• Applied Chemistry for Engineering
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• v.4 no.2
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• pp.300-307
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• 1993

The phase-transfer polymerization of methyl methacrylate with tricaprylmethylammonium chloride-$Na_2S_2O_4-CCl_4$ initiator system was investigated in an aqueous-organic two-phase system. The observed rates of polymerization were compared with those obtained from the polymerization mechanism proposed with a cyclic phase-transfer initiation step. The rate of polymerization was found to be proportional to the concentration of $Q^+$ and square root of ${S_2O_4}^{-2}$ in the aqueous solution and the feed quantity of $CCl_4$ and MMA.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.5
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• pp.602-614
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• 1997

In order to evaluate the effects of equivalence ratio, initial pressure and temperature on the laminar flame propagation process, and combustion radicals characteristics, experimental approaches are carried out in methane-air premixture using a constant volume chamber. Local and average radical intensities were measured to determine the time and spatial correlations between each radicals; C $H^{*}$(431 nm), $C_{2}$$^{*}$ (517 nm) and O $H^{*}$(309 nm) . The results are showed that two kinds of equation were proposed for the cases of continuous flame and intermittent flame type to evaluate actual equivalence ratio using relative intensities with each radicals. Both equations were agreed with actual equivalence ratio within 10% errors range. And schlieren photo and CCD image were compared with flame sizes at equivalence ratio 1.0.o 1.0.

• 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.

• Korean Journal of Plant Resources
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• v.26 no.2
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• pp.149-158
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• 2013

The objective of this study was to investigate the antioxidative capacity of ethanol extracts from Sanguisorbae officinalis L. root (Sanguisorbae radix) in vitro. The concentration of Sanguisorbae radix extract at which DPPH radical scavenging activity was inhibited by 50% was 0.33 mg/mL, which was similar to $IC_{50}$ of ${\alpha}$-tocopherol (0.40 mg/mL), as compared to 100% by pyrogallol as a reference. Total antioxidant status was examined by total antioxidant capacity against ABTS radical reactions. Total antioxidant capacities of Sanguisorbae radix extract were significantly (p<0.05) higher than those of ${\alpha}$-tocopherol. Superoxide scavenging activities of Sanguisorbae radix extract were significantly (p<0.05) higher than those of catechin. Oxygen radical absorbance capacities of Sanguisorbae radix extract were significantly (p<0.05) higher than those of ascorbic acid. Cupric reducing antioxidant capacities of Sanguisorbae radix extract were significantly (p<0.05) higher than those of ${\alpha}$-tocopherol. Sanguisorbae radix extract prevented supercoiled DNA strand breakage induced by hydroxyl radical and peroxyl radical. Total phenolic contents of Sanguisorbae radix extract at concentrations of 0.5 and 5 mg/mL were 0.50 and 3.33 mM gallic acid equivalents, respectively. Sanguisorbae radix extract at concentration of 0.01, 0.1 and 0.5 mg/mL inhibited 0.2 mM tert-butyl hydroperoxide-induced cytotoxicity by 33.8, 79.1 and 96.9%, respectively, in HepG2 cell culture system. Thus, strong antioxidant and cytotoxicity-ihnibiting effects of Sanguisorbae radix extract seem to be due to, at least in part, the prevention from free radicals-induced oxidation as well as high levels in total phenolic contents.

• Korean Journal of Food Science and Technology
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• v.43 no.2
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• pp.200-205
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• 2011

In this study, antioxidant and anti-inflammatory effects of ethanol extracts from medicinal herb mixtures were investigated in vitro. Contents of total polyphenols in ethanol extracts from Houttuynia cordata Thunb. (HC), Carthamus tinctorius L. (CT), and MIX-2 (Houttuynia cordata Thunb., Acanthopanax gracilistylus Smith, Carthamus tinctorius L., Kalopanax pictus) were 58.98, 60.79 and 57.74 mg/g respectively. Radical scavenging activities of the ethanol extracts were examined using ${\alpha},{\alpha}$-diphenyl-${\beta}$-picrylhydrazyl radicals and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) assay. Anti-inflammatory effects of ethanol extracts from medicinal herbs composites were examined using 5-lipoxygenase (5-LO), cyclooxygenase-2 (COX-2) and nitric oxide (NO) inhibition assays. The ethanol extracts from medicinal herb mixtures showed higher 5-LO and COX-2 inhibition activities than those from single medicinal herbs. The ethanol extracts from medicinal herb mixtures also showed strong anti-inflammatory activity through inhibition of NO production.

