• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.3046-3054
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• 2013

Synthesis of Carbon Nanotube bundles has been achieved by simple and economical solvothermal procedure at very low temperature of $180^{\circ}C$. The product yield obtained was about 70-75%. The optimization of reaction conditions for an efficient synthesis of CNTs has been presented. The CNTs are obtained by reduction of hexachlorobenzene in the presence of Na/Ni in cyclohexane. The X-ray diffraction, Fourier transform infrared and Raman spectral studies have inferred us the graphene structure of the products. The CNTs formed as the bundles were viewed on scanning electron microscope, transmission electron microscope and high-resolution transmission electron microscope. These are the multiwalled CNTs with outer diameter of 5-10 nm, the inner diameter 2-4 nm and cross sectional diameter up to 5 nm. Brunauer-Emmett-Teller (BET) based $N_2$ gas adsorption studies have been made to obtain BET surface area and $H_2$ storage capacity. Effect of the experimental variables such as reaction temperature, amount of catalyst and the amount of carbon source were investigated. It is found that they affect significantly on the product nature and yield.

• Journal of Hydrogen and New Energy
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• v.25 no.1
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• pp.79-86
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• 2014

In Dimethyl Ether (DME) indirect production processes, DME have a reforming process to separate Methanol. DME has a high cetane number and Methanol has a high octane number. Each fuel has a different combustion characteristics and reactivity. So, this paper was investigated on the combustion characterisitics of DME and Methanol. Basically, Methanol has a effect of retarding ignition. However, Within 10% of total carbon mole number in DME, Methanol slightly changed the onset timing of Low Temperature Reaction (LTR) with increasing thermal-ignition preparation range. It means that controlling combustion phasing of DME can be possible without eliminated LTR. In case of IMEP, the ranges.

• Korean Chemical Engineering Research
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• v.55 no.1
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• pp.99-106
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• 2017

In this study, mixed catalytic char gasification of Indonesia low-rank coal Kideco was investigated under nitrogen atmosphere and isothermal conditions at a fixed reactor. The effects of the temperature were investigated at various temperature (700, 750, 800, $850^{\circ}C$). The effects of blend ratio of catalysts ($K_2CO_3$, Ni) were investigated with different blend ratios (1:9, 3:7, 5:5, 7:3 and 9:1). The sample was prepared by mixing with $K_2CO_3$ physically and by ionexchange method with Ni. The data from thermogravimetric analyzer and gas chromatography were applied to four gassolid reaction kinetic models including shrinking core model, volumetric reaction model, random pore model and modified volumetric reaction model.

• Nuclear Engineering and Technology
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• v.35 no.6
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• pp.507-514
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• 2003

Recently dry decontamination/surface-cleaning technology using plasma etching has been focused in the nuclear industry. In this study, the applicability of this new dry processing technique are experimentally investigated by examining the etching reaction of $UO_2$, Co, and Mo in r.f. plasma with the etchant gas of $CF_4/O_2$ mixture. $UO_2$ is chosen as a representing material for uranium and TRU (TRans-Uranic) compounds while metallic Co and Mo are selected because they are the principal contaminants in the used metallic nuclear components such as valves and pipes made of stainless steel or inconel. Results show that in all cases maximum etching rate is achieved when the mole fraction of $UO_2\;in\;CF_4/O_2$ mixture gas is $20\%$, regardless of temperature and r.f. power. In case of $UO_2$, the highest etching reaction rate is greater than 1000 monolayers/min. at $370^{\circ}C$ under 150 W r.f. power which is equivalent to $0.4{\mu}m/min$. As for Co, etching reaction begins to take place significantly when the temperature exceeds $350^{\circ}C$. Maximum etching rate achieved at $380^{\circ}C\;is\;0.06{\mu}m/min$. Mo etching reaction takes place vigorously even at relatively low temperature and the reaction rate increases drastically with increasing temperature. Highest etching rate at $380^{\circ}C\;is\;1.9{\mu}m/min$. According to OES (Optical Emission Spectroscopy) and AES (Auger Electron Spectroscopy) analysis, primary reaction seems to be a fluorination reaction, but carbonyl compound formation reaction may assist the dominant reaction, especially in case of Co and Mo. Through this basic study, the feasibility and the applicability of plasma decontamination technique are demonstrated.

• Journal of the Korean Ceramic Society
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• v.46 no.5
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• pp.534-539
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• 2009

Reaction Bonded Silicon Carbide(RBSC) has been used for engineering ceramics due to low-temperature fabrication and near-net shape products with excellent structural properties such as thermal shock resistance, corrosion resistance and mechanical strength. Recently, attempts have been made to develop hot gas filter with gradient pore structure by RBSC to overcome weakness of commercial clay-bonded SiC filter such as low fracture toughness and low reliability. In this study a fabrication process of porous RBSC with multi-layer pore structure with gradient pore size was developed. The support layer of the RBSC with multi-layer pore structure was fabricated by conventional Si infiltration process. The intermediate and filter layers consisted of phenolic resin and fine SiC powder were prepared by dip-coating of the support RBSC in slurry of SiC and phenol resin. The temperature of $1550^{\circ}C$ to make Si left in RBSC support layer infiltrate into dip-coated layer to produce SiC by reacting with pyro-carbon from phenol resin.

