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Lee, Min-Joo;Lee, Byung-Dae
- Journal of the Korean Chemical Society
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- v.65 no.1
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- pp.9-14
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- 2021
In this study, the DFT calculation was performed using the B3LYP/6-31G(d,p) basis sets for the reaction process in which phenanthrene decomposes due to the chain reaction of two OH radicals on phenanthrene in the gaseous state of 298 K at 1 atm. As a result of the calculation, even when two OH radicals act on phenanthrene in a chain, the reaction for producing phenanthren-9-ol is predicted to be more advantageous than the reaction for producing phenanthren-1-ol. On the other hand, it was predicted that the OH addition process at room temperature would be advantageous for the priority of the OH addition and H abstraction process.
https://doi.org/10.5012/jkcs.2021.65.1.9 인용 PDF KSCI

Kim, Chang-Gyu;Moon, Jae-Seung;Lee, Won-Jong
- Korean Journal of Metals and Materials
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- v.49 no.10
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- pp.797-804
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- 2011
In this study, the mechanisms of the three steps (the polymer deposition step, the polymer etching step and the Si etching step) that constitute the Bosch process were investigated. The effects of radicals and ions on each step were quantitatively analyzed by comparing the simulated aspect ratio dependency of the deposition or etch rate with the experimental results. In the polymer deposition step, fluorocarbon polymer is deposited by chemical reactions of $CF_x$ radicals, of which the reaction probability is 0.13. Although the polymer etching step and the Si etching step were conducted under the same conditions, the etching mechanisms of polymer and Si were found to be quite different. In the polymer etching step, both chemical etching and physical sputter-etching contribute to the polymer etching. Whereas, in the Si etching step, Si is chemically etched by F radicals, of which the reactivity is greatly increased by the bombardment of energetic ions.
https://doi.org/10.3365/KJMM.2011.49.10.797 인용 KSCI

Woo, Jeong Hyang;Shin, So Lim;Chang, Young Deug;Lee, Cheol Hee
- FLOWER RESEARCH JOURNAL
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- v.17 no.3
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- pp.158-164
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- 2009
Present studies were conducted to investigate the effects of water and 80% ethanol solvent on antioxidant activities of flower extracts of Chrysanthemum frutescens, Coreopsis lanceolata, Matricaria recutica, and Hieracium pilosella. Extraction yields of water extracts ranged 27.15~40.25% and 80% ethanol extracts 24.92~42.84%, respectively. In all species polyphenol and flavonoid contents were higher with 80% ethanol extraction, especially in C. lanceolata. Same results were obtained with scavenging effects on DPPH and ABTS radicals and ferrous ion chelating effects. Scavenging activity of flower extracts on DPPH radicals was highest in H pilosella - higher than that of synthetic antioxidant DHT. Higher scavenging activity on ABTS radicals was observed with M. recutica. Generally Compositae flower extracts exhibited higher scavenging activity on ABTS radicals than DPPH. Scavenging activity on ABTS radicals of M. recutica and P pilosella were superior to those of ascorbic acid and BHT. Ferrous ion chelating effects were much higher with H. pilosella flower extracts by 80% ethanol. Chelating effects of 4 species were much lower than those of EDTA. In conclusion, to develop natural antioxidant from above 4 Compositae species, 80% ethanol is recommended for efficient solvent to obtain maximum antioxidant isolation and activity.

Chun, Sukyoung;Chang, Soonwoong
- Journal of the Korean GEO-environmental Society
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- v.12 no.10
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- pp.57-62
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- 2011
This study investigated the effects of various inorganic anions($Cl^-$, $NO_3{^-}$, $HCO_3{^-}$) on the Methyl tert Butyl Ether(MTBE) degradation by photocatalysis using statistical method. Generally, this process in general demands the generation of hydroxyl radicals(OH radical) in solution in the presence of UV light. The generation of radicals were affected by inorganic anions in solution that inhibited the photodegradation by their trapping hydroxyl radicals. The effects of inorganic anions were mathematically described as the independent variables such as $Cl^-$, $NO_3{^-}$, and $HCO_3{^-}$, and these were designed by mixture analysis that was one of the response surface methodology(RSM). Regression analysis on ANOVA showed significant p-value(p<0.0001) and high coefficients for determination value($R^2$=99.28%, ${R^2}_{adj}$=98.91%). Contour and response surface plots showed that the effects of inorganic anions for MTBE photodegradation based on $UV/H_2O_2$ process. In the result, $Cl^-$ and $HCO_3{^-}$ inhibited the photodegradation of the MTBE by their trapping hydroxyl radicals, and the interaction by these two factors was observed.
https://doi.org/10.14481/jkges.2011.12.10.7 인용 PDF KSCI