• 한국자동차공학회논문집
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• 제11권1호
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• pp.55-63
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• 2003

In a diesel engine, air-fuel mixture formation and ignition delay period have great influence on the performance of engine. Their main factors are combustion chamber shape, fuel injection system. air volume, air flow and so on. So, the combustion process in the cylinder is complex because of many factors which have direct and indirect effects on it. In this study, we take into consideration of scavenging pressure and scavenging temperature that are hewn as the main factor to the combustion process of two-stroke D.1. diesel engine. It is taken a picture of the combustion flame process for combustion chamber of re-entrant type and cylindrical type. So, it is applied to the basis data of combustion chamber design from an image analysis.

• Preventive Nutrition and Food Science
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• 제18권1호
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• pp.80-84
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• 2013

This study was conducted to evaluate the increase of DPPH radical scavenging activity of meat substitute by heating. The meat substitute showed higher DPPH radical scavenging activity than those of other foods rich in protein such as beef, pork, chicken, and soybean curd. The DPPH radical scavenging activity of meat substitute was dependent upon concentration, heating temperature and heating time of meat substitute. The DPPH radical scavenging activity of meat substitute was enhanced with increasing heating temperature and time. The increase of DPPH radical scavenging activity was only applied to meat substitute without showing any activation in other foods rich in protein such as beef, pork, chicken, and soybean curd.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.291-291
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• 2017

The effects of bioactivity, binding polyphenolic contents, DPPH radical scavenging activity, ABTS radical scavenging activity, xanthine oxidase and immune activity on the storage temperature and durations of Codonopsis lanceolata root were evaluated in vitro. The contents of total polyphenol and flavonoid content by storage temperature and storage period was no significant difference according to the storage period, but it was found that the content was higher at lower storage temperature. The DPPH free radical scavenging activity at six different concentrations, 500, 1000, 2500, 5000, 10000 and 20000 mg/L are measured, the scavenging activity according to different storage temperature and storage period showed relatively the higher the activity in the shorter storage period or the lower storage temperature. The ABTS radical scavenging activity did not show a significant difference under various storage temperature and storage period conditions. The xanthine oxidase inhibitory activity of C. lanceolata extract tended to decrease more, depending on the longer storage period or the higher storage temperature. In different storage period and storage temperature conditions, the immune cell growth of C. lanceolata extract promoted a concentration-dependent manner in both human T cell and B cell, and did not show a significant difference. These results of this study suggested that the root of C. lanceolata may assist in the potential biological activities, and can be used as a source of human health products.

• Journal of Advanced Marine Engineering and Technology
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• 제21권4호
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• pp.421-429
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• 1997

This study is theoretically examined the influences on the performance of diesel engine super¬charged by exhaust gas turbine with the change of excess air factor, admission ratio, total efficien¬cy of turbine and compressor, scavenging pressure ratio, and scavenging temperature. In this study, all calculations are carried out by computer, and the theoretical engine performance is com¬pared with the actual engine performance which is offered from engine manufacturer. Following results are acquired by this study. The mean effective pressure is increased with decrease of excess air factor or increase of scavenging pressure ratio. As the admission ratio or total efficiency of tur¬bine is increased, the mean effective pressure is increased but the specific fuel consumption is decreased. Mean calculation error compared with the actual engine performance is under 5 per¬cents, therefore, this calculation method can be used in the design of diesel engine.

• Journal of Ginseng Research
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• 제36권4호
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• pp.411-417
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• 2012

Ginseng seeds were treated with different autoclaving temperatures and autoclaving times, and extracted with 80% methanol to measure changes in antioxidant activity. The antioxidant activity of ginseng seeds treated by autoclaving was measured by 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity, 2,2'-aziono-bis(3-ethylbenzthiazoline)-6-sulfonic acid radical scavenging activity, superoxide dismutase SOD-like activity, ferric reducing antioxidant power (FRAP), and total phenolic compound content. As autoclaving temperature and time were increased, the L lightness value decreased and the redness value tended to increase. Total phenolic compound content was about three times higher in ginseng seeds treated with autoclaving at 130°C than in ginseng seeds that were not treated. DPPH radical scavenging activity and ABTS radical scavenging activity increased as autoclaving temperature and time were increased. In particular, when the concentration was 100 ppm, the ABTS radical scavenging activity was 91.80% in ginseng seeds treated by autoclaving at $130^{\circ}C$, which was the highest antioxidant activity. FRAP and SOD-like antioxidant activity tended to increase significantly as autoclaving temperature and time were increased.

• 한국식품영양학회지
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• 제33권1호
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• pp.64-73
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• 2020

The purpose of this study was to investigate the antioxidant activity and β-glucan content of extracts extracted by varying the temperature at 30, 55 and 80℃ after hot air drying or freeze drying of Pleurotus ostreatus and Pleurotus eryngii. For the analysis antioxidant activity of each mushroom, β-glucan, total phenol, flavonoid contents, and DPPH·ABTS⁺·Nitrite assay were measured. Also, the β-glucan content, total flavonoid content and ABTS⁺ scavenging activity increased with freeze drying rather than hot air drying, and increased with increasing extraction temperature in both mushrooms. However, the total phenol and nitrite scavenging activity increased with hot air drying rather than freeze drying, and decreased with increasing temperature in both mushrooms. DPPH scavenging activity was not significant in both mushrooms, but decreased with increasing extraction temperature. Pearson's correlations between total flavonoid content and antioxidant activities were r=0.719~0.753 (p<0.01). As a result, the β-glucan content, total flavonoid content, and ABTS radical cation scavenging activity were highest during freeze drying and extraction at 80℃. And the highest total phenol content, DPPH radical scavenging activity and nitrite scavenging activity were obtained during hot air drying and extraction at 30℃.

