• Journal of the Korean institute of surface engineering
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• v.50 no.2
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• pp.91-97
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• 2017

The aim of this paper is to investigate the characteristics of electrochemical corrosion with the plasma ion nitriding temperature for 16Cr-10Ni-2Mo stainless steel. The corrosion behavior was analyzed by means of galvanostatic experiment in natural seawater that applied various current density with plasma ion nitriding temperature parameters. In result of galvanostatic experiment, relatively less surface damage morphology and the less damage depth was observed at a nitrided temperature of $450^{\circ}C$ that measured the thickest nitrided layer(S-phase). On the other hand, the most damage depth and unified corrosion behavior presented at a temperature of $500^{\circ}C$.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.121.1-121.1
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• 2014

Recently, much attention has been given to plasma production under liquid and its applications [1]. However, most of plasma production techniques reported so far utilize high voltage dc, ac, rf or microwave power [2], where damage to discharge electrodes and small discharge volume are remained issues. As an alternative of plasma production method under liquid, we have proposed pulsed microwave excited plasma using slot antenna, where damage to the slot electrode can be minimized and plasma volume can be increased. We have also reported improvement of treatment efficiency with use of reduced-pressure condition during the discharge [3]. To realize low pressure conditions in liquid, various alternative technique can be considered. One possible technique is simultaneous injection of microwave power and ultrasonic wave. Ultrasonic wave induces pressure fluctuation with the wave propagation and is so far used for cavitation production in the water. We propose utilization of reduced pressure induced by ultrasonic cavitation for improvement of the plasma production. Correlation between the plasma production and the ultrasonic power will be discussed.

• Journal of Nutrition and Health
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• v.44 no.5
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• pp.366-377
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• 2011

Glutathione S-transferase (GST) is a multigene family of phase II detoxifying enzymes that metabolize a wide range of exogenous and endogenous electrophilic compounds. GSTM1 and GSTT1 gene polymorphisms may account for inter-individual variability in coping with oxidative stress. We investigated the relationships between the level of lymphocyte DNA and antioxidative parameters and the effect on GST genotypes. GSTM1 and GSTT1 were characterized in 301 young healthy Korean adults and compared with oxidative stress parameters such as the level of lymphocyte DNA, plasma antioxidant vitamins, and erythrocyte antioxidant enzymes in smokers and non smokers. GST genotype, degree of DNA damage in lymphocytes, erythrocyte activities of superoxide dismutase, catalase, and glutathione peroxidase (GSH-Px), and plasma concentrations of total radical-trapping antioxidant potential (TRAP), vitamin C, ${\alpha}$- and ${\gamma}$-tocopherol, ${\alpha}$- and ${\beta}$-carotene, and cryptoxanthin were analyzed. Lymphocyte DNA damage assessed by the comet assay was higher in smokers than that in non-smokers, but the levels of plasma vitamin C, ${\beta}$-carotene, TRAP, erythrocyte catalase, and GSH-Px were lower than those of non-smokers (p < 0.05). Lymphocyte DNA damage was higher in subjects with the GSTM1- or GSTT1-present genotype than those with the GSTM1-present or GSTT1- genotype. No difference in erythrocyte antioxidant enzyme activities, plasma TRAP, or vitamin levels was observed in subjects with the GSTM1 or GSTT1 genotypes, except ${\beta}$-carotene. Significant negative correlations were observed between lymphocyte DNA damage and plasma levels of TRAP and erythrocyte activities of catalase and GSH-Px after adjusting for smoking pack-years. Negative correlations were observed between plasma vitamin C and lymphocyte DNA damage only in individuals with the GSTM1-present or GSTT1- genotype. The interesting finding was the significant positive correlations between lymphocyte DNA damage and plasma levels of ${\alpha}$-carotene, ${\beta}$-carotene, and cryptoxanthin. In conclusion, the GSTM1- and GSTT1-present genotypes as well as smoking aggravated antioxidant status through lymphocyte DNA damage. This finding confirms that GST polymorphisms could be important determinants of antioxidant status in young smoking and non-smoking adults. Consequently, the protective effect of supplemental antioxidants on DNA damage in individuals carrying the GSTM1- or GSTT1-present genotypes might show significantly higher values than expected.

