• 한국전기전자재료학회논문지
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• 제33권5호
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• pp.367-372
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• 2020

As packaging processes for atomic gyroscope vapor cells, the glass tube tip-off process, anodic bonding, and paste sealing have been widely studied. However, there are stability issues in the alkali metal which are caused by impurity elements and leakage during high-temperature processes. In this study, we investigated the applicability of a vapor cell low-temperature packaging process by depositing Au on a Pyrex cell in addition to forming an Au-Sn thin film on a cap to cover the cell, followed by laser irradiation of the Au/Au-Sn interface. The mechanism of the thin film bonding was evaluated by XRD, while the packaging reliability of an Ne gas-filled vapor cell was characterized by variation of plasma discharge behavior with time. Furthermore, we confirmed that the Rb alkaline metal inside the vapor cell showed no color change, indicating no oxidation occurred during the process.

• Nutritional Sciences
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• 제6권1호
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• pp.20-24
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• 2003

The effect of a-tocopherol on the formation and accumulation of phospholipid hydroperoxides, especially of phosphatidylcholine hydroperoxides, in the tissues of 2, 2 -azobis Hydrochloride (AAPH) - dosed rats was investigated. In a-tocopherol supplemented rats, the activities of glutathione peroxidase, catalase and superoxide dismutase were significantly inhibited, compared with the AAPH group. AAPH treatment led to oxidation of phospholipids in the liver, lungs, brain, plasma and red blood cells (RBC), resulting in a notable increase in phosphatidylcholine hydroperoxide (PCOOH). All tissues of the rats given an $\alpha$-tocopherol supplement showed an attenuation of the stimulating effect of AAPH, leading to low levels of formation of PCOOH. Also, the rats injected with AAPH and a-tocopherol showed relatively normal-appearing hepatocytes, except for a little loss of the granules. With regards to the morphological appearance of the liver, it was observed that oral intakes of a -tocopherol resulted in an antioxidant defense against attacks of peroxyl radicals. Thus, we suggest that a-tocopherol is potentially helpful in protecting membrane phospholipids against oxidative damage in vivo.

• Preventive Nutrition and Food Science
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• 제14권1호
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• pp.29-36
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• 2009

To compare antioxidative and antiaging effects between yellow soybean (YS) and Chungkukjang (CK) in vivo system, male Sprague-Dawley rats (n=24) were fed the diets containing YS and CK for 8 weeks, respectively. The YS and CK groups showed the preventive effects on lipid and protein oxidations in liver and plasma. Hepatic SOD and GSH-peroxidase activities were significantly inhibited in CK group. Superoxide anion radicals in cytosol significantly lowered in YS and CK groups compared with control group. In addition, dietary YS and CK effectively inhibited formation of the lipofuscin, the indicator of aging in heart and eye, especially the CK group had a stronger preventive activity in eye. The results of this study showed that YS and CK diet effectively suppressed the superoxide anion radical formation and tissue oxidation.

• 한국분말재료학회지
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• 제4권4호
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• pp.243-251
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• 1997

Engine valve-shaped TiAl-Mn intermetallics containing 43.5 to 47.5at%Al (Mn/Al=0.036) are successively fabricated by reactive sintering the elemental powder mixtures near-net shaped by extrusion and die forging. A duplex structure consisted of lamellar grains and equiaxed $\gamma$ grains is developed for all compositions, and the areal fraction of the lamellar grains(or equiaxed $\gamma$ grains) decreases (or increases) with increasing Al content. As Al content increased, the elongation increases with accompanying decrease in yield strength and ultimate tensile strength at both room temperature and 80$0^{\circ}C$. This indicates that the suitable composition is Ti-45at%Al-1.6at%Mn in considering the balance of ambient and elevated tensile properties. The reactive-sintered Ti-45Al-1.6Mn alloy shows superior oxidation resistance not only to the plasma arc melted one but also to the heat resistance steel STR35(representative exhaust valve head material for automotive engine). The reactive-sintered Ti-45Al-1.6Mn alloy coated with an oxidizing scale exhibits a better wear resistance than induction hardened martensitic steel STR11(representative exhaust valve tip material for automotive engine).

• 한국분말재료학회지
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• 제12권6호
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• pp.393-398
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• 2005

In-situ processing route was adopted to disperse carbon nanotubes (CNTs) into $Al_2O_3$ powders homogeneously. The $Al_2O_3$ composite powders with homogeneous dispersion of CNTs could be synthesized by a catalytic route for in-situ formation of CNTs on nano-sized Fe dispersed $Al_2O_3$ powders. CNTs/Fe/$Al_2O_3$ nanopowders were densified by spark plasma sintering (SPS). The hardness and bending strength as well as electrical conductivity increased with increasing sintering temperature. However, the electrical conductivity of the composites sintered at above $1500^{\circ}C$ showed decreased value with increasing sintering temperature due to the oxidation of CNTs.

