• Applied Chemistry for Engineering
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• v.2 no.4
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• pp.330-339
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• 1991

The acid properties of $V_2O_5-TiO_2/SiO_2$ catalysts and the partial oxidation of o-xylene into phthalic anhydride had been investigated in order to relate the acid property of catalyst to the catalytic activity. $V_2O_5$ had both weak (V=O) and strong (V-O-V) acid sites which gave pyridine desorption peaks at $230^{\circ}C$ and $300^{\circ}C$, respectively, and the amount of weak acid sites at $230^{\circ}C$ decreased with the increase of calcination temperature. On the other hand, the amount of weak acid sites increased considerably by increasing the amount of $TiO_2$ to the $V_2O_5-TiO_2/SiO_5$, and the maximum value was shown at 20 and higher mole % of $TiO_2$ with respect to $SiO_2$. In the oxidation of o-xylene, $V_2O_5-TiO_2/SiO_2$ enhandced more the total conversion and the selectivity to phthalic anhydride than $V_2O_5/SiO_2$, and the higher $TiO_2$ ratio to $V_2O_5$ increased the total conversion but could not change the selectivity to phthalic anhydride. Weak acid sites (V=O) led o-xylene to partial oxidation producing phthalic anhydride by adsorbing o-xylene weakly, while acid sites (V-O-V) led it to total oxidation producing CO and $CO_2$ by adsorbing it strongly.

• Journal of the Korean Ceramic Society
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• v.44 no.2 s.297
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• pp.79-83
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• 2007

To fabricate a thick, porous yttria-stabilized zirconia without cracking and warping, a method for the simultaneous control of the porosity and shrinkage was designed. As a pore former, a potato starch was used. For the control of shrinkage the oxidation of Al metal particles was used. For the sintering of the above powder mixtures, a partial sintering technique was used at $1300^{\circ}C$ for 10 min in air. Upon adding the additives, high open porosity above 53% and a low shrinkage level were obtained. As a result cracking and warping of the sintered body were deterred. This outcome most likely resulted from the compensation of sintering shrinkage due to the volume expansion caused by oxidation of the Al metal particles during heat-treatment.

• Journal of the Korean Institute of Gas
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• v.8 no.3 s.24
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• pp.52-56
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• 2004

Pd catalyst have been used in hydrogenation, oxidation, and low temperature combustion reaction. Recently, it is candidated as a possible reagents in the partial oxidation of methanol reformers of the fuel cell. Pd catalysts, even though it is very precious and expensive, catalytic functioning is good, but it still need to be improved in the matter of durability and low catalytic activity after calcination. In this study, we synthesize the improved Pd catalyst and study their chemical functioning.

• Archives of Pharmacal Research
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• v.1 no.1
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• pp.27-32
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• 1978

A procedure of $^3H$-radio labeling synthesis for the dammarane triterpene glycosides of Korean ginseng was established by using the ginsenoside $Rg_1$ as starting material. The protons in $C-{11}$ and $C_{13}$ of the aglycone moiety of the glycoside were exchanged with tritium by keto-enol tautomerization of 12-keto-ginsenoside $Rg_1$ which was prepared by partial acetylation, Sarett oxidation and saponification, producing nona-acetate, nonaside $Rg_1$. The acety1-ketone and 12-keto-derivative of ginsenotritated ketone was reduced by metallic sodium and isoproponol to produce the end product $^3H$-ginsenoside $Rg_1$ with 3% radio-chemical recovery in one experiment.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.327-328
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• 2006

We have demonstrated that textured $Al_2O_3-mullite-SiC$ nanocomposites can be fabricated by slip casting followed by partial oxidation - reaction sintering of mixed suspensions of $Al_2O_3$ and SiC powders in a high magnetic field. The sintered density was changed by the degree of oxidation at 1200C and 1300C. The degree of orientation of alumina in the nanocomposite was examined on the basis of the X-ray diffraction patterns and scanning electron micrographs. It is confirmed that alumina-oriented nanocomposites were fabricated. The three-point bending strength at room temperature was observed for the nanocomposites.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.455-456
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• 2006

We have demonstrated that textured $Al_2O_3-mullite-SiC$ nanocomposites can be fabricated by slip casting followed by partial oxidation. reaction sintering of mixed suspensions of $Al_2O_3$ and SiC powders in a high magnetic field. The sintered density was changed by the degree of oxidation at 1200C and 1300C. The degree of orientation of alumina in the nanocomposite was examined on the basis of the X-ray diffraction patterns and scanning electron micrographs. It is confirmed that aluminaoriented nanocomposites were fabricated. The three-point bending strength at room temperature was observed for the nanocomposites.

