• Journal of Aerospace System Engineering
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• v.3 no.3
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• pp.39-44
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• 2009

Humans rely on the availability of a supply of gaseous oxygen for survival. If the minimal requirements for oxygen are not met, both mental and physical abilities and performance are degraded rapidly. So oxygen systems are required for the aircraft operating at high altitude to prevent physical and psychological problems, or loss of consciousness in an aircraft pilot, flight crew, or passengers. If oxygen system and equipments are to be included in the type design of an airplane, applicant should consider applicable airworthiness requirements and operating rules. In this paper we analyze the various oxygen system requirements for the type of aircraft, oxygen system, and operating conditions.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2003.11a
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• pp.81-83
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• 2003

The present study attempted to observe what changes the supply of highly concentrated(30％) oxygen cause to people's ability and cerebrum lateralization of verbal cognition, compared to air of normal oxygen concentration(21％). The experiment consisted of two runs, one for verbal cognition test with normal air(21％ of oxygen) and for verbal cognition test with more oxygen in the air(30％ of oxygen). Functional brain images were taken form 3T MRI using the single-shot EPI method. There were more activations observed at the occipital, parietal, temporal, and frontal lobes, but there were no changes in cerebrum lateralization with 30％ oxygen administration. The result of task performance showed the accuracy increased at 30％'s concentration of oxygen rather than 21％'s. It is concluded that the positive effect on the verbal cognitive performance level by the highly concentrated oxygen administration was due to changeless increase of left and right cerebrum activation.

• Journal of Microbiology and Biotechnology
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• v.20 no.11
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• pp.1534-1538
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• 2010

Fed-batch cultures of Hansenula polymorpha were studied to develop an efficient biosystem to produce recombinant human serum albumin (HSA). To comply with this purpose, we used a high-purity oxygen-supplying strategy to increase the viable cell density in a bioreactor and enhance the production of target protein. A mutant strain, H. polymorpha GOT7, was utilized in this study as a host strain in both 5-l and 30-l scale fermentors. To supply high-purity oxygen into a bioreactor, nearly 100% high-purity oxygen from a commercial bomb or higher than 93% oxygen available in situ from a pressure swing adsorption (PSA) oxygen generator was employed. Under the optimal fermentation of H. polymorpha with highpurity oxygen, the final cell densities and produced HSA concentrations were 24.6 g/l and 5.1 g/l in the 5-l fermentor, and 24.8 g/l and 4.5 g/l in the 30-l fermentor, respectively. These were about 2-10 times higher than those obtained in air-based fed-batch fermentations. The discrepancies between the 5-l and 30-l fermentors with air supply were presumably due to the higher contribution of surface aeration over submerged aeration in the 5-l fermentor. This study, therefore, proved the positive effect of high-purity oxygen in enhancing viable cell density as well as target recombinant protein production in microbial fermentations.

• Environmental Engineering Research
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• v.19 no.1
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• pp.75-81
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• 2014

Methanotrophic denitrification under a non-aerated condition (without external supply of oxygen or air) was investigated in a bioreactor coupled with a membrane diffuser. Batch experiment demonstrated that both methane consumption and nitrogen production rates were not high in the absence of oxygen, but most of the nitrate was reduced into $N_2$ with 88% recovery efficiency. The methane utilized for nitrate reduction was determined at 1.63 mmol $CH_4$/mmol $NO_3{^-}$-N, which was 2.6 times higher than the theoretical value. In spite of no oxygen supply, methanotrophic denitrification was well performed in the bioreactor, due to enhanced mass transfer of the methane by the membrane diffuser and utilization of oxygen remaining in the influent. The denitrification efficiency and specific denitrification rate were 47% and 1.69 mg $NO_3{^-}-N/g\;VSS{\cdot}hr$, respectively, which were slightly lower than for methanotrophic denitrification under an aerobic condition. The average concentration of total organic carbon in the effluent was as low as 2.45 mg/L, which indicates that it can be applicable as a post-denitrification method for the reclamation of secondary wastewater effluent. The dominant fatty acid methyl ester of mixed culture in the bioreactor was $C_{16:1{\omega}7c}$ and $C_{18:1{\omega}7c}$, which was predominantly found in type I and II methanotrophs, respectively. This study presents the potential of methanotrophic denitrification without externally excess oxygen supply as a post-denitrification option for various water treatment or reclamation.

• Journal of Environmental Science International
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• v.14 no.9
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• pp.835-842
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• 2005

The three-dimensional eco-hydrodynamic model was applied to estimate the physical process in terms of COD (chemical oxygen demand) and net supply(or decomposition) rate of COD in Kamak Bay to find proper management plan for oxygen demanding organic matters. The estimation results of the physical process in terms of COD showed that transportation of COD is dominant in surface level while accumulation of COD is dominant in bottom level. In the case of surface level, the net supply rate of COD was 0 -0.50 mg/m2/day. The net decomposition rate of COD was 0 -0.04 mg/m2/day in middle level(3 -6m) and 0.05 -0.1 5 mg/m2/day in bottom level(6m -bottom). These results indicates that the biological decomposition and physical accumulation of COD are occurred predominantly at the northern part of bottom level. Therefore, it is important to consider both allochthonous and autochthonous oxygen demanding organic matters in the region.