• Journal of Nutrition and Health
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• 제29권8호
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• pp.881-888
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• 1996

The purpose of this study was to determine whether vitamin B6(B6) deficiency affects fuel utilization and blood cholesterol profile with exercise-training. Twenty-four rats were fed a B6 deficient(-B6) diet or a control (+B6) diet for 5 weeks and either exercised(EX) or nonexercised (NE). EX rats were exercised on treadmill(10$^{\circ}$, 0.5-0.8km/h) for 20 minutes everyday. Glucose(GLU), glycogen (GLY), protein(PRO), trglyceride(TG), free fatty acid(FFA), total cholesterl(TC), HDL-cholesterol(HDL-C) and LDL-choleterol(LDL-C) were compared in plasma(P), liver(L) and skeletal muscle(M) of rats. There was a vitamin effect on the level of P-GLU, P-TG, M-TG, L-GLY, L-PRO and an exercise effect on the level of P-PRO, P-FFA, M-PRO, L-GLY, L-TG, P-TC, P-HDL-C, P-LDL-C. Compared to +B6 rats were lower and there were no differences in P-GLU, P-FFA, P-TG. M-GLY, L-TG, P-TC and P-HDL-C. In EX group, the level of P-TG was higher and M-PRO was lower in -B6 rats. There were no differences in M-GLY, L-TG, P-TC and P-HDL-C. These results suggest that a lowered intake of vitamin B6 may impair the adaptation of animals to fuel metabolism related to a decrease of fatty acid oxidation and attenuates the exercise-traning effect on blood lipid profile.

• Archives of Pharmacal Research
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• 제28권6호
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• pp.667-674
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• 2005

The leaves of Persimmon (Diospyros kaki L.) has long been used for tea in Korea since it was thought to be effective against hypertension. An anticoagulant fraction was purified through gel filtration G-100, hydrophobic, gel filtration G-150, and FPLC, Phenyl superpose column chromatographies. The purified fraction was homogenous and its Mr was estimated 10,000 Da by gel filtration and SDS-PAGE. The purified fraction was sensitive to treatment of subtilisin B, but not to heat and its activity was not changed after periodate oxidation, indicating that the activity was not due to carbohydrates. It delayed thrombin time (TT), activated partial thromboplastin time (APTT), and prothrombin time (PT) using human plasma. TT was more sensitive than APTT and PT, suggesting that the anticoagulant activity may be caused by a degradation or a defect of fibrin or thrombin. It did not cause the hydrolysis of fibrin after incubation. However, it inhibited thrombin-catalyzed fibrin formation with a competitive inhibition pattern. These results indicate that it may be an antithrombotic agent and that it is bound to fibrinogen binding sites of thrombin.

• 한국주조공학회지
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• 제38권3호
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• pp.60-65
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• 2018

In the present study, the characteristics of Mg inverter cases for hybrid cars are investigated. Concerns over the use of lightweight materials to reduce energy use and to mitigate emission problems are inevitable in the twenty-first century. Magnesium is a promising material for the manufacturing of lightweight parts. Several cases for thermal cooling channels have been designed and simulated, and the effects of materials and coatings on the thermal cooling efficiency have been discussed. The effects of the coating thickness on heat extraction in an Mg inverter housing case using the PEO (plasma electrolyte oxidation) coating method were also discussed. In order to produce an inverter case by the diecasting process, the filling sequence and cooling behavior during the diecasting process were simulated. The optimized process conditions from the simulation result were then used in a trial diecasting experiment.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 춘계학술대회 논문집
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• pp.45-46
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• 2009

We have fabricated advanced metal-oxide-semiconductor (MOS) capacitors with thin (${\approx}10\;nm$) Inductive-Coupled Plasma (ICP) CVD $Si_xN_y$ dielectric layers and investigated electrical properties of nitrided $SiO_2$/4H-SiC interface after oxidizing the $Si_xN_y$ in dry oxidation and/or $N_2$ annealing. An improvement of electrical properties have been revealed in capacitance-voltage (C-V) and current density-electrical field (J-E) measurements if compared with non-annealed oxidized-SiN. The improvements of SiC MOS capacitors formed by oxidized-SiN have been explained in this paper.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2017년도 춘계학술대회 논문집
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• pp.160-160
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• 2017

Commercially pure titanium (Cp-Ti) and Ti alloys (typically Ti-6Al-4V) display excellent corrosion resistance and biocompatibility. Although the chemical composition and topography are considered important, the mechanical properties of the material and the loading conditions in the host have, conventionally. Ti and its alloys are not bioactive. Therefore, they do not chemically bond to the bone, whereas they physically bond with bone tissue. The electrochemical deposition process provides an effective surface for biocompatibility because large surface area can be served to cell proliferation. Plasma electrolyte oxidation (PEO) enables control in the chemical composition, porous structure, and thickness of the TiO2 layer on Ti surface. Silicon (Si) in particular has been found to be essential for normal bone and cartilage growth and development. Zinc (Zn) plays very important roles in bone formation and immune system regulation, and is also the most abundant trace element in bone. The objective of this work was to study on electrochemical behaviors of PEO-treated Ti-6Al-4V Alloy in solution containing Zn and Si ions. The morphology, the chemical composition, and the microstructure analysis of the sample were examined using FE-SEM, EDS, and XRD. The potentiodynamic polarization and AC impedance tests for corrosion behaviors were carried out in 0.9% NaCl solution at similar body temperature using a potentiostat. The promising results successfully demonstrated the immense potential of Si/Zn-TiO2 coatings in dental and biomaterials applications.