• Journal of Nutrition and Health
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• v.44 no.1
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• pp.16-28
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• 2011

Oxidative stress leads to the induction of cellular oxidative damage, which may cause adverse modifications of DNA, proteins, and lipids. The production of reactive species during oxidative stress contributes to the pathogenesis of many diseases. Antioxidant defenses can neutralize reactive oxygen species and protect against oxidative damage. The aim of this study was to assess the antioxidant status and the degree of DNA damage in Korean young adults using glutathione s-transferase (GST) polymorphisms. The GSTM1 and GSTT1 genotypes were characterized in 245 healthy young adults by smoking status, and their oxidative DNA damage in lymphocytes and antioxidant status were assessed by GST genotype. General characteristics were investigated by simple questionnaire. From the blood of the subjects, GST genotypes; degree of DNA damage in lymphocytes; the erythrocyte activities of superoxide dismutase, catalase, and glutathione peroxidase; plasma concentrations of total peroxyl radical-trapping potential (TRAP), vitamin C, ${\alpha}$- and ${\gamma}$-tocopherol, ${\alpha}$- and ${\beta}$-carotene and cryptoxanthin, as well as plasma lipid profiles, conjugated diene (CD), GOT, and GPT were analyzed. Of the 245 subjects studied, 23.2% were GSTM1 wild genotypes and 33.4% were GSTT1 wild genotype. No difference in erythrocyte activities of superoxide dismutase, catalase, or glutathione peroxidase, and the plasma TRAP level, CD, GOT, and GPT levels were observed between smokers and non-smokers categorized by GSTM1 or GSTT1 genotype. Plasma levels of ${\alpha}$- and ${\gamma}$-tocopherol increased significantly in smokers with the GSTT1 wild genotype (p < 0.05); however, plasma level of ${\alpha}$-carotene decreased significantly in non-smokers with the GSTM1 wild genotype (p < 0.05). DNA damage assessed by the Comet assay was significantly higher in non-smokers with the GSTM1 genotype; whereas DNA damage was significantly lower in non-smokers with the GSTT1 genotype. Total cholesterol and LDL cholesterol levels were significantly higher in non-smokers with the GSTT1 genotype than those with the GSTT1 wild genotype (p < 0.05). In conclusion, the GSTM1 genotype or the GSTT1 wild genotype in non-smokers aggravated their antioxidant status through DNA damage of lymphocytes; however, the GSTT1 wild type in non-smokers had normal plasma total cholesterol and LDL-cholesterol levels. This finding confirms that GST polymorphisms could be an important determinant of antioxidant status and plasma lipid profiles in non-smoking young adults. Further study is necessary to clarify the antioxidant status and/or lipid profiles of smokers with the GST polymorphism and to conduct a study with significantly more subjects.

• Transactions on Electrical and Electronic Materials
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• v.6 no.3
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• pp.87-90
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• 2005

$SiO_2$ via-hole etching with a high aspect ratio is a key process in fabricating ULSI devices; however, accumulated charge during plasma etching can cause etching stop, micro-loading effects, and charge build-up damage. To alleviate this concern, charge-up damage sensor was fabricated for the ultimate goal of real-time monitoring of accumulated charge. As an effort to reach the ultimate goal, fabricated sensor was used for electrical potential measurements of via holes between two poly-Si electrodes and roughly characterized under various plasma conditions using statistical design of experiment (DOE). The successful identification of potential difference under various plasma conditions not only supports the evidence of potential charge-up damage, but also leads the direction of future study.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1220-1224
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• 2007

The effects of plasma damages to the organic thin film transistor (OTFT) during the fabrication process are investigated; metal deposition process on the organic gate insulator by plasma sputtering mainly generates the process induced damages of bottom contact structured OTFTs. For this study, various deposition methods (thermal evaporation, plasma sputtering, and neutral beam based sputtering) and metals (gold and Indium-Tin Oxide) have been tested for their damage effects onto the Poly 4-vinylphenol(PVP) layer surface as an organic gate insulator. The surface damages are estimated by measuring surface energies and grain shapes of organic semiconductor on the gate insulator. Unlike thermal evaporation and neutral beam based sputtering, conventional plasma sputtering process induces serious damages onto the organic surface as increasing surface energy, decreasing grain sizes, and degrading TFT performance.

• Food Science and Biotechnology
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• v.18 no.1
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• pp.179-184
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• 2009

The aim of this study was to investigate effects of onion, red onion, or quercetin on plasma antioxidant vitamin, lipid peroxidation, and leukocyte DNA damage in rats fed a high fat-cholesterol diet. Forty SD male rats were assigned to normal control, high fat-cholesterol diet (HF), or HF+5% onion powder, HF+5% red onion powder, or HF+0.0l% quercetin. The HF diet resulted in significantly higher plasma lipid peroxidation which decreased with onion, red onion, or quercetin supplementation. Leukocyte DNA damage induced by HF diet decreased significantly in rats fed onion and red onion, while quercetin supplementation had no effect on preventing leukocyte DNA damage. $H_2O_2$ induced leukocyte DNA damage exhibited a highly significant negative correlation with plasma retinol and tocopherols. These results suggest that onion or red onion powder exerts a protective effect with regard to DNA damage in rats fed HF diet. However, 0.01% quercetin in pure form might not be effective at preventing DNA damage.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.177.1-177.1
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• 2015

