• Journal of the Korean Chemical Society
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• v.42 no.6
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• pp.696-702
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• 1998

The effect of alkali metal salt on the activity of Co-Mo catalyst which has high resistance to sulfur poisoning for water gas shift reaction(WGSR) was studied. Two groups of catalysts were prepared to investigate the effects of anion and cation in alkali metal salts. For K-doped catalysts made with various potassium salts having different anion, the catalytic activity was explained to depend mainly on the BET surface area. Among the catalysts prepared by various nitrates of alkali metal as precursor, the Li-doped catalyst showed the best activity, and the others did not make significant differences giving relatively low activities. And the change of BET surface area by varying the loading of alkali metal showed a similar trend to that of activity. In this case, the activity was dependent on both BET surface area and the ratio of $Mo^{6+}$ with a tetrahedral coordination symmetry to $Mo^{6+}$ with an octahedral one, $Mo^6+[T]/Mo^{6+}[O]$ value.

• Journal of the Korean Society for Heat Treatment
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• v.24 no.3
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• pp.127-132
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• 2011

The silicon-containing Diamond-like Carbon (Si-DLC) film as an low friction coefficient coating has especially treated a different silicon content by plasma-enhanced chemical vapor deposition (PECVD) process at $500^{\circ}C$ on nitrided-STD 11 mold steel with (TMS) gas flow rate. The effects of variable silicon content on the Si-DLC films were tested with relative humidity of 5, 30 and 85% using a ball-on-disk tribometer. The wear-tested and original surface of Si-DLC films were analysed for an understanding of physical and chemical characterization, including a changing structure, via Raman spectra and nano hardness test. The results of Raman spectra have inferred a changing intra-structure from dangling bonds. And high silicon containing DLC films have shown increasing carbon peak ratio ($I_D/I_G$) values and G-peak values. In particular, the tribological tested surface of Si-DLC was shown the increasing hardness value in proportional to TMS gas flow rate. Therefore, at same time, the structure of the Si-DLC film was changed to a different intra-structure and increased hardness film with mechanical shear force and chemical reaction.

• Applied Chemistry for Engineering
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• v.9 no.4
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• pp.595-602
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• 1998

${\alpha}$-sulfonated fatty acid methyl esters[$C_mH_{2m+1}CH(SO_3Na)COOC_nH_{2n+1}$], where hydrophobic group has carbon number of 12~18, were prepard by sulfonation of fatty acid methylester. The mole ratio of $SO_3$ to ester used was 1.3 and the reaction temperature was $70{\sim}90^{\circ}C$. The yield was found to be 97% by mixed gas reaction of inactive gas/gaseous $SO_3$. Studies on bleaching and neutralization processes in the pilot scale provided conditions applicable to industrial synthesis process.

• Korean Journal of Metals and Materials
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• v.48 no.4
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• pp.357-362
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• 2010

Ferromagnetic Mn-Al nanoparticles were prepared using a plasma arc discharge method. The influence of the process parameters on the vaporization rate, composition, particle size, and magnetic properties of the as-produced nanoparticles was investigated. The Mn content was found to be higher in the nanoparticles than in the corresponding mother materials, although the difference diminished with the reaction time. As the $H_2$ content in the reaction gas increased, both the vaporization rate and the particle size increased. With 30 at.% Mn, the average particle diameter was 35.2 nm under a pure Ar gas condition, whereas it was 95.4 nm at a Ar:$H_2$ ratio of 60:40. With the addition of a small amount of carbon, ${\varepsilon}$-phase nanoparticles were successfully synthesized. After a heat treatment in a vacuum for 30 min at $500^{\circ}C$, the nonmagnetic ${\varepsilon}$-phase was transformed into the ferromagnetic ${\tau}$-phase, and a very high coercivity of nearly 5.6 kOe was achieved.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.8 no.2
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• pp.95-101
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• 2022

Microfluidic radioimmunoassay (RIA) platform called µ-RIA spends less reagent and shorter reaction time for the analysis compared to the conventional tube-based radioimmunoassay. This study reported the design of µ-RIA chips optimized for the gamma counter which could measure the small samples of radioactive materials automatically. Compared with the previous study, the µ-RIA chips developed in this study were designed to be compatible with conventional RIA test tubes. And, the automatic gamma counter could detect radioactivity from the ¹²⁵I labeled anti-PSA attached to the chips. Effects of the multi-layer microchannels and two-phase flow in the µ-RIA chips were investigated in this study. The measured radioactivity from the ¹²⁵I labeled anti-PSA was linearly proportional to the number of stacked chips, representing that the radioactivity in µ-RIA platform could be amplified by designing the chips with multi-layers. In addition, we designed µ-RIA chip to generate liquid-gas plug flow inside the microfluidic channel. The plug flow can promote binding of the biomolecules onto the microfluidic channel surface with recirculation in the liquid phase. The ratio of liquid slug and air slug length was 1 : 1 when the ¹²⁵I labeled anti-PSA and the air were injected at 1 and 35 µL/min, respectively, exhibiting 1.6 times higher biomolecule attachment compared to the microfluidic chip without the air injection. This experimental result indicated that the biomolecular reaction was improved by generating liquid-gas slugs inside the microfluidic channel. In this study, we presented a novel µ-RIA chips that is compatible with the conventional gamma counter with automated sampler. Therefore, high-throughput radioimmunoassay can be carried out by the automatic measurement of radioactivity with reduced radiowaste generation. We expect the µ-RIA platform can successfully replace conventional tube-based radioimmunoassay in the future.

