• Proceedings of the KWS Conference
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• 1997.05a
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• pp.27-32
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• 1997

• Journal of Magnetics
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• v.7 no.3
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• pp.63-71
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• 2002

Three fabrication techniques for forming thin barrier layer with uniform thickness and large barrier height in magnetic tunnel junction (MTJ) are discussed. First, the effect of immiscible element addition to Cu layer, a high conducting layer generally placed under the MTJ, is investigated in order to reduce the surface roughness of the bottom ferromagnetic layer, on which the barrier is formed. The Ag addition to the Cu layer successfully realizes the smooth surface of the ferromagnetic layer because of the suppression of the grain growth of Cu. Second, a new plasma source, characterized as low electron energy of 1 eV and high density of $10^{12}$ $cm^{-3}$, is introduced to the Al oxidation process in MTJ fabrication in order to reduce damages to the barrier layer by the ion-bombardment. The magnetotransport properties of the MTJs are investigated as a function of the annealing temperature. As a peculiar feature, the monotonous decrease of resistance area product (RA) is observed with increasing the annealing temperature. The decrease of the RA is due to the decrease of the effective barrier width. Third, the influence of the mixed inert gas species for plasma oxidization process of metallic Al layer on the tunnel magnetoresistance (TMR) was investigated. By the use of Kr-O$_2$ plasma for Al oxidation process, a 58.8 % of MR ratio was obtained at room temperature after annealing the junction at $300{^{\circ}C}$, while the achieved TMR ratio of the MTJ fabricated with usual Ar-$0_2$ plasma remained 48.4%. A faster oxidization rate of the Al layer by using Kr-O$_2$ plasma is a possible cause to prevent the over oxidization of Al layer and to realize a large magnetoresistance.

• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.3
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• pp.672-677
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• 2008

In order to explore the anti-oxidization effect of oriental medicine and cereal medium(OCM) where Tricholoma matsutake mycelia were cultured, measurement of hot water extract and UMPM(extraction method using ultra sonic waves, micro waves, micro bubble) extract, the total polyphenol content of crude polysaccharide from each extract, SOD-like activity, electron donating ability(EDA), xanthine oxidase inhibitory activity, and tyrosinase inhibitory activity was conducted. The total polyphenol content of each extract was found to be 16.36% for hot water extract(HE) group and 15.73% for UMPM extract(UE) group and the amount of crude polysaccharide precipitated into ethanol of extracts was found to be 8.79% for UMPM ethanol extract(UEE) group and 6.48% for hot water ethanol extract(HEE) group. As a result of measurement of SOD-like activity by concentration of each extract, it was found to be 96.17% for UE group, 91.23% for HE group, 91.33% for UEE group, and 87.11% for HEE group at 20 mg/mL. In the case of EDA, it was found to be 47.55% for UE group, 44.93% for HE group, 25.38% for UEE group, and 18.36% for HEE group. And in the cases of the rates of xanthine oxidase inhibitory activity and tyrosinase inhibitory activity, as the concentration of each extract increased, the inhibition rate increased accordingly. As a result of comparison between hot water extract method and UMPM extract method using extracts obtained from oriental medicine compound medium where Tricholoma matsutake mycelia were cultured, all of the extracts were judged to have a high anti-oxidization effect. In particular, UMPM extracts were found to have higher polyphenol content, SOD-like activity, EDA, xanthine oxidase inhibitory activity and tyrosinase inhibitory activity compared to hot water extract method. In this regard, extracts obtained from OCM where Tricholoma matsutake mycelia were cultured are considered to have high availability as functional material when and if they are prepared using UMPM extract method.

• Resources Recycling
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• v.13 no.1
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• pp.28-38
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• 2004

The characteristics of cyanide decomposition in aqueous phase by electric oxidization have been explored in an effort to develop a process to recycle waste water. Considering current efficiency and voltage, the free cyanide decomposition experiment by electric oxidization indicated that 5 V of voltage and copper catalytic Cu/CN mole ratio 0.05 was the most appropriate condition, where current efficiency was 26%, and decomposition speed was 5.6 mM/min. High voltage and excess copper addition increased decomposition speed a little bit but not current efficiency. The experiment of free cyanide density change proves that high density cyanide is preferred because speed and current efficiency increase with density. Also, the overall decomposition reaction could be represented by the first order with respcect to cyanide with the rate constant of $1.6∼7.3${\times}$10^{-3}$ $min^{-1}$ The mass transfer coefficient of electric oxidization of cyanide came out as $2.42${\times}$10^{-5}$ $min^{-1}$ Furthermore, the Damkohler number was calculated as 5.7 in case of 7 V and it was found that the mass transfer stage was the rate determining step.

