• 한국수소및신에너지학회논문집
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• 제33권6호
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• pp.786-794
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• 2022

Green ammonia is a promising renewable energy carrier. Green ammonia can be used in various energy conversion devices (e.g., engine, fuel cell, etc.). Ammonia has to be fed with hydrogen for start-up and failure protection of some energy conversion devices. Ammonia can be converted into hydrogen by decomposition and partial oxidation. Especially, partial oxidation has the advantages of fast start-up, thermally self-sustaining operation and compact size. In this paper, thermodynamics, start-up and operation characteristics of ammonia partial oxidation were investigated. O₂/NH₃ ratio, ammonia flow rate and catalyst volume were varied as operation parameters. In thermodynamic analysis, ammonia conversion was maximized in the O₂/NH₃ range from 0.10 to 0.15. Ammonia partial oxidation reactor was successfully started using 12 V glow plug. At 0.13 of O₂/HN₃ ratio and 10 LPM of ammonia flow rate, ammonia partial oxidation reactor showed 90% of ammonia conversion over commercial Ru catalyst. In addition, Increasing O₂/NH₃ ratio from 0.10 to 0.13 was more effective for high ammonia conversion than increasing catalyst volume at 0.10 of O₂/NH₃.

• Biomolecules & Therapeutics
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• 제23권3호
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• pp.283-289
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• 2015

The half-dried leaves of Stewartia. pseudocamellia were extracted with hot water (SPE) and partitioned with n-hexane (SPEH), dichloromethane (SPED), and ethyl acetate (SPEE) successively. SPE and SPEE showed significant inhibitory effects against melanogenesis and tyrosinase activities. By bioassay-guided isolation, ten phenolic compounds were isolated by column chromatography from SPEE. The whitening effect of the isolated compounds from SPEE were tested for the inhibitory activities against melanogenesis using B16 melanoma cells, in vitro inhibition of tyrosinase, and L-3,4-dihydorxy-indole-2-carboxylic acid (L-DOPA) auto-oxidation assay. A cytotoxic activity assay was done to examine the cellular toxicity in Raw 264.7 macrophage cells. Of the compounds isolated, gallic acid and quercetin revealed significant inhibitory activities against melanogenesis compared to arbutin. In particular, quercetin exhibited similar inhibitory activities against tyrosinase and L-DOPA oxidation without cytotoxicity. These results suggested that SPE could be used as a potential source of natural skin-whitening material in cosmetics as well as in food products.

• 한국토양환경학회지
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• 제5권3호
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• pp.3-15
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• 2001

본 연구에서는 증류수와 인공지하수, 그리고 지하수를 대상으로 오존의 분해거동(오존의 자가분해, pH의 영향, 용해도)과 오존산화공정에 의한 디젤의 분해(디젤의 분해, TCE와 PCE의 분해, 수산화라디칼 scavenger의 영향, pH의 영향, 오존/과산화수소의 영향)를 조사하였다. 증류수와 지하수내에서 오존의 자가분해는 모두 2차 반응속도식을 보였고, 증류수(반감기 37.5 분)에서보다 지하수(반감기 14.7분)에서 훨씬 빠르게 오존이 분해되었으며, 알칼리성 조건하에서 두 액상에서 모두 오존의 분해는 촉진되었다. 또한 오존산화공정의 사용은 TCE와 PCE, 그리고 디젤에 대해 높은 산화처리속도를 나타내었다. 비록 지하수내에 존재하는 hydroxyl radical scavenger는 디젤의 분해에서 억제제로 작용하였지만, 높은 pH조건과 과산화수소의 첨가는 지하수내에서 디젤을 분해시키는 데 중요한 촉진제로서 작용하였다. 그러므로 오존산화공정은 디젤로 오염된 지하수를 처리하는 데 효과적으로 적용될 것이라 판단된다.

• International Journal of Safety
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• 제11권1호
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• pp.11-14
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• 2012

Hazard of Biodiesel (BDF) was studied. Biodiesel is a name for a variety of ester-based fuel made from vegetable oils. Recently importance of biodiesel is increasing, and its fires were sometimes reported. Therefore we studied on hazard of biodiesel comparing (petroleum) diesel oil and vegetable oil, raw materials of biodiesel. We found that biodiesel is auto-oxidized easily and ignites, and its flash point decreases when even small amount of methanol exists. And there are various raw materials to manufacture biodiesel, so we studied the difference of these materials, and their aging on safety.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 제5회 압연심포지엄 신 시장 개척을 위한 압연기술
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• pp.240-248
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• 2004

Recently, the customer's demands for automotive steel sheet have been diversified and sterned more. Therefore, as the tendency of auto industry light-weight, one among these requirements is the trend for high strength together with the thinness of automotive steel sheet. Because Mn added essentially in producing high strength steel sheet is bonded strongly with oxygen, the Fine oxidation layer was created at the welding face after the flash butt welding operated in entry section of pickling line. Thereby it was caused the crack or breakage of welding part in process of cold rolling. At this research, in order to protect the contact Mn with oxygen in atomosphere it was considered to fire oxygen with LNG and the related researches have been gone forward with the find out concrete and to apply them to operation.

