• 한국안전학회지
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• 제11권3호
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• pp.119-125
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• 1996

The experimental work is performed to obtain content levels and characteristics of flue gas in infrared mobile heaters for butane gas with varying the chamber size and its room temperature. The results showed that the oxygen depletion sensor device is operated at 18.3% of oxygen content. And the relation of oxygen content and carbon dioxide content in an enclosed space show linear aspect, but the content rate of carbon monoxide occurs at random without the level of oxygen content and carbon dioxide content.

• Corrosion Science and Technology
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• 제5권3호
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• pp.94-98
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• 2006

The next generation nuclear power reactor will use Pb-Bi as the cooling material. The steel structure materials such as HT-9 used in the reactor suffer from corrosion when they are exposed to high temperature Pb-Bi. Therefore corrosion should be prevented to use Pb-Bi as the coolant material without any safety problem. One method is to control the oxygen content in Pb-Bi. An appropriate amount of oxygen in Pb-Bi can produce a thin oxide layer on steel, and this layer protects the steel from corrosion attack. Since the required oxygen content in Pb-Bi is in the range of $10^{-5}$ to $10^{-7}$ wt%, this small oxygen content can be controlled by flowing a mixture of hydrogen gas and water vapor. The stagnant corrosion test of HT-9 samples was performed by controlling the oxygen content up to 2,000 hours. The corrosion behavior of HT-9 was analyzed at the temperatures of $500^{\circ}C$ and $650^{\circ}C$ with a reduced condition and a oxygen content of $10^{-6}$ wt%.

• 한국염색가공학회지
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• 제15권2호
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• pp.76-85
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• 2003

In this study, a continuous stabilization process is used to make high-performance carbon fiber from polyacrylonitrile(PAM)-based fibers. The effect of oxygen content of PAN-based fiber on the stabilization process and the properties of the resultant carbon fibers is investigated. In order to research the progress of stabilization reaction FT-IR, elemental analysis, density, DSC, etc are used. Stabilization is carried out in air atmosphere from the 200 to $300^\circ{C}$ temperature range. An increase of PAN-based fibers diameter reduces the oxygen content during the continuous stabilization process. A higher oxygen content increase the density, tensile strength and modulus in the resultant carbon fibers. The most appropriate oxygen content in the stabilized fiber should be about 12%. Fibers having more than 2% oxygen content yield carbon fibers with inferior properties. Those carbon fibers also have sufficient commercial availability.

• 한국연초학회지
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• 제18권1호
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• pp.49-53
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• 1996

This experiment was carried out to study the effect of oxygen on chemical composition and physical properties of tobacco leaves during flue-curing. The results obtained were as follows: Starch content decreased and sucrose content increased with increasing oxygen supply during curing. Glucose and fructose of the cured leaves showed high content at the 5-10% oxygen supply. Amino-N and nitrate-N increased with increasing oxygen supply. Total nitrogen and NH4-N showed the lowest value at the 5-10% and 10-15% oxygen supply in the cutters and leaf, respectively. Chlorophyll and chlorogenic acid increased, and total volatile base decreased with increasing oxygen supply. The activity of α-amylase increased at the latter period of flue-curing, and the maximum activity point were delayed 12 hours with increasing oxygen supply. Shatter index of cured leaves decreased with increasing oxygen supply. It was desirable to supply oxygen during flue-curing for the improvement of chemical and physical properties such as starch, total sugar, chlorogenic acid, and shatter index of cured leaves.

• 한국주조공학회지
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• 제35권4호
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• pp.75-79
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• 2015

Commercial Zr-based amorphous alloy was recycled and oxygen was introduced during the recycling process. The oxygen content can have a great effect on the glass forming ability and the mechanical properties of the alloy. Therefore, it was closely examined. The initial oxygen content in the raw material was 1,244 ppm. It was increased to 3,789 ppm in the alloy after ten recycling processes. As the recycling processes were repeated, the oxygen content increased. Specifically, after four recycling processes, it increased sharply as compared to that after three recycling processes. After ten recycling processes, the glass transition temperature (Tg) increased from 613 K to 634 K and the crystallization temperature (Tx) increased from 696 K to 706 K. On the other hand, the super-cooled liquid region (${\Delta}T=Tx-Tg$) decreased slightly from 83 K to 72 K while the reduced glass transition temperature (Trg = Tg/Tm) was 0.63, remaining constant even when the oxygen content was increased. These results indicated that the increased oxygen content deteriorated the glass forming ability. The bending strength as determined in a three-point bending test showed a sharp decrease from 3,055 to 2,062 MPa as the oxygen content was increased from 1,244 ppm to 3,789 ppm; the extension was also decreased from 3.02 to 1.74 mm. These findings meant that the alloy became brittle.

