• Korean Journal of Metals and Materials
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• v.49 no.2
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• pp.145-152
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• 2011

Mechanical and property corrosion resistance of Mg-Zn-Y alloys with an atomic ratio of Zn/Y of 6.8 are investigated using optical microscopy, scanning electron microscopy, transmission electron microscopy, uniaxial tensile test and corrosion test with immersion and dynamic potentiometric tests. The alloys showed an in-situ composite microstructure consisting of ${\alpha}$-Mg and icosahedral phase (I-phase) as a strengthening phase. As the volume fraction of the I-phase increases, the yield and tensile strengths of the alloys increase while maintaining large elongation (26~30%), indicating that I-phase is effective for strengthening and forms a stable interface with surrounding ${\alpha}$-Mg matrix. The presence of I-phase having higher corrosion potential than ${\alpha}$-Mg, decreased the corrosion rate of the cast alloy up to I-phase volume fraction of 3.7%. However further increase in the volume fraction of the I-phase deteriorates the corrosion resistance due to enhanced internal galvanic corrosion cell between ${\alpha}$-Mg and I-phase.

• Journal of the Korean Ceramic Society
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• v.47 no.6
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• pp.598-602
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• 2010

When metal oxides are added into crystalline glaze, colors of glaze and crystals are similar as colorants generally. But the case of NiO in zinc crystalline glaze is different from general color development. When NiO is added to zinc crystalline glaze it can develop two or three colors. The active use of color development mechanism by adding NiO to the zinc crystalline glaze to control color of the base glaze and crystal with stability is investigated. This report is expected to contribute to the ceramic industry in improving application of zinc crystalline glaze. For the experiment of NiO, the quantity of NiO additives is changed to the base glaze for the most adequate formation of willemite crystal from previous research and firing condition: temperature increasing speed $5^{\circ}C/min$, holding 1 h at $1270^{\circ}C$, annealing speed $3^{\circ}C/min$ till $1170^{\circ}C$, holding 2 h at $1170^{\circ}C$ then naturally annealed. The samples are characterized by X-ray diffraction (XRD), UV-vis, and Micro-Raman. The result of the procedure as follows; Ni substitutes for Zn ion then glaze develops blue willemite crystals, as if cobalt is used, on brown glaze base. When NiO quantity is increased to over 5 wt%, willemite size is decreased, and the density of the crystal is increased, at the same time $Ni_2SiO_4$ (olivine) phase, the second phase, has been developed. The excessive NiO is reacted with silicate in the glass then developed green $Ni_2SiO_4$ (olivine), and quantity of $Ni_2SiO_4$ (olivine) is increased as quantity of willemite is decreased. It is proved to create three colors, blue, brown and green by controlling the quantity of NiO to the zinc crystalline glaze and it will improve the multiple use of colors to the ceramic design.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.179-180
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• 2010

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.219-219
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• 2010

Silicides have been commonly used in the Si technology due to the compatibility with Si. Recently the silicide has been applied in solar cells [1] and nanoscale interconnects [2]. The modulation of Ni silicide phase is an important issue to satisfy the needs. The excellent electric-conductive nickel monosilicide (NiSi) nanowire has proven the low resistive nanoscale interconnects. Otherwise the Ni disilicide (NiSi2) provides a template to grow a crystalline Si film above it by the little lattice mismatch of 0.4% between Si and NiSi2. We present the formation of Ni silicide phases performed by the single deposition and the co-deposition methods. The co-deposition of Ni and Si provides a stable Ni silicide phase at a reduced processing temperature comparing to the single deposition method. It also discusses the Schottky contact formation between the Ni silicide and the grown crystalline Si film for the solar cell application.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.192.2-192.2
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• 2013

