• 한국가시화정보학회지
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• 제14권1호
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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.

• Current Photovoltaic Research
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• 제3권4호
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• pp.112-115
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• 2015

In this study, the surface of ITO films was modified using $N_2-O_2$ molecular plasma, and the effects of oxygen concentration in the plasma on the ITO surface properties were investigated. Upon plasma treatment of ITO films, the surface roughness of ITO films seldom changed up to the oxygen concentration in the range of 0% to 40%, while the roughness of the films slightly changed at or above the oxygen concentration of 60%. The contact angle of water droplet on ITO films dramatically changed with varying oxygen concentration in the plasma, and the minimum value was found to be at the oxygen concentration of 20%. The plasma resistance at this condition exhibited a maximum value, and the change of resistance showed an inverse relationship compared to that of contact angle. From these results, it was conjectured that the chemical reactions in the sheath of the molecular plasma dominated more than the physical actions due to energetic ion bombardment, and also the plasma resistance could be used as an indirect indicator to qualitatively diagnosis the state of plasma during the plasma treatment.

• 한국결정성장학회지
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• 제7권3호
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• pp.406-417
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• 1997

초크랄스키법들 의한 8인치 실리콘 단결정 성장계에 대칭과 비대칭 커스프 자장을 인가하여 결정을 성장시켰을 때 축방향으로 일정한 산소농도분포를 가질 수 있는 적절한 인가 자장의 크기와 비대칭도에 대한 수치해석적 연구를 수행하였다. 결정이 성장할 때 커스프 자장의 형태가 유지되는 방법으로 도가니의 위치를 변화시키는 방법과 인가코일의 위치를 변화시키는 방법을 비교하였다. 대칭 커스프 자장이 인가된 경우, 축방향으로 일정한 산소농도를 얻을 수 있는 자장의 강도변화는 결정이 성장함에 따라 아래로 볼록한 형태를 띠었다. 축밟향으로 일정한 산소농도분포를 갖기 위해 도가니의 위치를 변화시키는 방법과 코일의 위치를 변화시키는 방법을 비교한 결과 비슷한 산소농도의 표준편차값을 가짐을 알 수 있었다. 비대칭 자장이 인가된 경우, 축방향으로 일정한 산소농도 분포를 얻기 위해서는 비대칭도는 결정이 성장함에 따라 점차 증가하는 양상을 보였다.

• Nuclear Engineering and Technology
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• 제46권6호
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• pp.857-862
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• 2014

Mechanical alloying under various gas atmospheres such as Ar, an Ar-$H_2$ mixture, and He gases were carried out, and its effects on the powder properties, microstructure and mechanical properties of ODS ferritic steels were investigated. Hot isostatic pressing and hot rolling processes were employed to consolidate the ODS steel plates. While the mechanical alloyed powder in He had a high oxygen concentration, a milling in Ar showed fine particle diameters with comparably low oxygen concentration. The microstructural observation revealed that low oxygen concentration contributed to the formation of fine grains and homogeneous oxide particle distribution by the Y-Ti-O complex oxides. A milling in Ar was sufficient to lower the oxygen concentration, and this led a high tensile strength and fracture elongation at a high temperature. It is concluded that the mechanical alloying atmosphere affects oxygen concentration as well as powder particle properties. This leads to a homogeneous grain and oxide particle distribution with excellent creep strength at high temperature.

• 상하수도학회지
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• 제24권6호
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• pp.763-773
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• 2010

The removal efficiencies and a total oxygen transfer coefficient for food waste leachate(FWL) were estimated by using Jet Loop Reactor(JLR). Pure oxygen was used instead of air to improve oxygen concentration in the JLR for high total chemical oxygen demamd(TCOD) in FWL. In JLB, in order to examining the oxygen transfer characteristic, the circulation flowrate and oxygen flowrate were controlled with 7~10 L/min(1.5 L/min interval) and 0.2~0.5 L/min (0.1 L/min interval) and we experimented according to the each condition. As a result, Oxygen uptake rate(OUR) and oxygen transfer rate could be maximized than the oxygen flowrate to increase the circulation flowrate. In addition, it determined that JLR using the pure oxygen which can obtain the greatest oxygen transfer rate as it was the high-concentration organic wastewater like the food waste leachate through the continuous experiment was appropriate.