• Bulletin of the Korean Chemical Society
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• 제22권9호
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• pp.1015-1018
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• 2001

Vanadium oxide thin films with thickness of about 2000 $\AA$ have been prepared by radio frequency sputter deposition using a V2O5 target in a mixed argon and oxygen atmosphere with different Ar/O2 ratio ranging from 99/1 to 90/10. X-ray diffraction and X-ray absorption near edge structure spectroscopic studies show that the oxygen content higher than 5% crystallizes a stoichiometric V2O5 phase, while oxygen deficient phase is formed in the lower oxygen content. The oxygen content in the mixed Ar + O2 has a significant influence on electrochemical lithium insertion/deinsertion property. The discharge-charge capacity of vanadium oxide film increases with increasing the reactive oxygen content. The V2O5 film deposited at the Ar/O2 ratio of 90/10 exhibits high discharge capacity of 100 ${\mu}Ah/cm2-{\mu}m$ along with good cycle performance.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1153-1154
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• 2006

Effects of sintering conditions such as sintering temperature and heating rate on oxygen content, density, microstructure and toughness of sintered Mo were investigated. The oxygen content of the sintered Mo significantly depended on the sintering conditions. The oxygen content of the primary sintered(below 1673 K) Mo influenced the densifications. The number of pores at grain boundaries of the secondary sintered(at 2073 K)Mo depended on the oxygen content of the primary sintered Mo. Grain growth of the secondary sintered Mo was inhibited by the existence of pores at the grain boundaries. The secondary sintered Mo having larger number of pore and smaller grain size demonstrated higher strength.

• 한국해양공학회지
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• 제33권6호
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• pp.615-619
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• 2019

Various fluorides, i.e., CaF₂, Na₃AlF₆, K₂SiF₆, MnF₃, MgF₂, were added to the flux cored wire, and their effects on the oxygen content of the weld metal were investigated. The investigation showed that the oxygen content of weld metal was not influenced by the type of metallic elements in the fluoride; rather, it was influenced by the stability of the arc during welding. While the wire containing MgF₂ showed the most stable arc and the least amount of oxygen in the weld metal, the wire containing MnF₃ showed the least stable arc and the greatest amount of oxygen. Since the deoxidation of the weld metal was not affected by the deoxidation elements, such as Ca and Mg, it was possible to predict the oxygen content of the weld metal by the equilibrium Si-Mn deoxidation thermodynamic model.

• Asian-Australasian Journal of Animal Sciences
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• 제29권5호
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• pp.753-758
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• 2016

Moisture content influences physiological characteristics of microbes and physical structure of solid matrices during composting of animal manure. If moisture content is maintained at a proper level, aerobic microorganisms show more active oxygen consumption during composting due to increased microbial activity. In this study, optimum moisture levels for composting of two bedding materials (sawdust, rice hull) and two different mixtures of bedding and beef manure (BS, Beef cattle manure+sawdust; BR, Beef cattle manure+rice hull) were determined based on oxygen uptake rate measured by a pressure sensor method. A broad range of oxygen uptake rates (0.3 to 33.3 mg $O_2/g$ VS d) were monitored as a function of moisture level and composting feedstock type. The maximum oxygen consumption of each material was observed near the saturated condition, which ranged from 75% to 98% of water holding capacity. The optimum moisture content of BS and BR were 70% and 57% on a wet basis, respectively. Although BS's optimum moisture content was near saturated state, its free air space kept a favorable level (above 30%) for aerobic composting due to the sawdust's coarse particle size and bulking effect.

• Journal of Advanced Marine Engineering and Technology
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• 제29권6호
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• pp.662-670
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• 2005

With highly oxygenated fuels the smoke emissions decreased sharply and linearly with increases in the fuel oxygen content and entirely disappeared at an oxygen content of $38wt-\%$ even at stoichiometric mixture conditions The NOx also decreased monotonically with increases in oxygen content. and thermal efficiency slightly improved because of a reduction in cooling loss and improvement in the degree of constant volume combustion. The mechanisms of the significant reductions in emissions and improvement in engine performance were analyzed with a bottom view type DI diesel engine. Together with direct flame images, flame images were taken through an optical fetter passing only two wavelengths for use in 2-D two-color analysis. The results showed that luminous flame decreased significantly with increases in oxygen content and was not detected for neat dimethoxy methane(DMM). The decrease in flame luminosity with highly oxygenated fuels corresponds with decreases in soot and cooling losses, including those due to heat radiation. The 2-D two-color flame analysis indicated that the high temperature flame and high KL factor areas apparently decreased with increasing fuel oxygen content. These results correspond strongly with decreases in NOx. smoke. and cooling loss with increases in oxygen content.