• Food Science and Preservation
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• v.23 no.4
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• pp.585-590
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• 2016

In this study, the antioxidant and tyrosinase inhibitory activities of aqueous ethanolic extract from the immature fruits of Malus pumila cv. Fuji were evaluated. The antioxidant capacities of the extract was investigated employing radical scavenging assays using DPPH and $ABTS^+$ radicals. The skin-whitening effect of M. pumila cv. Fuji extract was tested using mushroom tyrosinase assay. In addition, the total phenolic content was measured by a spectrophotometric analysis. All tested samples showed a dose-dependent radical scavenging and tyrosinase inhibitory activities. Among the tested samples, the ethyl acetate (EtOAc)-soluble portion from the immature fruits of M. pumila cv. Fuji was showed the significant DPPH and $ABTS^+$ radicals scavenging activities. Also, the tyrosinase inhibitory activity of the ethyl acetate (EtOAc)-soluble portion from immature apples was higher than other solvent-soluble portion. These results suggest that unripe fruits of M. pumila cv. Fuji could be considered as a new valuable source of natural antioxidant and skin-whitening agents. Systematic investigation of immature fruits of Malus pumila cv. Fuji will be performed for the further development of its biological properties.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.9
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• pp.1357-1362
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• 2014

This study compared the antioxidant effects of two kinds of black raspberry extract, obtained from fruits of Rubus coreanus and Rubus occidentalis, which can be found in Korea. The fruits of R. coreanus and R. occidentalis were each extracted with 0%, 25%, 50%, 75%, and 100% ethanol (EtOH). Among the extracts of these two varieties, 50% EtOH extract of R. occidentalis showed the highest contents of total polyphenols ($46.96{\pm}2.78mg/g$) and flavonoid compounds ($11.77{\pm}0.81mg/g$). The 50% EtOH extract of R. occidentalis showed the highest antioxidant activity ($84.77{\pm}0.97%$) in terms of DPPH radical scavenging activity. On the contrary, 25% EtOH extract of R. occidentalis showed the best antioxidant activity ($29.65{\pm}2.41%$) in terms of ABTS radical scavenging activity. In the results of ferric reducing antioxidant power (FRAP) assay, 50% EtOH extract of R. occidentalis showed the highest antioxidant activity ($0.49{\pm}0.02%$). In the cytotoxicity test stimulated with $H_2O_2$, the extracts of 75% and 100% EtOH from R. occidentalis showed the highest cell viability ($93.54{\pm}3.37%$ and $97.19{\pm}0.74%$, respectively). According to our results, extracts of R. occidentalis showed higher antioxidant activities than extracts of R. coreanus. Especially, total polyphenol and flavonoid contents of R. occidentalis showed the highest significant correlation with FRAP by Pearson's correlation (P=0.005 and P=0.013, respectively).

• KSBB Journal
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• v.18 no.4
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• pp.282-288
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• 2003

For the screening of anti-inflammation and antioxidative activities, ethanolic extract of 40 species of traditional herbal medicines were examined their hyaluronidase inhibitory effect and radical scavenging activity in vitro. From the result of the hyaluronidase inhibitory activity using a Morgan-Elson assay, Astragali Radix, Eucommia Cortex, Schizandrae Fructus, Scutellaria Radix, Acanthopanacis Cortex, Chaenomelis Fructus, Amomum xanthioides Wallich and Moutan Radicis Cortex showed more than 50% hyaluronidase inhibitory effects at the concentration of 10 mg/mL. In the various solvent fractions (n-hexane, chloroform, ethyl acetate, water) prepared from ethanolic extracts, the ethyl acetate fraction of all extracts tested showed strong activity. Antioxidative activity was evaluated by assaying electron-donating ability to DPPH free radical and scavenging of hydroxyl radical (ㆍOH) generated through Fenton reaction, respectively. Rubus coreanus Miq, Moutan Radicis Cortex, Paeoniae Radix Alba, Plantaginis Semen and Sorbus commixta Hedl. showed high activity more than 90%, yet similar activity to $\alpha$-tocopherol and BHA at the concentration of 1 mg/mL in electron donating activity. The scavenging effects of ethanolic extracts on hydroxyl radical were investigated using a 2-deoxyribose oxidation method and tested all extracts showed significant radical scavenging activity. The experiment was also performed to examine whether herbal medicines having significant lipid peroxidation inhibitory activity, Schizandrae-Fructus is the strongest inhibitory activity in both linoleic acid and liposome peroxidation.

