• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2010.11a
• /
• pp.51-54
• /
• 2010

Physical characteristics of liquid and gaseous oxygen and the detailed ignition characteristics of oxygen system were introduced. Compatible and non-compatible materials for oxygen were discussed. To ensure the safety operation of the oxygen system, one of the most important point, cleaning, was reviewed. To design the gaseous and liquid oxygen system, key points were introduced. To safe operation, the operating procedure and considerations were introduced.

• Journal of the Semiconductor & Display Technology
• /
• v.15 no.1
• /
• pp.70-75
• /
• 2016

GZO films prepared on ITO glasses were annealed at various temperatures in a vacuum condition to research the relationship between oxygen vacancies and optical properties. GZO films after annealing in a vacuum showed the various optical-chemical properties depending on the annealing temperatures and oxygen gas flow rate during the deposition. The oxygen vacancy of GZO film prepared by oxygen gas flows of 22 sccm increased with increasing the annealing temperatures, because of the extraction of oxygen by the annealing. But the intensity of photoluminance of GZO with 22 sccm decreased in accordance with the annealing temperature, because of the reduction of ionized charge carriers. The oxygen vacancy by the extraction of oxygen enhanced a depletion, so the widen depletion had the strong Schottky barrier and the PL intensity due to the low carrier density decreased.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.25 no.11
• /
• pp.873-877
• /
• 2012

The effect of oxygen pressure in the synthesis of ZnO nanostructures through thermal evaporation of Zn powder was investigated. The thermal evaporation process was carried out in oxygen ambient for 1 hr at $1,000^{\circ}C$ under different pressures. The oxygen pressure was changed in range of 0.5 ~ 900 Torr. Any nanostructure was not formed on the specimens prepared at oxygen pressures lower than 10 Torr. When oxygen pressure was 100 Torr, ZnO nanowires were observed. With increasing the oxygen pressure to 500 Torr, the morphology of ZnO nanostructures changed from wire to tetrapod. For all the samples, room temperature photoluminescence spectra show a strong green emission peak at around 550 nm.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.4 no.1
• /
• pp.51-58
• /
• 1999

A mathematical model for a three phase fluidized bed bioreactor (TFBBR) was proposed to describe oxygen utilization rate, biomass concentration and the removal efficiency of Chemical Oxygen Demand (COD) in wastewater treatment. The model consisted of the biofilm model to describe the oxygen uptake rate and the hydraulic model to describe flow characteristics to cause the oxygen distribution in the reactor. The biofilm model represented the oxygen uptake rate by individual bioparticle and the hydrodynamics of fluids presented an axial dispersion flow with back mixing in the liquid phase and a plug flow in the gas phase. The difference of setting velocity along the column height due to the distributions of size and number of bioparticle was considered. The proposed model was able to predict the biomass concentration and the dissolved oxygen concentration along the column height. The removal efficiency of COD was calculated based on the oxygen consumption amounts that were obtained from the dissolved oxygen concentration. The predicted oxygen concentration by the proposed model agreed reasonably well with experimental measurement in a TFBBR. The effects of various operating parameters on the oxygen concentration were simulated based on the proposed model. The media size and media density affected the performance of a TFBBR. The dissolved oxygen concentration was significantly affected by the superficial liquid velocity but the removal efficiency of COD was significantly affected by the superficial gas velocity.

• Ocean and Polar Research
• /
• v.35 no.3
• /
• pp.229-237
• /
• 2013

We measured two-dimensional (2-D) oxygen distribution in the surface sediment layer of intertidal sediment using a simple and inexpensive planar oxygen optode, which is based on a color ratiometric image approach. The recorded emission intensity of red color luminophore light significantly changed with oxygen concentration by $O_2$ quenching of platinum(II)octaethylporphyrin (PtOEP). The ratios between the intensity of red and green emissions with oxygen concentration variation demonstrated the Stern-Volmer relationship. The 2-D oxygen distribution image showed microtopographic structure, diffusivity boundary layer and burrow in surface sediment layer. The oxygen penetration depth (OPD) was about 2 mm and the one-dimensional vertical diffusive oxygen uptake (DOU) was 12.6 mmol $m^{-2}d^{-1}$ in the undisturbed surface sediment layer. However, those were enhanced near burrow by benthic fauna, and the OPD was two times deeper and DOU was increased by 34%. The simple and inexpensive oxygen planar optode has great application potential in the study of oxygen dynamics with high spatiotemporal resolution, in benthic boundary layers.

• Transactions of the Korean hydrogen and new energy society
• /
• v.26 no.6
• /
• pp.600-608
• /
• 2015

As a candidate for cheap oxygen carrier, $CaSO_4$ based oxygen carriers have been developing. However, research on reaction characteristics and side reaction of $CaSO_4$ based oxygen carrier is very limited. There are many possible reactions for main components of syngas from coal. In this study, we prepared three $CaSO_4$ based oxygen carriers ($CaSO_4$-$Fe_2O_3$/bentonite, $CaSO_4$-$K_2CO_3$/bentonite, $CaSO_4$-CaO/bentonite) and performed reduction tests by hydrogen. Cyclic reduction-oxidation tests up to $5^{th}$ cycle are also conducted using hydrogen as fuel. Reduction reactivity of those $CaSO_4$ based oxygen carriers were compared with that of NiO based oxygen carrier (OCN703-1100). Real weight change fractions of $CaSO_4$ based oxygen carriers were higher than theoretical oxyen transfer capacity and reactivity of these particles decreased with the number of cycle increased. To check possible side reaction of $CaSO_4$ based oxygen carriers, $CaSO_4$ decomposition tests were carried out and $SO_2$ was detected even at $700^{\circ}C$. Consequently, we could conclude that $CaSO_4$ based oxygen carriers decompose and release $SO_2$ and this reaction lead reactivity decay of $CaSO_4$ based oxygen carries.

