• Bulletin of the Korean Chemical Society
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• v.22 no.12
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• pp.1328-1332
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• 2001

The structure and electrochemical properties of the LixCoyNi1-yO2 (y=0.1, 0.3, 0.5, 0.7, 1.0) system synthesized by solid state reaction with various starting materials have been investigated to optimize the characteristics and synthetic conditions of the LixCoyNi1-yO2. The first discharge capacities of LixCoyNi1-yO2 are 60 mAh/g-180 mAh/g with synthetic conditions. Among them, the LixNi0.7Co0.3O2, which was prepared with LiOH, NiO, and Co3O4 at $850^{\circ}C$, had the best electrochemical properties. The first discharge capacity of the compound was 180 mAh/g.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.101-104
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• 2018

An electric field was applied to a Mo conductive layer in the sandwiched structure of $glass/SiO_2/Mo/SiO_2/a-Si$ to induce Joule heating in order to generate the intense heat needed to carry out the crystallization of amorphous silicon. Polycrystalline silicon was produced via Joule heating through a solid state transformation. Blanket crystallization was accomplished within the range of millisecond, thus demonstrating the possibility of a new crystallization route for amorphous silicon films. The grain size of JIC poly-Si can be varied from few tens of nanometers to the one having the larger grain size exceeding that of excimer laser crystallized (ELC) poly-Si according to transmission electron microscopy. We report here the blanket crystallization of amorphous silicon films using the $2^{nd}$ generation glass substrate.

• Journal of Korean Neurosurgical Society
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• v.30 no.11
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• pp.1271-1277
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• 2001

Objectives : Since vertebroplasty has been introduced, we performed short segment pedicle screw fixation with augmented intra-operative vertebroplasty in patients with unstable thoraco-lumbar fracture. Our intentions are to demonstrate the efficacy and indication of this new technique compare to conventional methods. Material and Methods : The surgery comprised of pedicle screw fixations on one level above and below the fracture site, and the fractured level itself, if pedicle is intact, and intra-operative vertebroplasty under the fluoroscopic guide with in-situ postero-lateral bone graft. Also, in cases of bone apposition, we removed those with small impactor through a transfascetal route. During the last 2 years, we performed in seven(7) unstable thoraco-lumbar fracture patients who consisted of two different characteristics, those four(4) with primary or secondary osteoporosis and three(3) of young and very healthy. All patients were followed clinically by A.S.I.A. score and radiography. Results : Mean follow up period was 14 months. We observed well decompressed state via transfascetal route in cases of bone fragments apposition and no hardware pullout in osteoporotic cases, no poly-methyl-methacrylate (PMMA) leakage through the fracture sites into the spinal canal, and no kyphotic deformities in both cases during follow-up periods. All patients demonstrated solid bony fusion except one following osteoporotic compression fracture on other sites. Conclusions : In the management of unstable thoraco-lumbar fracture, we believe that this short segment pedicle screw fixation with augmented intra-operative vertebroplasty reduce the total length or levels of pedicle screw fixation without post-operative kyphotic deformity.

• Analytical Science and Technology
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• v.17 no.2
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• pp.173-179
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• 2004

The $BaTiO_3$ powders and thin films were prepared by an alkoxide modified sol-gel process (polymerization-complex route) using ethylene glycol. The stable starting (Ba-Ti)-mixed metal organic sol was made by addition of acetylacetone. The $BaTiO_3$ powders, which had a particle size of 40~77 nm, were crystallized from an amorphous to a tetragonal phase on annealing at 700 and $1100^{\circ}C$ for 1 h. From FT-IR, solid-state $^{13}C$ CP/MAS NMR spectroscopy and X-ray diffractometry, the trace of the Ba-Ti-oxycarbonate phase first appeared at $400^{\circ}C$. Hydrolyzed sol was spin coated on a quartz wafer at 3500 rpm for 60 s and pyrolyzed at $1100^{\circ}C$ for 1 h. After heat treatment, the coated layer became dense and smooth.

• Journal of the Korean Ceramic Society
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• v.40 no.4
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• pp.340-345
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• 2003

B $i_2$ $O_3$-Ti $O_2$ composite dielectric ceramics have been prepared by a conventional solid state ceramic route. The composite ceramics were prepared with starting materials of different origin and the microwave dielectric properties were investigated. The sintered ceramics were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray microanalysis, Raman and microwave methods. Structural and microstructural analyses identified two separate phases: Ti $O_2$(rutile) and B $i_2$ $Ti_4$0$_{11}$. The separate grains of titania and bismuth titanate were distributed uniformly in the ceramic matrix. The composition 0.88Ti $O_2$-0.12B $i_2$ $Ti_4$ $O_{11}$ was found to have a Q$\times$f of 9300 GHz (measured at a frequency of 3.9 GHz), a temperature coefficient of frequency, $\tau$$_{cf}$ near zero and a high relative permittivity, $\varepsilon$r of 83. The microwave dielectric properties were measured down to 20$^{\circ}$K K. The quality factor increased on cooling the ceramic samples.les.

