• Korean Journal of Materials Research
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• v.4 no.6
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• pp.662-668
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• 1994

The physical and electrical characteristics of sub-l0nm thick capacitor dielectrics formed by wet oxidation of silicon nitride(oxide/nitride composite) and by removing the top oxide of oxidized silicon nitride(0xynitride) are described. For the capacitors with an oxide/nitride composite layer, the capacitance decreases sharply, but the breakdown field increases with an increase in the wet oxidation time at $900^{\circ}C$. For the capacitors with oxynitride layers, the values of both the capacitance and the breakdown field increase with increasing wet oxidation time. The reduction of effective thickness and the improved quality of oxynitride film are responsible for the improved capacitance and increased breakdown fields, respectively. In addition, intrinsic TDDB characteristics and early breakdown failure rate of oxynitride film are improved with increasing oxidation time. Consequently, the oxynitride film is suitable for dynamic memories as a thin dielectric film.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.89-89
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• 2009

높은 소수반송자 수명(life-time)을 가지는 고품위 실리콘 기판은 고효율 실리콘 이종접합 태양전지 제작을 위한 중요 요소 기술 중 하나이다. 본 연구에서는 n-type c-Si 기판을 이용한 고효율 실리콘 이종접합 태양전지제작을 위해 hot water oxidation(HWO) 공정을 이용하여 고품위 실리콘 기판을 제작하였다. 실리콘 기판의 특성 분석은 Qusi-steady state photoconductance (QSSPC)를 이용하여 소수반송자 수명을 측정하였으며, 기판의 면저항 및 wetting angle을 측정하여 공정에 따른 특성변화를 분석하였다. Saw damage etching 된 기판을 웨이퍼 표면으로부터 particle, 금속 불순물, 유기물 등의 오염을 제거하기 위해 $60{\sim}85^{\circ}C$로 가열된 Ammonia수, 과산화수소수($NH_4OH/H_2O_2/H_2O$), 염산 과산화수소수($HCL/H_2O_2/H_2O$) 및 실온 희석불산(DHF) 중에 기판을 각각 10분 정도씩 침적하여, 각각의 약액 처리 후에 매회 10분 정도씩 순수(DI water)에서 rinse하여 RCA 세정을 진행한 후 HWO 공정을 통해 기판 표면에 얇은 산화막 을 형성시켜 패시베이션 해주었다. HF를 이용하여 자연산화막을 제거시 HWO 공정을 거친 기판은 매끄러운 표면과 패시베이션 영향으로 기판의 소수 반송자 수명이 증가하며, 태양전지 제작시 접촉저항을 감소시켜 효율을 증가 시킬수 있다. HWO 공정은 반응조 안의 DI water 온도와 반응 시간에 따라 life-time을 측정하여 진행하였으며, 이후 PE-CVD법으로 증착된 a-Si:H layer 및 투명전도 산화막, 금속전극을 증착하여 실리콘 이종접합 태양전지를 제작하였다.

• Journal of the East Asian Society of Dietary Life
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• v.10 no.4
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• pp.274-280
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• 2000

The effect of heated oil on human nutrition has recently become of great interest to nutritionists and food chemists. However, the detrimental effect of heated oil has been hardly studied extensively and many problems have still remained unsolved. This study was carried out to investigate the storage stability of the heated oils at room temperature (25$\pm$5$^{\circ}C$), with the variation in storage conditions (addition of spices and herbs) for 7 weeks period. The rancidity of the oils according to storage time and condition was measured and compared with TBA, ferric thiocyanate, and DPPH method. For fresh oil, when stored for 7 weeks at room temperature, her was no significant change in the degree of oxidation. But for the heated oil with frying materials, the degree of oxidation significantly increased at 5 weeks(p<0.05). When stored with spices and herbs, the degree of oxidation significantly decreased with storage period(p<0.05). Antioxidative activity of herbs, especially sage group was higher than that of any other group.

• Nuclear Engineering and Technology
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• v.29 no.2
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• pp.93-98
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• 1997

Air-oxidation experiments on unirradiated and irradiated UO$_2$ were performed at temperature from 150 to 375$^{\circ}C$ for investigating the long-term storage behavior of spent PWR fuel. The rate of oxidation was monitored by a thermogravimetric analyzer(TGA) and an X-ray diffraction(XRD). The correlation between the onset-time for U$_3$O$_{8}$ formation and temperature was given as follows, logt(hr) = -12.89+7650/T(K), 423$_2$ pellet, the oxidation rate of irradiated UO$_2$ increase more rapidly at the initial stage and shows a lower saturation point at the later Stage. The Oxidation rate of high bumup UO$_2$ and gadolinia-doped UO$_2$(Gd$_2$O$_3$-UO$_2$) were observed to be much slower than that of unirradiated UO$_2$ pellets.s.

• Carbon letters
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• v.6 no.1
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• pp.31-40
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• 2005

The carbon nanofibers (CNFs) were synthesized through the catalytic decomposition of hydrocarbons in a quartz tube reactor. The CNFs prepared from $C_3H_8$ at $550^{\circ}C$ was selected as the purification sample due to the higher content of impurity than that prepared from other conditions. In this study, we carried out the purification of CNFs by oxidation in air or carbon dioxide after acid treatment, and investigated the influence of purification parameters such as kind of acid, concentration, oxidation time, and oxidation temperature on the structure of CNFs. The metal catalysts could be easily eliminated from the prepared CNFs by liquid phase purification with various acids and it was verified by ICP analysis, in which, for example, Ni content decreased from 2.51% to 0.18% with 8% nitric acid. However, the particulate carbon and heterogeneous fibers were not removed from the prepared CNFs by thermal oxidation in air and carbon dioxide. This result can be explained by that the direction of graphene sheet in CNFs is vertical to the fiber axis and the CNFs are oxidized at about the similar rate with the impurity carbon.

