• Composites Research
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• v.15 no.6
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• pp.16-23
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• 2002

In this work, the effect of anodic oxidation on surface characteristics of high strength PAN-based carbon fibers was investigated in mechanical interfacial properties of composites. The surface properties of the carbon fibers were determined by acid-base values, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and contact angles. And their mechanical interfacial properties of the composites were studied in interlaminar shear strength (ILSS) and critical stress intensity factor ($K_{IC}$). As a result, the acidity or the $O_{ls}/C_{ls}$ ratio of carbon fiber surfaces was increased, due to the development of the oxygen functional groups. Consequently, the anodic oxidation led to an increase in surface free energy of the carbon fibers, mainly due to the increase of its specific (or polar) component. The mechanical interfacial properties of the composites, including ILSS and $K_{IC}$, had been improved in the anodic oxidation on fibers. These results were explained that good wetting played an important role in improving the degree of adhesion at interfaces between fibers and epoxy resin matrix.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.6
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• pp.1063-1067
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• 2004

To elucidate the effect of protein films containing an antioxidant on lipid oxidation of fish paste products during storage, zein and soy protein isolate (SPI) films containing green tea extract were prepared and their physical properties were examined. Tensile strength and elongation of the protein films decreased by the addition of green tea extract compared to the control. Due to the addition of green tea extract, SPI film had an increase in yellowness, but zein film had a decreased yellowness. Wrapping of fried fish paste products by the zein and SPI films containing the antioxidant retarded lipid oxidation at 2 day storage by 3.6 mg MDA/kg sample and 3.6 mg MDA/kg sample, respectively, for instant fish paste compared to the control. For processed fish paste, they decreased the degree of lipid oxidation by 1.6 mg MDA/kg sample and 0.6 mg MDA/kg sample, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.551-556
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• 2018

The material normally used in hot dip galvanizing facilities is SM45C (carbon steel for mechanical structure, KS standard), mainly because of its price. During this process, the oxidation of the plating facility occurs due to the heat of the Zn fumes coming from the molten zinc. Since the cycle time of the current facilities is 6 months, much time and money are wasted. In this study, the corrosive properties of various materials (Inconel625, STS304, SM45C) were investigated by oxidation in a high temperature and Zn fumes environment. The possibility of applying the hot-dip galvanizing equipment was investigated for each material. The Zn fumes were generated by directly bubbling Ar gas into Zn molten metal in a 650 degree furnace. High-temperature, Zn fumes corrosion was conducted for 30 days. The sample was removed after 30 days and the oxidation of the surface was confirmed with EDS and SEM, and the corrosion properties were examined using potentiodynamic polarization tests.

• Progress in Superconductivity
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• v.7 no.2
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• pp.130-134
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• 2006

Buffer layers such as $CeO_2\;and\;Yb_2O_3$ films for YBCO coated conductors were deposited on (100) $SrTiO_3$ single crystals and (100) textured Ni substrates by a metal organic chemical vapor deposition (MOCVD) system of the hot-wall type. The substrates were moved with the velocity of 40 cm/hr. Source flow rate, $Ar/O_2$ flow rate and deposition temperature were main processing variables. The degree of film epitaxy and surface morphology were investigated using XRD and SEM, respectively. On a STO substrate, the $CeO_2$ film was well grown epitaxially above the deposition temperature of $450^{\circ}C$. However, on a Ni substrate, the XRD showed NiO (111) and (200) peaks due to Ni oxidation as well as (111) and (200) film growth. For the films deposited with $O_2$ gas as oxygen source, it was found that the NiO film was formed at the interface between the buffer layer and the Ni substrate. The NiO layer interrupts the epitaxial growth of the buffer layer. It seems that the epitaxial growth of the buffer layer on Ni metal substrates using $O_2$ gas is difficult. We are considering a new method avoiding Ni oxidation with $H_2O$ vapor instead of $O_2$ gas.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.159.1-159.1
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• 2011

Partial oxidation reformer was fabricated and operated using commercial transportation fuels. Fuel injector and heating coil were used for fuel atomization and startup, respectively. The reformer was designed to produce syngas for $150{\sim}200W_e$ class solid oxide fuel cell. The reformer was operated in the $O_2$/C range between 0.6 and 0.8 while the capacity was fixed at $150W_e$. The temperature range in catalyst bed was between $500^{\circ}C$ and $900^{\circ}C$. Only 83% fuel was converted to $H_2$, CO, $CO_2$ and $CH_4$ at the operating conditions. The lowest temperature increase to $700^{\circ}C$ when the reformer was operated at $200W_e$, Although the temperature profiles was improved, fuel conversion was 88%. On the other hand, fuel was completely converted when micro-reactor operated at the same condition. This difference maybe due to aromatic compounds formation at homogeneous region. In addition, a significant amount of coke deposition was observed at vent line. Homogeneous reaction depends on the degree of mixing. For this purpose, two fluid nozzle and Ultra sonic injector were compared to investigate the effect of atomization. Sauter mean diameter(SMD) of Ultra sonic injector was lower than two-fluid nozzle at test condition. However, conversion efficiency and fuel conversion were not improved by using two-fluid nozzle. these results imply that the temperature of homogeneous reaction region should be controlled to prevent coke formation.

