• Journal of the Korean Chemical Society
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• v.35 no.6
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• pp.689-698
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• 1991

Activated oxidation catalysts are generated by the treatment of pentadentate Schiff base cobalt(Ⅱ) complexes with the oxygen saturated DMF solution. Oxidation of 2,6-di-tert-butylphenol by homogeneous oxidation catalysts of superoxo type pentadentate schiff base cobalt(Ⅲ) complexes yields 2,6-di-tert-butylbenzoquinone(BQ) as a major product. And $O_2$/Co mole ratio of homogeneous oxidative catalysts such as [Co(Ⅲ)(sal-DET)]$O_2$ and [Co(Ⅲ)(sal-DPT)]$O_2$by PVT method of the oxygen absorption in DMSO and pyridine solution was 1:1, 1:1.52 in DMF solution and ${\mu}$-peroxo type cobalt(Ⅲ) complexes formed at solid state. The redox reaction processes of superoxo type cobalt(Ⅲ) complexes as homogeneous oxidation catalysts were investigated by cyclic voltammetry and DPP method at a glassy carbon electrode. As a result of electrochemical measurements the reduction processes of oxygen adducted superoxo type cobalt(Ⅲ) complexes occurred to four steps including prewave of $O_2$-in 0.1M TEAP-DMSO and 0.1 M TEAP-Pyridine as supporting electrolyte solution.

• Journal of Sensor Science and Technology
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• v.5 no.5
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• pp.79-84
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• 1996

A $1\;{\mu}m$ thick n-type GaAs layer with Si doping density of $1{\times}10^{17}/cm^{3}$ and a $500{\AA}$ thick undoped single crystalline AlAs layer were subsequently grown by molecular beam epitaxy on the $n^{+}$ GaAs substrate. The AlAs/GaAs layer was oxidized in $N_{2}$ bubbled $H_{2}O$ vapor($95^{\circ}C$) ambient at $400^{\circ}C$ for 2 and 3 hours. From the result of XPS analysis, small amounts of $As_{2}O_{3}$, AlAs, and elemental As were found in the samples oxidized up to 2 hours. After 3 hours oxidation, however, various oxides related to As were dissolved and As atoms were diffused out toward the oxide surface. The as-grown AlAs/GaAs layer was selectively converted to $Al_{2}O_{3}/GaAs$ at the oxidation temperature $400^{\circ}C$ for 3 hours. The oxidation temperature and time is very critical to stop the oxidation at the AlAs/GaAs interface and to form a defect-free surface layer.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.91-91
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• 2011

This paper describes development procedure of the four types of fuel cell's blowers: pressurized fuel blower, selective oxidation air blower, cathode air blower, and burner air blower. Diaphragm blowers having two heads are selected to maintain force balance when the rotating arms are moving by the driving motor. Dimensions of a diaphragm cavity is designed according to the optimal design procedure using numerical simulation and experimental measurement. Experimental apparatus is designed by considering the bower characteristics having low flow rate and high pressure. Test blower is operated by a diaphragm, which has suction and discharge port on the top of the blower. For analyzing the internal flow of the blower, three-dimensional Navier-Stokes analysis is introduced in the present study. Throughout the optimal design of the blowers, blower performance is enhanced by reducing the unbalance motion of the rotating arm and loss region in the diaphragm cavity.

• Journal of the Korean Society of Industry Convergence
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• v.2 no.1
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• pp.105-112
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• 1999

Model predicting the respiration rate of pear under modified LDPE film pouch has been developed. The assumptions of the model have three bases; 1) respiration rate is depending on $CO_2$ and $O_2$ concentration in the package, 2) the oxidation of glucose in pear generates carbon dioxides, and 3) gases permeation through the package film bases on the Langmuir adsorption theory and Fick's law. The simulated results agreed fairly well with the experimental data so as this model to be useful in designing the modified atmospheric packaging system.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.6
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• pp.621-630
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• 1998

The concentrations of organic carbon (OC) and elemental carbon (EC) in fine aerosols were determined from the samples collected at the two background sites of Kosan in Cheju Island and Kangwha. Samplings were carried out during the spring and winter of 1996 and the fall and winter of 1997. PM25 particles were collected on the prefired quartz filters for 24 hours and analyzed by the selective thermal oxidation method. The concentrations of OC at the sites were higher than those commonly observed from clean areas around the world, but those of EC at both sites were lower than, or comparable to, other clean areas in the world. Both the OC and EC levels at Kangwha were higher than those at Kosan. According to backward trajectory analysis, most air pollutants collected at the two sites were from China. It was found that the OC and EC concentrations in air masses from southern China were higher than those from northern China.

• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.98-103
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• 2007

The number of vehicles employing diesel engines is rapidly rising. Accompanying this trend, application of an after-treatment system is strictly required as a result of reinforced exhaust regulations. The Diesel Particulate Filter (DPF) system is considered as the most efficient method to reduce particulate matter (PM), but the improvement of a regeneration performance at any engine operation point presents a considerable challenge by itself. Temperature, gas compostion and flow rate of exhaust gas are important parameters in DPF evaluation, especially regeneration process. Engine dynamometer and degment tester are generally used in DPF evaluation so far. But these test method couldn't reveal the effect of various parameters on real DPF, such as O2 concentration, amount of soot and exhaust gas temperature. This research has studied the possibility using dump combustor that used to take an approach lean premixed combustion in gas turbine for a DPF power and optimized. It is possible that utilize the system as DOC (Diesel Oxidation Catalyst) and SCR(Selective Catalytic Reduction) assessments test as well as DPF evaluation

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1402-1404
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• 2001

Josephson junction arrays of the type $Nb/Al-Al_2O_3/Nb$ were prepared by DC magnetron sputtering. The tunnel barrier was formed by in-situ thermal oxidation. Individual junctions were defined using selective niobium etching process(SNEP). The characteristic curves of Josephson junction arrays fabricated with and without cooling the substrate were represented. The junctions deposited without cooling showed poor characteristics(high leakage current, low gap voltage), and a high quality Josephson junction array of 2,000 junctions with high hysteresis was obtained with cooling and when operated at 74.6 GHz, it generated stable quantized voltage steps up to 2.2 V.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.8
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• pp.1580-1584
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• 2009

We have theoretically analyzed the monolithic integration of vertical cavity lasers with depleted optical thyristor (VCL-DOT) structure and experimentally demonstrated optical logic gates such as AND-gate, OR-gate, and INVERTER implemented by VCL-DOT for an optical programmable gate array. The optical AND and OR gates have been realized by changing a input bias of the single VCL-DOTs and all kinds of optical logic functions are also implemented by adjusting an intensity of the reference input beams into the differential VCL-DOTs. To achieve the high sensitivity, high slope efficiency and low threshold current, a small active region of lasing part and a wide detecting area are simultaneously designed by using a selective oxidation process. The fabricated devices clearly show nonlinear s-shaped current-voltage characteristics and lasing characteristics of a low threshold current with 0.65 mA and output spectrum at 854 nm.

• YAKHAK HOEJI
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• v.54 no.6
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• pp.474-480
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• 2010

Conformationally locked nucleosides are important in searching selective agonists and antagonists for P2Y receptors. There were two previous synthetic works of the crucial intermediate, cyclopentenyl alcohol (3), which had some inefficiency like using too strong dianionic base and synthesis of racemate. Here we describes a facile synthesis of the intermediate using Sharpless epoxidation and the opening of epoxide ring using zinc, followed by Grubb's metathesis as key steps. The intermediate was converted to the southern bicyclo[3.2.0]heptane for confirming its usefulness.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.10
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• pp.855-859
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• 2007

Hydrogen as an energy carrier in fuel cell offers perhaps the largest potential benefits of reduced emissions of pollutants and greenhouse gases. The generation of high-purity hydrogen from hydrocarbon fuels is essential for efficient operation of fuel cell. Reduction of carbon monoxide to an acceptable level of 10ppm involves high temperature and low temperature water gas shift (WGS), followed by selective oxidation of residual carbon monoxide. The WGS reactor was designed and tested in this study to produce hydrogen-rich gas with CO to less than 5000 ppm. In the water gas shift operation, gas emerges from the reformer is taken through a high temperature shift (HTS) catalyst to reduce the CO concentration to about $2{\sim}4%$ followed to about 5000 ppm via a low temperature shift (LTS) catalyst.