• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.6
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• pp.233-235
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• 2004

Shaped single crystals of Bi : $Y_3Ga_5O_{12}$(Bi = 0.041, 0.047 and 0.061 mol%) were grown by the micro-pulling-down method. Optical absorption spectra show an absorption band at 288 nm ascribed to the lowest energy $6s^2$ \longrightarrow 6s6p transition of $Bi^{3+}$ , while luminescence spectra demonstrate the band at 314 nm ascribed to the reverse radiative transition of the excited $Bi^{3+}$ centres. At room temperature, dominant decay time component was found to be about 440 ns with a minor slower component 580 ns.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.06a
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• pp.253-259
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• 1997

The iron doped GaAs single crystals were grown by liquid phase epitaxial method and its some physical properties were evaluated with a view to investigate the crystal quality and emission property. The isomer shift of 0.303mm/sec is calculated from low-temperature M ssbauer spectroscopy and we know that charge state of iron ion is 3+ in GaAs crystal. In low temperature photoluminescence, the deep emission bands with wide-line width have been observed at 0.99eV and 1.15eV in addition to sharp excitonic peaks. We attributed that these deep emissions are originated from substitutional Fe-acceptor which has charge state of 3+ and 2+, respectively.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.06a
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• pp.121-124
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• 1997

Emergence of advanced materials has been realized by the great demands for sophisticated state devices in high technology industry. It is the ear of speedy evolution of science and technology, in particular, materials processing technology, which enables us to synthesize any materials with respect to its purity and its perfection of crystal structure and shape (form) that have, heretofore not been available. The availability of ultra pure, fine raw materials, single crystals and thick/thin film materials has been largely responsible for such startling progresses that have been made in the realization of unforeseen, functional devices for high technology industry. Of the functional devices such as passive as active devices, non-silicon devices are mostly passive. Piezoelectric, electro-optic, magneto-optic devices, etc. are some of the examples. In this paper, magneto-optic materials for Faraday device, which is little known, are reviewed including its processing toward practical applications.

• Progress in Superconductivity and Cryogenics
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• v.3 no.1
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• pp.50-55
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• 2001

A new type of flywheel energy storage system that has a horizontal axle with High $T_c$, superconductor bearings using Y123 single-domained crystals was developed.The dynamic Properties, stiffness and damping of the high $T_c$, superconductor radial bearings were experimentally estimated using a imbalance excitation method. The imbalance excitation method applied to this rotor- bearing system identified the identified stiffness and damping of the high temperature superconductor beatings to be 2.8 $3.3 {\times} 10^5 N/m and 775 204$ Nsec/m respectively.

• Journal of the Korean Chemical Society
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• v.10 no.2
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• pp.98-102
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• 1966

A spectrochemical method for the determination of the major impurities, such as aluminum, iron, magnesium and silicon, in rutile single crystals and variously doped rutile is presented. By applying higher current (12 amp) and a 1:2 sample-to-graphite dilution by weight, the elaborate sample preparation needed for conventional fusion technique was avoided, and relatively higher detection limits were established. Average deviations are approximately ${\pm}8%$ for iron and magnesium in the concentration ranges of 0.007 to 0.7% and 0.006 to 0.6% respectively, and ${\pm}5%$ for aluminum and silicon in the range of 0.005 to 0.5%.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.5
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• pp.191-194
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• 2008

We will focus on the horizontal Bridgman growth system to analyze the transport phenomena numerically, because the simple furnace system and the confined growth environment allow for the precise understanding of the transport phenomena in solidification process. In conventional melt growth process, the dopant concentration tends to vary significantly along the crystal. In this work, we propose the modification of crucible geometry for improving the productivity of silicon single-crystal growth by controlling axial specific resistivity distribution. Numerical analysis has been performed to study the transport phenomena of dopant impurities in conventional and proposed Bridgman silicon growth using the finite element method and implicit Euler time integration. It has been demonstrated using mathematical models and by numerical analysis that proposed method is useful for obtaining crystals with superior uniformity along the growth direction at a lower cost than can be obtained by the conventional melt growth process.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.364.1-364.1
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• 2016

We report the characteristics of individual ultra-long SnO2 nanowires(NWs) grown on sapphire(0001) substrates by vapor transport method. NWs, with typical lengths of >$400{\mu}m$, grew in the form of NW bundles under a hydrogen reducing atmosphere, without metal catalysts. The individual NWs were examined using high-resolution X-ray diffraction, transmission electron microscopy, and micro-Raman spectroscopy. The results revealed that the SnO2 NWs grew as high-quality, tetragonal-rutile-phase single crystals with mosaic distributions of $0.02^{\circ}$ and $0.026^{\circ}$ in the (101) and (110) planes, respectively.

• Journal of environmental and Sanitary engineering
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• v.10 no.1
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• pp.126-131
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• 1995

Chitinase, a potential pathogensis- related portein, was induced in the leaves of 30 day - old bean( phaseolus vulgaris ) plant with the treatment of 10 $\mu $ /mℓ ethylen for 30hrs. Chitinase was purified from the mature tissue of bean leaves( phaseolus vulgaris ) by ammonium sulfate precipitation followed by affinity chromatography on a regenerated chitin and sephadex G-75 chromatography. The purified chitinase gave a single band SDS- PAGE to be 32,000 Dalton. In order to elucidate the three- dimensional structure of chitinase and to shed light on the functional mechanism of this class of enzymes, the enzyme was tried to crystallize( Sitting Drop Method). Crystals grew at room temperature to their final size within two weeks(0.2mm $\times $0.2mm $\times $ 0.1 mm ), This enzyme are still continuing to crystallize for the study of X- ray.

• Journal of the Korean Ceramic Society
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• v.26 no.5
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• pp.645-654
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• 1989

Specimens of WC-Co were indented to measure the resulting crack size and unindented samples were fractured in 3-point flexure to obtain the strength and to measure characteristic features on the fracture surface. Fracture toughness was determined using fractography and compared to those determined using identation techniques. We show that principles of fracture mechanics can be applied WC-Co composites and can be used to analyze the fracture process. The fracture surfaces were examined by scanning electron microscopy and optical microscopy. Characteristic feature observed in glasses, single crystals and polycrystalline materials known as mirror, mist, hackle, and crack branching were identified for these composites. We discuss the importance of fracture surface analysis in determining the failure-initiating sources and the failure behaviorof WC-Co composites.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.1
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• pp.117-125
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• 1997

Ferroelastic $CsPbCl_3$ crystals were grown by the Czochralski method and Bridgman method. From XRD, DTA and the dielectric measurements, we investigated the structure and confirmed the phase transition temperatures of it. Using the polarizing microscope, we observed the ferroelastic domains and the temperature dependence of the domains. For the orientation states, we obtained the consistent result with the theoretical investigation by the crystallographical consideration. For Aizu species m3mF2/m(p) 12 orientation states are represented crystallographically.