• Nuclear Engineering and Technology
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• v.53 no.7
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• pp.2221-2228
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• 2021

One-dimensional oxygen transport relation is indispensable to study the oxygen distribution in the LBE-cooled system with an oxygen control device. In this paper, a numerical research is carried out to study the oxygen transport characteristics in a gas-phase oxygen control device, including the static case and dynamic case. The model of static oxygen control is based on the two-phase VOF model and the results agree well with the theoretical expectation. The model of dynamic oxygen control is simplified and the gas-liquid interface is treated as a free surface boundary with a constant oxygen concentration. The influences of the inlet and interface oxygen concentration, mass flow rate, temperature, and the inlet pipe location on the mass transfer characteristics are discussed. Based on the results, an oxygen mass transport relation considering the temperature dependence and velocity dependence separately is obtained. The relation can be used in a one-dimensional system analysis code to predict the oxygen provided by the oxygen control device, which is an important part of the integral oxygen mass transfer models.

• Journal of Industrial Technology
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• v.25 no.A
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• pp.151-156
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• 2005

Auto exhausts and air pollution can become trapped in the cabin of vehicle, reducing the amount of oxygen available for breathing. Driver may feel sleepy, headaches, nausea, confusion, dizziness and lower levels of oxygen can damage the driver's general health. Consequently, oxygen generator purified oxygen into the car to help driver get the oxygen driver's body needs. In this study, in order to evaluate the oxygen generator performance, the samples that the various conditions(humidity(50%, 100%), flow and oxygen concentration) were examined. There were three types of oxygen generator; sample 1($2.5{\ell}/min$, $36%O_2$), sample 2($4.5{\ell}/min$, $41%O_2$) and sample 3($5{\ell}/min$, $39%O_2$). As the humidity increased from 50% to 100%, the oxygen concentration of the sample 1(36%), 2(41%) and 3(39%) was reduced $31%O_2$, $38%O_2$ and $38%O_2$, respectively. Also, the each sample measured that effect of human in car on oxygen concentration, if the oxygen concentration is one person in car, each sample of oxygen concentration was $20.8%O_2$, $23.7%O_2$ and $21.2%O_2$. From the above results, it was shown that oxygen generator for car, if the oxygen concentration is increased, effect of humidity is reduced, and that in the sample of supplying a high-rate of oxygen, the oxygen concentration is increased. It was suggested that effect of humidity on oxygen generator for car can be reduced according to the supply of oxygen.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.4
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• pp.173-180
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• 2005

In this study, changes in verbal cognitive performance, blood oxygen saturation and heart rate due to 30％ concentration oxygen supply were observed. Five male (24.6±0.9) and five female (22.2±1.9) college students were asked to perform 28 verbal cognitive tasks of the same difficulty during two types of oxygen (concentration 21％, 30％) administration. The experimental sequence consisted of Rest1 (1 min.), Control (1 min.), Task (4 min.), and Rest2 (4 min.) and the physiological signals such as blood oxygen saturation and heart rate were measured throughout the stages. The experimental result showed that the performance increased significantly at 30％'s concentration of oxygen rather than 21％'s, which shows oxygen supply has positive influence on verbal cognitive performance. When 30％ concentration oxygen is supplied, the oxygen saturation in the blood significantly increased comparing to 21％. The heart rate showed no significant difference. Significant correlations were found between changes in oxygen saturation and cognitive performance. It is suggested that 30％ oxygen can stimulate brain activation by increasing actual blood oxygen concentration in the process of cognitive performance.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.6
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• pp.74-80
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• 1992

The purpose of this study is to improve the performance of gasoline engine. Combustion-characteristics orignated from supplying cylinder with fuel-air mixture which was formed by the rise of oxygen-concentration in air with oxygen-enriching membrane have been investigated. The results showed that the poor-limit of oxygen-concentration was increased by shortening combustion-duration because the rise of oxygen-concentration in fuel-air mixture resulted in the promotion of combustion-velocity. Also, the generation of large output of power was expected from combustion in proportion as the amount of oxygen was increased.

