• 한국자동차공학회논문집
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• 제2권5호
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• pp.48-57
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• 1994

The specific power output and thermal effeciency of any two-stroke engine are dependent on its scavenging behavior. Among the many factors which influence on the scavenging process, the cylinder head shape is one of the important factor. Hence in this study three different type models of cylinder head shape which are the cylindrical, the spherical and the arbitrary shape are studied to show the effects of the turbulent scavenging process in the cylinder with one inlet port, two side ports and one exhaust port. A modified version of KIVA-II which strip out of or add planes of cells across the mesh above the piston for flow simulation of two-stroke engine is used. The $k-{\varepsilon}$ turbulent model is used. The results show that the flow in a two-stroke engine cylinder of the spherical head shape among the three different type model is a desirable for efficient scavenging.

• Food Science and Biotechnology
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• 제18권2호
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• pp.419-424
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• 2009

Water and 70% ethanol extracts obtained from a sea cucumber (Stichopus japonicus) body wall by heat reflux or pressurized solvent extraction showed 2,2-diphenyl-1-picrylhydrazyl ($DPPH^{\cdot}$) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation ($ABTS^{{\cdot}+}$) scavenging activities comparable to those of fruits and vegetables. The highest activities were observed for the water extract from heat reflux extraction. Crude saponins exhibited higher radical scavenging activities than the soluble matters in the extracts. However, they were responsible for only about 3 to 15% of the scavenging activities of the extracts. Total phenolic contents showed a significant correlation with $DPPH^{\cdot}$ scavenging activities, suggesting a significant contribution of phenolic constituents to the antioxidant properties of the extracts. However, total flavonoid contents showed little correlation with the radical scavenging activities. The results suggest that the water or 70% ethanol extract obtained from sea cucumber body wall by simple heat reflux extraction could provide considerable antioxidant benefits.

• 셀메드
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• 제5권2호
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• pp.14.1-14.6
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• 2015

Antioxidative and free radical scavenging properties of different stem extracts of Euphorbia trigona were evaluated and correlated with its total phenolic content. Aqueous, acetone and methanolic extracts of shade dried stem were obtained and were concentrated in vacuo. The antioxidant and free radical scavenging activities of stem extracts was determined by 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging assay, reducing power assay, deoxyribose degradation assay and $Fe^{2+}$ chelating assay. Total phenolic contents (TPC) were evaluated using Folin-Ciocalteu reagent. The results confirmed that the plant is a rich source of polyphenolic compounds which are invariably higher compared to other herbs. All extracts showed TPC in the range of 146.6 - 168.6 mg/g gallic acid equivalents at $300{\mu}g/ml$ of extract. Among the three extracts ME showed highest scavenging activity as evidenced by maximum scavenging of DPPH (83.2%), $OH{\bullet}$ radicals (94.81%), $Fe^{2+}$ chelating activity (88.59%) and a high reducing power 0.623 at $300{\mu}g/ml$. Our results demonstrate that Euphorbia trigona, an unexplored xerophytic plant could be potential source of natural antioxidants and phytotherapeutic agents. The plant possess invariably high amount of polyphenolic compounds with a broad spectrum of antioxidant properties and could be further used for food, feed and pharmaceutical applications.

• Advances in Traditional Medicine
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• 제5권3호
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• pp.209-215
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• 2005

This study was conducted to investigate the efficacy of antioxidative activity and nitrite scavenging ability of each fractions from Phyllostachys bambusoides S. et Z. (P. bambusoides) trunk ethanolic extract using reverse-phase flash chromatography. Among the each fractions, fraction 3 $(H_2O\;:\;MeOH\;=\;1:1)$ showed high DPPH free radical scavenging activity (81.33%) at $80\;{\mu}g/mL$ concentrations and strongly inhibited autooxidation of pyrogallol by superoxide dismutase-like activity (45.8 %) at 0.46 mg/mL concentrations compared with different fractions. The fraction 3 was also increased to 76.62% cell viability against hydrogen peroxide-mediated cytotoxicity. Nitrite scavenging ability was the most remarkable under pH 1.2 condition among various pH regions examined and effectively exhibited to 65.6% by treatment of the fraction 3 with a concentration of 0.2 mg/ml. In general, nitrite scavenging ability decreased with higher pH condition. These results suggest that fraction 3 from P. bambusoides ethanolic extract can be used for bioacitve and functional materials.

