• 한국식품영양과학회지
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• 제34권1호
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• pp.99-106
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• 2005

클로로필의 광산화에 미치는 $\beta$-카로텐과 비타민 C의 역할을 linoleic acid emulsion 모델 시스템과 피부조직 균질액을 이용하여 조사하고 이와 더불어 각각의 성분들의 조합시 일어나는 변화를 살펴보았다. Linoleic acid emulsion 모델 시스템에서 클로로필과 $\beta$-카로텐은 고농도에서 자외선 H에 의한 광산화를 촉진시키는 것으로 나타났으며 고농도의 비타민 C는 이를 억제시켰다. 갓김치에 함유되어 있는 클로로필, $\beta$-카로텐, 비타민 C 농도를 참고하여 이들을 조합하였을 때 자외선 B에 의한 광산화를 억제시켰으며 $\beta$-카로텐의 경우 단독으로 사용되었을 때에는 산화를 촉진하였으나 다른 항산화성분들과 함께 사용될 경우 항산화활성을 나타내었다. ICR mouse의 피부조직 균질액에 클로로필, $\beta$-카로텐, 비타민 C를 단독 또는 혼합하여 첨가하였을 때 클로로필 a, b 및 $\beta$-카로텐의 첨 가는 광산화를 가속화시켰다. 비타민 C의 경우 50 ppm을 첨가하였을 때에는 아무런 효과를 나타내지 않았으나 500 ppm을 첨가하였을 때에는 자외선 B에 의한 광산화를 효과적으로 억제시켰다. 500 ppm의 비타민 C에 클로로필과 $\beta$-카로텐을 혼합하였을 때에도 광산화가 억제되었으며 비타민 C의 농도가 중요하게 작용하였다.

• 에너지공학
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• 제25권3호
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• pp.18-26
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• 2016

대부분의 변압기에 사용되고 있는 절연유는 석유계 원료를 이용한 광유계 절연유였으나 유출시 환경오염, 낮은 인화점으로 인한 화재 위험성을 가지고 있어 보다 친환경 식물성 원료를 활용한 절연유 도입이 최근 검토되고 있다. 그러나 식물성 절연유의 높은 생분해성과 인화점으로 절연유로서의 높은 적용가능성에도 불구하고 장기운전에 의한 열화가 미치는 영향에서는 아직 많은 연구가 필요한 실정이다. 따라서 본 연구에서는 변압기의 구성요소를 감안하고 실제 운전조건보다 높은 $150^{\circ}C$에서 2주간의 가속열화 시험을 통해 전산가, 수분, 절연파괴전압 등의 주요물성 변화를 통해 식물성 절연유 산화특성과 이 과정에서 생성되는 용존 가스 분석을 실시였다. 이를 통해 식물성 절연유가 기존 광유계 절연유 대비 친수성에 의한 전산가 상승에도 불구하고 절연성능을 유지하는 특징을 가지고 있으며 가스 성분 비교를 통해 주어진 온도 조건에서 우수한 열안정성을 나타내고 있음을 확인하였다.

• 대한화학회지
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• 제46권1호
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• pp.14-18
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• 2002

산화질소 분자(NO)가 전자 한 개를 받아 산화질소 음이온$(NO^-)$으로 환원되는 반응의 정도가 진동에너지에 따라 크게 달라질 수 있음을 제시하였다. NO와 $NO^-$의 포텐샬에너지 표면은 진동에너지가 많아짐에 따라 NO 분자가 전자를 받아 $NO^-$음이온으로 바뀔수 있는 에너지적 측면을 가짐을 보여준다. 또한, 진동 파동함수간의 Franck-Condon 인자를 계산하였다. 진동에너지가 많아지면 NO에서 $NO^-$로 바뀔 경로가 더 많이 증가함을 보인다. 이 결과는 NO 분자에게 적절한 빛을 조사시킴으로 $NO^-$이온으로의 환원반응속도를 조절할 수 있음을 의미한다.

• 한국재료학회지
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• 제19권9호
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• pp.481-487
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• 2009

The photocatalysts of Fe-ACF/$TiO_2$ compositeswere prepared by the sol-gel method and characterized by BET, XRD, SEM, and EDX. It showed that the BET surface area was related to adsorption capacity for each composite. The SEM results showed that ferric compound and titanium dioxide were distributed on the surfaces of ACF. The XRD results showed that Fe-ACF/$TiO_2$ composite only contained an anatase structure with a Fe mediated compound. EDX results showed the presence of C, O, and Ti with Fe peaks in Fe-ACF/$TiO_2$ composites. From the photocataytic degradation effect, $TiO_2$ on activated carbon fiber surface modified with Fe (Fe-ACF/$TiO_2$) could work in the photo-Fenton process. It was revealed that the photo-Fenton reaction gives considerable photocatalytic ability for the decomposition of methylene blue (MB) compared to non-treated ACF/$TiO_2$, and the photo-Fenton reaction was improved by the addition of $H_2O_2$. It was proved that the decomposition of MB under UV (365 nm) irradiation in the presence of $H_2O_2$ predominantly accelerated the oxidation of $Fe^{2+}$ to $Fe^{3+}$ and produced a high concentration of OH radicals.

• 한국전기전자재료학회논문지
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• 제11권3호
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• pp.174-180
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• 1998

In this work, the properties of FRP, which is applied recently in the composite insulating materials, by thermal treatment were investigated. The specimens were epoxy glass laminates fabricated by thermal press method and had the volume content of 46[%] cutted $45^{\circ}C$ in the fiber direction and 1.0[mm] thickness. The experimental results showed that the amount of weight loss, wettability, surface potential, and surface resistivity increased up to 200[$^{\circ}C$] as a function of temperature. Usually, most degradations caused the hydrophilic to decrease the contact angle. But, in this work on thermal-degradated FRP, we can confirm the introduction of hydrophobic properties by cross-linking and the ablation of polar small-molecules rather than chain scission and oxidation. Finally, weight loss and contact angle increased. These phenomena show the existence of hydrophobic surface. With the change to the hydrophobic surface and the electrical potential and resistivity on FRP surface increased. But, the dielectric properties and tensile stength are decreased.

