• Journal of Mechanical Science and Technology
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• v.16 no.9
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• pp.1156-1165
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• 2002

The characteristics of combustion and radiation heat transfer of an oxygen-enhanced diffusion flame was experimentally analyzed. An infrared radiation heat flux gauge was used to measure the thermal radiation of various types of flames with fuel, air and pure oxygen. And the Laser Induced Incandescence (LII) technique was applied to characterize the soot concentrations which mainly contribute to the continuum radiation from flame. The results show that an oxygen-enhanced inverse diffusion flame is very effective in increasing the thermal radiation compared to normal oxygen diffusion flame. This seems to be caused by overlapped heat release rate of double flame sheets formed in inverse flame and generation of higher intermediate soot in fuel rich zone of oxygen-fuel interface, which is desirable to increase continuum radiation. And the oxygen/methane reaction at slight fuel rich condition (ø=2) in oxygen-enhanced inverse flame was found to be more effective to generate the soot with moderate oxygen availability.

• Journal of Korean Society on Water Environment
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• v.18 no.2
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• pp.213-220
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• 2002

In this study the effects of initial pH, temperature, dissolved oxygen concentration, and sediment depth on the release of phosphorus from sediment in Lake Sihwa were investigated. No phosphorus release occurred at $10^{\circ}C$ for all pH values. DO concentrations were decreased and equilibrium was obtained 4-8 days after phosphorus release started. The DO concentrations were less than 1 mg/L. Sediment depth had little effect on phosphorus release rate. In order to control the released phosphorus, raw sludge and chalk were used. Results showed that a portion of phosphorus was removed by adsorption to chalk and raw sludge. About 90 % phosphorus removal was observed using sludge and calcinated chalk from the water sample in Lake Sihwa.

• Fire Science and Engineering
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• v.34 no.2
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• pp.1-6
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• 2020

The energy released by various burning material has a wide range of its magnitude and transient characteristics, the measurement of the heat release rate(HRR) has been considered as one of the most challenging issue among the parameters related to fire. This study compares the measured HRR calculated by the oxygen consumption (OC) method and the carbon dioxide generation (CDG) method using a laboratory-scale fire calorimeter. The feasibility of the CDG method is examined by analyzing the relative error. The relationship between the oxygen depletion factor and CO₂ mass flow rate, which is a key parameter in HRR calculations, showed strong linearity at 6 % for the methane burner fire. The contribution of HRR by CO was less than 7% compared with the of HRR by CO₂ in the CDG calculation method. The linearity of the OC and CDG methods with respect to HRR of the referenced methane burner in a quasi-steady state was less than 1%; this indicates that the CDG method can be utilized as a complementary method in heat release rate measurement.

• Fire Science and Engineering
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• v.28 no.5
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• pp.1-7
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• 2014

The present study has been conducted to analyse the effects of various pool diameters on the measurement of heat release rate (HRR) of heptane fire using large scale cone calorimeter (LSC). The burning rate which is the major parameter for HRR compared with the previous model suggested by A. Hamins. The combustion efficiency for heptane by oxygen consumption method is about 91%, which is almost same with the previous results of 92% suggested by J. Gore. The convective HRR by enthalpy consumption method was 54% lower than HRR by oxygen consumption method. This results are practical use for establishing the reliability of heat release rate for fire experiment.

• 수도
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• s.50
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• pp.20-25
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• 1989

Water quality of river is greatly influenced by sediments of planktons, suspended solids and organic matters being transported by efflenced. The water quality is also affected by their release at the place of sediments with slow flow of water. This paper deals with the Characteristics of Oxygen consumption of sediments in small river which is greatly vary with time. Some typical samples of sediment were taken from both aerobic and anaerobic condition reserved for several months. and, the samples of sediment were checked on the relative ratio of oxygen consumption by nitrification.

• Toxicological Research
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• v.4 no.1
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• pp.23-35
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• 1988

The role of calcium in the production of oxygen radical which causes reperfusion damage of ischemic heart has been examined. The reperfusion damage was indrced in isolated Langendorff perfused rat hearts by aortic clamping for 60 min followed by reperfusion with oxygenated Krebs-Henseleit solution with or without 1.25 mM $CaCl_2.$ On reperfusion of the ischemic hearts with the calcium containing solution, the release of cytosolic enzymes (LDH and CPK) increased abruptly. These increased release of enzymes were significantly inhibited by additions of oxygen radical scavengers (SOD, 5,000 U; catalase, 12,500 U) into the reperfusion solution. In the hearts isolated from rats pretreated with allopurinol(20 mg/kg orally, 24 hr and 2 hr prior to the experiments), the levels of enzymes being released during reperfusion were significantly lower than that of the control. However, in the hearts perfused with the calcium-free but oxygenated solution, the increase in the release of cytosolic enzymes during reperfusion was neither inhibited by oxygen radical scavengers nor by allopurinol pretreatment. For providing the evidence of oxygen radical generation during the reperfusion of ischemic hearts in situ, the SOD-inhibitable reduction of exogenously administered ferricytochrome C was measured. In the hearts perfused with the calcium containing solution, the SOD-inhibitable ferricytochrome C reduction increased within the first minute of reperfusion, and was almost completely inhibited by allopurinol pretreatment. When the heart was perfused with the calcium free solution, however, the reduction of ferricytochrome C was not only less than that in the calcium containing condition, but also was not so completely inhibited by allopurinol pretreatment. By ischemia, xanthine oxidase (XOD) in the ventricular tissue was changed qualitatively, but not quantitatively. In the heart made ischemic with the calcium containing condition, the oxygen radical producing O-form of XOD increased, while the D- and D/O-form decreased. However, in the ischemic heart reperfused with the calcium free condition, the D/O-form of XOD was elevated without significant increase in O-form of the enzyme. It is suggested from these results that the calclum may play a contributing role in the genesis of reperfusion damage by promoting the conversion of xanthine oxidase from the D/O-form to the oxygen radical producing O-form in the ischemic myocardium.