• Korean Journal of Plant Resources
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• v.29 no.5
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• pp.539-546
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• 2016

The aim of this study was to analyze antioxidant activity, total phenolics, and vitamin C content in unripe and ripe jujube cultivar and to investigate correlation between antioxidant and chemical constituents including total phenolics and vitamin C. The antioxidant activity was measured by the DPPH radical scavenging activity, ABTS radical scavenging activity, and reducing power. Although, the weight, diameter and soluble solids of Zyziphus jujuba fruit were increased with the progress of ripening, antioxidant activity and total phenolics were decrease during ripening. The highest free-radical scavenging activity (at 2.5 ㎎/㎖) and reducing power (at 1 ㎎/㎖) in fruit were 81.75% (Bokjo, unripe) and 0.80 (Mudeung, unripe), respectively. The highest total phenolic content in unripe fruit of Mudeung was 62.50 ㎍/g. A linear correlation (r=0.911) was shown between DPPH radical scavenging activity and total phenolic content.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.23 no.1
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• pp.75-132
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• 1997

피부는 항시 산소와 접촉하고 있고 자오선 조사에 크게 노출되어 있다. 따라서, 활성산소종으로 유도된 피부의 광산화적 손상 위험이 실질적으로 증가하고 있다. 활성산소종이란 한 무리로서 수퍼옥사이드 음이온과 히드록실 라디칼과 같은 산소 중심의 라디칼을 포함할 뿐만 아니라, 과산화수소나 싱글렛 옥시전과 같은 몇 종류의 비라디칼종들, 그 외의 다른 것으로, 활성산소종과 생체 성분과의 반응으로 유래된 과산화 라디칼, 알콕실 라디칼, 히드로과산화물 식세포에서 살균작용을 나타내는 HOCl등을 포함한다. 피부에는 복잡한 항산화 방어망이 발달되어 활성산소종에 대항하여 보호작용을 한다. SOD, 카탈라아제, 글루타치온퍼옥시다제 등의 항산화효소와 $\alpha$-토코페롤, 아스코르브산, 카로티노이드 등의 비효소적 항산화 물질들이 피부 항산화 방어망을 구축하고 있다. 그러나 계속된 자외선에의 노출로 생성된 과잉의 활성산소종은 실질직으로 피부의 효소적 그리고 비효소적 항산화 방어를 위태롭게 한다. 따라서 균형은 산화상태 쪽으로 유리하게 기울어진다 결과적으로 산화적 스트레스는 세포 성분들에 대한 손상을 야기시킨다. 지질 과산화, 단백질 산화, 탄력 섬유인 콜라겐과 엘라스틴의 사슬절단 밀 비장성적인 교차결합, 히아루론산 사슬의 절단, 멜라닌 생성반응 촉진, DNA 산화와 같은 생체 구성 성분들의 손상이 일어난다. 결국에는 탄력감소, 주름살 및 기미, 주근깨 등으로 특징 지워지는 피부노화가 가속화된다. 따라서 필요한 항상화제를 함유한 식품이나 화장품을 통한 계속적인 항산화제 보충으로 피부 항산화 방어망을 견고히 할 때 피부노화는 지연되고 억제될 것이다.주거를 구분하고 있는 것으로 조사되었으나, 아직까지 절반 가량(52.2%)의 상점들이 다른 사람 소유의 건물을 전 ·월세로 임대하여 사용하고 있음을 알 수 있었다. 이상에서 살펴본 바와 같이 고수동굴 주변의 상업적 특성은 90년대에 들어서면서 자기 고장에 있는 관광자원을 내 고향의 자랑거리로 생각하고 이를 지역발전의 밑거름으로 활용하고자 하는 인식이 늘어나고 있음을 알 수 있었다. 그러나, 관광지로서의 특성이라 할 수 있는 다른 관광동굴과의 차별성이 부족하다고 할 수 있다. 즉 다른 지역의 기념품점에서 구입할 수 없는 고수동굴만이 갖고 있는 특징적인 기념품을 판매함으로써 관광객의 구매욕구를 높인다거나 고수동굴의 일주관광 후 관광객을 좀 더 머무르게 할 수 있는 시설의 개발이 더 필요하다.유의한 차이를 나타내는 항목이 많았으며 12주에서 vehicle과 유의적인 차이를 나타내는 항목도 많으므로 3-APPA가 APSA 보다 광범위한 피부노화 억제 효과를 갖는 물질이라고 할 수 있다.주도적 역할을 수행해야 할 것이다. 넷째, 선박금융제도의 개선과 신금융상품의 개발이 요구된다. 내수 수요인 계획조선의 지원조건을 개선하고 연불수출자금을 BBC자금으로 활용토록하여 국내 선주들의 신조를 유도해야 할 것이다. 그 외에 향후 금융개방화에 맞추어 해외자금을 활용한 리스금융, 상사금융 등의 민간신용제도를 더욱 활성화하고 선진국의 선박금융기법에 대한 연구 및 도입 등 선주들에게 다양한 선박건조자금을 제공하여 내수기반 확충에도 노력해야 할 것 이다.있었다., 인삼이 성장될 때 부분적인 영양상태의 불충분이나 기후 등에 따른 영향을 받을 수 있기 때문에 앞으로 이에 대한 많은 연구가