• 한국연소학회:학술대회논문집
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• 한국연소학회 2002년도 제25회 KOSCI SYMPOSIUM 논문집
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• pp.41-47
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• 2002

Oxygen has been used extensively in various industries for many years. Despite earlier successful attempts to use oxygen in industrial combustion furnaces, its full theoretical researches have only recently begun to be realized. The aim of this study is to investigate the effect of oxygen enriched combustion. This paper analyzes the characteristics of oxygen enriched combustion, and deals with the experimental investigation of the flame temperature and NOx concentration in exhaust gas. The flame temperature, concentration of exhaust gas were measured and flame configurations were photographed according to the variation of oxygen concentrations in oxidizer.

• Food Science and Biotechnology
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• 제18권1호
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• pp.73-78
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• 2009

Processed meatball products were packaged in a passive package without oxygen scavenger as 1 control and 3 active packages of which have PP-based oxygen scavenger master batch materials (OSMB) of 40, 80, and 100%(w/w) in the middle layer and stored at 23 and $30^{\circ}C$ up to 9 months. Quality changes of packaged products were evaluated by measuring the oxygen concentration of the headspace in containers, thiobarbituric acid (TBA), color, and flavor. The oxygen concentration of the package having 100% OSMB was lower than those of 40 and 80%. The color changes and TBA values of the meat ball in the package containing 100% OSMB were the least among the treatments. Using principal component analysis (PCA), the control showed more flavor change than the packages containing oxygen scavenger. As a result, all active packages could extend the shelf life of the meatball products compared with that of the passive package.

• 한국환경과학회지
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• 제11권1호
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• pp.85-91
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• 2002

The effects of initial concentration of dissolved oxygen content, Cu(II) and EDTA in an aqueous Cu(II)-EDTA solution on $TiO_2$ photo-oxidation of EDTA were investigated using $TiO_2$ (Degussa P-25) and UV irradiation at $20{\circ}C$. In the presence of dissolved oxygen and/or Cu(II) the photo-oxidation rates of EDTA were enhanced. The rates linearly increased in the range of initial Cu(II) concentration below 1.79 mM, while abode this concentration those were kept constant. The trend or the EDTA photo-oxidation rates appeared to be akin to the Langmuir-Hinshelwood equation farm and the k values calculated were 0.05 mM/min for the free-EDTA system, and 0.17 mM/min far the Cu(II)-EDTA system. These meant the aqueous EDTA decomposition was enhanced due to weakening of the intra-molecular bond strength of EDTA by complexation with Cu(II) added. It was concluded the decomposition of aqueous EDTA by $TiO_2$ photo-oxidation was maximum in the presence of dissolved oxygen supplied by air purging and of Cu(II) with its concentration for 1:1 Cu(II)-EDTA complexation ratio.

• 인지과학
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• 제16권3호
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• pp.189-197
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• 2005

본 연구에서는 $40\%$ 농도의 산소 공급에 따른 2·bark 과제 수행 능력, 혈중 산소 포화도, 심박동율의 변화를 관찰하고자 한다. 1명의 남자 (평균 $25.8\pm1.3$세)와 5명의 여자 (평균 $23.0\pm1.0$세) 대학생을 대상으로 두 가지 농도의 산소$(21\%,\;40\%)$를 공급하면서 2-back 과제를 수행하게 하였다. Rest1 (1분), 0-back Task (1분), 2-back Task (2분), Rest2 (4분)의 네 단계의 순서로 실험이 진행되었고, 전 단계에서 혈중 산소 포화도와 심박동율의 생리 신호가 측정되었다. $21\%$에 비해 $40\%$ 산소 농도에서 평균 정답률이 유의하게 증가하여, 고농도 산소 공급이 2-back 과제 수행 능력에 긍정적인 영향을 미친다는 사실을 도출할 수 있었다. $21\%$에 비해 $40\%$의 산소가 주어질 때 혈중 산소 포화도는 증가하였고 심박동율은 감소하였다. 이것은 인지 처리 수행 시 $21\%$에 비해 $40\%$의 산소 공급이 실제 혈중 산소 농도를 증가시켜 인지처리에 따른 뇌 활성화를 촉진시킬 수 있다는 사실을 의미하고, 공급된 과산소에 의해 심박동율이 감소한다는 사실을 의미하는 것이다.

