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Oxidation Effect of Graphene Nanoplatelets on the Mechanical Properties and Bonding Performance of Epoxy Paint Material (그래핀 나노플레이트릿의 산화가 에폭시 도막재료의 역학적 및 부착 특성에 미치는 영향)

  • Son, Min-Jae;Kim, Gyu-Yong;Lee, Sang-Kyu;Sasui, Sasui;Eu, Ha-Min;Nam, Jeong-Soo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2020.06a
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    • pp.181-182
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    • 2020
  • In this study, oxidized graphene nanoplatelet(GO) was prepared by oxidizing graphene nanoplatelet(GNP) with nitric acid in order to solve the problem of dispersion of GNP, one of nano materials. GNP/Epoxy and GO/Epoxy were prepared by mixing GNP, GO with 0.1, 0.3, 0.5 and 1.0 wt.% in epoxy and the mechanical properties, bond performance were evaluated. As a result, GNP/Epoxy and GO/Epoxy showed higher tensile strength than Neat Epoxy at the 0.1, 0.3 wt.%. Especially, when 0.1 wt.% of GO was incorporated into epoxy resin, it showed highest tensile strength. It was confirmed that acid treatment of GNP was effective in improving the mechanical properties of epoxy paint. However, graphene material was found that it was not effective in improving the bond strength of the epoxy paint.

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Effect of Garlic Supplement and Exercise on Plasma Lipid and Antioxidant Enzyme System in Rats (마늘의 섭취와 운동이 혈장지질과 항산화효소계에 미치는 영향)

  • Yoon Gun-Ae
    • Journal of Nutrition and Health
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    • v.39 no.1
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    • pp.3-10
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    • 2006
  • Effects of garlic powder supplementation on blood lipid profile and antioxidant system were investigated in rats with and without swimming exercise. Sprague-Dawley rats of four experimental groups were fed for 4 weeks diets containing $15\%$ beef tallow and $1\%$ cholesterol; control without garlic and exercise, Go with $2\%$ garlic alone, Ex with exercise alone, GoEx with $2\%$ garlic and exercise. Rats were trained 40 min a days a days a week. Group Ex and GoEx showed significant lowering in body weight gain and fat accumulation. In Go, Ex and GoEx, plasm TG and LDL-C were lower and HDL-C was higher, although not significantly, compared to levels in control. Total cholesterol was significantly reduced in group Go, and Ex and GoEx were lower than control. The total/HDL cholesterol ratio was also found to be significantly different, decreasing the ratios in Go, Ex and GoEx. The hepatic TBARS increased significantly in group Ex $(51.7{\pm}3.43nM/g\;liver)$, while TBARS in Go and GoEx were low $(35.68{\pm}3.61,\;39.30{\pm}5.55nM/g\;liver)$ and similar to control's one. The activity of hepatic SOD in Go and GoEx tended higher than control and Ex without garlic. The hepatic catalase showed significantly the highest activity in Go. Activity of GSH-px was significantly low in Ex with $0.14{\pm}0.03$ unit/mg protein, and control, Go and GoEx had higher activities of $0.23{\pm}0.08,\;0.20{\pm}0.07,\;0.22{\pm}0.01\;unit/mg$ protein, respectively. Lower activities of antioxidant enzymes in Ex are likely to associated with the highest level of TBARS. It seems that a decrease in TBARS in GoEx relative to Ex was related to the increase in GSHpx and SOD with garlic supplemented, which led to compensate the oxidative stress from exercise. The results suggests that exercise or garlic supplement exerts blood lipid attenuating effect. In adition, garlic supplementation could strengthen the antioxidant potential against exercise-induced oxidants, partly by modulating oxidant enzyme activity. These effects of garlic may make it a beneficial agent on CVD.