• Journal of the Korean Wood Science and Technology
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• 제23권3호
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• pp.23-27
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• 1995

Several characteristic results of physical and optical properties of paper treated by UV light were obtained in the previous papers(Kim et al. 1988). In this paper, folding endurance and brightness of paper prepared by spraying photostabilizer were examined in order to elucidate photodegradation phenomena, UV light absorber and radical scavenger were most effective in preventing of folding endurance decrease. These results may be indicated that depolymerization of cellulose and hemicellulose chains leading to degradation of paper mechanical properties mainly caused by radical reaction. Ineffective hydroperoxide decomposer may be explained because of auto-oxidation reactions before forming stable compound from hydroperoxide.

• 약학회지
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• 제43권4호
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• pp.494-501
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• 1999

The skin whitening effects of pine needle extract, hop extract and chestnut inner shell extract were evaluated both in vitro and in B 16 mouse melanoma cell lines. Each extracts significantly inhibited tyrosinase activity, dopa auto-oxidation and melanin biosynthesis in vitro and in B 16 cell lines. In vitro, hop extract inhibited melanin biosynthesis 15 times stronger than kojic acid at $10{\;}\mu\textrm{g}/ml$ concentration. Each extracts were stronger inhibitors of melanin biosynthesis than kojic acid in B 16 mouse melanoma cell at less than $4{\;}\mu\textrm{g}/ml$ concentration. These results show that extracts fo pine needle, hop and chestnut inner shell could be developed as skin whitening component of cosmetics.

• International Journal of Automotive Technology
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• 제7권3호
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• pp.251-259
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• 2006

For practical application on the HCCI engine, the solution of subjects, such as control of auto-ignition timing and avoidance of knocking, is indispensable. This study focused on the technique of controlling HCCI combustion appropriately, changing the mixture ratio of two kinds of fuel. Methane and DME/n-Butane were selected as fuels. The influences, which the mixing ratio of two fuels does to ignition timing, ignition temperature, rate of heat release and oxidation reaction process, were investigated by experiment with 4-stroke HCCI engine and numerical calculation with elementary reactions.

• 한국식품과학회지
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• 제40권3호
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• pp.257-264
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• 2008

본 연구에서는 호주산과 스페인산 올리브 잎의 이화학적 특성중 총 플라보노이드 함량, 총 페놀 함량, 항산화기능과 아질산염 소거능력을 측정하였다. 총 플라보노이드 함량은 호주산과 스페인산 모두 올리브 잎 80% 에탄올 추출물에서 각각 22.7, 23.9%으로 가장 높았으며 전체적으로는 물 분획물(1.5% 내외)이 상대적으로 낮았다. 총 페놀 함량의 경우도 부탄올 분획물(18% 내외)이 가장 높았으며 올리브 잎 80% 에탄올 추출물과 물 분획물 순으로 유의적으로 높은 페놀함량을 나타냈다. SOD 유사활성능은 0-36.08%의 범위이었으며 모든 추출물 및 분획물에서 농도가 높아짐에 따라 활성도가 증가하였고 올리브 잎 80% 에탄올 추출물이 36.08%로 활성이 가장 높았다. DPPH radical 제거활성은 호주산 올리브 잎의 80% 에탄올 추출물이 63.32%로 가장 높은 활성을 나타냈다. Linoleic acid와 함께 시료를 처리하여 지질과산화를 억제하는 정도는 호주산 올리브 잎 분획물은 시간 경과에 따라 농도 의존적으로 비교적 일정하게 산화억제활성이 나타난 반면 스페인산 올리브 잎의 경우 몇몇 분획물에서 약한 산화억제활성을 나타냈을 뿐 산화억제활성을 거의 나타내지 않았다. 발암물질인 nitrosamine 생성의 원인물질인 nitrite 제거활성을 확인한 결과 농도 의존적으로 증가하는 경향을 나타냈다. 부탄올 분획물은 nitrite 제거활성이 65.70, 73.10%로 높은 소거능을 보였으며 헥산과 물 분획물은 제거능력이 없거나 낮은 것으로 나타났다.

• 대한화장품학회지
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• 제37권2호
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• pp.153-159
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• 2011

이 연구에서는 천연 항산화소재와 미백소재 개발을 위하여 미강을 Bacillus subtilis에 접종하여 $40^{\circ}C$에서 36 h 동안 발효한 미강추출(RFB)과 80 % ethanol을 이용한 미강추출물(RB)을 사용하여 연구하였다. 추출물의 free radical 소거활성, superoxide radical 소거활성, hydroxyl radical 소거활성은 농도 $100 \;{\mu}L$/mL에서 가장 큰 활성을 나타내었고 리놀산을 이용한 지질과산화 억제 활성 또한 농도 $100 \;{\mu}L$/mL에서 가장 큰 활성을 나타내었고, RB에 비하여 RFB의 더 높은 항산화 능을 확인하였다. Mushroom tyrosinase의 활성 저해효과는 $100 \;{\mu}L$/mL 농도에서 mushroom tyrosinase 의 활성을 80 % 저해하였으며 이는 vitamin C에 비해 더 높은 활성을 나타내었다. 그러므로 우리는 미강 발효추출물이 우수한 항산화와 미백 효능을 갖는 화장품 소재로서 개발 가능성이 클 것으로 기대된다.