• International Journal of Automotive Technology
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• v.6 no.6
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• pp.555-561
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• 2005

This experimental study was executed to obtain basic data for actual engine operation using radical induced ignition method (RI) which can achieve emission reduction and high efficiency due to the rapid bulk combustion. In this study, a direct injection diesel engine was converted into SI type engine with a sparkplug. The modified SI type engine can be divided into two classes. One is the SI engine with a sparkplug only at the cylinder head, and the other is the SI engine with the sparkplug which is enveloped in a sub-chamber. Also, a basic experimental was conducted in order to investigate combustion mechanism of radical induced injection before the experiment execution for actual engine using the modified SI engine. The bulk combustion phenomenon of radical induced ignition method was analyzed from the basic experiment by using a constant volume chamber. Volume value of sub-chamber used in this experiment is approximately $0.2\%$ of one of the main combustion chamber. In this paper, combustion characteristics using radical induced injection method was compared with that of using spark ignition method according to change in the engine speed and equivalence ratio. As a result, in the case of the radical induced injection engine, the combustion duration and cycle variation were respectively reduced ranged from $\Phi$(equivalence ratio)=0.8 (lean mixture ratio) to $\Phi$=1.0 (stoichiometric ratio).

• Preventive Nutrition and Food Science
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• v.13 no.2
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• pp.77-83
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• 2008

To further the goal of isolating Bacillus sp. from commercial chungkukjang (CKJ) for a development of a probiotic dietary adjunct using soymilk or milk, antioxidant activity of CKJ purchased from the Sunchang Traditional Village in Chunbook province was examined. Six CKJ samples were evaluated and 3 were selected based on the results of the physicochemical analysis and sensory evaluation for further antioxidant study. $IC_{50}$ for DPPH scavenging activity of methanol extracts of CKJ ranged from 238.1 to 345.7 ${\mu}g/mL$. CKJ exhibited over 80% scavenging of ${\cdot}OH$ and ONOO- at concentrations of 100 ${\mu}g/mL$ and 250 ${\mu}g/mL$, respectively. $O_2^-$ and NO scavenging activities of three CKJ were increased in a dose dependent manner with the concentration tested from 100 to 1000 ${\mu}g/mL$. In this study, the methanol extract of CKJ exhibited a great reduction capability and powerful free radical scavenging activity, especially against OH. and ONOO-, which are the most toxic radicals responsible for oxidative damage in the body. However, radical scavenging effects of CKJ on DPPH, $O_2^-$, and nitrite radical were rather moderate. In conclusion, CKJ may reduce the oxidative stress in the body by scavenging the free radicals.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.1
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• pp.115-118
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• 2003

This study was conducted to determine optimal extraction condition and free radical scavenging effect of ethanol extracts of Campell Early grape seeds and skins at different temperatures, and of organic solvent fractionated from ethanol extracts of grape seeds and skins. The free radical scavenging effect was tested using 1,1-diphenyl-2-picrylhydrazyl (DPPH) method and expressed as dose required for a 50% reduction of DPPH radical (RC$_{50}$). The extraction yields were increased with increasing the extraction temperature but it was not related with ethanol concentrations. The ethanol extract of grape seeds obtained at 5$0^{\circ}C$ showed the more stronger RC$_{50}$ (16.8 $\mu\textrm{g}$/mL) than those of both 3$0^{\circ}C$ and 78$^{\circ}C$. The ethylacetate fraction obtained from ethanol extract of grape seed showed the strongest RC$_{50}$ (15.4 $\mu\textrm{g}$/mL). Overall, both ethanol extracts and their fractions of grape seeds showed significantly stronger free radical scavenging effect than those of skin extracts.racts.

