• 전기학회논문지
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• 제57권10호
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• pp.1790-1795
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• 2008

Energy scavenging is a technique that converts ambient energy, for example, vibration and light, to electrical energy in order to supply power to low power electronic devices such as ubiquitous sensors. In this paper, we propose an optimal operation condition of power delivery circuit and design strategy for energy scavenging system in which the generated power is order of microwatt and, consequently, efficient handling of power is critical. We also propose that high data transmission rate is more realistic optimal design objective rather than high energy efficiency. It is shown that disconnection of load from the storage capacitor right after data transmission reduces energy wasting and that optimal value of storage capacitor can be determined at this condition. The feasibility of our propose is proved by experiments and we believe that the proposed design strategy will promote the application of piezoelectric micropower generator to the ubiquitous sensor networks.

• Preventive Nutrition and Food Science
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• 제14권3호
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• pp.195-200
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• 2009

This study was carried out to investigate the biological activities of star anise extracts obtained from four different solvents (water, methanol, ethanol and chloroform) by measuring total polyphenol and flavonoid contents, DPPH radical scavenging, hydroxyl radical scavenging, nitrite scavenging activity and antimicrobial activity. The methanol extract showed the highest extraction yield, followed by ethanol, water and chloroform. The properties of the extracting solvents significantly affected the total polyphenol content. Methanol extracts contained more total polyphenols than any other extracts. The highest DPPH radical scavenging activity was found in methanol extract. The hydroxyl radical and nitrite scavenging activity were highest in methanol and ethanol extracts. In antimicrobial activity, water extract showed stronger activities than methanol and ethanol extract against Micrococcus luteus and Bacillus subtilis, and no inhibitory effects on Gram negative bacteria were found in all extracts at the concentration used.

• 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.

• 한국수산과학회지
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• 제50권4호
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• pp.359-365
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• 2017

To develop new functional materials, Saccharina japonica (S. japonica) was cultivated with Phellinus linteus (P. linteus) mycelia by solid culture. S. japonica was fermented with P. linteus mycelia. The various radical scavenging activities of extracts of fermented S. japonica with P. linteus mycelia (FSPM) were investigated and compared to the antioxidant capabilities of unfermented S. japonica and P. linteus mycelia. The antioxidant activities of FSPM extracts were evaluated using ferric reducing antioxidant power (FRAP) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity. FSPM showed stronger free radical scavenging abilities than P. linteus mycelia or S. japonica alone. These results indicate that fermentation of S. japonica changes its chemical nature and could provide beneficial antioxidant effects.

• Mycobiology
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• 제34권3호
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• pp.124-127
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• 2006

This study was aimed at evaluating the antioxidant activities of methanol extract of Thamnolia vermicularis. The antioxidant activity, reducing power, superoxide anion radical scavenging and free radical scavenging activities were studied. The antioxidant activity of the extract correlated with its concentration ($0.2{\sim}2\;mg/ml$) in the reaction mixtures containing linoleic acid. Upto 67% of lipid peroxidation was inhibited by 2 mg/ml of the lichen extract. The extract showed strong free radical scavenging activity similar to that of BRA (positive control) in a manlier of concentration dependent. The lichen extract also showed moderate effects on superoxide anoin scavenging activity and reducing power, which was not so effective as that of Quercetin and BHA used as positive controls. This study suggests that T. vermicularis lichen can be used as a novel source of natural antioxidant.

• 한국식품조리과학회지
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• 제23권1호통권97호
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• pp.19-24
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• 2007

This study investigated the antioxidant and synergistic effects and nitrite scavenging ability of some phenolic compounds(catechin, rutin, quercetin and naringin), The electron donating abilities of naringin, quercetin, rutin and catechin were 6.7%, 92.8%, 87.6% and 92.21%, respectively, The antioxidant activities in O/W emulsion substrates were in order of rutin > quercetin > catechin > naringin. The antioxidant effect of rutin was stranger than that of BHT or ${\alpha}$-tocopherol. ${\alpha}$-tocopherol showed synergistic effect with catechin and quercetin, but ascorbic acid not showed effect. The nitrite scavenging abilities of catechin, quercetin, rutin and naringin were 99.9%, 98.6%, 25.5% and 0.2%, respectively. The nitrite scavenging abilities of quercetin and actechin were very potent as compared with those of BHT and ascorbic acid.

• 한국대기환경학회지
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• 제15권1호
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• pp.1-11
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• 1999

In this work, a theoretical model has been formulated which allows the study of the scavenging efficiencies of aerosol particles by the rain drops. Aerosol particles are scavenged by the simultaneous brownian diffusion, interception and inertial impaction force. In addition the calculations based on the collision efficiency model are carried out for the collision of aerosol particles with diameter range 0.01~30 $mu extrm{m}$ and rain drops with diameter 0.02$\times$$2^{n/3}$(n=1, 2, …, 17)cm. The results indicate that: (1) the below-cloud scavenging affects mainly the coarse particles (＞3 ${\mu}{\textrm}{m}$), the fine particles remaining almost unchanged; (2) the scavenging efficiencies by below-cloud in the heavy rain (rain intensity, 10 mm/hr) surpass the efficiency found in the drizzle rain (rain intensity, 1 mm/hr).

• 한국식품영양과학회지
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• 제29권1호
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• pp.106-110
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• 2000

We investigated the active oxygen scavenging activity and active compound from Humulus japonicus. The ethyl acetate and butanol fraction exhibited strong scavenging effects on hydroxyl radical. Furthermore active compound was isolated and purified using Amberlite XAD-2 column chromatography and preparative HPLC from ethyl acetate fracton, and major compound was identified as a luteolin-7-O-$\beta$-D-glucoside by the MS, UV, 1H-NMR and 13C-NMR analyses. Luteolin-7-O-$\beta$-D-glucoside exhibited strong scavenging effect on active oxygens such as superoxide radical, hydroxyl radical and hydrogen peroxide.

• 한국식품영양학회지
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• 제34권2호
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• pp.181-186
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• 2021

Antioxidant properties and antioxidant activities were analyzed for water extracts and 50% and 70% ethanol extracts of the leaf of Angelica gigas Nakai. The polyphenol and flavonoid contents in water, 50%, and 70% ethanol extract of the leaf of Angelica gigas Nakai, it was found that the polyphenol contents were 18.75 mg GAE/g, 28.95 mg GAE/g, and 34.73 mg GAE/g, respectively, and flavonoid contents were respectively. The DPPH IC50 scavenging activity was 45.84 mg/mL, 36.44 mg/mL, 19.11 mg/mL, respectively, and theABTS+ radical scavenging ability (1 mg/mL) was 28.73%, 22.79%, and 12.70%, respectively. Tyrosinase inhibitory activity, 70% ethanol extract, 50% ethanol extract, and water extract 33.14%, and 4.53%, respectively. Nitrite scavenging activity, 70% ethanol extract, 50% ethanol extract, and water extract were in the order of 1 mg/mL scavenging activity, 36.43%, 34.80%, and 18.85%, respectively.

• 한국산업융합학회 논문집
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• 제22권3호
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• pp.259-264
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• 2019

In this study, we experiment by making and designing of compression ignition diesel engine witch has air cooling, 2-cylinder and 2-strokes. Also, we make controller witch can control injection timing and period by arbitrary manual operation for change of injection timing. We also study experimentally in change about pressure and power of combustion chamber by increasing density of air which comes into cylinder because of increasing scavenging pressure. Through this, we confirmed that output change and scavenging pressure can develop performance of the engine by scavenging efficiency of a chamber and development of volume efficiency.