• Clinical and Experimental Reproductive Medicine
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• 제31권3호
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• pp.155-168
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• 2004

Objective: Melatonin, which is secreted by pineal gland play an important role in the regulation of ovarian function via seasonal rhythm and sleep in most mammals. It also has a role in the protection of cells by removing toxic oxygen free radicals brought about by metabolism. In the present study, effects of melatonin on the mouse oocyte maturation were examined using two different culture conditions provided with 5% or 21% oxygen concentration. Material and Method: Immature mouse oocytes were obtained from the ovarian follicles of $3{\sim}4$ weeks old ICR strain mice intraperitoneally injected with 5 I.U. PMSG 44 hour before. Under stereomicroscope, morphologically healthy oocytes with distinct germinal vesicle (GV) were liberated from the graafian follicles and collected using mouth-controlled micropipette. They were then cultured for 17 hour at $37^{circ}C$, 5% $CO_2$ and 21% $O_2$ (95% air) or 5% $CO_2$, 5% $O_2$ and 90% $N_2$. New modified Hank's balanced salt solution (New MHBS) was used as a culture medium throughout the experiments. Effects of melatonin were examined at a concentration of $0.0001{\mu}M$, $0.01{\mu}M$ or $1.0{\mu}M$. For the prevention of spontaneous maturation of immature oocytes during culture, dibutyryl cyclic AMP (dbcAMP) and/or hypoxanthine were included in the medium. Results: Under 21% oxygen condition, oocytes cultured in the presence of $0.01{\mu}M$ melatonin showed a significantly higher maturation rates, in terms of germinal vesicle breakdown (95.0% vs 89.0%) and polar body formation (88.1% vs 75.4%), compared to those cultured with $0.0001{\mu}M$ or $1.0{\mu}M$ melatonin. However, no difference was observed in oocytes cultured under 5% oxygen whether they were treated with melatonin or not. In the presence of $0.01{\mu}M$ melatonin, oocytes either cultured under 21% or 5% oxygen exhibited no difference in the polar body formation (85.6% vs 86.7%). However, in the absence of melatonin, oocytes cultured under 21% oxygen exhibited lower polar body formation (74.7%). When oocytes were cultured in the presence of dbcAMP alone or with varying concentrations of melatonin, those treated with both compounds always showed better maturation, i.e., germinal vesicle breakdown and polar body formation, compared to those cultured with dbcAMP alone. At the same concentration of melatonin, however, oocytes exposed to 21% oxygen showed poor maturation than those to 5% oxygen. Similar results were obtained from the experiments using hypoxanthine instead of dbcAMP. Conclusion: Based upon these results, it is suggested that melatonin could enhance the meiotic maturation of mouse oocytes under 21% oxygen concentration, and release oocytes from the meiotic arrest by dbcAMP or hypoxanthine regardless of the concentration of oxygen, probably via the removal of oxygen free radicals.

• 대한기계학회논문집B
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• 제37권10호
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• pp.879-886
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• 2013

본 연구에서는 고농도 EGR을 사용하는 DME 예혼합압축자기착화 연소의 근본적인 연소메커니즘을 이해하기 위해 수치해석 시뮬레이션을 수행하였다. EGR과 과급의 영향을 조사하면서 동시에 산소 분압과 산소 농도중 어느 것이 LTR 발열비율을 결정하는 핵심요소인지 확인하였다. EGR 비율과 과급압력을 매개변수 정하기 위해서 1) EGR 비율변화에 따라 산소농도, 산소함유량을 변화시키는 조건 2) 산소농도를 거의 일정하게 유지하면서 과급을 하여 산소 분압을 변화시키는 조건, 3) EGR과 과급을 조합하면서 산소 분압을 일정하게 유지 하기 위해 산소농도를 변화시키는 조건 세가지 조건에서 화학반응수치계산을 수행하여 검증했다. 연구결과 EGR율이 증가하면 연소의 시작, 종료시기가 지연되고, 과급을 하게 되면 연소의 시작, 종료시기가 앞당겨지는 것을 확인했다. EGR과 과급이 LTHR 발열비율 증가에 영향을 미치는 것도 확인하였다.

