• Journal of the Korean Society of Combustion
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• v.3 no.1
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• pp.11-19
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• 1998

The influence of oxidant addition on soot formation is investigated experimentally with ethylene, propane and mixture fuel co-flow diffusion flames. Oxidant addition into fuel shows the increase of integrated soot volume fractions for ethylene, ethylene/ethane and ethylene/methane mixture flames. However, the increase of integrated soot volume fraction with oxidant addition was not significant for propane and ethylene/propane mixture flames. This discrepancy is explained with $C_2\;and\;C_3$ chemistry at the early stage of soot formation process. The oxidant addition increases the concentration of $C_3H_3$ in the soot formation region, and therefore, enhances soot formation process. A new soot formation rate model that includes both dilution effect and chemical effect of oxygen is suggested to interpret the increase of integrated soot volume fractions with oxidant addition into ethylene. Also, the role of adiabatic flame temperature for the chemical effect of oxygen addition into fuel was reviewed. The influence of oxidant or diluent addition into fuel on soot formation process are the fuel dilution effect, the adiabatic flame temperature altering effect and/or the chemical effect of oxygen. Their relative importance could change with fuel structure and adiabatic flame temperature.

• The Korean Journal of Food And Nutrition
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• v.28 no.1
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• pp.40-46
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• 2015

Hamcho (Salicornia herbacea) extracts were evaluated for total polyphenol content, antioxidant and pro-oxidant activities. The total polyphenol content was 1.81 g and 0.72 g per 100 g of dried sample in water and ethanol extracts respectively. Both water and ethanol extracts of Hamcho significantly exhibited antioxidant activity. The scavenging activity of hydroxyl radical was 13.8~26.2% and 14.2~16.0% in water and ethanol extracts respectively. The inhibitory effect of conjugated diene formation was 24.6~39.1% and 28.4~39.6% in water and ethanol extracts respectively. However, pro-oxidative effect was also observed in the Hamcho extracts. The Hamcho water extract showed the pro-oxidant effect by enhancing the formation of hydroxyl radical and conjugated diene. The ethanol extract of Hamcho induced conjugated diene formation at 0.5 mg/mL but not at 1 mg/mL. The hydroxyl radical formation was not induced by the Hamcho ethanol extract. Taken together, these results show that Hamcho extracts can act as pro-oxidants by generating hydroxyl radical or conjugated diene in addition to their antioxidant properties. Therefore, this study suggests that the physiological properties of Hamcho and its use as food materials should be considered with caution because antioxidant dietary plants such as Hamcho possess possible adverse effects induced by pro-oxidant activity.

• Journal of odor and indoor environment
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• v.17 no.4
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• pp.381-388
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• 2018

In this study, various conditions and phenomena that occur in the process of removing odorous VOCs by using electrolyzed oxidant were examined. The formation of hypochlorous acid, which is an oxidant produced by electrolysis, was investigated and the properties of the oxidizing agent used to decompose toluene, xylene, and cyclohexane were investigated. As a result, it was found that the production rate and the final concentration of the oxidizing agent increased with the current density. It was found that the degree of removal varies depending on the property of each pollutant. Interestingly, in the batch experiments in which the pH of the produced oxidant was controlled, it was found that the degree of elimination varied depending on the pH of the substance. These results suggest that the difference in the concentration and distribution of hypochlorous acid (HOCl) and hypochlorite ($OCl^-$) due to the pH change leads to the difference in oxidizing power on the oxidation characteristics of each substance. Styrene and terpineol showed better degradation characteristics than toluene and xylene in odorous VOC removal experiments by spraying electrolytic oxidant using a lab-scale continuous reactor. In conclusion, the removal of odorous VOCs by the electrolytic oxidant can have various applications in that it can oxidize pollutants of various spectra.

• Journal of the Korean Chemical Society
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• v.18 no.6
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• pp.443-446
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• 1974

The regenerated lubricating oils for an internal combustion engine, obtained from the sulfuric acid and clay treatment, showed an improved thermal oxidation stability regardless of additives, especially anti-oxidant, originally presented in the oils. It is believed that such improvement is due to the formation of anti-oxidant materials, which is observed by the in crease of 25 % of aromatic compounds.