플라즈마 건식 식각공정은 반도체 공정에 있어 증착 및 세정 공정과 함께 중요한 공정중 하나이다. 기존 연구에서는 높은 식각 속도, 종횡비, 대면적에 대한 균일도 증가를 위하여 플라즈마 이온 밀도의 증가와 전자 온도를 감소시키기 위한 노력을 하고 있으며 플라즈마 식각분석 연구에서는 분광학 분석 기법을 활용하여 플라즈마에 의하여 활성화된 식각 가스와 박막 표면의 반응 메커니즘 연구가 진행 중에 있다. 그러나 지금까지의 플라즈마 식각연구에서는 플라즈마 식각 공정에서 발생되는 박막의 damage에 대한 연구는 전무하다. 본 연구에서는 플라즈마 식각과정에서 발생되는 박막 표면의 damage 연구를 위하여 Nano-indenter에 의한 분석 기법을 제시하였다. Nano-indentation 기법은 박막 표면을 indenter tip으로 직접 인가하여 박막 표면의 기계적 특성을 분석하고 이를 통하여 플라즈마에 의한 박막 표면의 물성 변화를 정량적으로 측정한다. 실험에서 플라즈마 소스는 Adaptively Coupled Plasma (ACP)를 사용하였고 식각 가스로는 HBr 가스를 주로 사용하였으며, 플라즈마 소스 파워는 1000 W로 고정 하였다. 연구 결과에 의하면 식각공정 챔버 내 압력이 5, 10, 15 및 20 mTorr로 증가함에 따라 TEOS SiO2 박막의 강도가 7.76, 8.55, 8.88 및 6.29 GPa로 변화되는 것을 측정하였고 bias power에 따라서도 다르게 측정됨을 확인하였다. 이 결과를 통하여 Nano-indentation 분석 기법을 활용하여 TEOS SiO2 박막의 식각공정의 변화에 따른 강도변화를 측정함으로써 플라즈마에 의한 박막 표면의 damage를 정량적으로 측정 가능함을 확인하였다.

• Journal of Nutrition and Health
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• v.39 no.8
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• pp.773-785
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• 2006

Vitamin E in the body system plays an important role in preventing chronic diseases by decreasing the oxidative stress by free-radicals. However, there are not enough researches on analyzing the primary factors affecting vitamin E levels in the blood in Korean adults. Therefore, the purpose of this research was to examine blood tocopherol levels and the primary factors affecting the status. A complete lifestyle survey was performed on 314 Korean adult men and surveyed their smoking, drinking and exercising habits. The average plasma level of ${\alpha}-\;and\;{\gamma}-tocopherol$ showed similar mutual relations with plasma total cholesterol (TC), triglyceride (TG), or low density lipoprotein cholesterol (LDL-C) levels (p<0.001). Plasma ${\alpha}-tocopherol$ level of the subjects did not show any difference as smoking, drinking and exercising habits changed. However, ${\gamma}-tocopherol$ per TG showed much lower figure in smokers than non smokers (p < 0.05). Amongst diet factors, plasma ${\alpha}-tocopherol$ level showed negative correlations with Vitamin E intake, while ${\gamma}-tocopherol$ level showed positive correlations with Vitamin E intake. Erythrocyte superoxide dismutase (SOD) activity and plasma tocopherol showed negative correlations, and catalase activity and plasma ${\alpha}-tocopherol$ showed positive correlationship. The level of cell DNA damage of Iymphocyte and plasma ${\alpha}-\;or\;{\gamma}-tocopherol$ showed negative correlations. As a result of this research, the factors that affect Korean adult men's plasma ${\alpha}-tocopherol$ level are plasma TG, LDL-C and cell DNA damage in Iymphocyte, while the factors that affect ${\gamma}-tocopherol$ level are plasma TG, LDL-C and vitamin E intake based on multiple regression analysis. These findings implies that the level of different types of tocopherol depends on slightly different factors. A further research is needed on the factors involved in the differentiation of the types of tocopherol.

• Journal of the Korean Ceramic Society
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• v.34 no.11
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• pp.1121-1128
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• 1997

In this study, the Ar plasma treatment was used to improve the surface roughness of Poly-Si1-xGex thin film deposited by RTCVD. The surface roughness and the resistivity of Si1-xGex thin film were investigated with variation of Ar plasma treatment parameters (electrode distance, working pressure, time, substrate temperature and R.F power). When the Ar plasma treatment was used, the cluster size decreased by the surface etching effect due to the increasing surface collision energy of particles (ion, neutral atom) in plasma under the conditions of decreasing electrode distance and increasing pressure, time, temperature, and R. F power. Although the surface roughness value decreased by the reduction of the cluster size due to surface etching effect, however, the resistivity increased. This may be due to the surface damage caused by the increasing surface collision energy. It was concluded that the surface roughness could be improved by the Ar plasma treatment, while the resistivity was increased by the surface damage on the substrate.