• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1186-1191
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• 2010

Colored cubic zirconia specimen made by skull melt process were annealed in vacuum at the temperature of $1200^{\circ}C{\sim}1400^{\circ}C$ for 10~60 minutes to enhance the color. All the seven specimen become darker and eventually be black as annealing temperature and time increase. The black samples turned into original colors when we elevated the temperature with oxy-acetylene torch for around 10 minutes in the air. Finally, we could tune the colors of cubic zirconia either anneal in vacuum or the black samples in the air to obtain the proposed colors. Our proposed new process may be appropriate to fabricate the precious synthetic colored cubic zirconia to simulate the natural colored gem quality diamonds.

• Journal of the Korean Chemical Society
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• v.29 no.2
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• pp.129-136
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• 1985

In the atomic absorption spectrometry using an air-acetylene flame, the interferences of Zr, Sn, Al, Sb, $SO_4^{2-},\;VO_3^-,\;and\;SiO_3^{2-}$, on the calcium absorption and the repression of this interference by the addition of cerium have been studied. The interference by Zr, Sn, Al, Sb, $SO_4^{2-},\;VO_3^-,\;and\;SiO_3^{2-}$ existed as the same concentration as calciurn ($3.0 {\times} 10^{-4}$M) in the sample solution are completely released by the addition of cerium twice as much as interfering cation. The interferences by the mixed interfering cations (Zr, Sn, Al and Sb) and by the mixed interfering anions ($SO_4^{2-},\;VO_3^-,\;and\;SiO_3^{2-}$) are larger than by each interfering cation and anion, and the releasing effect by cerium ($1.5 {\times} 10^{-2}$M) is effective up to some degree of the concentration of mixed interfering cations and of mixed interfering anions. The releasing effect by cerium to the mixed solution of interfering cations and anions is applicable to quite wide range of concentration.

• Fire Science and Engineering
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• v.26 no.5
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• pp.35-40
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• 2012

Numerical investigation was performed to study on the soot formation characteristics in the WSR according to the CO addition. Ethylene and pure air were used as a fuel and an oxidizer, respectively, and three different equivalence ratios (2.0, 2.5, 3.0) were used in the calculation. The resulted CO mole fraction of 10 % CO addition showed the maximum value in spite of the least CO supply. This means that the conversion of CO to soot and other carbon compounds is weakened under incipient soot formation. The soot volume fraction was decreased with increasing the CO addition because the important species for soot formation such as pyrene and acetylene, were decreased with the addition of CO. When the equivalence ratio was 2.5, the soot volume fraction shows the highest value, which results from the contribution of fuel rich condition and reacting temperature. Furthermore, surface growth rate and species concentrations justified the HACA mechanism for soot formation.

• Journal of Microbiology and Biotechnology
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• v.13 no.6
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• pp.955-959
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• 2003

Rhizobium tropici CIAT 899 is capable of synthesizing inactive apo-glucose dehydrogenase (GDH). To become an active holo enzyme, the GDH requires a cofactor, PQQ. When R. tropici CIAT 899 was grown in a broth culture medium containing hydroxyapatite and pyrrolo quinoline quinone (PQQ), pH decreased while the concentration of soluble P increased. The solubilization of hydroxyapatite was associated with the production of gluconic acid and 2-ketogluconic acids. The organic acid production and P solubilization were greatly enhanced when the bacterium was grown with air supply. Effect of R. tropici CIAT 899 with (CI＋PQQ) and without PQQ (CI) on the common bean growth was examined. Shoot and root weight, and N and P contents in CI＋PQQ treatment, were significantly higher than those in control and CI treatment. Nodule weight and acetylene reducing activities were also significantly higher in CI＋PQQ treatment than in other treatments.

• 한국연소학회:학술대회논문집
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• 2001.11a
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• pp.169-178
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• 2001

Among the recent research ideas to reduce hydrocarbon emissions emitted from SI engines till light-off of catalyst since cold start are those exploiting non-thermal plasma technique and photo-catalyst that draws recent attention by virtue of its successful application to practical use to clean up the atmosphere using the feature of its relative independence on temperature. Based on the previous research results obtained with model exhaust gases using an experimental emissions reduction system that utilizes the non-thermal plasma and photo-catalyst technique, further investigation was conducted on a production N/A 1.5 liter DOHC engine during cold start to warm-up. For the effects of non-thermal plasma-photocatalyst combined reactor, 10% concentration reduction was achieved with the fuel component paraffins, and the large increase in non-fuel paraffinic components and acetylene concentrations were similar to those of base condition. However the absolute value was locally a bit higher than those of base condition since the products was made from the dissociation and decomposition of highly branched paraffins by plasma-photocatalyst reactor. Olefinic components were highly decomposed by about 75%, due to these excellent decompositions of olefins which have relatively high MIR values, and the SR value was 1.87 that is 30% reduction from that of base condition, then, the photochemical reactivity was lowered.

• Journal of Preventive Medicine and Public Health
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• v.31 no.2 s.61
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• pp.265-274
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• 1998

To investigate the change of nitric oxide(NO), copper, and zinc in serum on smoking and alcohol ingestion in young adults, this study was performed in a cross-sectional study in 127 healthy men in Korea who had HBsAg(-), HCVAb(-), and no symptomatic liver, heart, gastrointestinal, chronic diseases, and inflammatory sign(lower than 10,000 white blood cell count in CBC). At the men's entry into the study, blood samples were drawn from each subject and immediately centrifuged for analysis of NO, copper, and zinc. Each man completed a questionnaire that provided information on smoking, alcohol intake and present and past medical history NO was analyzed by HPLC(Green et al., 1982), copper and zinc by atomic absorption spectrophotometer with air-acetylene flame and total cholesterol(TC) by Spectrum EPX. Smoking(number of cigarettes per day and pack-year) and alcohol intake was grouped fertile. Copper was adjusted for age and zinc and for age and TC. NO, copper, and zinc on smoking and alcohol ingestion were analyzed in general linear models, respectively. NO, copper and zinc in serum did not show statistical differences between non-smoking and high-smoking group and no-alcohol intake and high-alcohol intake group. This study suggested that copper, zinc, and NO was not. good biological marker for early effect by smoking and alcohol intake in young adults. However, selection bias should be considered in evaluation of this result. A large prospective study will be needed in advance on usefulness of copper, zinc, and NO as a marker for risk factors and early change of atherosclerosis.

• Journal of the Korean institute of surface engineering
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• v.57 no.1
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• pp.22-30
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• 2024

This study reports a direct growth of carbon nanotubes (CNTs) on the surface of LiCoO₂ (LCO) powders to apply as highly efficient cathode materials in lithium-ion batteries (LIB). The CNT synthesis was performed using a thermal chemical vapor deposition apparatus with temperatures from 575 to 625 ℃. Ferritin molecules as growth catalyst of CNTs were mixed in deionized (DI) water with various concentrations from 0.05 to 1.0 mg/mL. Then, the LCO powders was dissolved in the ferritin solution at a ratio of 1g/mL. To obtain catalytic iron nanoparticles on the LCO surface, the LCO-ferritin suspension was dropped in silicon dioxide substrates and calcined under air at 550℃. Subsequently, the direct growth of CNTs on LCO powders was performed using a mixture of acetylene (10 sccm) and hydrogen (100 sccm) for 10 min. The growth behavior was characterized by scanning and transmission electron microscopy, Raman scattering spectroscopy, X-ray diffraction, and thermogravimetric analysis. The optimized condition yielding high structural quality and amount of CNTs was 600 ℃ and 0.5 mg/mL. The obtained materials will be developed as cathode materials in LIB.