• Corrosion Science and Technology
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• v.17 no.5
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• pp.218-224
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• 2018

Alloy 617 is a candidate Ni-based superalloy for intermediate heat exchanger (IHX) of a high-temperature gas reactor (VHTR), because of its good creep strength and corrosion resistance at high temperature. Small amount of impurities such as $H_2O$, $H_2$, CO and $CH_4$ are introduced inevitably in helium, as a coolant during operation of a VHTR. Reactions of material and impurities are accelerated with increase of temperature to $950^{\circ}C$ of operating temperature of a VHTR, leading to material corrosion aggravation. In this circumstance, high-temperature corrosion tests were performed at $950^{\circ}C$ in air and impure helium environments, up to 250 hours in this study. Oxidation rate of $950^{\circ}C$ in an air environment was higher than that of impure helium, explained by difference in outer oxide morphology and microstructure as a function of oxygen partial pressure. An equiaxed Cr-rich surface oxide layer was formed in an air environment, and a columnar Cr-rich oxide was formed in an impure helium environment.

• Journal of the Korean Society of Safety
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• v.6 no.3
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• pp.27-34
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• 1991

This paper is for the properties of the oxidation-proof of the partially discharged and of the molecular motion on chlorinated PE Film. this paper also shows the properties of the molecular motion of the ${\gamma}$ ray irradiated PE Film. 1 In the surface of the PE Film enforce chlorination, C-Cl be distributed up to 10 $\mu$m deep. 2. In according to the development of the chlorination, the measure of crystalization decreased and cross link occured. 3. Chlorination PE Film control the oxidation on ozone to occuratlon by partial discharge and it lost bonding chlorine. 4. in according to chlorination, ${\gamma}$ absorption in motion of CH2 main chain of PE drcreased by chlorine stbstitution.

• Journal of Microbiology and Biotechnology
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• v.16 no.3
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• pp.469-474
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• 2006

Partial nitrification blocking of the oxidation of nitrite ($NO_{2}^{-}$) to nitrate ($NO_{3}^{-}$) has cost-efficient advantages such as lower oxygen and organics demand for nitrification and denitrification, respectively. A nitrifying membrane bioreactor of submerged type was operated for the treatment of synthetic ammonium wastewater with the purpose of nitrite build-up without affecting the efficiency of ammonium oxidation. A high ammonium concentration (1,000 mg/l) was completely converted to nitrate at up to 2 kg $N/m^3$ day under sufficient aeration. The control of pH under sufficient aeration was not a reliable strategy to maintain stable nitrite build-up. When the dissolved oxygen concentration was kept at 0.2-0.4 mg/l by adjusting the aeration rate, about 70% of nitrite content was obtained with ammonium oxidation efficiency higher than 93%. The increase of suction pressure due to membrane fouling was not significant under lowered aerating environment over a 6-month period of operation. The composition of nitrifier community, including relative abundance of nitrite oxidizers in a nitrite-accumulating condition, was quantified by fluorescence in situ hybridization analysis.

• Environmental Engineering Research
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• v.19 no.1
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• pp.23-29
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• 2014

In this study, aerobic granules were applied to a lab-scale aerobic granule sludge airlift reactor (AGSAR) and the ammonium nitrogen oxidation performance was evaluated at different ammonium nitrogen loading rate (NLR). At least 99% of the initial ammonium nitrogen was oxidized at an NLR of 0.27 and 0.53 kg $NH_4{^+}-N/m^3{\cdot}day$, for both aerobic granules (control), and nitrifying aerobic granules (NAGs). The ammonium nitrogen oxidation deteriorated, when the NLR was increased to 1.07 kg $NH_4{^+}-N/m^3{\cdot}day$. The NAGs were characterized by complete nitrification, while partial nitrification was observed in the control.