• The Korean Journal of Pharmacology
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• v.32 no.2
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• pp.201-209
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• 1996

Restoration of the blood flow after a period of ischemia is accompanied by generation of toxic oxygen radicals. This phenomenon may account for the occurrence of reperfusion-mediated tissue injury in ischemic hearts. In in vitro studies, although oxygen radicals can be generated from a variety of sources, including xanthine oxidase system, activated leucocytes, mitochondria and others, the most important source and mechanism of oxygen radical production in the post-ischemic reperfused hearts is unclear. In the present study, we tested the hypothesis that the respiratory chain of mitochondria might be an important source of oxygen radicals which are responsible for the development of the reperfusion injury of ischemic hearts. Langendorff-perfused, isolated rat hearts were subjected to 30 min of global ischemia at $37^{\circ}C$, followed by reperfusion. Amytal, a reversible inhibitor of mitochondrial respiration, was employed to assess the mitochondrial contributions to the development of the reperfusion injury. Intact mitochonria were isolated from the control and the post-ischemic reperfused hearts. Mitochondrial oxygen radical generation was measured by chemiluminescence method and the oxidative tissue damage was estimated by measuring a lipid peroxidation product, malondialdehyde(MDA). To evaluate the extent of the reperfusion injury, post-ischemic functional recovery and lactate dehydrogenase(LDH) release were assessed and compared in Amytal-treated and -untreated hearts. Upon reperfusion of the ischemic hearts, MDA release into the coronary effluent was markedly increased. MDA content of mitochondria isolated from the post-ischemic reperfused hearts was increased to 152% of preischemic value, whereas minimal change was observed in extramitochondrial fraction. The generation of superoxide anion was increased about twice in mitochondria from the reperfused hearts than in those from the control hearts. Amytal inhibited the mitochondrial superoxide generation significantly and also suppressed MDA production in the reperfused hearts. Additionally, Amytal prevented the contractile dysfunction and the increased release of LDH observed in the reperfused hearts. In conclusion, these results indicate that the respiratory chain of mitochondria may be an important source of oxygen radical formation in post-ischemic reperfused hearts, and that oxygen radicals originating from the mitochondria may contribute to the development of myocardial reperfusion injury.

• Korean Journal of Environment and Ecology
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• v.33 no.2
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• pp.228-236
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• 2019

This study investigated the effect of the sediment phosphorus fraction sampled from the southern coast of Korea on the release characteristics of sediments by environmental changes of water quality. We conducted the release experiment in the laboratory for 20 days and measured the phosphorus fraction properties, the environmental factors of water quality, and the release rate of total phosphorus. The results showed a decrease in dissolved oxygen by the growth of microorganisms in the water layer, leading to the anaerobic condition in which the redox potential of the sediments decreased. As such, the decreasing variability of phosphates bonded to iron oxide in the sediment phosphorus was higher after 20 days of the release experiment than the first day. It means that the metal ions and the separated inorganic phosphorus transfer into the water when the iron oxide is reduced. The separated inorganic phosphorus is easily absorbed by the plankton. The analysis of total phosphorus in the water layer showed that it continuously increased to up to 0.304 mg/L for 20 days, and the release rate had a high correlation with the decrease of dissolved oxygen after 5 days of culture. Therefore, it is necessary to pay attention to the characteristics of iron bonded to phosphorus in the phosphorus fraction and dissolved oxygen to manage the eutrophication of the system.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.190.1-190.1
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• 2003

It has been previously reported that silica dose-dependently caused the increase of histamine release and arachidonic acid release in RBL 2H3 cells. In this study. to investigate role of arachidonic acid in inflammatory response including histamine release and reactive oxygen species (ROS) generation. we observed effects of mellitin on histamine release and ROSgeneration in RBL 2H3 cells. (omitted)

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.297.2-297.2
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• 2002

Previous report showed that histamine release by HCI was mediated via reactive oxygen species (ROS) generation in RBL 2H3 cells. To investigate action of protein kinase on histamine release and ROS generation. we observed effects of protein kinase inhibitors on histamine release and ROS generation in RBL 2H3 cells stimulated by HCI HCI dose-dependently increased both histamine release and ROS generation. HCI-induced histamine release was significantly inhibited by bisindolmaleimide (10 ${\mu}$M). DHC (10 ${\mu}$M). , and wortmannin (10 ${\mu}$M), but not by PD098059 (10 ${\mu}$M). ON the other hand. HCI-induced ROS generation was significantly inhibited by DHC (10 ${\mu}$M). but not by bisindolmaleimide(10 ${\mu}$M). wortmannin (10 ${\mu}$M). and PD098059 (10 ${\mu}$M). However KN-62 did not inhibited both. These results showed that involvement of protein kinase in regulation of histamine release and ROS generation may be different and only tyrosine kinase may be associated with regulation of both histamine release and ROS generation in RBL 2H3 cells.