• Preventive Nutrition and Food Science
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• 제21권4호
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• pp.355-360
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• 2016

The influence of extraction temperature, powder concentration, and extraction time on the antioxidant properties of aqueous ginger extract was investigated. The possibility of estimating the antioxidant properties of the extract from its absorbance and colour properties was also investigated. Results indicated that powder concentration was the most significant factor to consider in optimizing antioxidant extraction. However, temperature and time still influenced the 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity while extraction temperature influenced the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of the extract. Using the total phenol content, total flavonoid content, ABTS radical scavenging activity, and DPPH radical scavenging activity of the extract, the multiresponse optimization condition for extraction of antioxidant based on the experimental range studied is $96^{\circ}C$, 2.10 g/100 mL, and 90 min. The absorbance of the ginger extract at 610 nm could be exploited for rapid estimation of its total flavonoid and polyphenol with a $R^2$ of 0.713 and 0.753, respectively.

• 한국식품저장유통학회지
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• 제22권5호
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• pp.708-713
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• 2015

고구마 잎을 건조 채소화 하기 위한 기초자료를 제공하기 위해서 열풍건조한 고구마 잎 메탄올 추출물에 함유된 총 탄닌, 총 플라보노이드, 총 폴리페놀 함량을 분석하고, 항산화 효과로 DPPH 라디칼 소거활성, ABTS 라디칼 소거능, 아질산염 소거능 등을 분석 비교 검토하였다. 총 탄닌 함량은 신미 $40^{\circ}C$에서 10.87 mg/g, $70^{\circ}C$에서 7.28 mg/g으로 감소되었고, 총 플라보노이드는 하얀미 $40^{\circ}C$에서 55.37 mg/g, $70^{\circ}C$에서 39.63 mg/g으로 감소되었다. 즉 저온건조가 고온건조보다 이들 물질의 함량이 많았다. DPPH 라디칼소거 활성은 신미와 하얀미 $40^{\circ}C$에서 84.33%와 85.25%로 가장 높았으며, ABTS 라디칼 소거능도 $40^{\circ}C$ 처리구에서 80%가 넘는 높은 값이었다. 아질산염 소거능은 신미와 하얀미가 $40^{\circ}C$에서 76.15%와 73.74%로 가장 높았고 $70^{\circ}C$에서는 낮았다. 품종 간에는 하얀미가 신미보다 페놀성 물질과 항산화 물질이 더 많은 것으로 나타났다. 즉 건조한 고구마 잎의 항산화 효과는 품종간의 차이는 있었으나, $40^{\circ}C$ 시료에서 높고, $70^{\circ}C$ 시료에서 낮았다. 이는 건조온도에 의해 영향을 받는 것으로서 낮은 온도에서 건조하는 것이 유효성분의 감소가 적어 항산화 능력이 높은 결과이었다.

• Food Science and Biotechnology
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• 제16권6호
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• pp.1041-1045
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• 2007

Heated onion juice was partitioned using the solvents hexane, chloroform, ethyl acetate, and butanol. The ethyl acetate fraction showed the strongest scavenging effect on the ABTS radical. The antioxidant activities of the ethyl acetate fraction from raw and heated onion (120, 130, and $140^{\circ}C$) were evaluated using radical scavenging assays. Radical and nitrite scavenging activities were higher in heated onion than raw onion, and the higher the temperature of heat treatment, the greater the radical and nitrite scavenging activities. Heated onion ($140^{\circ}C$, 2 hr) was more effective than raw onion, having higher DPPH radical scavenging (5.7-fold), hydroxyl radical scavenging (6.4-fold), superoxide radical scavenging (2.3-fold), hydrogen peroxide scavenging (11.8-fold), and nitrite scavenging (4.3-fold) activities. Onion increased its physiologically active materials after heating, and in this regard, heated onion can be used as biological material for the manufacture of health foods and supplements.

• 한국해양바이오학회지
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• 제9권2호
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• pp.43-48
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• 2017

Temperature is a major factor that affects the physiochemical properties of compounds. This study focus on the determination of thermostability and the effect of temperature on antioxidant activities of Ecklonia cava (E. cava) ethanoic extract. The ethanoic extracts of E. cava were evaluated at $30^{\circ}C$, $60^{\circ}C$ and $90^{\circ}C$ for 0 to 7 days. The antioxidant activities were determined by DPPH, hydroxyl radical and hydrogen peroxide scavenging activities. The intracellular reactive oxygen species (ROS) scavenging activity was investigated using DCFH-DA assay. Results revealed that the ethanoic extract of E. cava incubated at different temperatures for 0 to 7 days, showed stable scavenging activities on DPPH, hydroxyl radical and hydrogen peroxide. The ROS scavenging activities of ethanoic extract and ascorbic acid were also investigated. The extract showed a stable ROS scavenging activity from 0 to 7 day at $90^{\circ}C$. However, the scavenging activity of ascorbic acid at $90^{\circ}C$ decreased starting from day 3. These results indicated that the antioxidant effects of this food grade ethanoic extract of E. cava could remain stable during the employed temperatures of food processing.