• Journal of the Korean Applied Science and Technology
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• v.27 no.2
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• pp.137-143
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• 2010

Oxide semiconductors Thin-film transistors are an exemplified one owing to its excellent ambient stability and optical transparency. In particular zinc oxide (ZnO) has been reported because It has stability in air, a high electron mobility, transparency and low light sensitivity, compared to any other materials. For this reasons, ZnO TFTs have been studied actively. Furthermore, we expected that would be satisfy the demands of flexible display in new generation. In order to do that, ZnO TFTs must be fabricated that flexible substrate can sustain operating temperature. So, In this paper we have studied low-temperature process of zinc oxide(ZnO) thin-film transistors (TFTs) based on silicon nitride ($SiN_x$)/cross-linked poly-vinylphenol (C-PVP) as gate dielectric. TFTs based on oxide fabricated by Low-temperature process were similar to electrical characteristics in comparison to conventional TFTs. These results were in comparison to device with $SiN_x$/low-temperature C-PVP or $SiN_x$/conventional C-PVP. The ZnO TFTs fabricated by low-temperature process exhibited a field-effect mobility of $0.205\;cm^2/Vs$, a thresholdvoltage of 13.56 V and an on/off ratio of $5.73{\times}10^6$. As a result, We applied experimental for flexible PET substrate and showed that can be used to ZnO TFTs for flexible application.

• Journal of the Korean Electrochemical Society
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• v.12 no.2
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• pp.173-180
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• 2009

In order to develop a novel polymer electrolyte membrane for direct methanol fuel cell (DMFC), styrene monomer was graft-polymerized into poly(tetrafluoroethylene perfluoropropyl vinyl ether) (PFA) film followed by a sulfonation reaction. The graft polymerization was prepared by the $\Upsilon$-ray radiation-grafting method. Subsequently, sulfonation of the radiation-grafted film was carried out in a chlorosulfonic acid/1,2-dichloroethane (2 v/v%) solution. The chemical, physical, electrochemical and morphological properties of the radiation-grafted membranes (PFA-g-PSSA) were characterized by fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The water uptake, ionic conductivity, and methanol permeability of the PFA-g-PSSA membrane were also measured. The cell performances of MEA prepared with the PFA-g-PSSA membranes were evaluated and the cell resistances were measured by an impedance analyzer. The MEA using PFA-g-PSSA membranes showed superior performance for DMFCs in comparison with the commercial Nafion 112 membrane.

• Journal of Physiology & Pathology in Korean Medicine
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• v.19 no.5
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• pp.1356-1362
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• 2005

The purpose of this study os to investigative the effect of Carrageenan-Induced Pain on lower limb muscle and ligament of rat. To evaluate pain mechanism in muscle and ligament, pain was induced by the injection of 2% $0.1m{\ell}$ carrageenan into the left lower limb muscle of rats after rats were anesthesized with 3% enflurane. Rats were killed on 72 hours after pain induction under the anesthesia. anterior rectus femoris muscle and its ligament were removed from rat hind limb. Morphological changes of them were peformed by the observation of light and electron microscopes. In the light microscopic findings, the muscle cells were polyheadral and situated with each other without small gap in control group. nucleus of cell was seen along the cell margin, and muscle cell groups were divided by regular narrow gap in cross section. In the pain-induced group, muscle cell groups were divided each other by the irregular gap, and some of groups formed larger than other cell groups by the fusion. Intercellular gap of most cell groups were increased compared with control groups. And also, perimysium of muscle cell groups was swollen in cross section. In control group, muscle cells contacted each other closely and each cell was divided by perimysium. The intracellular gaps were not seen between myofibrills, and also striations were well defined between muscle cells in longitudinal section. In pain-induced group, muscle cells were divided by the small intracellular gaps. And also, muscle cell showed many a short cross or longitudinal intercellular gaps in longitudinal section. In light microscopic findings of control group, tendon was composed with many tendon fibers contacted each other closely without gap. The free margin of tendon was fused, and apso the tendon fibers did not invaded between muscles. In pain-induced group, tendon was divided small groups by intertendinous gap, and also the margin of tendon divided by small groups. In the free margin, tendon invaded into muscle cells, and also fibroblasts between tendon fibers were long and lance-shaped. From these results, it is suggested that pain induction by carrageenan injured rat skeletal muscle and ligament by the morphological changes.