• Bulletin of the Korean Chemical Society
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• 제31권9호
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• pp.2613-2617
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• 2010

Chloroprene is a chlorine substituent of 1,3-butadiene. Butadiene rubber (BR) and chloroprene rubber (CR) composites were thermally aged at 60, 70, 80, and $90^{\circ}C$ for 2 - 185 days in a convection oven and changes of the crosslink densities by the accelerated thermal aging were investigated. The crosslink densities increased as the aging time elapsed and as the aging temperature became higher. Degrees of the crosslink density changes of the BR composite were on the whole larger than those of the CR one except the short-term thermal aging at 60 and $70^{\circ}C$. The crosslink densities abnormally increased after themal aging at high temperatures for a long time. Activation energies for the crosslink density changes of the rubber composites tended to increase with increase of the aging time and the variation showed a local minimum. The activation energies of the CR composite were lower than those of the BR one. The experimental results were explained with a role of ligand of chlorine atom of CR in a zinc complex, steric hindrance by chlorine atom of CR, and oxidation of rubber chain.

• 한국염색가공학회지
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• 제15권2호
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• pp.86-92
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• 2003

It is already known that the color of wool fabric dyed with disazo acid dyes could be changed in dyeing process and this is accelerated under alkaline condition. Focus was given to figuring out the mechanism of this color change, through the LC-MS analysis. In this study, no color change was seen in wool fabrics dyed with C. I. Acid Blue 113 under weak acidic, neutral and weak alkaline conditions for 1hour. However, the wool fabrics dyed under weak alkaline condition for a long time over 3 hours fumed reddish orange. When the wool fabrics dyed under weak acidic, neutral and weak alkaline conditions were treated with $0.5g/L\;Na_2C0_3$ solution, all of them turned reddish orange. On the other hand, the color of silk fabrics dyed with C. I. Acid Blue 113 were not changed after the same alkaline treatment. Wool contains cystine and cysteine, whereas silk does not. Due to the reversible reduction/oxidation process of cystine and cysteine in wool dyeing, the C. I. Acid Blue 113 of the dis-azo type is decomposed by reduction and consequently turned them into the reddish orange mono-azo types dye.

• 한국식품조리과학회지
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• 제28권2호
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• pp.123-131
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• 2012

This study was carried out for the purpose of inquiring into the effects on shelf-life, quality characteristics and antioxidative activities of Majakgwa with regard to the use turmeric powder at varying concentrations in the recipe. Chemical composition analysis showed that the contents of crude fat, crude protein and carbohydrates are high in turmeric powder. With an increase of the amount of turmeric powder used in Majakgwa recipes, dough pH was higher than that of the control group. Antioxidative activities were the highest in the groups with 3% and 9% turmeric powder content, and the value increased largely after 12 days of storage. Excellent antioxidative activities were observed in the 6% turmeric content group. For recipes with turmeric contents of more than 15%, oxidation was accelerated from early on in storage. The hardness, brittleness and bitterness increased significantly with the increase of the turmeric content. The intensity, chromaticity, crunch and intensity of the surface colors, all increased significantly with the increase of turmeric content. The general preference ratings for Majakgwa with added turmeric was highest for the 9% content recipe. Over all Majakgwa recipes with 6~9% turmeric powder content were found to ideal.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.1996-2000
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• 2008

In autothermal reforming reaction, oxygen to carbon ratio (OCR) and steam to carbon ratio (SCR) are significant factors, which control temperature and carbon deposition into the reactor. The OCR is more sensitive than the SCR to affect the temperature distribution and reforming efficiency. In conventional operation, hydrocarbon fuel, steam, and oxygen was homogeneously mixed and injected into the reactor in order to get hydrogen-rich gas. The temperature was abruptly raised due to fast oxidation reaction in the former part of the reactor. Deactivation of packed catalysts can be accelerated there. In the present study, therefore, the effect of the oxygen distribution is introduced and investigated to suppress the carbon deposition and to maintain the reactor in the mild operating temperature (e.g., $700{\sim}800^{\circ}C$). In order to investigate the effect numerically, the following models are adopted; heterogeneous reaction model and two-medium model for heat balance.

• 한국세라믹학회지
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• 제28권8호
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• pp.626-634
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• 1991

The specimens for the corrosion test were made by hot-pressing of SiC power with 2 wt% Nl2O3 and 10wt% Al2O3 additions at 200$0^{\circ}C$ and 205$0^{\circ}C$. The specimens were corroded in 37 mole% NaCl and 63 mole% Na2SO4 salt mixture at 100$0^{\circ}C$ up to 60 min. SiO2 layer was formed on SiC and then this oxide layer was dissolved by Na2O ion in the salt mixture. The rate of corrosion of the specimen containing 10 wt% Al2O3 was slower than that of the specimen containing 2 wt% Al2O3. This is due to the presence of continuous grain boundary phase in the specimen containing 10 wt% Al2O3. The oxidation of SiC produced gas bubbles at the SiC-SiO2 interface. The rate of corrosion follows a linear rate law up to 50 min. and then was accelerated. This acceleration is due to the disruption oxide layer by the gas evolution at SiC-SiO2 interface. Pitting corrosion has found at open pores and grain boundaries.