• Preventive Nutrition and Food Science
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• v.7 no.2
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• pp.179-183
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• 2002

Lycopene as a natural antioxidant may provide protection against a broad range of epithelial cancers and chronic diseases. Lycopene concentrate extracted from tomatoes can be used as functional food. Lycopene would undergo degradation via isomerization and oxidation under different processing conditions, which impact its bioactivity and reduce the fuuctionality for health benefits. Heat and light induce lycopene oxidation and isomerization of all-trans form to cis form. The effects of thermal treatment and light irradiation on the stability of lycopene were determined. Results have shown that lycopene stability depends on the extent of oxidation and isomerization. Cir-isomers are less stable than trans-isomers. The level of cis-isomers increased as treatment time increased but only for a short period during the beginning of the treatment. The major effect of thermal treatment and light irradiation was a significant decrease in the total lycopene content. A true assessment of health benefits of lycopene concentrate depends on the lycopene content and the composition of all trans-isomers and cia-isomers.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.2
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• pp.42-52
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• 2015

In this study, cellulose nanofibrils (CNF) were modified through carboxymethylation or TEMPO-mediated oxidation and their effects on ionicity and characteristics of sheet, film, and foam were investigated. Carboxymethylation was carried out on pulp fibers as a pre-treatment before preparation of CNF. The gel-like and translucent CNF hydrogel was obtained by grinding of carboxymethylated cellulose fibers. Carboxymethylated CNF film and freeze dried sheet showed higher transparency than that of untreated CNF. The CNF sheet with high strength and the CNF foam without large ice crystals were obtained by using the carboxymethylated CNF. TEMPO-mediated oxidation was carried out as a post-treatment of CNF. The zeta potential and charge demand of TEMPO-oxidized CNF were increased with an increase in oxidation time and addition amount of NaClO. The density of sheet made of TEMPO oxidized CNF was increased with the amount of oxidizing agent. The TEMPO oxidized cellulose nanofiber (TOCN) which was obtained from supernatant after centrifugation could be converted to transparent film.

• Economic and Environmental Geology
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• v.32 no.1
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• pp.101-111
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• 1999

Sedimentary organic matter, exposed to continental surficial environment, reacts with oxygen supplied from the atmosphee and forms carbon-containing oxidation products. Knowledge of the rate and mechanisms of sedimentary organic matter weathering is important because it is one of the major controls on atmospheric oxygen level through geologic time. Under the abiological conditions, the oxidation rate of coal organic matter by molecular oxygen is enhanced by the increase of oxygen concentration and temperature. At ambient temperature and pressure, aqueous coal oxidation results in the formation of dissolved $CO_2$ dissolved organic carbon and solid oxidation products which are all quantitatively significant reaction products. The effects of pH, ultraviolet light, and microbial activity on the weathering of sedimentary organic matter are poorly contrained. Based on the results of geochmical and environmental studies, it is believed that the photochemical reaction should play an important role in the decomposition and oxidation of sedimentary organic matter removed from the weathering profile. At higher pH conditions, the production rate of DOC can be accelerated due to base catalysis. These high molecular weight oranic matter can react with man-made pollutants such as heavy metal ions via adsorption/desorption or ion exchange reactions. The effect of microbial activity on the oxidative weathering of sedimentary organic matter is poorly understood and remains to be studied.

• Carbon letters
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• v.4 no.4
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• pp.185-191
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• 2003

Two types of carbon fiber based high modulus- and isotropic-pitch were exposed to isothermal oxidation in air and $CO_2$ gas and the weight change was measured by TGA apparatus. The kinetic equation was introduced $f=1-{\exp}(-at^b)$ and the constant b was obtained in the range of 1.02~1.68 for the isotropic fiber and obtained 0.91~1.93 for the high modulus fiber respectively. In considering the effect of the atmosphere for isothermal oxidation, the value of the constant b obtained in the carbon dioxide was higher than that obtained in the air. Therefore, it was found that the pitch based carbon fiber shows sigmoidal characteristic when it is oxidized in the carbon dioxide. In addition, it was also found that $k_f = 0.5$, which was reaction constant at f = 0.5, was a very useful parameter for evaluation of the oxidation reactivity of pitch based carbon fibers. According to the consideration, it is suggested that the conversion-time curves of the pitch based carbon fibers are correlated by normalized equation $f=1-{\exp}(-A{\tau}^B)$, where ${\tau}=t/t_f= 0.5$.

• Journal of Periodontal and Implant Science
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• v.37 no.4
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• pp.767-777
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• 2007

The present study was performed to evaluate the effect of Tetracycline-HCI on the change of implant surface microstructure according to application time. Anodic oxidation surface were utilized. Implant surface was rubbed with 50mg/ml Tetracycline-HCI solution for ${\frac{1}{2}}min.$, 1min., $1{\frac{1}{2}}min.$, 2min., $2{\frac{1}{2}}min.$, and 3min. respectively in the test group. Then, specimens were processed for Ra Value test and scanning electron microscopic observation. The results of this study were as follows. 1. The anodic oxidation surface roughness tests don't show significant difference on conditioning with saline and Tetracycline-HCI. 2. The anodic oxidized surfaces showed the craterous structures. The surface conditioning with Tetracycline-HCI didn't influence on its micro-morphology. In conclusion, Anodic oxidation implant surface is stable to detoxificate with 50mg/ml Tetracycline-HCI of implant surface.