• Bulletin of the Korean Chemical Society
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• v.10 no.3
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• pp.258-261
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• 1989

The electrochemical behaviors of 4-(2)-thiazolylazo)-resorcinol (TAR) in acetonitrile solution was studied by DC polarography, cyclic voltammetry, controlled-potential coulometry and UV-Vis spectroscopy. The electrochemical reduction of TAR occurs in four-one electron reduction steps in acetonitrile solution. The products of the first and the third electron transfer are speculated to be a relatively stable anion radical. The second electron transfer to the dianion is followed by a chemical reaction producing a protonated species. The product of the fourth electron transfer also produces the corresponding amine compounds with a following reaction. Also every reduction wave was diffusion controlled. The first reduction wave is considerably reversible and the other waves are less reversible.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3545-3546
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• 2013

• The Korea Journal of Herbology
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• v.29 no.4
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• pp.69-76
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• 2014

Objectives : Gami-Chunggisan extract (GCE) is one of the oriental traditional medicine. We investigated the antioxidant effect and reduction of pro-inflammatory cytokine as a functional ingredient for cosmetic products from the GCE. Methods : GCE was prepared by extracting with 80% ethanol. We analyzed total polyphenol and antioxidant activities. To evaluate antioxidant activity, we measured 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging assay. Also we measured the production of reactive oxygen species (ROS) and nitric oxide (NO) on Raw264.7 cells. We researched reduction of anti-inflammatory cytokines from concentration of GCE on Raw264.7 cells. Results : Total polyphenol quantity of GCE was included 46.6 mg/g. The GCE showed ABTS free radical scavenging ability with more than 89% at $1000{\mu}g/m{\ell}$. In addition the DPPH free radical scavenging ability from the GCE was activated over 93% at $1000{\mu}g/m{\ell}$. Production of the ROS was decreased by approximately 26%, upon the GCE treatment at concentration of $100{\mu}g/m{\ell}$. The GCE at $100{\mu}g/m{\ell}$ concentration showed inhibitory effect on NO production by 38%. Production of IL-$1{\beta}$ and IL-6 were decreased by approximately 56% and 36%, respectively upon GCE treatment at $100{\mu}g/m{\ell}$. Also, production of TNF-${\alpha}$ was decreased by approximately 79% at $100{\mu}g/m{\ell}$. Moreover, the GCE showed inhibitory effects on the expression of the IL-$1{\beta}$, IL-6 and TNF-${\alpha}$ genes in LPS-induced Raw 264.7 cells. Conclusions : From the results above, we conclude that the GCE indicated significant antioxidant effects and induced reduction of pro-inflammatory cytokine.

• Journal of the Korean Society of Combustion
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• v.9 no.4
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• pp.28-34
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• 2004

Numerical simulations of freely propagating flames burning $H_2/HCl/Air$ Air mixtures were performed at atmospheric pressure in order to understand the effect of hydrogen chloride on flame structures. The chemical and physical effects of hydrogen chloride on flame structures were observed. A chemical kinetic mechanism was developed, which involved 26 gas-phase species and 198 forward elementary reactions. Under several equivalence ratios the flame speeds were calculated and compared with those obtained from the experiments, the results of which were in good agreement. As hydrogen chloride as additive was added into $H_2/Air$ flame, the flame speed, radical concentration and NO production rate were decreased. The chemical effect of hydrogen chloride caused the reduction of radical concentration, and then the decrease of the net rate of NO production. It was found that the influence in the reduction of $EI_{NO}$ with the addition of hydrogen chloride was attributed more due to the chemical effect than the physical effect.

• Journal of Chest Surgery
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• v.21 no.5
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• pp.803-815
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• 1988