• Current Photovoltaic Research
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• 제4권3호
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• pp.124-129
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• 2016

Recently industry has voiced a need for optimally designing the production process of low-cost, high-quality ingots by improving productivity and reducing production costs with the Czochralski process. Crystalline defect control is important for the production of high-quality ingots. Also oxygen is one of the most important impurities that influence crystalline defects in single crystals. Oxygen is dissolved into the silicon melt from the silica crucible and incorporated into the crystalline a far larger amount than other additives or impurities. Then it is eluted during the cooling process, there by causing various defect. Excessive quantities of oxygen degrade the quality of silicone. However an appropriate amount of oxygen can be beneficial. because it eliminates metallic impurities within the silicone. Therefore, when growing crystals, an attempt should be made not to eliminate oxygen, but to uniformly maintain its concentration. Thus, the control of oxygen concentration is essential for crystalline growth. At present, the control of oxygen concentration is actively being studied based on the interdependence of various factors such as crystal rotation, crucible rotation, argon flow, pressure, magnet position and magnetic strength. However for methods using a magnetic field, the initial investment and operating costs of the equipment affect the wafer pricing. Hence in this study simulations were performed with the purpose of producing low-cost, high-quality ingots through the development of a process to optimize oxygen concentration without the use of magnets and through the following. a process appropriate to the defect-free range was determined by regulating the pulling rate of the crystals.

• Journal of Microbiology and Biotechnology
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• 제9권5호
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• pp.548-553
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• 1999

A production of $\beta-Carotene$was attempted in a fed-batch culture of Blakeslea trispora by controlling both foam and dissolved oxygen in the presence of surfactant, Span 20. Results obtained from the shake flask cultures indicated that a high concentration of dissolved oxygen was needed for both cell growth and $\beta-Carotene$ synthesis, and the optimal concentration of glucose was found to be in the range of 50-100 g/l. In order to maintain the dissolved oxygen concentration level at higher than 50% of air saturation, pure oxygen was automatically sparged into the medium with air. Foam was controlled by bypassing air from the submerged aeration to the headspace in response to the foam that was caused by Span 20. High agitation speed was found to be detrimental to the cell growth due to shear damage, even though it provided sufficient dissolved oxygen. On the other hand, a low aeration speed caused stagnant regions in the fermentor because of improper mixing. Thus, for the fed-batch operation, agitation speed was increased gradually from 300 to 700 rpm to prevent cell damage at the initial stage of fermentation and to give efficient mixing for a viscous culture broth as the culture proceeded. By controlling dissolved oxygen and foam, a high concentration of $\beta-Carotene$otene (1,190 mg/l) was obtained in 6 days of the fed-batch culture of B. trispora with 2.5% of the dry cell weight, which was approximately 5 times higher than that of the batch cultures.

• 한국연소학회지
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• 제17권1호
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• pp.12-21
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• 2012

Simultaneous measurements of oxygen concentration and temperature using diode laser in the combustion environment are successfully accomplished. A single DFB type diode laser of 760 nm line centre frequency is used and the scanned-wavelength direct absorption spectroscopy method and wavelength modulation spectroscopy method are applied to measure absorption signals below 793 K temperature region. The experimental results show that oxygen concentration are measured within 1% accuracy and temperature are measured within 5% accuracy. This new method of simultaneous measurements of concentration and temperature with a single diode laser shows a great promise.

• Computers and Concrete
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• 제12권5호
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• pp.669-680
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• 2013

This paper unveils a new computer based stabilization methodology for automated modeling analysis and its experimental verification for corrosion in reinforced concrete structures under the effect of varying oxygen concentration. Various corrosion cells with different concrete compositions under four different environmental conditions (air dry, submerged, 95% R.H and alternate wetting-drying) have been investigated under controlled laboratory conditions. The results of these laboratory tests were utilized with an automated computer-aided simulation model. This model based on mass and energy stabilization through the porous media for the corrosion process was coupled with modified stabilization methodology. By this coupling, it was possible to predict, maintain and transfer the influence of oxygen concentration on the corrosion rate of the reinforcement in concrete under various defined conditions satisfactorily. The variation in oxygen concentration available for corrosion reaction has been taken into account simulating the actual field conditions such as by varying concrete cover depth, relative humidity, water-cement ratio etc. The modeling task has been incorporated by the use of a computer based durability model as a finite element computational approach for stabilizing the effect of oxygen on corrosion of reinforced concrete structures.