• Journal of the Korean Society of Visualization
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• v.10 no.1
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• pp.34-39
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• 2012

In the present study, oxygen transfer process across gas-liquid interface in a Y-shape micro-channel is quantitatively visualized using the micro laser induced fluorescence (${\mu}$-LIF) technique. Diffusion coefficient of Oxygen ($D_L$) is estimated based on the experimental results and compared to its theoretical value. Tris ruthenium (II) chloride hexahydrate was used as the oxygen quenchable fluorescent dye. A light-emitting diode (LED) with wavelength of 450 nm was used as the light source and phosphorescence images of fluorescent dye were captured by a CMOS high speed camera installed on the microscope system. Water having dissolved oxygen (DO) value of 0% and pure oxygen gas were injected into the Y-shaped microchannel by using a double loading syringe pump. In-situ pixel-by-pixel calibration was carried out to obtain Stern-Volmer plots over whole flow field. Instantaneous DO concentration fields were successfully mapped according to Stern-Volmer plots and DL was calculated as $2.0675{\times}10^{-9}\;m^2/s$.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.1
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• pp.6-11
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• 2023

Objective: This study was conducted to identify the cause of suffocation accident. Methods: We analyzed the components of zinc concentrates by ICP-OES (inductively coupled plasma optical emission spectroscopy) and tested the oxygen consumption by zinc concentrates in a 13.2-liter closed chamber. Results: Zinc, sulfur and iron were the main components of the four types of zinc concentrates, and accounted for 76~89% by weight. Zinc concentrates (0.5 or 0.927 kg) depleted the oxygen concentration from 20.9% to 7.4~18.9% during seven days. The rate of oxygen consumption was in the range of 3.0~11.0 mM/day·kg-sample at 21~24℃ and around 95% of free air space within the closed chamber. Conclusion: Since zinc concentrate consumes oxygen in a confined space, measures should be taken to prevent suffocation accident (such as ventilation and monitoring of oxygen concentration).

• Science of Emotion and Sensibility
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• v.11 no.1
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• pp.105-112
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• 2008

This study investigated the effect of 40% oxygen administration on the addition task performance in three levels of difficulties and physiological signals. Ten male and female college students were selected as the subjects for this study. The experiment consisted of two runs: one was a addition task, with normal air (21% oxygen) administered and the other was with hyperoxic air (40% oxygen) administered. The experimental sequence in each run consisted of Rest1 (3 min), Task1 (1 min, one digit addition task), Task2 (1 min, two digit addition task), Task3 (1 min, three digit addition task), and Rest2 (4 min). Blood oxygen saturation and heart rate were measured throughout the five phases. The accuracy rates of the addition task were enhanced with 40% oxygen administration compared to 21% oxygen. Difference in the accuracy rates grew higher with the rise of difficulty. When 40% concentration oxygen is supplied, blood oxygen saturation increased and heart rate was decreased comparing to 21%. This study showed that the supply of high concentration oxygen increases blood oxygen saturation, which in turns accelerates brain activation resulting from cognitive process and enhances arithmetic abilities. Particularly when difficulty is high, demand for oxygen increases and, as a result, the effect of high concentration oxygen becomes more significant.

• Journal of Chest Surgery
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• v.23 no.6
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• pp.1084-1089
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• 1990

Plasma protein concentration, plasma albumin concentration, hematocrit, and arterial blood gas tension were measured in 15 mongrel dogs undergoing heart transplantation with cardiopulmonary bypass. The hemodilution due to priming solution resulted in a 49% decrease in plasma protein concentration, a 57% decrease in plasma albumin concentration, a 46%a decrease in hematocrit. The measurements had returned to preperfusion values 1 hour after the end of cardiopulmonary bypass. The intraoperative changes in plasma protein and albumin concentration did not correlate with changes in alveolar-arterial oxygen tension gradients[D[A\ulcorner PO2]]. It is concluded that, in the absence of an increase in left atrial pressure, marked decrease in plasma protein concentration can be tolerated without the occurrence of pulmonary edema. And further study should be done to determine how to prepare an ideal priming solution.

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

• The Korean Journal of Physiology
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• v.2 no.2
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• pp.53-61
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• 1968

Maximal oxygen debt, lactate and excess lactate were measured in 13 men with low hematocrit ratio before and after maximal exercise. Maximal exercise run was performed on a treadmill and the duration of run was 2 minutes 45 seconds in each subject. Hematocrit ratio ranged between 35 and 47%, the mean being 39.8%. The following results were obtained. 1. Maximal oxygen debt expressed on basis of body weight increased as the hematocrit ratio decreased. The correlation coefficient between the two was r= -0.770. 2. The time necessary for decreasing to 50% of total maximal $O_2$ debt(half time) became longer as the hematocrit ratio decreased. In normal men the half time was about 4 minutes and at the longest it was 12 minutes in men with the lowest hematocrit ratio. 3. The lactate concentration reached its peak value after 3 minutes of recovery. Thereafter, the time course of decrease in lactate concentration coincided roughly with that of respiratory oxygen debt curve. To reach to the resting level, however, it took longer time than that of respiratory oxygen debt. 4. Resting concentrations of lactate was 1.28 mM/l, pyruvate 0.13 mM/l and L/P ratio was 9.8. Peak value of ${\Delta}L$ after exercise reached to the value of 10.4 mM/l and ${\Delta}L/P$ reached 26.0. Peak excess lactate after exercise was 6.34 mM/l. 5. The part of oxygen debt accounted for by the oxygen equivalent of excess lactate was only 38.4%. A better relationship between lactate and oxygen debt was observed and the part of oxygen debt accounted for by the oxygen equivalent of lactate was 63.3%. 6. Peak value of lactate after maximal exercise increased as the hematocrit ratio decreased. 7. Respiratory oxygen debt of 100 ml/kg was accounted for by lactate more than 60% and only 30% was by excess lactate. 8. Excess lactate was not a good index of respiratory oxygen debt.

