrO2 interacted to bring about coupled grain growth, and the growth of ZrO2 crystallite size rapidly occurred within $\theta$-Al2O3 matrix. Segregation did not occur in the system Al2O3-15v/o ZrO2(＋3m/o Y2O3) and Y2O3 acted as a stabilizer to ZrO2. The lattice strain of tetragonal ZrO2 was increased by the constraint effect of Al2O3 matrix.

• Journal of the Korean Chemical Society
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• v.33 no.2
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• pp.263-270
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• 1989

Aluminum alkoxide, $Al(OC_3H_7\^i)_3\;and\;Al(OC_4H_9^s)_3$, were synthesized using aluminum sheet and corresponding alcohols to prepare various phase alumina in high purity. Aluminum hydroxides were prepared by hydrolysis of synthesized Al-alkoxides and from reagent $AlCl_3$. The catalytic properties of ${\gamma}$ and ${\eta}-Al_2O_3$ prepared at various temperatures were investigated and the reaction kinetics of ${\alpha}-Al_2O_3$ formation from $Al(OH)_3$ was considered.

• Korean Journal of Materials Research
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• v.5 no.6
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• pp.644-649
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• 1995

The sinterability and the microstructure of Al doped UO$_2$-6wt%Gd$_2$O$_3$pellets, which were doped using Al(OH)$_3$, ADS(aluminium distearate), Al(OH)$_3$+ ADS mixture and sintered at 1$700^{\circ}C$ for 4h in H$_2$, atmospheres, were examined. The sintered densities of Al doped UO$_2$-6wt%Gd$_2$O$_3$pellets were more than 94% T.D.. The open porosity in ADS doped pellets was dramatically decreased. And the amounts of pores less than l${\mu}{\textrm}{m}$ and larger than 10${\mu}{\textrm}{m}$ were decreased regardless of the kinds of doped Al compounds. And the average pore size of Al doped UO$_2$-6wt%Gd$_2$O$_3$pellets was ranged between 2 and 3${\mu}{\textrm}{m}$. While grain structure of non-doped UO$_2$-6wt%Gd$_2$O$_3$pellets was revealed to be duplex type (rocks in sands), that of Al doped pellets to be uniformly equiaxid type. Especially, the grain size in ADS doped pellets was averaged to 4.6${\mu}{\textrm}{m}$.

• Korean Journal of Materials Research
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• v.12 no.6
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• pp.493-498
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• 2002

$Al_2O_3$ is a promising gate dielectric because of its high dielectric constant, high resistivity and low leakage current. Since $OH^-$ radical in $Al_2O_3$ films deposited by ALD using TMA and $H_2O$ degrades the good properties of $Al_2O_3$, TMA and $O_3$ were used to deposite $Al_2O_3$ films and the effects of $O_3$ on the properties of the $Al_2O_3$ films were investigated. The growth rate of the $Al_2O_3$ film under the optimum condition was 0.85 $\AA$/cycle. According to the XPS analysis results the $OH^-$ concentration in the $Al_2O_3$ film deposited using $O_3$ is lower than that using $H_2O$. RBS analysis results indicate the chemical formula of the film is $Al_{2.2}O_{2.8}$. The carbon concentration in the film detected by AES is under 1 at%. SEM observation confirms that the step coverage of the $Al_2O_3$ film deposited by ALD using $O_3$ is nearly 100%.

• Journal of the Mineralogical Society of Korea
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• v.22 no.4
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• pp.307-312
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• 2009

Motukoreaite and quintinite-3T, Mg-Al layered double hydroxides, were found in the Sinyangri Formation of Jeju Island. They fill the pores of basaltic volcaniclastic sediments in globular and botryoidal aggregates of fine platy particles. Globular aggregates of quintinite-3T were crusted with the parallel overgrowth of motukoreaite plates. X-ray diffraction data and chemical composition are consistent with those reported in literature, while the Mg/Al ratio of motukoreaite is higher. Structural formula of motukoreaite and quintinite-3T derived from electron microprobe analysis are $Na_{1.6}Ca_{0.1}Mg_{40.7}Al_{20.7}Si_{0.9}(CO_3)_{13.6}(SO_4)_{7.4}(OH)_{108}56H_2O$, and $Mg_{3.7}Al_{1.9}Si_{0.2}(OH)_{12}(CO_3)_{0.8}(SO_4)_{0.2}3H_2O$, respectively. Motukoreaite and quintinite-3T were formed by reaction between seawater and basaltic glass, and contributed to the cementation and lithification of the volcaniclastic sediments.

• Analytical Science and Technology
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• v.13 no.5
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• pp.584-591
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• 2000

The separation of Nd from the simulated $U_3Si/Al$ spent fuel solution with sequential two-step anion exchange separation has been studied. To prepare the simulated $U_3Si/Al$ spent nuclear fuel, unirradiated $U_3Si/Al$ whose composition consists of small $U_3Si$ particle dispersed in an Al matrix with Al cladding was dissolved with a mixture of 4 M HCl and 10 M $HNO_3$ and 8 or 15 fission product elements were added to the dissolved solution. The trace amount of silica in the solutions was removed by evaporating to dryness with HF and the U was adsorbed on the first anion exchange resin. Neodymium can be purely isolated from the fission product elements with a methanol-nitric acid eluent using the second anion exchange resin. A large excess of Al didn't influence on the elution velocity of Nd, but reduced the eluted contents of Nd, Al, Eu, Gd, Sm and Sr, A large amount of Al was removed first from the column with 3 mL of loading solution (0.8 M $HNO_3$/99.8% MeOH) before Nd elution by the eluent [0.04 M $HNO_3$-99.8% MeOH(1:9)]. The recovery of Nd was more than 94%, regardless of Al contents. Taking the 9 to 13 mL fraction of eluate was effective to purely isolate Nd.

• Journal of the Korean Ceramic Society
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• v.24 no.1
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• pp.23-32
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• 1987

Synthesis of high purity ultrafine Si3N4 and ${\beta}$-Sialon powders was investigated via the simultaneous reduction and nitriding of amorphous SiO2, SiO2-Al2O3 system prepaerd by hydrolysis of alkoxides, using carbonablack as a reducing agent. In Si(OC2H5)4-C2H5 OH-H2 O-NH4OH system, hydrolysis rate increased with increasing reaction temperature and pH. Pure ${\alpha}$-Si3N4 was formed at 1350$^{\circ}C$ for 5 hrs in N2 atmosphere. In Si(OC2H5)4-Al(OC3H7)3-C6H6-H2 O-NH4OH system, weight loss increased as Si/Al ratio decreased. Single phase ${\beta}$-Sialon consisted of Si/Al=2 was formed at 1350$^{\circ}C$ in N2 and minor phases of ${\alpha}$-Si3N4, AIN, and X-phase were existed besides theSialon phase at other Si/Al ratios. The Si3N4 and Sialon powders synthesized from alkoxides consisted of uniform find particles of 0.05-0.2$\mu\textrm{m}$ in diameter, respectively.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.826-829
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• 2004

An increasing interest in fire safety engineering can currently be identified in Korea and overseas. The fire-resistant characteristics of spray coating material for fire protection with or without nano $Al(OH)_3$ colloid has been experimentally investigated and the results are presented in this paper. The fire-resistance characteristics of spray coating material with nano $Al(OH)_3$ were superior to those without $Al(OH)_3$. Especially, spray coating material with nano material showed that thermal characteristic in the early days was remarkably excellent.