• 연구논문집
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• 통권28호
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• pp.49-58
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• 1998

포핏밸브형 2행정 기관의 소기 시스템 형상 변화에 따른 소기유동 및 소기효율의 개선 효과를 해석하기 위해, 각 흡기포트 형상별 소기 유동 가시화와 소기효율 정량화 연구를 수행하고자 한다. 소기시스템의 형상은 기계연구원에서 독자 개발한 RSSV(Rotatable Shrouded Scavenging Valve)의 슈라우드 각도를 변화시켰으며, 소기 효율 정량화를 위해 정상상태하에서 등유와 착색된 물을 사용한 single-cycle method. 동적모사장치(dynamic simulatior)에서 $CO_2$와 $O_2$가스를 사용한 가스추출법(gas sampling method)을 적용하였으며 실제 기관에서의 소기 효율을 측정하기 위해 압력 선도를 해석하였다. 위 실험들의 결과로부터 $90^circ$슈라우드 밸브가 가장 높은 효율을 가지는 것으로 판명되었으며, 특히 이들 실험방법들은 2행정 엔진 개발에 있어 시간과 비용을 절감하는데 아주 유용한 기법임을 알 수 있었다.

• 한국수산과학회지
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• 제30권6호
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• pp.909-915
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• 1997

The nitrite scavenging effect of methanol extracts of marine algae were evaluated to discover new natural nitrite scavengers. Among the tested seaweeds, Ecklonia stolonifera, an edible brown algae, showed the strongest scavenging effect. The MeOH extract was then sequentially partitioned into $CH_2Cl_2,\;CH_2Cl_2$ insoluble interface, EtOAc, n-BuOH, and $H_2O$ layers. The EtOAc and n-BuOH fraction demonstrated high levels of nitrite-scavenging activity while the $CH_2Cl_2,\;CH_2Cl_2$ insoluble interface, and $H_2O$ fractions were inactive. A column chromatography of the EtOAc fraction through silica gel and Sephadex LH-20 yielded phloroglucinol and a new compound tentatively named phlorotannin A. The nitrite scavenging activity of phloroglucinol $(IC_{50}=3.9{\mu}g/ml)$ was more potent than that of L-ascorbic acid $(IC_{50}=65.0{\mu}g/ml)$. However, phlorotannin A $(IC_{50}=193.2{\mu}g/ml)$ showed only low levels of activity. From the above results, it is possible to suggest that both the MeOH extract and their fractions and isolated phloroglucinol and phlorotannin A obtained from E. stolonifera may be applicable as scavengers of nitrite, which is a precursor for the formation of carcinogenic N-nitroso compounds.

• Preventive Nutrition and Food Science
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• 제18권3호
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• pp.196-202
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• 2013

Citron seed extracts (CSEs) were made using distilled water (CSEW), ethanol (CSEE), and n-hexane (CSEH), to measure the total polyphenol contents, DPPH and ABTS radical scavenging activities, and anti-complementary activity. The total polyphenol content was observed the highest in CSEE (188.71 ${\mu}g/mL$), and occurred in the following order: CSEE>CSEW (141.11 ${\mu}g/mL$)>CSEH (26.19 ${\mu}g/mL$) at 10 mg/mL. CSEE (63.56%) and CSEW (56.61%) showed significantly higher DPPH radical scavenging activities when compared with CSEH (28.57%). ABTS radical scavenging activities of CSEE (45.53%) and CSEW (40.02%) were also observed to be higher, whereas CSEH did not show ABTS radical scavenging activity. Anti-complementary activity of CSEE (26.85%) showed a greater activity than that of CSEW (7.84%) at 1,000 ${\mu}g/mL$. Limonin and nomilin contents had the highest values (1.882% and 2.089%) in CSEE, and with 0.327% and 0.139% in CSEW; however, CSEH showed relatively very low values at 0.061% and 0.026%, respectively. Among the CSEs tested, CSEE as a by-product from citron may provide an important source of dietary antioxidant compounds with rich polyphenol and limonoid contents, and immunopotentiating activity, including the complement activation factor.