Crystalline order and surface stability of 1,4,5,8,9,11-hexaazatriphenylene-hexanitrile (HATCN) thin films on organic surface were investigated using grazing incidence wide angle x-ray scattering and x-ray reflectivity measurements. In the initial growth regime (less than 20 nm), HATCN molecules were stacked to low crystalline order with substantial amorphous phase. Meanwhile, a thicker film with 50 nm thickness showed high crystalline order of hexagonal phase with three different orientational domains. The domain distribution was quantitatively obtained as a function of tilted angle. By an organic-inorganic interface formation of IZO/HATCN thin film from an indium zinc oxide (IZO) electrode deposition, the surface stability of HATCN film was investigated and the sharp interface was confirmed by the x-ray reflectivity measurement.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.175-175
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• 2000

Si(100) surfaces were exposed to gas-phase thermal-energy hydrogen atoms, H(g). We find that thermal H(g) atoms etch, amorphize, or penetrate into the crystalline silicon substrate, depending on the employed Ts range during the H(g) exposure. We find that etching is enhanced as Ts is lowered in the 300-700K range, while amorphous silicon hydride (a-Si:H) formation dominates at a Ts below 300K. This result was well explained by the fact that formation of the etching precursor, SiHx(a), and amorphization are both facilitated by a lower Ts, whereas the final step for etching, SiH3(a) + H(g) longrightarrow SiH3(g), is suppressed at a lower Ts. we also find that direct absorption of H(g) by the crystalline bulk of Si(100) substrate occurs within a narrow Ts window of 420-530K. The bulk-absorbed hydrogen evolved out molecularly from Si(100) at a Ts 80-120K higher than that for surface monohydride phase ($\beta$1) in temperature-programmed desorption. This bulk-phase H uptake increased with increasing H(g) exposure without saturation within our experimental limits. Direct absorption of H(g) into the bulk lattice occurs only when the surface is atomically roughened by surface etching. While pre-adsorbed hydrogen atoms on the surface, H(a), were readily abstracted and replaced by D(g), the H atoms previously absorbed in the crystalline bulk were also nearly all depleted, albeit at a much lower rate, by a subsequent D(g) at the peak temperature in TPD from the substrate sequentially treated with H(g) and D(g), together with a gas phase-like H2 Raman frequency of 4160cm-1, will be presented.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.230-233
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• 2008

The vanadium rich ash of petroleum coke can give a slagging problem during because of the high melting point of $V_2O_3$. For continuous removal of the slag, petroleum coke is often mixed with coal, and the viscosity of the mixed slag is an important property, determining the gasification temperature. The viscosities of the mixed slag from various mixing ratios of petroleum coke and a bituminous coal were investigated. When mixed with a crystalline coal slag, $T_{cv}$ was increased at a higher the coke content in the mixed feed. When the $V_2O_3$ concentration was greater than 4.5%, it was difficult to get accurate measurements of $T_{cv}$. The SEM/EDX analyses of the cooled slag revealed that the major crystalline phase was anorthite, and $T_{cv}$ should be related to the formation temperature of anorthite. The SEM/EDX analyses also showed that, at low concentrations of vanadium, part vanadium formed a crystalline phase with Al-Si-Ca-Fe, and the rest remained in the glassy phase, suggesting that vanadium existed as a slag component at the low viscosity region. At a high concentration, vanadium forms a phase with Ca, and the Ca-V phase was separated from the slag phase, and formed a layer above the slag. FeO in petroleum coke also played an important role determining viscosity: at high temperatures, increased FeO lowered the viscosity, but as it formed a spinel phase, the depletion of FeO in the slag resulted in a higher viscosity.

• 한국전자현미경학회:학술대회논문집
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• 2002.11a
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• pp.46-48
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• 2002

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1266-1267
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• 2008

Liquid crystalline polymer BB-3(1-methyl) takes two kinds of glass phases which are liquid crystalline glass and liquid glass below the glass temperature. This study is aimed to analyze the phase transitions of those samples with variation of temperature. For the analyzing temperature dispersion of dielectric constants was measured and the results were analyzed.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.542-544
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• 2007

New liquid crystalline Y-shaped molecules containing 1,3,4-oxadizoles have been synthesized with variation of terminal groups (R = H, $OCH_3$ or $OC_8H_{17}$). The structures of obtained compounds were identified by FT/IR and NMR spectrometry, and their thermal and liquid crystalline properties were investigated by DSC and polarizing optical microscope.