• Applied Chemistry for Engineering
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• v.18 no.2
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• pp.155-161
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• 2007

In this study, the reactivity of a $SnO_2-ZrO_2$(Sn/Zr = 2/1) catalyst for $SO_2$ reduction by CO was investigated in order to optimize the various reaction conditions such as temperature, gas hourly space velocity (GHSV), and [CO]/[$SO_2$] molar ratio. The reaction temperature in the range of $300{\sim}550^{\circ}C$, space velocity in the range of $5000{\sim}30000cm^3/[g_{-cat}{\cdot}h]$ and [CO]/[$SO_2$] molar ratio in the range of 1.0~4.0 were employed. The optimum temperature, GHSV, and [CO]/[$SO_2$] molar ratio were determined to be $325^{\circ}C$, $10000cm^3/[g_{-cat}{\cdot}h]$, and 2.0, respectively; under these conditions, $SO_2$ conversion was over 99% and sulfur selectivity was over 95%. In addition, the effect of $H_2O$ content on the $SO_2$ reduction by CO was also investigated. As the $H_2O$ content increased from 2 vol% up to 6 vol%, the reactivity and sulfur selectivity decreased. In case of 2 vol% $H_2O$ content, the reaction temperature and [CO]/[$SO_2$] molar ratio were varied in the range of $300{\sim}400^{\circ}C$ and 1.0~3.0. The optimum temperature and [CO]/[$SO_2$] molar ratio were $340^{\circ}C$ and 2.0, respectively under which $SO_2$ conversion and sulfur selectivity were about 90% and 87%, respectively.

• Journal of Surface Science and Engineering
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• v.41 no.5
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• pp.189-193
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• 2008

In this study, we carried out an investigation of the etching characteristics (etch rate, selectivity to $SiO_2$ and $HfO_2$) of TiN thin films in the $CH_4$/Ar inductively coupled plasma. The maximum etch rate of $274\;{\AA}/min$ for TiN thin films was obtained at $CH_4$(80%)/Ar(20%) gas mixing ratio. At the same time, the etch rate was measured as function of the etching parameters such as RF power, Bias power, and process pressure. The X-ray photoelectron spectroscopy analysis showed an efficient destruction of the oxide bonds by the ion bombardment as well as showed an accumulation of low volatile reaction products on the etched surface. Based on these data, the ion-assisted chemical reaction was proposed as the main etch mechanism for the $CH_4$ containing plasmas.

• Journal of the Korean Ceramic Society
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• v.49 no.4
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• pp.380-384
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• 2012

This paper deals with the recent developments of high thermal conductivity silicon nitride ceramics. First, the factors that reduce the thermal conductivity of silicon nitride are clarified and the potential approaches to realize high thermal conductivity are described. Then, the recent achievements on the silicon nitride fabricated through the reaction bonding and post sintering technique are presented. Because of a smaller amount of impurity oxygen, the obtained thermal conductivity is substantially higher, compared to that of the conventional gas-pressure sintered silicon nitride, while the microstructures and bending strengths are similar to each other between these two samples. Moreover, further improvement of the thermal conductivity is possible by increasing ${\beta}/{\alpha}$ phase ratio of the nitrided sample, resulting in a very high thermal conductivity of 177 W/($m{\cdot}K$) as well as a high fracture toughness of 11.2 $MPa{\cdot}m^{1/2}$.

• Applied Chemistry for Engineering
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• v.4 no.3
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• pp.591-600
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• 1993

Chlorination of tungsten from scheelite ore in a fluidized bed reactor has been investigated to develope tungsten extractive metallurgical process by the chlorination. All of the results in this experiment showed tungsten component could be sucessively chlorinated in a fluidized bed reactor. The proper conditions are as follows; reaction temperature $900^{\circ}C$, reaction time : 20min, $Cl_2$ gas velocity : 3.2cm/sec and petroleum coke-to-scheelite ore weight ratio : 0.2. Also the mean diameters of scheelite and petroleum coke were $150.5{{\mu}m}$ and $750.9{{\mu}m}$ respectively. Under these conditions, over 95% of tungsten component in scheelite was chlorinated.

• Transactions on Electrical and Electronic Materials
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• v.14 no.1
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• pp.12-15
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• 2013

In this study, we carried out an investigation of the etching characteristics (etch rate, and selectivity to $SiO_2$) of $ZrO_2$ thin films in a $CF_4$/Ar inductively coupled plasma (ICP) system. The maximum etch rate of 60.8 nm/min for $ZrO_2$ thin films was obtained at a 20 % $CF_4/(CF_4+Ar)$ gas mixing ratio. At the same time, the etch rate was measured as a function of the etching parameter, namely ICP chamber pressure. X-ray photoelectron spectroscopy (XPS) analysis showed efficient destruction of the oxide bonds by the ion bombardment, as well as an accumulation of low volatile reaction products on the etched surface. Based on these data, the ion-assisted chemical reaction was proposed as the main etch characteristics for the $CF_4$-containing plasmas.