• Korean Journal of Food Science and Technology
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• v.25 no.6
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• pp.775-779
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• 1993

The effects of water activity and light on the oxidation of carotenoid were studied using both the model systems of carrot lipids and freeze dried carrot. Autoxidation of crude lipids from the freeze dried carrot and the stability of carotenoids in controlled systems varing water activities and/or lights were examined. The degree of autoxidation of crude lipid stored at $30^{\circ}C$ for 16 days was significant(p< 0.05) and 71.8% destruction of carotenoid in the crude lipids were observed. When the powdered solid models of freeze dried carrot were stored at $30^{\circ}C$ for 35 days under various water activities and the presence of light, the maximum stability of carotenoid was found at $a_{w}$ 0.42 and the damaging effect of lights on the stability of carotenoid was significant (p<0.05). The absoprtion spectra of carotenoids changed according to the degree of oxidation, but shifts of the maximum wavelength was not observed.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.2
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• pp.97-104
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• 2016

In the preparation of Ag-coated Cu flakes using L-ascorbic acid as a reductant for the electroless Ag plating, the effects of pretreatment methods and the reductant concentration on the uniformity of Ag coating layer and the anti-oxidation property of Ag-coated Cu flakes during the heating in air were evaluated. It was found that the removal degree of surface oxide layer during the pretreatment has great influence on the uniformity of Ag coating layer and the formation degree of hole defects in the flakes has slight effect on the anti-oxidation property of Ag-coated Cu flakes. It was also verified that the reductant concentration has great influence on the coverage uniformity and thickness of Ag coating, thus it was could be considered a main process parameter. When the reductant concentration was 0.04 M, high-quality Ag-coated Cu flakes was obtained. When the concentration increased to 0.06 M, however, the anti-oxidation property of Ag-coated Cu flakes became remarkably worse owing to remnant of Cu surface non-coated with Ag by the formation of pure Ag fine particles.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.5
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• pp.419-430
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• 1987

The damage of plasmid DNA by lipid peroxidation and its inhibition were investigated through the model system of DNA and linoleic acid at $37^{\circ}C$. The degree of DNA damage increased in proportion to the increase of concentration and peroxidation of linoleic acid. DNA damage induced from linoleic acid peroxidation was greatly inhibited by the addition of active oxygen scavengers, especially, singlet of oxygen scavenge$(\alpha-tocopherol,\;cysteine)$ and superoxide anion scavenger(superoxide dismutase, ascorbic acid) in reaction system. These active oxygens, such as superoxide anion and hydrogen peroxide were rapidly generated in the early stage of peroxidation (POV below 100 mg/kg) and also scanvenged by the addition of superoxide dismutase and catalase, respectively. Hydroperoxide isolated from autoxidised linoleic acid showed DNA damage. Hydroperoxide induced-DNA damage was not inhibited by active oxygen scavengers. Lipid oxidation products, malonaldehyde and hexanal, also influenced on the DNA damage. Accordingly, it is speculated that DNA damage by lipid oxidation products is due to active oxygens such as singlet oxygen and superoxide anion formed in the early stage of peroxidation, direct action of hydroperoxide and formation of low molecular carbonyl compound-DNA complex. Furthermore, DNA damage induced by lipid peroxidation was remarkably inhibited by the addition of active oxygen scavengers and natural antioxidative fractions extracted from garlic and ginger. These antioxidative fractions also suppressed the generation of active orygens and linoleic acid oxidation. It is assumed that the inhibition of DNA damage by garlic and ginger extracts is due to the scavenging effect of active oxygens and the inhibition of hydroperoxide and oxidation products formation.

• Polymer(Korea)
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• v.37 no.1
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• pp.61-65
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• 2013

In this work, the anodic oxidation of carbon fibers was carried out to enhance the mechanical interfacial properties of carbon fibers-reinforced epoxy matrix composites. The surface characteristics of the carbon fibers were studied by FTIR, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). Also, the mechanical interfacial properties of the composites were studied with interlaminar shear strength (ILSS), critical stress intensity factor ($K_{IC}$), and critical strain energy release rate ($G_{IC}$). The anodic oxidation led to a significant change in the surface characteristics of the carbon fibers. The anodic oxidation of carbon fiber improved the mechanical interfacial properties, such as ILSS, $K_{IC}$, and $G_{IC}$ of the composites. The mechanical interfacial properties of the composites anodized at 20% sulfuric/nitric (3/1) were the highest values among the anodized carbon fibers. These results were attributed to the increase of the degree of adhesion at interfaces between the carbon fibers and the matrix resins in the composite systems.

• Korean Journal of Food Science and Technology
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• v.29 no.3
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• pp.446-451
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• 1997

The primary alcohol groups of four kinds of polysaccharides (com starch, rice starch, sweet potato starch, and cellulose), with different structures and water solubilities, were oxidized to carboxyl groups using 2,2,6,6-tetramethyl-1-piperidine oxoammonium ion (TEMPO) at $25^{\circ}C$. The optimum pH, TEMPO content, and NaBr content for the TEMPO/hypobromite-catalyzed oxidation of the polysaccharides were $10.5{\sim}11.0$, 10 mmol/mol primary alcohol, and 0.49 mmol/mol primary alcohol, respectively. The oxidation degree for the primary alcohol group was more than 90% for all four kinds of the polysaccharides. The oxidation process greatly increased the water solubility of the polysaccharides. Water-insoluble polysaccharide such as cellulose became water-soluble to the extent of 8.42% (w/v). And also, the polysaccharides with very low water solubility (less than 0.10% (w/v)) such as com starch, rice starch, and sweet potato starch had high water solubility of approximately 45%(w/v). The gel-forming abilities with calcium ion were determined. The oxidized polysaccharides are new anionic polymers with unique structures that could have application as gums, gels, and films.