• Korean Journal of Food Science and Technology
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• v.37 no.6
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• pp.951-956
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• 2005

Selection of oxygen-tolerant strains and elucidation of their oxygen tolerance mechanism were crucial for effective use of bifidobacteria. Oxygen-tolerant bifidobacteria were able to significantly remove environmental oxygen (oxygen removal activity) as compared to oxygen-sensitive strains. Most oxygen removal activity was inhibited by heat treatment and exposure to extreme pH (2.0) of bifidobacterial cell. NADH oxidase was major enzyme related to oxygen removal activity. Oxygen-tolerant bifidobacteria possessed high NADH peroxidase activity level to detoxify $H_2O_2$ formed from reaction of NADH oxidase. Addition of oxygen to anaerobic culture broth significantly increased activities of HADH oxidase and NADH peroxidase within 1hr and rapid increment of oxygen concentration was prevented. Results showed NADH oxidase and NADH peroxidase of oxygen-tolerant bifidobacteria played important roles in elimination of oxygen and oxygen metabolite $(H_2O_2)$.

• Journal of the Korean Society of Visualization
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• v.14 no.1
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• pp.51-56
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• 2016

Oxygen is a key factor in aerobic reactions and most biological activities. Visualization of oxygen distribution of a chemical process or biological system has been a very challenging object despite of its significance and potential impact. To monitor and visualize the spatial distribution of oxygen concentration, various techniques such as electro-chemical probe, polarographic electrode, LIF(laser-induced fluorescence) and so on have been introduced. Oxygen planar optode which utilizes the oxygen quenching of fluorescence light is one of the currently available methods for time-resolved visualization of oxygen distribution on a planar surface. In this study, we utilized VisiSens oxygen planar optode system to visualize the spatial distribution of oxygen concentration on leaves of Korean azalea. As a result, temporal variation of oxygen concentration distribution caused by respiratory activity of the leaf could be quantitatively monitored.

• Journal of Ceramic Processing Research
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• v.20 no.1
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• pp.18-23
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• 2019

Chemical looping combustion (CLC) is a promising carbon capture and storage (CCS) technology whose efficiency and cost primarily relies on the oxygen carrier materials used. In this paper, gadolinium-doped ceria (GDC, Ce0.9Gd0.1O1.95) was added as a promoter to improve the oxygen transfer rate of MgMnO3-δ oxygen carrier materials. Increasing GDC content significantly increased the oxygen transfer rate of MgMnO3-δ-GDC composites for the reduction reaction due to an increase in the surface adsorption of CH4 via oxygen vacancies formed on the surface of the GDC. On the other hand, the oxygen transfer rate for the oxidation reaction decreased linearly with increasing GDC content due to the oxygen storage ability of GDC. Adsorbed oxygen molecules preferentially insert themselves into oxygen vacancies of the GDC lattice rather than reacting with (Mg,Mn)O to form MgMnO3-δ during the oxidation reaction.

• 한국연소학회:학술대회논문집
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• 2003.05a
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• pp.231-239
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• 2003

In this study, the waste of landfill was treated using advanced enriched oxygen combustion system. The oxygen concentration of this study was 21%, 25%, 30% and 40% and the operating capacity was 200 g/min and the residence time was 10 minutes. As increased the oxygen concentration of combustion air. temperature of the incinerator was increased and the temperature was increased rapidly when the oxygen concentration was 30%. As increased the oxygen concentration, the NOx (ppm) of flue gas increase d for thermal NOx, however the CO (ppm) of flue gas decreased according to the increase of combustion efficiency . The optimum operation condition of incineration was obtained when the oxygen concentration is 30%${\sim}$40%. The unburned carbon of ash decreased from 10% to 4% when the oxygen concentration was increased from 21% to 30%, therefore the high combustion efficiency can be obtained if used the oxygen enriched combustion system.

• Journal of the Korean Society of Tobacco Science
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• v.18 no.1
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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.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.690-693
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• 2003

An Si substrate (100) was oxidized at $400^{\circ}C$ in inductively coupled oxygen plasma. Interstitial oxygen was found in the Si substrate at the initial stage of oxidation by IR measurements. An x-ray rocking curve of Si substrates showed a lower peak intensity due to lattice distortion by the interstitial oxygen. The refractive index of thin oxides, below which interstitial oxygen existed in the Si substrate, was smaller than the refractive index of thick oxides, below which no interstitial oxygen existed. The interstitial oxygen was found by plasma oxidation using $O_{2}$ gas and $N_{2}O$ gas. The inductively coupled plasma oxidation using $N_{2}O$ gas was performed by atomic oxygen, not by molecular oxygen, indicating that atomic oxygen in plasma is responsible for the incorporation of interstitial oxygen.