• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05d
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• pp.45-48
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• 2003

BiSrCaCuO thin films were fabricated by atomic layer-by-layer deposition using an ion beam sputtering method. 10 wt% and 90 wt% ozone mixed with oxygen were used with ultraviolet light irradiation to assist oxidation. At early stages of the atomic layer by layer deposition, two dimensional epitaxial growth which covers the substrate surface would be suppressed by the stress and strain caused by the lattice misfit, then three dimensional growth takes place. Since Cu element is the most difficult to oxidize, only Sr and Bi react with each other predominantly, and forms a buffer layer on the substrate in an amorphous-like structure, which is changed to $SrBi_2O_4$ by in-situ anneal.

• BMB Reports
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• v.32 no.5
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• pp.440-444
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• 1999

Membrane lipid peroxidation processes yield reactive aldehydes that may react with copper,zinc superoxide dismutase (Cu,Zn SOD), one of the key antioxidant enzymes against oxidative stress. We investigated this possibility and found that exposing Cu,Zn SOD to malondialdehyde (MDA) or 4-hydroxynonenal (HNE) caused the loss of dismutase activity, cross-linking of peptides, and an increase in protein oxidation, reflected by the increased level of carbonyl groups. When Cu,Zn SOD that had been exposed to MDA or HNE was subsequently analyzed by amino acid analysis, histidine content was found to be significantly lost. Both MDA-and HNE-treated Cu,Zn SOD were resistant to proteolysis, which may imply that damaged proteins exist in vivo for a longer period of time than the native enzyme. The lipid peroxidation-mediated damage to Cu,Zn SOD may result in the perturbation of cellular antioxidant defense mechanisms, and subsequently lead to a pro-oxidant condition.

• Journal of Nutrition and Health
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• v.29 no.7
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• pp.721-728
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• 1996

The level of oxidative tissue damage caused by free radicals generated from ethanol oxidation was determined in the myocardium of chronic ethanol fed-rats and the protective action of various radical scavenging enzymes was monitored, also. Adult male Sprague-Dawley rats were given ethanol in an amount of 36% of total calories via Lieber-DeCarli liquid diet for 6 weeks. Control group was pair-fed with the diet containing isocaloric amount of dextrin-maltose instead of ethanol. Chronic ethanol administration resulted in the increased amount of myocardial thiobarbituric acid reactive substance(TBARS), th parameter of lipid peroxidation, under our experimental condition. Chronic ethanol ingestion did not cause any change in activities of either glutathione peroxidase or glutathione reductase and glucose-6-phosphate dehydrogenase were decreased after ethanol treatment. Therefore, chronic ethanol administration seemed to cause considerble changes in cellular defense function against oxidative tissue damage in rat myocardium through glutathione utilizing system and radical generation system. However the ultimate net result of chronic ethanol inestion on the myocardium of rat was the oxidative tissue damage revealed by increased TBARS content.

• Journal of Nutrition and Health
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• v.30 no.9
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• pp.1102-1108
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• 1997

The purpose of this study was to find the extent of lipid peroxidation of erythrocytes in cigarette smokers, and to determine the relative effectiveness of $\beta$-carotene, canthaxanthin , and $\alpha$-tocopherol as antioxidants. Thirty smokers and 30 nonsmokers participated in this study . No significant differences according to age, sex, and height were shown. Cigarette smokers in this study had higher hemoglobin concentrations and more oxidation of hemoglobin than non-smokers. In addition, the erythrocytes of cigarette smokers had significantly higher MDA concentrations than crythrocytes of nonsmokers, which suggests that smokers may have tocopherol were studied in vitro by measuring the concentration of malondialdehyde(MDA) and precent hemolysis of erythrocytes. The addition of any antioxidant to erythrocytes significantly decreased MDA concentrations(p<0.05) while antioxidants showed nonsignificant inhibition of hemolysis. Among the antioxidant used in this study, canthaxanthin showed the greatest inhibition of both lipid peroxidationand hemolysis. Meanwhile, $\alpha$-tocopherol showed potent inhibition of lipid peroxidation, but not of hemolysis.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.05a
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• pp.411-414
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• 1999