• Journal of Welding and Joining
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• v.30 no.5
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• pp.64-69
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• 2012

Sn-Bi eutectic alloy has been widely used as one of the key solder materials for step soldering at low temperature. The Sn-58Bi solder paste containing chloride flux was adopted to compare with that using the chloride-free flux. The paste was applied on the electroless nickel-immersion gold (ENIG) surface finish by stencil printing, and the reflow process was then performed at $170^{\circ}C$ for 10 min. After reflow, the solder joints were aged at $125^{\circ}C$ for 100, 200, 300, 500 and 1000 h in an oven. The interfacial microstructures were obtained by using scanning electron microscopy (SEM), and the composition of intermetallic compounds (IMCs) was analyzed using energy dispersive spectrometer (EDS). Two different IMC layers, consisting of $Ni_3Sn_4$ and relatively very thin Sn-Bi-Ni-Au were formed at the solder/surface finish interface, and their thickness increased with increasing aging time. The wettability of solder joints was investigated by wetting balance test. The mechanical property of each aging solder joint was evaluated by the ball shear test in accordance with JEDEC standard (JESD22-B117A). The results show that the highest shear force was measured when the aging time was 100 h, and the fracture mode changed from ductile fracture to brittle fracture with increasing aging time. On the other hand, the chloride flux in the solder paste did not affect the shear force and fracture mode of the solder joints.

• Applied Chemistry for Engineering
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• v.18 no.1
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• pp.77-83
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• 2007

It is essential that second order nonlinear optical materials have low optical propagation losses in the wavelengths of second harmonic generation for practical applications in waveguides. Three dipolar chromophores substituted with nitro, cyano, and alkyl sulfone as an electron withdrawing group were prepared. The UV-Vis absorption spectra of the cyano and alkylsulfone chromophores showed a blue-shift compared to the nitro chromophore. The introduction of oxadiazole segment in the chromophore structure led to similar spectral shift. The blue-shift can produce low optical loses at second harmonics. The chromophores were successfully attached to a polyimide, yielding side chain polymers. The nonlinear optical property of the prepared optical polymers was determined by measuring electro-optic coefficient at 1.55 mm. The polymers exhibited high glass transition temperature of over $185^{\circ}C$ and thermal stability to $300^{\circ}C$ through differential scanning calorimeter analysis and thermal gravimetric analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2391-2400
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• 2015

Weather proof steels are used for steel bridges due to its high corrosion resistance under atmospheric conditions. However, instead of forming stabilized rust layers, general rust occurs on weather proof steels under high humidity condition close to seawater or shady places. In Japan, therefore, they perform rust stabilization treatment instead of unpainted treatment due to severe atmospheric conditions. However, most of domestic weather proof steels were constructed unpainted in the form of closed box-girder, which makes the periodical repetition of dry and wet hard to occur. For the steel bridges constructed on the Han river, the evaporation of water, dew condensation due to temperature change, and stagnant water due to rain affect harmfully on the formation of passive film on weather proof steels. Thus, in this research, in order to analyze corrosion properties inside the closed box-girder for the unpainted weather proof steel bridge in the waterworks safety zone, multiple ways of analysis such as observation with eyes, cellophane-tape test, steel thickness measurement, surface corrosion potential measurement, electron microscope analysis, and X-ray diffraction analysis of the rust were performed. As a result, unstable rust layer was observed inside the closed box-girder, and severe corrosion was observed on the top and bottom of the flanges due to the effects of stagnant water caused by rain, dew condensation, and de-icing materials.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.5 no.1
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• pp.1-8
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• 2005

Glutaric acidemia (GA) type II is a very rare inherited disorder that have no accruate figure on its icidende. People with Glutaric acidemia type II have an enzyme that does not work properly. Two specific enzymes are associated with Glutaric acidemia type II:1. Electron transfer flavoprotein (ETF), 2. ETF-ubiquinone oxidoreductase (ETF-QO). Both of these enzymes have similar functions in the body, and children with Glutaric acidemia type II may lack one or the other of these enzymes. They play an important role in breaking down fats and proteins, and help the body to produce energy. GA II clinically manifested as (1) neonatal onset with congenital anomalies (2) neonatal onset without anomalies, and (3) mild and/or later onset. The first two groups are sometimes said to have multiple acyl CoA dehydrogenation deficiency-severe and the third to have multiple acyl CoA dehydrogenation deficiency-mild. The course and age at presentation of later-onset glutaric acidemia type II is extremely variable, therefore it is difficult to diagnosis. We experienced one case of late onset form glutaric acidemia type II with afebrile status epilepticus-like convulsion.