• The Korean Journal of Ecology
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• v.9 no.1
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• pp.19-24
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• 1986

Effects of temperature, pH, light-and-dark and degree of oxygen supply on germination of Papaver somniferum L. seeds were investigated. The optimum temperature of the germination was 2$0^{\circ}C$, but the germination was decreased as temperatures changed to the upper and lower. The largest elongation of both radicle and hypocotyl also occurred at 2$0^{\circ}C$. The best germination occurred at pH 7 but this decreased suddenly the above and below of that pH value. Although no effect of light-and-dark on the germination was, this was restricted under limited. oxyten supply in terms of underwater germination as compared with abovewater one.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.83-85
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• 2013

With an increase in the use of low rank coals in power plants, various operational issues were raised in the fuel storage and supply, combustion, boiler and flue gas treatment systems. In the fuel storage and supply system, the main issue is the self-heating propensity of low rank coals leading to spontaneous combustion in yard storage, transport and pulverization. This study evaluated the reactivity of various sub-bituminous and bituminous coals with oxygen at low temperatures by analyzing the temperature increase characteristics of coals under a constant flow rate of oxygen supply. The results were quantified to a self-heating index and the relation with the fuel properties were evaluated.

• KSBB Journal
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• v.16 no.5
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• pp.516-522
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• 2001

The large-scale production of antibiotics by filamentous mycelial organism requires and adequate supply of dissolved oxygen. In terms of productivity, it means that oxygen transfer is the rate-limiting step. Therefore, the oxygen transfer coefficients(K$\_$L/A) were determined in a broth involving a filamentous mycelial organism such as Streptomyces avermitilis for use in fermentations. To determine (K$\_$L/A) inn a stirred vessel, a great deal of effort is required to provide all the cells with a sufficient oxygen supply. To overcome the oxygen limitation in a batch culture, a fed-batch culture was applied to control the growth rate by an intermittent supply of nutrients. Thus, it was possible to maintain a suitable dissolved oxygen concentration at a low agitation rate. The optimal agitation speed was 350 rpm at low cell concentrations (below 7 g/L) by considering the efficiency of agitation and shear stress. The (K$\_$L/A) was found to decrease from 64.26 to 29.21h.$\^$-1/ when the biomass concentration was increased from 9.82 to 12.06 g/L. In addition, and increase in viscosity was also observed during the growth phase. By comparing the (K$\_$L/A) values for the various agitation and aeration rates, it was found that the effect of an increase in (K$\_$L/A) by aeration was reduced dramatically at high biomass concentrations. However, this effect was not observed when altering the agitation rate. This suggests that controlling the dissolved oxygen concentration by altering the agitation rate was more efficient than increase the aeration rate.

• KSBB Journal
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• v.14 no.6
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• pp.672-676
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• 1999

Encapsulated Aspergillus niger was prepared in order to inspect the effect of oxygen supply on the production of citric acid. A. niger cells which had been immobilized in the calcium alginate capsule grew and mycellia penetrated through the capsule membrane after two days of cultivation and covered over all of the capsule after eight days. The mycellia became loose when the nitrogen source was sufficient of oxygen was deficient. The larger amount of encapsulated cells were put into a given growth medium, the smaller quantity of citric acid was produced. The increase of volumetric oxygen transfer coefficient from 1.8 $hr^-$ to 2.55 $hr^-$ in the flask culture accelerated cell growth rate but did not influence the production of citric acid. The high oxygen supply rate($k_La:\;150\;hr^-$) in the concentric air lift reactor hastened the growth of cells and hindered the production of the citric acid. The reduction of nitrogen source level in the growth medium in the concentric air lift reactor increased citric acid production by 40 percent of that of flask cultivation and the culture period was shortened by 3 days. The variation of the geometry of the concentric air lift reactor did not influence the growth rate of encapsulated cells and production rate of citric acid.

• Clinical and Experimental Reproductive Medicine
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• v.46 no.4
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• pp.189-196
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• 2019

Objective: We aimed to evaluate the effects of different oxygen conditions (20% [high O₂], 5% [low O₂] and 5% decreased to 2% [dynamic O₂]) on mouse pre- and peri-implantation development using a novel double-channel gas supply (DCGS) incubator (CNC Biotech Inc.) to alter the oxygen concentration during in vitro culture. Methods: The high-O₂ and low-O₂ groups were cultured from the one-cell to the blastocyst stage under 20% and 5% oxygen concentrations, respectively. In the dynamic-O₂ group, mouse embryos were cultured from the one-cell to the morula stage under 5% O₂ for 3 days, followed by culture under 2% O₂ to the blastocyst stage. To evaluate peri-implantation development, the blastocysts from the three groups were individually transferred to a fibronectin-coated dish and cultured to the outgrowth stage in droplets. Results: The blastocyst formation rate was significantly higher in the low-O₂ and dynamic-O₂ groups than in the high-O₂ group. The total cell number was significantly higher in the dynamic-O₂ group than in the low-O₂ and high-O₂ groups. Additionally, the apoptotic index was significantly lower in the low-O₂ and dynamic-O₂ groups than in the high-O₂ group. The trophoblast outgrowth rate and spread area were significantly higher in the low-O₂ and dynamic-O₂ groups than in the high-O₂ group. Conclusion: Our results showed that a dynamic oxygen concentration (decreasing from 5% to 2%) had beneficial effects on mouse pre- and peri-implantation development. Optimized, dynamic changing of oxygen concentrations using the novel DCGS incubator could improve the developmental competence of in vitro cultured embryos in a human in vitro fertilization and embryo transfer program.