• 산업식품공학
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• 제15권1호
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• pp.6-14
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• 2011

The polysaccharides from fruit body of Auricularia auricula and Tremella fuciformis were extracted using hot water, and partially purified through ethanol precipitation and dialysis. Free radical scavenging activities of the crude and purified polysaccharides were examined and compared each other. Free radical scavenging activities of the partially purified polysaccharides were higher than those of crude polysaccharides. DPPH free radical, ABTS radical and SOD-like activities of partially purified polysaccharide at 1 mg/mL of concentration from A. auricula were 61.7, 9.6 and 38.9%, respectively, while those of T. fuciformis were 9.6, 5.7 and 15.3%, respectively. Results of site and non-site specific hydroxyl radical scavenging activities indicated that the partially purified polysaccharide fractions from A. auricula and T. fuciformis exhibited the hydroxyl radical scavenging effect by hydrogen donating ability and iron ion chelating ability. Also, reducing powers of A. auricula and T. fuciformis were 77.1 and 14.7% of BHT (0.1%) as standard, respectively. It was suggested that antioxidant activities of A. auricula were about 1.4~6.4 times higher than those of T. fuciformis due to different levels of polyphenol content.

• 한국자원식물학회지
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• 제26권5호
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• pp.548-556
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• 2013

시설오이로 많이 재배되고 있는 4 품종을 선발하여 생육단계별로 DPPH radical 소거활성, 아질산염 소거활성, ABTS 소거활성 그리고 항산화효소 활성에 대하여 비교 분석하였다. 장죽청장 품종이 모든 생육단계에서 DPPH radical 소거활성이 상대적으로 높게 나타났으며, 그 외 품종들 간에는 큰 차이를 보이지는 않았다. 또한 생육단계별로는 수확기에 못 미친 미성숙단계에서 DPPH radical 소거 활성이 높게 나타났다. 아질산염 소거활성은 pH가 1.2일 경우 모든 품종과 생육단계에서 40% 이상 분해시켰으며, 특히 장형낙합과 신조은백다다기 품종이 상대적으로 높은 활성을 보였다. 또한 pH 4.0에서는 추출물 모두에서 30% 이상의 아질산염 소거활성을 나타냈으며, pH 6.0에서는 대부분 활성이 없었다. ABTS 소거활성은 장죽청장과 늘푸른 청장 품종이 다른 품종보다 상대적으로 다소 높은 소거능을 나타냈고, 생육단계별로는 대부분의 품종에서 ABTS 소거능에 큰 차이를 보이지는 않았다. SOD 활성은 모든 품종과 전 생육단계에서 95% 이상의 높은 활성을 보였으며, 품종 간에 거의 유의한 차이를 나타내지 않았다. CAT 활성은 전체적으로 장죽청장과 늘푸른청장 품종이 그리고 APX 활성은 늘푸른청장, 장형낙합 품종에서 상대적으로 높은 활성을 나타냈고, POX 활성은 생육단계별로 뚜렷한 경향을 보여 수확기에 이를수록 활성이 현저히 감소하는 결과를 나타냈다. 본 실험의 결과, 오이의 높은 항산화능을 확인함으로서 향후 향장소재 및 식품소재로서의 이용 가치성을 증대시킬 수 있음을 시사한다.

• 한국작물학회지
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• 제60권3호
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• pp.366-373
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• 2015

This study was conducted to clarify the antimicrobial effect, antioxidant and tyrosinase inhibitory activities of the biological composition having the Phytolacca americana, and to enhance the natural materials utilization of foods and cosmetics. The antimicrobial activities of the different parts of P. americana were evaluated using the agar diffusion test. The antimicrobial activity of P. americana was relatively high in Malassezia furfur known as a skin fungi and Vibrio parahaemolyticus compared to Escherichia coli and Staphy-lococcus epidermidis. However, the antimicrobial activity in Vibrio parahaemolyticus did not show at all parts of P. americana. Both the DPPH radical scavenging activity and ABTS radical scavenging activity have been increased with the higher concentration of methanol extract. In particular, leaf extract of P. americana exhibited the highest activity both ABTS radical scavenging activity and DPPH radical scavenging activity. The nitrite scavenging activity was decreased when the pH was changed from pH 1.2 to pH 6.0. The highest nitrite scavenging activity was exhibited from the methanol extract of fruit, followed by root, stem, and leaf at pH 1.2. However, the nitrite scavenging activity at pH of 6.0 was not almost detected. All plant parts of P. americana showed tyrosinase inhibitory activity. The highest activity was found in the stem, and followed by root, leaf, and fruit in order. These tyrosinase inhibitory activity was progressively increased in a concentration-dependent manner. In this experiment on the methanol extracts of different organ from P. americana, we confirmed that the extract of P. americana showed potent tyrosinase inhibitory activity. Taken together, we conjectured that the P. americana had the potent biological activities, therefore this plant having various functional components could be a good material for development into source of natural food additives and cosmetics.