• Korean Journal of Plant Resources
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• v.24 no.1
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• pp.30-39
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• 2011

This study was conducted to investigate the antioxidative activity and cytotoxicity of fermented Allium victorialis extract. The results were as follows; The total polyphenol content of A. victorialis extract was 2.63 mg/g, and that of fermented A. victorialis extract was 1.65 mg/g which decreased a little by fermentation. The total flavonoid content of A. victorialis extract was 57.77 mg/g, and that of fermented A. victorialis extract was 62.27 mg/g, and this could increase a little from fermentation. Electron donating ability of A. victorialis extract was lower than vitamin C(97.71%), but before fermentation it was 82.29% and after fermentation it became 82.40%. Nitrite scavenging ability of A. victorialis extract before and after fermentation showed lower numerical value than that of butylated hydroxytoluene(BHT) at pH 2.5 but that of A. victorialis extract expressed higher than that of BHT. Superoxide dismutase-like activity showed relatively low level, 15%. Nitrite production increased by A. victorialis extract but was inhibited after fermentation. Methyl diamphetamine (MDA) content was inhibited with increased concentration of A. victorialis extract compared with $H_2O_2$ treatment but there was not any difference before and after fermentation. Therefore, production of lipid peroxide(LPO) was inhibited by A. victorialis extract. Cell viability of fibroblast cell was tend to slightly decrease with increased concentration of A. victorialis extract, but not different with control.

• Microbiology and Biotechnology Letters
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• v.38 no.4
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• pp.434-441
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• 2010

The Plants and their extracts containing polyphenol have been shown to be associated with decreased the cause of aging and variety of disease such as reaction oxygen species (ROS) and reactive nitrogen species (RNS) in several recent studies. We conducted to investigate whether the extracts and fractionation isolated from Aster glehni Fr. Schm. has an inhibitory effect association with oxidation or inflammation. The Aster glehni Fr. Schm. 70% aq. MeOH was fractioned according to polarity with n-hexane layer, EtOAc layer, n-BuOH layer and water layer. The electron donating ability of EtOAc, n-BuOH solvent fraction from Aster glehni Fr. Schm. was about 58.0%, 46.4% at $50\;{\mu}g/mL$, respectively. The superoxide anion radical inhibitory effect of EtOAc extracts was about 64.65% at $50\;{\mu}g/mL$, and n-BuOH extracts was 35.66% at $50\;{\mu}g/mL$. EtOAc layer to the inhibition activity of hyaluronidase and lipoxygenase were inhibited about 24.37%, 29.5% at $5\;{\mu}g/mL$. In the anti-inflammation effect of EtOAc layer inhibited the generation of nitric oxide. also, these results showed that EtOAc extract inhibited 81.5% at $50\;{\mu}g/mL$ on the expressions of iNOS protein in Raw264.7 cell line.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.5
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• pp.227-231
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• 2010

Super hydrophilic $TiO_2$ thin films with photocatalytic property were successfully fabricated on a glass substrate by liquid phase deposition (LPD). The $TiO_2$ thin film formed nano particles on a surface at $70^{\circ}C$. As an immersion time in $TiF_4$ solution increased, the thickness of thin films gradually increased. $TiO_2$ thin film showed a water contact angel of below ca. $5^{\circ}$ and the transmittance of ca. 75~90 % in visible range. In addition, $TiO_2$ thin film showed the photocatalytic property to decompose methyl orange solution by the illumination of UV light. The surface morphologies, optical properties and contact angel of prepared thin films with a different immersion time were measured by field emission scanning electron microscope (FE-SEM), atomic force microscope (AFM), UV-Vis spectrophotometer and contact angle meter.