• Journal of Preventive Medicine and Public Health
• /
• v.26 no.4 s.44
• /
• pp.551-564
• /
• 1993

Since the widespread application of hyperbaric oxygenation in clinical medicine, the problems of oxygen toxicity have been attracting a deep interest from the researchers on hyperbaric medicine as a practical issue. Among extensive research trials, the study on the protective agents oxygen toxicity occupied one of the most challenging field. As the mechanisms of oxygen toxicity, the role of the oxygen free radicals produced by peroxidation process are strongly accepted by the leading researchers on oxygen toxicity, the probable protective effects of antioxidant against oxygen toxicity are sustaining a sufficient rational. Maltol ($2-methyl-3-hydroxy-{\gamma}-pyrone$) which is known to be a component of Korean red ginseng has been reporting to have an antioxidant action. But, further study is needed to provide definite evidence for this compound to be an antioxidant, since the action was based on the results which were obtained under in vitro experiment. In this study, the author attempted to evaluate the effect of maltol as protective agent against oxygen toxicity through the observation of death rate, convulsion rate, time to convulsion and microscopic pathological changes in some organs of experimental rats exposed to various conditions. The findings observed are as follows : 1) The death rate, convulsion rate, time to convulsion, lung/weight ratio and microscopic pathological finding of lung were identified as reliable objective and quantitative indices for oxygen toxicity. 2) Maltol showed excellent protective effect against pulmonary oxygen toxicity as an antioxidant.

• Journal of Preventive Medicine and Public Health
• /
• v.5 no.1
• /
• pp.105-110
• /
• 1972

On 6 healthy adult males aged 20-30 years, oxygen pulse was observed during carrying sand bags weighing 10, 20 and 30 kg on a level treadmill running with speeds of 3, 4 and 5 km/hr. The results obtained were as follows. 1. Oxygen pulse during load carrying on a level treadmill was proportionately increased with an increase of work load, average oxygen uptake per minute. Regression equation of oxygen pulse (y: $m\iota$/beat) on the average oxygen uptake (x:$\iota$/min) required for each grade of work was expressed as y=3.34x+5.99, $s_{y.x}=0.858$). 2. Oxygen pulse reached the highest value 2-5 minutes after the start of load carrying, and thereafter it decreased gradually to some extend as the load carrying was continued. Rate of decrease in the oxygen pulse was greater in lighter works. 3. In lighter works requiring less than $2.0\iota/min$ of oxygen uptake, no difference in oxygen pulse could be seen between methods of carrying even when the same amount of load was carried. In heavier works requiring more than $2.0\iota/min$ of oxygen uptake, oxygen pulse was larger in case of carrying a load by embrace, in both hands and on head than on back or on shoulder.

• Journal of Korean Society on Water Environment
• /
• v.25 no.6
• /
• pp.896-901
• /
• 2009

In this study, in order to apply the air and pure oxygen in the Jet Loop Reactor (JLB) in which the oxygen transfer rate is high, differentiate the operation mode according to each air flowrate and liquid flowrate and investigate the oxygen transfer characteristic, an experiment was carried out. The oxygen concentration with the air flowrate ($Q_g$) and liquid flowrate ($Q_L$) was identical but the oxygen transfer coefficient ($K_L{\cdot}a$) is linear depending on degree of two factors. The width of an increase is small in $0.1min^{-1}$ when the air flowrate is 0.2 L/min with increasing the liquid flowrate. Whereas, the increment was exposed to be very high for $1.5min^{-1}$ when the air flowrate was 5 L/min. In the experiments using the pure oxygen, it was 30 mg/L of oxygen concentration finally and it was 3.5 times than using the air. But the time reached the saturated concentration was similar to using the air, and $K_L{\cdot}a$ was similar to using the air too. Analysis between two independent variable and oxygen transfer of the correlation is the same model like $K_L{\cdot}a={0.0161Q_L}^{1.5371}{Q_g}^{0.5433}$ using with coefficient non linear regression analysis. It was resulted that the liquid flowrate were approximately three times than air flowrate on effect to oxygen transfer rate.

• Transactions of the Korean hydrogen and new energy society
• /
• v.25 no.1
• /
• pp.87-96
• /
• 2014

Direct combustion characteristics of coal and oxygen carrier were measured in the thermogravimetric analyzer using four coals and two different oxygen carriers. The direct combustion efficiency decreased in order of Roto, Kideco, Sunhwa and Hyper coal for both oxygen carriers. Moreover, OCN703-1100 oxygen carrier showed better combustion efficiency than OCN706-1100 oxygen carrier for all four coals. The reduction characteristics of two oxygen carriers for $CH_4$, CO and $H_2$ gases were measured in the thermogravimetric analyzer to investigate why OCN703-1100 oxygen carrier showed better combustion efficiency than OCN706-1100 for all coals. The OCN703-1100 oxygen carrier represented higher reduction rate than OCN706-1100 for all reducing gases. Moreover, the total pore area and the porosity of OCN703-1100 were higher than those of OCN706-1100 oxygen carrier. The total volatile gas and volatile components of four coals were measured in a batch type fluidized bed reactor to investigate why the direct combustion efficiency decreased in order of Roto, Kideco, Sunhwa and Hyper coal for both oxygen carriers. The direct combustion efficiency was proportional to the total amount of ($CH_4+CO+H_2$) produced during devolatilization of coals.