The present experiments were performed to confirm the hypothesis that xanthine oxidase[XOD], as a source and mechanism of oxygen radical production, plays an important role in the genesis of the reperfusion injury of ischemic myocardium. The experimental ischemic-reperfusion injury was induced in isolated, Langendorff preparations of rat hearts by 60 min. Of global ischemia with aortic clamping followed by 20 min. of reperfusion with oxygenated Krebs-Henseleit solution[pH 7.4, 37*C]. The results were as follows: 1. The releases of creatine phosphokinase and a lipid peroxidation product, malondialdehyde[MDA] into the coronary effluent were abruptly increased upon reperfusion of ischemic hearts. The increases of the enzyme and MDA were suppressed significantly in the hearts removed from rats pretreated with allopurinol, a specific XOD inhibitor[20mg/kg, oral, 24 hrs and 2 hrs before study]. This effect of allopurinol was comparable to that of oxygen radical scavengers, superoxide dismutase[5, 000U] and catalase[12, 500 U]. 2. The increased SOD-inhibitable reduction of ferricytochrome C, which was infused to the hearts starting with reperfusion, was significantly suppressed in allopurinol pretreated hearts. 3. Activities of myocardial XOD were compared in the normal control hearts and the ischemic ones. Total enzyme activities were not different in both hearts. However, comparing with the control, the ischemic ones showed higher activity in 0-form and lower activities in D-form and D/O-form. 4. In the ischemic hearts, phenylmethylsulfonyl fluoride, a serine protease inhibitor, prevented significantly the increase of 0-form and the decreases of D and D/O-form, while thiol reagents did not affect the changes of the enzyme. 5. The increase of 0-form and the decreases of D and D/0-form were not significant in both calcium-free perfused and pimozide, a calmodulin inhibitor, treated ischemic hearts. 6. The SOD-inhibitable reduction of ferricytochrome C were suppressed by PMSF and pimozide treatment as well as by calcium-free perfusion. It is suggested from these results that in the ischemic rat myocardium, xanthine oxidase is converted to oxygen radical producing 0-form by calcium, calmodulin-dependent proteolysis and plays a contributing role in the genesis of ischemic-reperfusion injury by producing oxygen free radicals.

• The Korean Journal of Food And Nutrition
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• v.31 no.5
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• pp.729-736
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• 2018

This study was performed to facilitate development of new food materials by comparing general components, functional components and antioxidant activity of cherry, aronia, and maquiberry. Cherry revealed higher content of water (6.71%), crude protein (4.61%) and crude protein (5.33%) than aronia and maquiberry. Crude fat content of cherry fruits was the lowest at 1.46%. Content of iron per 100 g was 0.96 mg in cherry, significantly higher than other berries. Total phenolic content of cherry, aronia and maquiberry was 31.32~95.05 GAE mg/g. Total flavonoid content in water extract was 2.07 QE mg/g in cherry, compared with aronia and maquiberry. FRAP reduction power of cherry, aronia and maquiberry was $86.94{\sim}331.83TEAC\;{\mu}mol/g$. FRAP reduction power ($156.50TEAC\;{\mu}mol/g$) of cherry was higher than that of aronia ($121.72TEAC\;{\mu}mol/g$) at $95^{\circ}C$ deionized water extract. In the case of water extract, $117.00TEAC\;{\mu}mol/g$, and cherry was higher in ABTS radical scavenging ability than aronia ($86.55{\mu}mol/g$). DPPH radical scavenging activity of cherry, aronia and maquiberry was $26.34{\sim}493.53TEAC\;{\mu}mol/g$. DPPH radical scavenging activity was lowest in cherry. In conclusion, in place of foreign expensive aronia and maquiberry, the price of cherry is low and use of cherry widely distributed has increased and is used as a material of functional food.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.3
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• pp.194-199
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• 2001

The turbulent flow resistance of water solution with polymer is reduced as compared with that of pure water. This effects is named th drag reduction and offers the significant reduction of the pumping power and the energy consumption. But the intense shear forces and the high temperature experienced by the polymer solution when passing through the pipes cause the degradation a loss of drag reduction effectiveness. Especially, the degradation behavior is found to be strongly dependent on temperature. This mechanical and thermal degradation can be avoided by adding materials such as surfactant to the polymer solution, which enhance the bonding force between molecules. In the present study, Copolymer and SDS were utilized and they were mixed in 10 different mixture ratios, while total concentration was fixed as 100wppm. Degradation of Copolymer-SDS mixture solutions was investigated experimentally in closed loop at the temperature of $10^{\circ}C\; and\; 80^{\circ}C$ with various flow average velocities of 1.5 m/sec, 3.0m/sec, and 4.5m/sec. Degradation characteristics of polymer solution without surfactant show a radical loss of drag reduction effectiveness at high temperature. Degradation alleviation ability of surfactant is especially effective at high temperature. Consequently, this results show that the addition of surfactant to the polymer solution can control unfavorable degradation phenomena for high temperature systems.