• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2965-2970
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• 2008

Effects of split injection and oxygen-enriched air on soot emissions in a DI diesel engine were studied by the KIVA-3V code. When split injection is applied, the second injection of fuel into a cylinder results in two separate stoichiometric zones which increases soot oxidation. As a result, soot emissions are decreased with split injection. When oxygen-enriched air is applied together with split injection, higher concentration of oxygen helps secondary combustion which results in a higher temperature in the cylinder. The increased temperature promotes growth reaction of acetylene with soot but doesn't improve the acetylene formation during the second injection of fuel. As more acetylene is consumed in the growth reaction of acetylene, the net acetylene mass in the cylinder is decreased, which leads to a decrease of soot formation. With an increase of soot oxidation caused by split injection, the soot emissions are decreased significantly. However, to avoid excessive NOx emissions with increased oxygen concentration, the level of oxygen concentration should be lower than 22% in volume.

• Biomedical Science Letters
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• v.15 no.1
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• pp.87-91
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• 2009

In photodynamic therapy (PDT), oxygen plays important role. Because of singlet oxygen which is produced by activated photosensitizer after laser irradiation of specific wavelength. The aim of this study is to find how oxygen concentration affects anticancer effect in PDT. Groups were divided into PDT with oxygen applied group and only PDT applied group. PDT with oxygen applied group supplied oxygen for 15 minute before laser irradiation. In vitro, CT-26 cell was incubated with various concentration of photofrin $(50.0{\sim}0.05{\mu}g/ml)$ and was irradiated with 632nm diode laser 6hr after application of photofrin. The cell viability of two groups was assessed by MTT assay. In vivo, CT-26 cell line was transplanted into the subcutaneous tissue of BALB/c mouse. The anticancer effect of two groups was measured by tumor volume change. In vitro study, the cell viability was significantly decreased at $1.56{\sim}3.13{\mu}g/ml$ in PDT with oxygen applied group. In vivo study, the PDT with oxygen applied group significantly higher reduction rate of tumor volume 7 days after PDT compared to PDT only group. The high oxygen concentration might enhance the anticancer effect of the photodynamic therapy.

• Journal of the Korean Society of Visualization
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• v.9 no.1
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• pp.36-41
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• 2011

It is highly needed to measure the dissolved oxygen (DO) concentration field in water for a variety of purposes such as biological, industrial, environmental monitoring and medical application. Application of PSP (Pressure Sensitive Paint) which is sensitive to oxygen concentration has been carried out to measure DO concentration field using PtOEP/PS film and intensity based method under the UV-LEDs illumination. A micro round water jet having 100% of DO was obliquely impinged on to a PtOEP/PS film coated plate placed in a 0% of DO water container. DO concentration fields on the impinging plate were quantitatively visualized with a $2.94\;{\mu}m$ of spatial resolution. Through pixel-by-pixel calibration, uncertainty of each pixel by different sensitivity, different dye concentration and non-uniformity of illumination was removed. It is demonstrated that the high DO concentration region was coincided with the impingement area. The DO concentration gradient due to DO diffusion was affected by Reynolds number.

• 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 Korean Tunnelling and Underground Space Association
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• v.18 no.2
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• pp.175-181
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• 2016

In this paper, the liquid air was selected as the refrigerant in artificial ground freezing to be used for rapid ground freezing and to reduce the risk of suffocation and the applicability of liquid air was verified. In order to evaluate the stability of the liquid air, the oxygen concentration of mixtures with liquid nitrogen and liquid oxygen was experimentally examined to meet the oxygen concentration criteria in the Occupational Safety and Health Act. In addition, the effects of the mixture ratio of liquid nitrogen and liquid oxygen, pressure and flow rate change in the storage vessel on the oxygen concentration in the liquid air were investigated. As a result, the ratio of liquid nitrogen and liquid oxygen 8: 2 was shown to meet the oxygen concentration standards. Pressure and flow rate change in the storage vessel did not have significant effects on the oxygen concentration in the liquid air.