• Journal of Korean Society of Water and Wastewater
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• v.9 no.4
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• pp.87-96
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• 1995

The Electron/Hole Pair is generated when the activation energy produced by ultraviolet ray illuminates to the semiconductor and OH- ion produced by water photocleavage reacts with positive Hole. As a results, OH radical acting as strong oxidant is generated and then Photocatalytic oxidation reaction occurs. The photocatalytic oxidation can oxidate the non-degradable and hazardous organic substances such as pesticides and aromatic materials easier, safer and shorter than conventional water treatment process. So in this study, many factors influencing the oxidation of chlorophenols, such as inorganic electrolytes addition, change of oxygen and nitrogen atmosphere, temperature, pH, oxygen concentration, chlorophenol concentration, were throughly examined. According to the experiments observations, it is founded that the rate of chlorophenol oxidation follows a first-order reaction and the modified Langmuir-Hinshelwood relationship. And the photocatalytic oxidation occurs only when activation energy acting as Electron/Hole generation, oxygen acting as electron acceptor to prevent Electron/Hole recombination, $TiO_2$ powder acting as photocatalyst are present. The effects of variation of dissolved oxygen concentration, temperature and inorganic electrolytes concentration on 2-chlorophenol oxidation are negligible. And the lower the organic concentration, the higher the oxidation efficiency becomes. Therefore, the photocatalytic oxidation is much effective to oxidation of hazardous substances at very low concentration. The oxidation is effective in the range of 0.1 g/L-10 g/L of $TiO_2$. Finally when the ultra-violet ray is illuminated to $TiO_2$, the surface characteristics of $TiO_2$ change and Adsorption/Desorption reaction on $TiO_2$ surface occurs.

• Macromolecular Research
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• v.8 no.1
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• pp.1-5
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• 2000

The valiclity of the simple mathematical model for facilitated transport in a solid state membrane developed previously has been examined againsts the carrier concentration and membrane thick-ness. Membranes are prepared with copolymer of styrene and 4-vinylpyridine as a matrix and Co(salen) as a carrier. 4-Vinylpyridine is incorporated to provide the coordination site for Co(salen) carrier. Oxygen permeability through the facilitated transport membrane is linearly increased with the square of its thick-ness, as predicted by the mathematical model. However, the oxygen permeability does not increase linearly with the carrier concentration. This seems to be due to the deactivation of the carrier by dimerization at high carrier concentrations as well as the reduced chain mobility by coordination of bulky Co(salen) carrier.

• Fire Science and Engineering
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• v.15 no.4
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• pp.34-40
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• 2001

The spontaneous ignition of hydroxypropyl methyl cellulose(HPMC) was investigated at constant ambient temperature in the oven and minimum ignition temperature of dust clouds with Godbret-Creenwald Furnace respectively, In the experiments of the vessel filled with sample. the larger the vessel was the lower the spontaneous ignition temperature and ambient temperature was calculated from the Frank-Kamenetskii thermal ignition theory. The minimum ignition temperature for the dust cloud state was found under 21% oxygen concentration. At the experiment with the change of oxygen concentration, HPMC was not ignite at 10% $O_2$and so the limiting oxygen concentration was obtained at 10%.

• Environmental Analysis Health and Toxicology
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• v.17 no.4
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• pp.357-362
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• 2002

Tests for the toxicity of tributyltin (TBT) were conducted on mysid collected from Dadepo beach, Pusan, Korea. The toxic effects of tributyltin on the survival, growth and oxygen consumption of the mysid, Neomysis awatschensis have been evaluated. Mysids were exposed to several concentrations of TBT (0, 0.56, 1.15, 3.07 and 6.12 $\mu\textrm{g}$/L) for 6 weeks. Survival rate was decreased with increases in concentration and exposure time and the reduction of more than 40％ occurred at TBT concentration greater than 1.15 $\mu\textrm{g}$/L after 6 weeks. Growth rate was significantly decreased at concentrations greater than 1.15 $\mu\textrm{g}$/L. Oxygen consumption rate was also decreased in a concentration-dependent way and significantly decreased to 39,47 and 69％ of the control at 1.15, 3.07 and 6.12 $\mu\textrm{g}$/L, respectively. These results indicate that the contamination of aquatic environment by TBT has the potential to significantly reduce coastal and estuaries recruitment of mysids.