70 ${\AA}$-thick oxides nitridied at various conditions were reoxidized at pemperatures of 900$^{\circ}C$ in dry-O$_2$ ambients for 5～40 mininutes. The gate oxide interface porperties as well as the oxide substrate interface properties of MOS(Metal Oxide Semiconductor) capacitors with various nitridation conditions, reoxidation conditions and pure oxidation condition were investigated. We stuided I$\sub$g/-V$\sub$g/ characteristics, $\Delta$V$\sub$g/ shift under constant current stress from electrical characteristics point of view and breakdown voltage from leakage current point of view of MOS capacitors with SiO$_2$, NO, RNO dielectrics. Overall, our experimental results show that reoxidized nitrided oxides show inproved charge trapping porperites, I$\sub$g/-V$\sub$g/ characteristics and gate $\Delta$V$\sub$g/ shift. It has also been shown that reoxidized nitridied oxide's leakage currented voltage is better than pure oxide's or nitrided oxide's from leakage current(1${\mu}$A) point of view.

• Tribology and Lubricants
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• v.9 no.1
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• pp.38-44
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• 1993

The present study was undertaken to investigate the dry wear characteristics of die steel STD 11 for cold molding. The wear test was experimentally carried out under different conditions using a wear device, which was made in laboratory, and in which annular surfaces of wear testing specimens wear rubbed in dry sliding condition with varying the sliding speed, contact pressure, and sliding distance. The wear loss by variation of sliding speed was much in 0.3 m/sec and less in higher speed range above its sliding speed according to formation of the boundary lubrication film. The critical sliding speed with maximum value of the specific wear rate switched over to lower speed side according. as contact pressure increased. The critical sliding distance was increased with decrease in oxidation reaction velocity. The depth below subsurface showing maximum hardness (Hv) came out at the position, $60 \mu m$, of the maximum shear stress due to strain hardening.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.5
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• pp.729-736
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• 1990

Oxide (RTO), nitrided-oxide(NO), and reoxidized-nitrided-oxide(ONO) films were formed by sequential rapid thermal processing. The film composition was investigated by Auger electron spectroscopy(AES). The Si/SiO2 interface and SiO2 surface are nitrided more preferentially than SiO2 bulk. When the NO is reoxidized, [N](atomic concentration of N) in the NO film decreased` especially, the decrease of [N] at the surface is considerable. The weaker the nitridation condition is, the larger the increase of thickness is as the reoxidation proceeds. The elelctrical characteristics of RTO, NO, and ONO films were evaluated by 1-V, high frequency (1 MHz) C-V, and high frequency C-V after constant current stress. The ONO film-which has 8 nm thick initial oxide, nitrided in NH3 at 950\ulcorner for 60 s, reoxidized in O2 at 1100\ulcorner for 60 s-shows good electrical characteristics such as higher electrical breakdown voltage and less variation of flat band voltage under high electric field than RTO, and NO films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.04b
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• pp.121-124
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• 2004

The research on the porous silicon having low wafer stress during the oxidation process in IPOS(Isolation by Porous Oxidized Silicon) were carried out. Fine pores with less than 100A of diameter were found in the porous silicon which from p-type Si by electrochemical etching. In this study, it is possible to make the porous silicon with 59% of porosity.

• Journal of the Korean Society of Safety
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• v.24 no.3
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• pp.1-6
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• 2009

Recently power plants and oil refineries are focusing on capacity enlargement for better efficiency through higher temperature and higher pressure. Thickness of boiler tubes becomes lessened due to oxidation and erasion caused by high temperature bums gas flowing over tubes outside. Accordingly, mechanical stress of tubes is increasing and that is a critical factor to make a crack and fracture. To prevent those sorts of accidents, aging assessment for proper periodic repair and replacement should be conducted reliably and reasonably. We performed IIT test on Cr-Mo steel, one of the most heat-resistant materials for facilities in power plants, and we report the test result and the considerable effectiveness of IIT test.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.208-211
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• 2002

$Bi_2Sr_2CuO_x$(Bi-2201) thin films were fabricated by atomic layer-by-layer deposition using an ion beam sputtering method. 10 wt% and 90 wt% ozone mixed with oxygen were used with ultraviolet light irradiation to assist oxidation. At early stages of the atomic layer by layer deposition, two dimensional epitaxial growth which covers the substrate surface would be suppressed by the stress and strain caused by the lattice misfit, then three dimensional growth takes place. Since Cu element is the most difficult to oxidize, only Sr and Bi react with each other predominantly, and forms a buffer layer on the substrate in an amorphous-like structure, which is changed to $SrBi_2O_4$ by in-situ anneal.