• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.1006-1014
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• 1996

A series of catalysts, $NiO-ZrO_2/WO_3$, for ethylene dimerization were prepared by coprecipitation from a solution of nickel chloride - zirconium oxychloride mixture followed by dry impregnation with an aqueous solution of ammonium metatungstate and calcination in air. On the basis of the results obtained from x-ray diffraction and DSC, the addition of NiO and $WO_3$ to $ZrO_2$ shifted the transition of $ZrO_2$ from amorphous to a tetragonal phase toward higher temperatures due to the interaction between NiO(or $WO_3$) and $ZrO_2$. $NiO-ZrO_2$ without $WO_3$ was inactive for the ethylene dimerization, but $NiO-ZrO_2/WO_3$ was found to be very active even at room temperature. The high catalytic activity of $NiO-ZrO_2/WO_3$ was closely correlated with the increase of acid strength by the inductive effect of $WO_3$.

• Journal of the Korean Vacuum Society
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• v.21 no.3
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• pp.178-184
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• 2012

Carbon coils could be synthesized on nickel catalyst layer-deposited silicon oxide substrate using $C_2H_2$ and $H_2$ as source gases and $SF_6$ as an additive gas under thermal chemical vapor deposition system. The characteristics (formation density and morphology) of as-grown carbon coils were investigated as functions of additive gas flow rate and the cycling on/off modulation of $C_2H_2/SF_6$ flows. Even in the lowest $SF_6$ flow rate (5 sccm) in this work, the cycling on/off modulation injection of $SF_6$ flow for 2 minutes could give rise to the formation of nanosized carbon coils, whereas the continuous injection of $SF_6$ flow for 5 minutes could not give rise to the carbon coils formation. With increasing $SF_6$ flow rates from 5 to 30 sccm, the cycling on/off modulation injection of $SF_6$ flow confines the geometry for the carbon coils to the nanosized ones. Fluorine's role of $SF_6$ during the reaction was regarded as the main cause for the confinement of carbon coils geometries to the nano-sized ones.

• Journal of the Korean Electrochemical Society
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• v.12 no.2
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• pp.189-195
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• 2009

$\beta-Ga_{2}O_{3}$ nanorods were synthesized by chemical vapor deposition method using nickel-oxide nanoparticle as a catalyst and gallium metal powder as a source material. The average diameter of nanorods was around 160 nm and the average length was $4{\mu}m$. Also, we confirmed that the synthesis of nanorods follows the vapor-solid growth mechanism. From the results of X-ray diffraction and HR-TEM observation, it can be found that the synthesized nanorods consisted of a typical core-shell structure with single-crystalline $\beta-Ga_{2}O_{3}$ core with a monoclinic crystal structure and an outer amorphous gallium oxide layer. Li/$\beta-Ga_{2}O_{3}$ nanorods cell delivered capacity of 867 mAh/g-$\beta-Ga_{2}O_{3}$ at first discharge. Although the Li/$\beta-Ga_{2}O_{3}$ nanorods cell showed low coulombic efficiency at first cycle, the cell exhibited stable cycle life property after fifth cycle.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.3
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• pp.323-328
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• 2006

The purpose of this paper was to investigate the reforming characteristics and optimum operating condition of the GlidArc-assisted $C_3H_8$ reforming reaction for the synthesis gas(SynGas) production without formation of carbon black from propane using GildArc plasma reforming. Also, in order to increase the hydrogen production and the propane conversion rate, 13 wt % nickel catalyst was filled into the catalytic reactor and parametric screening studies were conducted, in which there were the variations of vapor mole ratio$(H_2O/C_3H_8),\;CO_2$ mole ratio($CO_2/C_3H_8$), input power and injection flow rate. When the variations of vapor mole ratio, $CO_2$ mole ratio, input power and injection flow rate were 1.86, 0.48, 1.37 kW and 14 L/min, respectively, the conversion rate of the propane reached its most optimal condition, or 62.6%. Under the condition mentioned above, the dry basic concentrations of the SynGas were $H_2\;44.4%,\;CO\;18.2%,\;CH_4\;11.2%,\;C_2H_2\;2.0%,\;C_3H_6\;1.6%,\;C_2H_4\;0.6%\;and\;C_3H_4$ 0.4%. The conversion rate of carbon dioxide was 29.2% and the concentration ratio of hydrogen to carbon monoxide($H_2/CO$) in the SynGas was 2.4.

• Applied Chemistry for Engineering
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• v.34 no.2
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• pp.126-130
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• 2023

In response to environmental demands, pyrolysis is one of the practical methods for obtaining reusable oils from waste plastics. However, the waste plastic pyrolysis oils (WPPO) are consumed as low-grade fuel oil due to their impurities. Thus, this study focused on the upgrading method to obtain naphtha catalytic cracking feedstocks from WPPO by the hydroprocessing, including hydrotreating and hydrocracking reaction. Especially, various transition metal sulfides supported catalysts were investigated as hydrotreating and hydrocracking catalysts. The catalytic performance was evaluated with a 250 ml-batch reactor at 370~400 ℃ and 6.0 MPa H₂. Sulfur-, nitrogen-, and chlorine-compounds in WPPO were well eliminated with nickel-molybdenum/alumina catalysts. The NiMo/ZSM-5 catalyst has the highest naphtha yield.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.2
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• pp.92-98
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• 2012

Purpose: The aim of this study was to evaluate the effects of different abutment materials on abutment screw loosening and settling-down effect in conical connection type implant system. Materials and methods: Three types of abutment, cementation, gold UCLA, and metal UCLA abutment were used. Two UCLA groups were fabricated in a similar pattern to cementation abutment. Type III gold alloy and Nickel-Chromium alloy was used for casting gold UCLA abutment and metal UCLA abutment, respectively. Fixture and abutment were tightened to 30 Ncm by using digital torque controller and re-tightening was conducted with same force after 10 minutes. Digital torque gauge was used to measure loosening torque and fixture/abutment length was measured by digital micrometer. Dynamic loads between 25 N and 250 N were applied with $0^{\circ}$ angle to the abutment axis. After loading, fixture/abutment length was re-measured and amount of settlement was calculated. Loosening torque value was also measured for comparison Results: All three groups showed significant differences of length when comparing before and after loading, but there was no significant difference of settling amount in all groups. Loosening torque values were significantly decreased when comparing before and after loading in all groups($P$<.05). However, there was no significant difference in loss of loosening torque values when compared to groups. Conclusion: In internal conical connection type implants, dynamic load affected on settlement and loosening torque of implant, but there was no differences between abutments materials. Likewise gold UCLA abutment, metal UCLA abutment might be able to withstand functional load.