• KSBB Journal
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• v.18 no.6
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• pp.495-499
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• 2003

The effect of operating parameters (reaction temperature and time) and reaction modes (batch and semi-batch) on the behavior of amino acid production from hydrothermal decomposition of fish-derived wastes was investigated. The amino acids obtained in batch experiments at temperature of 250$^{\circ}C$ were mainly alanine (Ala) and glycine (Gly) at maximum yield of 65 and 28mg/g-dry fish, respectively. At relatively lower temperature of 200$^{\circ}C$, the yield of high-molecular-weight amino acids such as aspartic acid (Asp) and serine (Ser) is high, but decreases as temperature increases. It is likely that high-molecular-weight amino acids decompose faster than low-molecular ones. Semi-batch mode of reaction suppressed decomposition of amino acids into organic acids (or volatile materials) by continuously removing the products from the reaction zone as soon as they are formed. Thus, large amount of high-molecular-weight amino acids such as Asp and Ser at this reaction mode was observed.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.134-137
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• 2009

Commercially available elemental powders of Cu, Zn, Sn and Se were employed for crystallizing a stannite-type $Cu_2ZnSnSe_4$ compound by means of solid state reaction. $Cu_2ZnSnSe_4$ reaction chemistry was also modeled based on differential-thermal analysis and X-ray powder diffraction results. It was observed that Se tends to react preferably with Cu to form CuSe and $CuSe_2$ phases at low reaction temperature. The formation of $Cu_5Zn_8$ intermetallic phase was found to be the intermediate reaction path for the binary ZnSe formation. A solid state reaction at $320^{\circ}C$ reacted elemental powderst obinary selenides of CuSe, ZnSe and SnSe completely. The crystallization of $Cu_2ZnSnSe_4$ was was detected to begin at $300^{\circ}C$ and its weight fraction increased with an increase of reaction temperature, which most probably formed from the reaction between $Cu_2SnSe_3$ and ZnSe.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.8
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• pp.652-657
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• 1998

We have performed spin-spray ferrite plating of $Fe{_3}{-X}-Ni_XO_4$(X=0.17~0.26) films in the temperature region $T=80~95[^{\circ}C]$. A reaction solution and an oxidizing solution were supplied to a reaction chamber by supply pump. The solubility limit of Ni increases as the substrate temperature increase, from X=0.17 at $80[^{\circ}C]$ to X=0.26 at $95[^{\circ}C]$. All the films are polycrystalline with no preferential orientation, and the magnetization exhibits no definite anisotropy. Grain size in the films increases as X increases, reaching $0.87[\mu{m}]$ at X=0.26.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.149-154
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• 2001

The emission characteristics, flame stability, the composition of the flame zone and temperature profile were studied experimentally. The compositions of oxydant were varied by substituting $N_2$ with $CO_2$ at the constant $O_2$ concentration. Results showed that flame became unstable due to the high heat capacity, low transport rate and strong radiation effect of $CO_2$ in comparison with those of $N_2$. The reaction zone was cooled, broadened, as the conversion ratio of $CO_2$ to $N_2$ was increased. Temperature has a large effect on the NOx emission. The concentration of NOx in flue gas decreased due to the decreased temperature of reaction zone. It was also shown that the reaction was delayed by the cooling effect. As the conversion ratio of $CO_2$ to $N_2$ was increased, the emission of CO and the higher temperature zone increased due to the decrease of reaction rate by the cooling effect.

• Journal of the Korean Ceramic Society
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• v.23 no.1
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• pp.33-43
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• 1986

The synthesis of high-purity AlN by a vapor-phase reaction was investigated using the $NH_3-AlCl_3-H_2$ reacting system. The theoretical yields of AlN were determined from th thermodynamic equilibrium composi-tions. It was shown that the yields above 90% could by obtained even in the range of relatively low temper-ature of 600-1200K. The reaction temperature and the initial amounts/ratios of the reacting gases showed significant effects on the yields but the total pressure did not. The experimental results showed that a high-purity AlN having a needle shape was the only product as a solid phase and its amount produced increased with the reaction temperature. While the degree of agglmera-tion of the synthesized AlN increased with the reaction temperature the size of each particle consisting of the agglomerates was independent of the temperature but grew from 0.09 to 0.115${\mu}{\textrm}{m}$ with the flow rate of NH3. These experimental results were compared with the theoretical aspects for the synthesis of a high-purity AlN.