• Korean Journal of Environmental Biology
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• v.21 no.4
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• pp.405-409
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• 2003

To study the tolerant capacity of anaerobic granular sludge (AGS) to oxygen using semi -dynamic batch experiment, the aerating time, pH of the basal media, reductive inorganic materials, microorganism, and microorganism metabolite were investigated. When the aerating time was higher or lower than 0.5 h, the producing gas activity of sludge was lower than that of the control. The oxygen tolerance of the experimental sludge was the highest at the initial pH 7.2. The producing gas activity of sludge I was higher than that of sludge II. And storage at $4^{\circ}C$ can low the lose of the oxygen tolerance capacity of granular sludge. The producing gas activity of sludge was the highest when KI was added. The growth of aerobic microorganisms and some metabolite could increase the producing gas activity of granular sludge.

• Electrical & Electronic Materials
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• v.8 no.4
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• pp.400-405
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• 1995

ZnO films have been grown easily with the conventional thermal evaporation method on SiO$\_$2/ coated Si wafers. Anhydrous zinc acetate has been used as evaporation source. Zinc-acetate was directly heated in the laboratory-made brass boat. Zinc-acetate was sublimed at the boat temperature of about 220.deg. C. The substrates were heated to 600.deg. C with home made tantalium heater. Oxygen has been flowed into the deposition chamber to change the partial pressure of oxygen. X-ray diffraction patterns showed all the films to be amorphous. The films deposited at high oxygen pressure exhibit higher resistivity than films at low pressure. Energy dispersive spectroscopy(EDS) and rutherford backscattering spectrometry(RBS) were conducted on the films to reveal the composition of the ZnO films.

• Korean Journal of Materials Research
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• v.17 no.6
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• pp.303-307
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• 2007

ZnO thin films were prepared by pulsed laser deposition on amorphous fused silica substrates at different ambient $O_2$ pressures varying from 0.5 to 500 mTorr, to observe the effect of ambient gas on their crystalline structure, morphology and optical properties. Results of X-ray diffraction, scanning electron microscopy, atomic force microscopy and photoluminescence studies showed that crystallinity, surface features and optical properties of the films significantly depended on the oxygen background pressure during growth. A low oxygen pressure (0.5 mTorr) seems to be suitable for the growth of highly c-axis oriented and smoother films possessing a superior luminescent property. The films grown at the higher $O_2$ pressures (50-500 mTorr) were found to have many defects probably due to an excessive incorporation of oxygen into ZnO lattice. We speculate that the film crystallinity could be affected by the kinetics of atomic arrangement during deposition at the higher oxygen pressures.

• The Korean Journal of Malacology
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• v.15 no.2
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• pp.127-131
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• 1999

Changes in Oxygen consumption and filtration rates were investigated to understand physiological rhythms for 24 hours of the Manila clam, Ruditapes philippinarum. physiological rhythms in the oxygen consumption and filtration rates at 15$^{\circ}C$ and 25$^{\circ}C$ were showed diurnal tidal rhythms, appearing two peaks for 24 hours: maximum at night-high tide and minimum at day-low tide. No rapid variations in oxygen consumption and filtration rates for 24 hours appeared at two different water temperatures.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.11 s.242
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• pp.1277-1284
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• 2005

The combustion characteristics of methane oxygen diffusion flames have been investigated to give basic information for designing industrial oxyfuel combustors. NOx reduction has become one of the most determining factors in the combustor design since the small amount of nitrogen is included from the current low cost oxygen production process. Flame lengths decreased with increasing fuel or oxygen velocity because of the enhancement of mixing effect. Correlation equation between flame length and turbulent kinetic energy was proposed. NOx concentration was reduced with increasing fuel or oxygen velocity because of the enhanced entrainment of the product gas into flame zone as well as the reduction of residence time in combustion zone.

• Journal of Microbiology
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• v.44 no.4
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• pp.466-471
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• 2006

In this study, we attempted to characterize the biomolecular effects of an atmospheric-pressure cold plasma (APCP) system which utilizes helium/oxygen $(He/O_2)$. APCP using $He/O_2$ generates a low level of UV while generating reactive oxygen radicals which probably serve as the primary factor in sterilization; these reactive oxygen radicals have the advantage of being capable to access the interiors of the structures of microbial cells. The damaging effects of plasma exposure on polypeptides, DNA, and enzyme proteins in the cell were assessed using biochemical methods.

• Journal of the Korean Ceramic Society
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• v.34 no.6
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• pp.561-568
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• 1997

The effects of sintering temperature and oxygen partial pressure on the electromagnetic properties of Mn-Zn ferrites were investigated. The grain increased with increasing temperature. The power loss at 100 kHz was decreased, while the power loss at 500 kHz was increased as the grain size increased with sintering temperature. Sintering with low oxygen partial pressure at 115$0^{\circ}C$ resulted in high density and initial permeability, and decreased the power loss at 100 kHz and 500 kHz. The oxygen partial pressure lower than 10-2 atm. during heating, significantly suppressed the hysteresis loss. However, the oxygen activity did not affect the grain size of sintered cores.

• Electrical & Electronic Materials
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• v.9 no.10
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• pp.1040-1046
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• 1996

Low voltage phosphor, ZnGa$_{2}$O$_{4}$:Mn, was synthesized and sintered at the high temperature in Ar or vacuum. By XRD analysis, it is confirmed that poly crystalline ZnGa$_{2}$O$_{4}$:Mn solid solution was formed. From EPMA analysis of the samples prepared in Ar and vacuum, the change of oxygen content was investigated and as a result, it was observed that the oxygen amounts were reduced in ZnGa$_{2}$O$_{4}$:Mn prepared in vacuum. It caused the deficiency in oxygen amounts in the phosphor and then consequently, it results in the formation of the energy level near 513 nm. It contributes to the improvement of the brightness of ZnGa$_{2}$O$_{4}$:Mn.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.211-215
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• 2004

For design of cryogenic propellant feeding system, one of the main requirements is to meet temperature requirement for satisfying turbo-pump NPSH requirement. In this paper improved method of estimating the thermal stratification in liquid oxygen tank is presented to help design. In the case of liquid rocket using turbo-pump, the inner pressure of liquid oxygen tank is maintained low, so vaporization of liquid oxygen is generally occurred. In this paper, inner process of LOX tank is analyzed by two phase flow modeling. The vaporization rate and required helium mass is investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.92-95
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• 2003

The dissolved oxygen sensors with thick film type were fabricated for low cost products and the electrical properties were investigated in the different operating temperatures. Pt paste was used for working electrode and Ag/AgCl paste for reference electrode. The fabricated devices have fast response of current changes according to dissolved oxygen concentrations in the applied voltage of $0.6{\sim}0.8V$. This is expected to apply a chip and/or disposal dissolved oxygen sensors.