• Journal of the Korean Ceramic Society
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• v.44 no.5 s.300
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• pp.151-154
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• 2007

Yttrium aluminum garnet, $Y_3Al_5O_{12}$ (YAG) is an extensively used solid-state laser host material. YAG nanocrystals were synthesized using low-temperature glycol method, a modified sol-gel method performed at low temperature that consists of a mixture of salts that are mostly nitrates in an aqueous media. Single-phase nanocrystalline YAG was obtained at $850^{\circ}C$, which is a much lower temperature than with other techniques such as a wet-chemical technique. The structural characterization is done by powder X-ray diffraction, scanning electron microscopy and transmission electron microscopy. A crystallite size range of 20-50 nm was observed for the materials prepared at $850-950^{\circ}C$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.6
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• pp.486-490
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• 2012

$La_{7.33}Bi_2(SiO_4)_6O_2$ specimens were fabricated by standard solid-state synthesis route for solid oxide electrolytes. The calcined powders exhibited uniform particles with a mean particle size of about $28{\mu}m$. The room-temperature structure of $La_{7.33}Bi_2(SiO_4)_6O_2$ specimens was analyzed as hexagonal, space group P63 or P63/m, and the unit cell volume increased with increase a sintering temperature. The specimens sintered at $1,175^{\circ}C$ showed X-ray patterns of homogeneous apatite single phase without the second phase such as $La_2Si_2O_7$ and $La_2SiO_5$. The specimen sintered at $1,175^{\circ}C$ showed the maximum sintered density of 5.49 $g/cm^3$. Increasing the sintering temperature, total conductivities increased, activation energy decreased and the values were $1.98{\times}10^{-5}Scm-1$ and 1.23 eV, respectively.

• Journal of the Korean Ceramic Society
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• v.43 no.2 s.285
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• pp.92-97
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• 2006

Dolomite type $BaSn(BO_3)_2$ ceramics with rhombohedral crystal structure has been synthesized via solid state reaction route. Dielectric properties were measured for the samples sintered at $1050\~1200^{\circ}C$ for 2 h in air. Dielectric constant, loss tangent, and temperature coefficient were increased with sintering temperature due to the evolution of $BaSnO_3$, secondary, phase. Optimum dielectric properties were obtained at the $BaSn(BO_3)_2$ ceramics sintered at $1100^{\circ}C.\;CuO/Bi_2O_3$ was added to $BaSn(BO_3)_2$ ceramics to lower the sintering temperature for LTCC application, then Co and Fe-based coloring agents were added for colorizing the LTCC tape. Typical dielectric properties of $BaSn(BO_3)_2$ ceramics with $5 wt\%\;CuO/Bi_2O_3\;and\;3wt\%$ Co-coloring agent that sintered at $900^{\circ}C$ were $\varepsilon_r=9.89,\;tan{\delta}=0.92\times10^{-3},\;and\;TCC=112ppm/^{\circ}C$. Thus obtained LTCC tape was co-fired with Ag paste for compatibility test and revealed no sign of Ag reaction with the ceramics.

• Progress in Superconductivity
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• v.11 no.1
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• pp.25-29
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• 2009

Polycrystalline samples of $(R_{0.8}Ca_{0.2})Ba_2Cu_3O_{7-z}$ (R = Lu and Y) were synthesized by a solid-state reaction route, and the phase stabilities were examined by heating at temperatures between $800^{\circ}C$ and $900^{\circ}C$ in various atmospheres. A comparative analyses of the x-ray diffraction data of the $(Lu_{0.8}Ca_{0.2})Ba_2Cu_3O_{7-z}$ and $(Y_{0.8}Ca_{0.2})Ba_2Cu_3O_{7-z}$ compounds showed that the 123 phase of both compounds is stable under heating in air and $O_2$ of 1 atm. However, contrary to the $(Y_{0.8}Ca_{0.2})Ba_2Cu_3O_{7-z}$ compound, the $(Lu_{0.8}Ca_{0.2})Ba_2Cu_3O_z$ compound was found to become unstable when heated in the low oxygen partial pressure below about 8 % $O_2\;in\;N_2$, Considering the instability of parent $LuBa_2Cu_3O_z$ compound, this result suggests that the phase stability of Lu-based 123 compounds is sensitive to both the composition and the oxygen partial pressure.

• Proceedings of the KIEE Conference
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• 2008.05a
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• pp.175-176
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• 2008

In this study, the sintering properties and structural properties of the $Mg_5Ta_4O_{15}$cation-deficient perovskite ceramics with $Li_2CO_3$ additions are investigated. The cation-deficient perovskite ceramics are prepared through the solid-state route. According to the XRD pattern, $Mg_4Ta_2O_9$, $MgTa_2O_6$ and $Mg_5Ta_4O_{15}$ phase existed in sintered pure $Mg_5Ta_4O_{15}$ ceramics. With $Li_2CO_3$, additions, the peak intensities of $Mg_4Ta_2O_9$ and $MgTa_2O_6$ phase were reduced. Also, diffraction intensity of the $Mg_5Ta_4O_{15}$ phase was increased with increments of $Li_2CO_3$ additions. The bulk densities were increased with increasing of $Li_2CO_3$ amount and approach the theoretical density of the $Mg_5Ta_4O_{15}$ ceramics, more and more. Microstructure of the $Mg_5Ta_4O_{15}$ ceramics were densified more and more by additions of $Li_2CO_3$. The bulk density of $Mg_5Ta_4O_{15}$+5wt% $Li_2CO_3$ ceramics sintered at $1500^{\circ}C$ for 10 hours was $5.88g/cm^3$.