Synthesis of Platinum-Reduced Graphene Oxide (Pt-rGO) Nanocomposite for Selective Detection of Hydrogen Peroxide as a Peroxidase-Mimic Catalyst

  • Doyun Park;Min Young Cho;Kuan Soo Shin
    • Journal of the Korean Chemical Society
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    • v.67 no.6
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    • pp.415-419
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    • 2023
  • In this study, we report the one-pot synthesis of reduced graphene oxide (rGO) containing platinum nanoparticles with catalytic activity to break down hydrogen peroxide as a peroxidase-mimicking catalyst. A single reducing agent was used to reduce graphene oxide and a platinum precursor at a moderately low temperature of 70℃. The rGO was homogeneously decorated with platinum nanoparticles. The catalytic activity of Pt-rGO was investigated for the oxidation of 3,3',5,5'- tetramethylbenzidine (TMB), a peroxidase substrate, in the presence of hydrogen peroxide. The Pt-rGO coupled with glucose oxidase was also able to detect glucose at millimolar concentrations (up to 1 mM). Our results show that the Pt-rGO composite is a promising catalyst for the detection of hydrogen peroxide. This method was also applied for the detection of glucose.

Target Observability Analysis of Time-to-go Polynomial Guidance Law (Time-to-go 다항식 유도 법칙의 표적 가관측성 분석)

  • Lee, Chang-Hun;Kim, Tae-Hun;Tahk, Min-Jea
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.38 no.7
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    • pp.664-672
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    • 2010
  • This paper provides the target observability analysis of time-to-go polynomial guidance law with bearing-only measurement. In this study, a direct approach is used to analyze the target observability. Since the observability condition of a constant-velocity target is given by the function of LOS angle only, the target observability characteristic is determined by substituting the closed form solution of LOS angle to the observability condition directly. The analysis results show that the target observability is depended on the choice of guidance gain, initial intercept condition and guidance command shape. After that this mathematical analysis result is evaluated and demonstrated by number of simulation.

Clinical Effect of Gyeongok-go: A Systematic Review of Randomized Controlled Trials (경옥고의 임상 효능 : 체계적 고찰)

  • Kang, Heekyung;Han, Changwoo
    • The Journal of Internal Korean Medicine
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    • v.43 no.3
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    • pp.423-435
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    • 2022
  • Purpose: The purpose of this study was to confirm the clinical efficacy of Gyeongok-go. Methods: Public/Publisher MEDLINE (PubMed), Cochrane Central Register of Controlled Trials (CENTRAL), Excerpta Medica dataBASE (EMBASE), Research Information Sharing Service (RISS), ScienceON, Korean Traditional Knowledge Portal (KTKP), and China National Knowledge Infrastructure (CNKI) were searched for randomized controlled clinical trials administering Gyeongok-go as an intervention, published from inception to December 31, 2021. The risk-of-bias of the included trials was assessed with the Cochrane risk-of-bias tool for randomized trials version 2. From the experimental and control groups of the selected trials, the mean value (or rate) of each outcome was extracted and statistically compared. Results: Statistically significant mean differences were in VO2max (MD 6.82), post-exercise heart rate (MD -8.76 at 5 min, -11.58 at 30 min, -14.6 at 60 min), senescence scale (MD -6.52), Th1 cells and Th2 cells in pulmonary tuberculosis (MD 2.79 and -1.64), yin-deficient and qi-deficient score (MD -9.64 and -9.76), and phlegm-dampness score (MD 5.56). Overall risk-of-bias was 20% low risk, 80% some concerns, and 0% high risk. There were no reports of adverse events. Conclusions: Gyeongok-go is likely to have the effect of improving cardiorespiratory endurance, increasing fatigue recovery ability, reducing senescence, and enhancing immune function in tuberculosis patients. Also, it is more suitable for those who are yin-deficient or qi-deficient, and those with phlegm-dampness probably need caution.

Effects of time-to-go freezing on PN guidance loop stability

  • Rew, Dong-Young;Tahk, Min-Jae
    • 제어로봇시스템학회:학술대회논문집
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    • 1995.10a
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    • pp.283-286
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    • 1995
  • Due to finite bandwidth of missile dynamics, guidance commands in PN guidance tend to diverage as the missile approaches to the target. In this paper, a new method based on the short-time stability theorem is introduced to extend the stability region.

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