• Journal of Energy Engineering
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• v.3 no.1
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• pp.77-83
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• 1994

아연-산화은 2차전지는 높은 에너지 밀도의 이점을 가진 반면, 짧은 사이클수명(설계 및 사용방법에 따라 10∼200 사이클)을 가진 단점이 있다. 산화은 전극의 비싼 가격 때문에 높은 에너지 밀도가 요구되는 분야에서 제한적으로 사용되고 있다. 본 논문은 수중운동체계의 추진용으로 사용하기 위한 신뢰성이 높은 아연-산화은 전지의 개발을 다루었다. 고율방전에서 양극 활물질의 양에 따른 전압 특성과 음극활물질의 첨가제에 따른 사이클 수명 비교 시험을 실시하였다. 본 연구결과 우수한 전압 특성과 고율방전에서10회 이상의 사이클 수명을 갖는 아연-산화은 2차전지를 개발하였다.

• Proceedings of the KSEEG Conference
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• 2003.04a
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• pp.43-47
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• 2003

산화환경에 노출된 폐광석에 포함되어 있는 황화광물은 산소와 물과의 화학반응을 통한 산화작용을 받게 되고 주변 환경에 유해한 금속원소의 용출이 발생될 것으로 예상된다. 그러나 용해된 금속이온은 침전(precipitation), 공침(coprecipitation), 흡착(adsorption)반응에 의해 수용액으로부터 제거되어 자연적으로 고정화될 수 있다. 이번 연구는 서보광산의 폐광석 내 용해된 중금속원소들의 이동을 제한하는 요인으로서 2차 산화광물의 침전 및 용해된 중금속 원소들의 흡착 가능성을 광물학적으로 연구하였다. (중략)

• Polymer(Korea)
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• v.37 no.2
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• pp.156-161
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• 2013

Phenolic antioxidants are effective stabilizers that provide excellent long-term heat stability by preventing thermo-oxidative degradation during processing and service life. However, under a selected set of circumstances, certain types of phenolics have been susceptible to discoloration due to prolonged storage in an environment containing oxides of nitrogen. It is investigated that the effect of addition of secondary antioxidant and chemical structure of primary antioxidant on discoloration of amorphous poly-${\alpha}$-olefin (APAO), which is especially prone to be decomposed in high processing temperature. From the result, it is concluded that a higher level of steric hindrance of phenolic antioxidant provided by long alkyl chain allows a more enhanced synergic effect with secondary antioxidant.

• Tribology and Lubricants
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• v.6 no.2
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• pp.1-15
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• 1990

본 해설에서는 윤활 오일에서 구리 반응 억제제와 철의 부식 억제제에 관한 내용을 검토한 것으로 자동산화 화정의 초기 생성과 연쇄적인 전파, 확산 및 종료 그리고 1차 및 2차 산화 억제제에 관해서 서술한 것이다. 구리 반응 억제제와 부식 억제 성질 및 작용이 고려되고 첨가제로써의 응용에 관해 조사하였다.

• Journal of the Korean Magnetics Society
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• v.20 no.5
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• pp.191-195
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• 2010

We have investigated the effect of the removal of an initial oxide layer and the anodization time on the growth of the porous alumina layer. The porous alumina layer was fabricated by two-step anodization process with phosphoric acid. We have observed the changes in the uniformity of the pore structure by varying the removing time of the initial oxide layer after the first anodization with phosphoric acid and chromic acid, and noted that its uniformity improves with the removing time. We have also determined the thickness of the alumina layer after the final anodization process and found that the thickness increases linearly with the anodization time. Under 150 V of anodization voltage with phosphoric acid, the growth rate of the porous alumina layer is determined to be 22.5 nm/min.

• Resources Recycling
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• v.12 no.6
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• pp.19-25
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• 2003

This experiment was carried out to examine the effect of iron oxide roasting for Sr-ferrite magnet. Chloride content was decreased with raising the 2 nd roasting temperature of iron oxide for ruthner process iron oxide. The optimization temperature for roasting of ruthner process iron oxide was around $800^{\circ}C$ as average particle size 1.5∼1.9 $\mu\textrm{m}$, apparent bulk density 1.4 g/$m\ell$ and chloride content 0.05%. The relation between Br and HcJ by sintering temperature for Sr-ferrite magnet was found to be Br≒-0.258HcJ＋494. In case of having a vibrating disk mill for the ruthner process iron oxide, the magnetic properties were Br 421 mT and HcJ 251 kA/m.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.132-136
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• 2003