• YAKHAK HOEJI
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• v.37 no.1
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• pp.95-99
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• 1993

Peroxidase activity of cytochrome P-450 was examined using N, N-dimethylaniline (NDA) as a substrate and cumene hydroperoxide (CHP) as an oxidant. The initial rates of the N-demethylation for varied concentrations of NDA (0.05-0.5 mM) by P-450 at different fixed concentrations of CHP (0.02-0.2 mM) were determined. The results suggest that P-450 proceeds its peroxidative reaction by the rapid equilibrium random bi bi mechanism to form a ternary complex with substrate and oxidant as an active intermediate.

• YAKHAK HOEJI
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• v.48 no.2
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• pp.111-116
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• 2004

The ethanol extracts of mixed vegetables (Bioactive Vegetables, BV), mixed fruits (Bioactive Fruits, BF) and their liquid formulation (Chungpae Plus , CP) were evaluated for their antioxidative and antigenotoxic activities. They were shown to possess the significant free radical scavenging effect against 1,1-diphenyl-2-picryl hydrazine (DPPH) radical generation and were revealed to show the inhibitory effect of lipid peroxidation as measured by malondialdehyde (MDA) formation although the potencies were not higher than those of vitamin C. They did not possess any pro-oxidant effect on bleomycin-Fe(III) dependent DNA degradation, whereas vitamin C showed strong pro-oxidant effect. Furthermore, oral administration of BV and BF inhibited micronucleated reticulocyte (MNRET) formation of mouse peripheral blood induced by KBrO3 treatment in vivo. CP also showed significant inhibition under same experimental condition. Therefore, the liquid formulation (CP) containing BV and BF may be a useful natural antioxidative and antigenotoxic agent by scavenging free radicals, inhibition of lipid peroxidation and protecting chromosomal damage.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.23 no.1
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• pp.23-43
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• 2010

Objective : This study was performed to assess the effects of Aloe and Violae herba extracts on skin disease and skin beauty. Methods : Anti-oxidant effects were measured by the scavenging for DPPH radical, xanthine oxidase activity. Anti-inflammatory effects were examined by relations in NO synthesis, IL-$1{\beta}$, IL-6, TNF-$\alpha$, NF-kB, COX-2, MAP kinase. The skin wrinkle formation effects were measured by collagenase and elastase activities. The whitening effects were examined by tyrosinase activities, melanin synthesis in MNT-1 cell. Results : 1. In an anti-oxidant test, Aloe and Violae herba extracts showed high radical scavenging activity. 2. In an anti-inflammatory test, Aloe and Violae herba extracts strongly inhibited the lipopolysaccharide(LPS)-induced nitric oxide(NO) release from the RAW 246.7 macrophage cells. Aloe and Violae herba extracts also inhibited the LPS-induced IL-$1{\beta}$ and COX-2 expressions. The inhibitory effects of Aloe and Violae herba extracts on macrophage activation were via the inhibition of NF-kB, evidenced by transient transfection assay. Furthermore, Aloe and Violae herba extracts weakly inhibited the activation of Jun-N-terminal kinase(JNK) but they did not have any effects on p38 MAP kinase in RAW 264.7 cells. 3. In the skin wrinkle formation assay, Aloe extract strongly inhibited collagenase and elastase, whose activity are tightly related with the wrinkle formation. 4. In the skin whitening assay, Aloe and Viloae herba extracts weakly inhibited tyrosinase activity, however, it was not statistically significant. Besides they did not have any effects on melanin synthesis, indicating that they could not be applicable for skin whitening. Conclusion : This study show that Aloe and Violae herba extracts may play a significant role in skin disease and skin beauty.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.23 no.3
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• pp.11-32
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• 2010