• Proceedings of the Korean Magnestics Society Conference
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• 2003.12a
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• pp.50-50
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• 2003

• Korean Journal of Materials Research
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• v.13 no.11
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• pp.742-748
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• 2003

The structural parameters such as Lc, La and d of $CO_2$activated isotropic carbon fibers(ACFs) were obtained from XRD in order to understand a development mechanism of micropores. And the structural parameters were compared with specific surface area(SSA) data. The $d_{002}$, Lc, and La of the original fiber were measured to be 4.04$\AA$, 6.2$\AA$, and 23.6$\AA$, respectively. Carbonization of outer-parts and oxidization of inner-parts of the original fibers were far from completeness. It was observed that the structural changes of the ACFs during activation take place severely, therefore the carbonization and the oxidization of the fibers take place simultaneous with pore developments. The $d_{002}$ of the ACFs was increased to be 2.80$\AA$, and the La of the ACFs was decreased to be 17.0$\AA$ by activation. It was shown that the pores are developed continuously from the outer-parts to the inner-parts of the fibers, therefore the SSA increases as a result of the development of pores fully to the inner-parts of the fiber when the burn-off degree was over :39%. It seems that the (002) planes of crystallites contribute to the micropore wall related to the super high SSA.SSA.

• Computers and Concrete
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• v.20 no.1
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• pp.111-118
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• 2017

The present study established prediction models based on multiple nonlinear regressions (MNLRs) and backpropagation neural networks (BPNs) for the expansion of cement mortar caused by oxidization slag that was used as a replacement of the aggregate. The data used for the models were obtained from actual laboratory tests on specimens that were produced with water/cement ratios of 0.485 or 1.5, within which 0%, 10%, 20%, 30%, 40%, or 50% of the cement had been replaced by oxidization slag from electric-arc furnaces; the samples underwent high-temperature curing at either $80^{\circ}C$ or $100^{\circ}C$ for 1-4 days. The varied mixing ratios, curing conditions, and water/cement ratios were all used as input parameters for the expansion prediction models, which were subsequently evaluated based on their performance levels. Models of both the MNLR and BPN groups exhibited $R^2$ values greater than 0.8, indicating the effectiveness of both models. However, the BPN models were found to be the most accurate models.

• Journal of the Korean Magnetics Society
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• v.9 no.5
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• pp.245-250
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• 1999

The effect of substrate and oxidization time on $substrate /Py/Al_2O_3/Co\;(Py=Ni_{81}Fe_{19})$ tunnel junction was studied. Samples were prepared without breaking vacuum by changing shadow masks in-situ. The resistance of tunnel junctions increased, but measured MR decreased with oxidization time. Negative MR observed for samples of tunnel resistivity lower than 0.17 M$\Omega$ $({\mu}m)^2$. MR resistivity decreased with the change of substrates in the order of thermally oxidized Si(111), Si(100), Coring Glass 2948, Corning Glass 7059. Sign change and the variation of MR was explained with non uniform current effect.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.144.1-144.1
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• 2013

Recently, we have developed the local oxidization and hydrogenization method for graphene layer using atomic force microscope(AFM) tip at room temperature and ambient pressure. With this method we could create locally oxidized or hydrogenized area on the graphene layer with various size from nanometer to micrometer scale, by controlling the amplitude and polarity of the voltage supplied between conducting AFM tip and the graphene layer. We investigated the chemical states of functionalized C atoms in the graphene layer using scanning photoelectron microscopy. By measuring C 1s core level X-ray Photoemission Spectra of the C atoms and suitable fitting process carried on the measured spectra, we could obtain the fraction of oxidization and hydrogenization under various condition, and the evolution of each chemical state during thermal annealing process.

• Food Science and Preservation
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• v.13 no.3
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• pp.413-419
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• 2006

This study was investigated to analyze the antioxidant activity or extracts form Elaeagnus multiflora Thunb for development to the functional materials. The antioxidative activities of water ethanol and methanol extracts from the Elaeagnus multiflora Thunb were analyzed by electron donating ability (EDA), anti-oxidization activity, superoxide dismutase (SOD)-like activity, The superoxide anion radical-scavenging activity, and nitrite scavenging ability. The Etectron donating ability of methanol extract was higher in 1.0 mg/mL of extraction solution than those of ethers. The anti-oxidization activity of ethanol and methanol extracts by thiocyanate method using linolenic acid system was higher than those of the water extract. The SOD-like activity was increased with increase of the extract concentration in each extracts. The SOD-like activity was highest in 2.0 mg/mL of methanol extract. The superoxide anion radical-scavenging activity was increased with increase of the concentration in the ethanol extract and methanol extract. The nitrite scavenging ability of water extracts in 1.0 mg/mL of extraction soiution in pH 1.2 was higher than ethanol extrats and methanol extracts. The nitrite scavenging ability of all extracts was decreased according to increase of pH.