폐광된 광산에 방치된 폐광석에 함유되어 있는 황화광물이 분해되어 다른 광물에 흡착되거나, 산화환경에 안정한 형태의 2차 광물로 침전 혹은 공침 되는가에 대한 연구는 광산복 원을 결정하는데 직접적인 지구화학적 자료로 활용될 수 있다. 따라서 이번 연구에서는 청양광산에 방치된 폐광석을 대상으로 XRD, SEM/EDS연구를 이용하여 산화작용으로 인한 황화광물 주변에 침전된 2차 광물에 대한 광물학적 연구를 수행하였다. 광물학적 연구 결과, 산화환경에서 황화광물의 산화작용으로 인하여 용출된 중금속 이온과 철과 망간 이온들은 침전(Fe, Mn, Pb), 공침 (Fe, Mn, As, Pb) 및 흡착(As, Cu, Pb, Zn) 등의 화학반응을 통하여 다시 고정화됨으로서, 현장에서 자연적으로 정화되고 있는 것이 확인되었다.

• Korean Journal of Plant Resources
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• v.24 no.2
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• pp.236-242
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• 2011

In this present study, we investigated the anti-oxidant activity, the inhibition ability of lipid peroxidation, and the protective effect of cow pulmonary epithelium (CPAE) cells under oxidative stress using green tea and 3 types of fermented teas of Jeju Island. To compare the physiological activity of non-fermented and 3 types of fermented teas, the fermented time was controlled with 0 hr. (non fermented tea, G), 12 hrs. (20% fermented tea, F20), 17 hrs. (50% fermented tea, F50) and 24 hrs. (80% fermented tea, F80), respectively. Scavenging ability on DPPH radicals of 80 ${\mu}g/mL$ concentration of F20 was similar to that of 50 ${\mu}M$ epigallocatechin gallate (EGCG) but it was stronger than those of G, F50 and F80. All extracts tested inhibited LDL oxidation but G and F20 inhibited LDL oxidation 25~30% more than F50 and F80 at 40 ${\mu}g/mL$ concentration which was similar to that of 50 ${\mu}M$ EGCG. We observed that the CPAE cells treated with the tea extracts had a significant increase in cell viability, especially the cells under oxidative stress with 1 mM $H_2O_2$ as compared with the control group (no treatment with tea extracts). These findings suggested that all tea extracts containing fermented tea had a protective effect on oxidative stressed CPAE cells through their free radical scavenging activity. It can be concluded that F20 extracted from 20% fermented tea has the most significant antioxidative effects that inhibit lipid peroxidation and protect the CPAE cells under oxidative stress.

• Korean Journal of Food Science and Technology
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• v.29 no.6
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• pp.1094-1100
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• 1997

Effects of sodium hypochlorite (NaOCl) concentration, temperature and pH on oxidation mechanism of corn starch were investigated. The rate of oxidation was dependent on the concentration of hypochlorite, pH and temperature of oxidation. The reaction was either first or second order depending on the concentration of NaOCl. At oxidant concentration of $0.75{\sim}3.0%$ active Cl/g starch, the reaction was first-order and it was second-order at $3.75{\sim}4.5%$ active Cl/g starch. The first-order rate constants were increased with increasing oxidant concentration. The rate of oxidation of starch was highest at pH 7 and decreased with increasing acidity or alkalinity of the medium. As the reaction temperature increased, the rate of oxidation was increased.

• Clean Technology
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• v.26 no.3
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• pp.211-220
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• 2020

This experimental study investigates the design parameters to achieve ultra low NOx combustion of coal using a 80 kW capacity single-burner furnace. The influence of key design parameters such as SN, overall and burner-zone equivalence ratios, primary/secondary air ratio, overfire air (OFA) ratio were tested for a total of 81 cases. The results showed that weak swirl intensity of the burner leads to higher NOx emission whereas strong swirl intensity accompanies increased CO concentration desipte lower NOx emission. Therefore, finding an appropirate swirl intensity is essential for the burner design. Larger flow rate of secondary air increased NOx emission, whereas smaller flow rate stretches the flame and increased CO emission. The lowest NOx emission of 82 ppm (6% O₂) was achieved at the optimal condition of the present burner deisgn. It is expected to furrther lower the NOx emission by introducing splitting the burner secondary air into three or four streams.