• Nuclear Engineering and Technology
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• v.53 no.7
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• pp.2221-2228
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• 2021

One-dimensional oxygen transport relation is indispensable to study the oxygen distribution in the LBE-cooled system with an oxygen control device. In this paper, a numerical research is carried out to study the oxygen transport characteristics in a gas-phase oxygen control device, including the static case and dynamic case. The model of static oxygen control is based on the two-phase VOF model and the results agree well with the theoretical expectation. The model of dynamic oxygen control is simplified and the gas-liquid interface is treated as a free surface boundary with a constant oxygen concentration. The influences of the inlet and interface oxygen concentration, mass flow rate, temperature, and the inlet pipe location on the mass transfer characteristics are discussed. Based on the results, an oxygen mass transport relation considering the temperature dependence and velocity dependence separately is obtained. The relation can be used in a one-dimensional system analysis code to predict the oxygen provided by the oxygen control device, which is an important part of the integral oxygen mass transfer models.

• KSBB Journal
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• v.28 no.1
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• pp.24-30
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• 2013

Dissolved oxygen, pH and cell concentration have been online monitored in cultivation processes with Escherichia coli by using a $MABOOMS^{TM}$ (microplate-based bioreactor with optical online monitoring systems). Fluorescent sensing membranes containing Ru ${(dpp)_3}^{2+}$ or HPTS were prepared with GA sol-gel matrix and coated into a well of a 24-well microplate. Fluorescence intensity was measured and correlated to the dissolved oxygen or pH. Cell concentrations were also online monitored by measuring optical reflectance at 650 nm. A well of a 24-well microplate could also be divided into 4 parts, each of which was coated with fluorescent sensing membranes for the detection of dissolved oxygen or pH. The 24-well microplate coated with fluorescent sensing membranes or a 4-divided sensing membrane. was used to online monitor the dissolved oxygen, pH and cell concentration during E. coli cultivations. The online monitoring results showed the characteristics of cell growth in cultivation processes very well.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.11
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• pp.41-46
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• 2015

This study was conducted to discover a substitute of $SF_6$ gas. $SF_6$ gas is widely used across the industries. Thanks to superior electrical properties, in particular, it has been commonly used in electrical industry. However, there have been a lot of studies on its serious effect on global warming. As a substitute of this synthetic gas, a mixture of dry air and $N_2/O_2$ was chosen in this study. In case of $N_2/O_2$, dielectric strength differs depending on the mixing ratio. This study examined dielectric breakdown and flashover after adjusting oxygen percentage in the dry air. This test was conducted in a quasi-uniform electric field depending on pressure, oxygen concentration and gas mixtures. The test results found that dielectric voltage and flashover voltage were the highest at a certain oxygen concentration. It is the results of this photoionization and electron attachment of oxygen.

• The Korean Journal of Food And Nutrition
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• v.24 no.4
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• pp.803-807
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• 2011

Human umbilical Mesenchymal Stem Cell(uMSC) has been known as one of major component to regenerate connective tissues such as bone, cartilage, fat and others. The effect of low(5%), normotensive(20%) oxygen and freezing-thawing damage on proliferation of uMSC were investigated. low oxygen concentration culture of uMSC resulted in enhanced proliferation significantly($p$ <0.05) than 20% of oxygen culture. After the freezing-thawing injury to uMSC, 5% oxygen culture showed marked proliferation of uMSC than that of 20% oxygen($p$ <0.05) in the 5th passage of uMSC. Expression of antioxidant enzymes such as superoxide anion 1 and glutathione peroxidase 1 appeared marked in 20% oxygen cultured uMSC, which suggest oxidative stress could induce less proliferation of uMSC. Above findings would suggest proliferation of uMSC in 5% of oxygen will give more yields.

• Journal of Sensor Science and Technology
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• v.10 no.4
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• pp.259-265
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• 2001

FET-type dissolved oxygen sensor has the Pt working electrode around the pH-ISFET. Appling a voltage to the working electrode, the hydrogen ion which is proportional to the dissolved oxygen concentration occurs around the pH sensing gate and we can measure the dissolved oxygen concentration by detecting pH concentration through the pH-ISFET. In this paper, a dissolved oxygen measurement system using FET-type dissolved oxygen sensor array which adopt a specific algorithm to enhance the reliability has been developed and we compared its performance with the commercial dissolved oxygen measurement system.