• 산업공학
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• 제18권2호
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• pp.178-183
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• 2005

In this study, changes in memory performance, blood oxygen saturation and heart rate according to 30% concentration oxygen supply were observed. Ten healthy male and female college students (male:$25.8{\pm}0.8$ years, female: $24.2{\pm}1.9$ years) participated in the study. The experiment was performed as Rest (1min.), Control task (1min.), Word presentation (1min.), Reaction time task (1min.), Distractor (2min.), and Word recall (1min.) and the physiological signals such as blood oxygen saturation and heart rate were measured throughout the stages. Subjects who received 30% oxygen recalled more words than those who received 21% oxygen, which shows 30% oxygen supply has influenced positively on memory cognitive performance. When 30% concentration oxygen is supplied, the blood oxygen saturation in the task phases was increased and the heart rate decreased when comparing to 21%. It means that 30% oxygen can stimulate brain activation by increasing actual blood oxygen concentration in the process of cognitive performance, and the heart rate decreases because enough oxygen is supplied to process the cognitive performance.

• 한국가축번식학회지
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• 제22권1호
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• pp.43-50
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• 1998

The effect of oxygen tension on embryonic development in co-culture was evaluated from the standpoint of the reduction of dissolved oxygen concentration by the oxygen consumption of feeder cells. Three co-culture systems using bovine oviductal epitherial cells (BOEC), African green monkey kidney cells (Vero cells) or buffalo rat liver cells (BRLC) have been compared in terms of development of bovine embryos derived from oocytes matured and fertilized in vitro. Among the co-cultured embryo, Vero cells su, pp.rted the highest developmental rate (29%) and the other two showed the similar rates. When the co-cultures were incubated in three different oxygen tension such as 5, 10, 20% oxygen atmosphere, embryos co-cultured with Vero cells at 10%-O2 resulted in the highest percentage of development. From the measurement of oxygen consumption of feeder cells, BRLC consumed 1.38　10-10 mg-O2/min/cell which was higher than 0.94　10-10 and 0.26　10-10mg-O2/min/cell for Vero cells and BOEC, respectively. Based on the oxygen consumption data, the phenomena of optimum oxygen tension required in embryo development in vitro has been analyzed, and we suggested that gas phase oxygen concentration, oxygen consumption rate of feeder cells and the number of feeder cells should be considered for the design of optimal co-culture system for effective fertilization of embryos in vitro.

• Environmental Analysis Health and Toxicology
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• 제17권3호
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• pp.219-224
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• 2002

This study was carried out to examine the effects of bis (tribytyltin)oxide (TBT), endocrine disrupting compounds (EDCs). on the changes of survival, growth and oxygen consumption rate in the oliver flounder, Paralichthys olivaceus. Oliver Flounders were exposed to sublethal concentration of TBT (0, 1.67, 3.20, 6.30 and 12.50 $\mu\textrm{g}$/L) during 6 weeks. Survival rate was decreased in a concentration and exposure period-dependent way and suddenly the reduction of more than 20% occurred at TBT concentration greater than 3.20 $\mu\textrm{g}$/L. after exposure 6 weeks. Growth rate and feed efficiency significantly decreased at concentration greater than 3.20 $\mu\textrm{g}$/L. Oxygen consumption rate was also decreased in a concentration-dependent way and significantly decreased to 17,48 and 67％ than that of the control at the TBT concentration of 3.20, 6.32 and 12.50 $\mu\textrm{g}$/L, respectively. This study revealed that high TBT concentration ($\geq$3.20 $\mu\textrm{g}$/L) reduced growth and oxygen consumption rates of the juvenile oliver flounder suggesting potential influence on the natural mortality of Paralichthys olivaceus in the coastal areas.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XII)
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• pp.240-244
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• 2003

A novel integrated method for increasing dissolved oxygen concentration in culture media has been developed. It involves adding hydrogen peroxide to the medium, which is then decomposed to oxygen and water by catalase and adding vegetable oil to the medium as antifoam agent and oxygen vector. A new apparatus for automated addition of hydrogen peroxide to the bioreactor to keep the dissolved oxygen concentration constant over the range $10-100%\;{\pm}\;5%$ was tested. A significant increase (over threefold) of cultivation time was obtained while the dissolved oxygen concentration remained stable ($30%\;{\pm}\;5%$). Therefore, use of corn oil mixed with Ca-stearate as oxygen vector and antifoam and hydrogen peroxide as oxygen source to control excessive foam that was generated by microorganism biosurfactant, GB16-BS produced at Bacillus sp. GB16 cultivation was appropriate for stable cultivation.

• 한국안전학회지
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• 제10권2호
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• pp.84-91
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• 1995

The characteristics of critical spontaneous ignition of granulated activated carbon were investigated In atmospheres of differing oxygen concentration. At the same concentration the larger vessels yielded the lower critical spontaneous ignition temperature. At the same vessel, as the concentration of oxygen was reduced, Ignition occurred later and at higher ambient temperature, and critical spontaneous ignition temperature increased. The apparent activation energy calculated from the Frank-Kamenetskii's ignition theory appeared to be the slight different value respectively and the mean apparent activation energy was 19850㎈/㏖.