Objective : The aim of this study is to determine the effects of Dendrobii herba extract and Punica granatum extract on skin disease and skin beauty. Methods : To investigate in vitro anti-oxidant activity assay, ethanol extracts of medicinal plants tested by DPPH radical, xanthine oxidase activity. In the next experiment, to investigate anti-inflammatory activity assay, examined by relations in NO synthesis, IL-$1{\beta}$, IL-6, TNF-${\alpha}$, NF-${\kappa}B$, COX-2, MAP kinase. To study Skin wrinkle formation effect, we were examined by tyrosinase activities, melanin synthesis in MNT-1 cell. Results : 1. In an anti-oxidant test, Dendrobii and Punica granatum extract showed high radical scavenging activity. 2. In an anti-inflammatory test, Dendrobii herba and Punica granatum extract weakly inhibited the lipopolysaccharide(LPS)-induced nitric oxide(NO) release from RAW 246.7 macrophage cells. Dendrobii herba and Punica granatum extract also inhibited LPS-induced IL-$1{\beta}$ and COX-2 expressions. The inhibitory effect of Dendrobii herba and Punica granatum extract on macrophage activation were via the inhibition of NF-${\kappa}B$, evidenced by transient transfection assay. however, Dendrobii herba and Punica granatum extract did not have any effects about activation of Jun-N-terminal kinase(JNK) and inhibition of p38 MAP kinase in RAW 264.7 cells. 3. In the skin wrinkle formation assay, Dendrobii herba and Punica granatum extract weakly inhibited collagenase and elastase, however it was not statistically significant. 4. In the skin whitening assay, Dendrobii herba and Punica granatum extract weakly inhibited tyrosinase activity, however, it was not statistically significant. They did not have any effect on melanin synthesis, indicating that they could not be applicable for skin whitening. Conclusion : Dendrobii herba extract and Punica granatum extract may play a significant role in skin disease and skin beauty.

• Archives of Pharmacal Research
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• v.28 no.7
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• pp.775-783
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• 2005

The ethanol extract of the peony root (Paeonia Lactiflora Pall, Paeoniaceae) as well as its major active components including gallic acid and methyl gallate were evaluated for their protective effects against free radical generation and lipid peroxidation. In addition, the protective effects against hydrogen peroxide-induced oxidative DNA damage in a mammalian cell line were examined. The ethanol extracts of the peony root (PREs) and its active constituents, gallic acid and methyl gallate, exhibited a significant free radical scavenging effect against 1,1-diphenyl-2-picryl hydrazine (DPPH) radical generation and had an inhibitory effect on lipid peroxidation, as measured by the level of malondialdehyde (MDA) formation. The PREs did not have any pro-oxidant effect. They strongly inhibited the hydrogen peroxide-induced DNA damage from NIH/3T3 fibroblasts, as assessed by single cell gel electrophoresis. Furthermore, the oral administration of 50% PRE (50% ethanol extract of peony root), gallic acid and methyl gallate potently inhibited the formation of micronucleated reticulocytes (MNRET) in the mouse peripheral blood induced by a $KBrO_3$ treatment in vivo. Therefore, PREs containing gallic acid and methyl gallate may be a useful antigenotoxic antioxidant by scavenging free radicals, inhibiting lipid peroxidation and protecting against oxidative DNA damage without exhibiting any pro-oxidant effect.

• Journal of Environmental Science International
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• v.1 no.1
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• pp.19-33
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• 1992

The high oxidants, which occur the daily maximum concentrations in the afternoon, are transported into the other region via long range transport mechanisms or trapped within the shallow mixing boundary layer and then removed physically (deposition, transport by mountain wind, etc.) and chemically (reaction with local sources). Therefore, modeling formation of photochemical oxidants requires a complex description of both chemical and meteorolog ital processecs . In this study, as a part of air quality studies, we reviewed various aspects of photochemical modeling on the basis of currently available literature. The result of the review shows that the model is based on a set of coupled continuity equations describing advection, diffusion, transport, deposition, chemistry, emission. Also photochemical oxidant models require a large amount of input data concerned with all aspects of the ozone life cycle. First, emission inventories of hydrocarbon and nitrogen oxides, with appropriate spatial and temporal resolution. Second, chemical and photochemical data allowing the quantitative description of the formation of ozone and other photochemically-generated secondary pollutants. Third, dry deposition mechanisms particularly for ozone, PAN and hydrogen peroxide to account for their removal by absorption on the ground, crops, natural vegetation, man-made and water surfaces. Finally, meteorological data describing the transport of primary pollutants away from their sources and of secondary pollutants towards the sensitive receptors where environmental damage may occur. In order to improve our present study, shortcomings and limitation of existing models are pointed out and verification Process through observation is emphasized.