• Composites Research
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• v.16 no.6
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• pp.33-40
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• 2003

The initial thermal degradation of polymer matrix composite is not observed easily. At the beginning of thermal degradation of polymer matrix composites, phase transformation such as chain scission, oxidation occur, and then micro delamination is produced in matrix and interface between matrix and fiber before blistering. Initial heat damage deteriorate mechanical properties of composites. We presented the detection method of the initial heat damage of composites conveniently using ultrasonic technique. Absorption coefficient and material velocity was measured with thermal degradation and degree of cure. The more thermal degradation was progressed, the more absorption coefficient was increased. When the cure temperature is more high, the absorption coefficient of cured composite is increased and material velocity is decreased. We concluded that cure temperature is more high, the defects such as void is increased and molecular structure cured at high temperature has cross-linking structure which is more absorb the ultrasonic waves.

• Korean Journal of Materials Research
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• v.32 no.6
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• pp.301-306
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• 2022

This study explored the possibility of forming a coating layer containing alginic acid on the surface of a magnesium alloy to be used as a biomaterial. We formed a coating layer on the surface of a magnesium alloy using a plasma electrolytic oxidation process in an electrolytic solution with different amounts of alginic acid (0 g/L ~ 8 g/L). The surface morphology of all samples was observed, and craters and nodules typical of the PEO process were formed. The cross-sectional shape of the samples confirmed that the thickness of the coating layer became thicker as the alginic acid concentration increased. It was confirmed that the thickness and hardness of the sample significantly increase with increasing alginic acid concentration. The porosity of the surface and cross section tended to decrease as the alginic acid concentration increased. The XRD patterns of all samples revealed the formation of MgO, Mg₂SiO₄, and MgF₂ complex phases. Polarization tests were conducted in a Stimulate Body Fluid solution similar to the body's plasma. We found that a high amount of alginic acid concentration in the electrolyte improved the degree of corrosion resistance of the coating layer.

• JSTS:Journal of Semiconductor Technology and Science
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• v.7 no.4
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• pp.254-259
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• 2007

In this report, several fabrication techniques for the formation of various nanochannels (with $SiO_2$, Si, or Quartz) are introduced. Moreover, simple fabrication technique for generating $SiO_2$ nanochannels without nanolithography is presented. By using different nanochannels, the degree of stretching DNA molecule will be evaluated. Finally, we introduce a nanometer scale fluidic channel with electrodes on the sidewall of it, to detect and analyze single DNA molecule. The cross sectional shape of the nanotrench is V-groove, which was implemented by thermal oxidation. Electrodes were deposited through both sidewalls of nanotrench and the sealing of channel was done by covering thin poly-dimethiysiloxane (PDMS) polymer sheet.

• Korean Journal of Oriental Medicine
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• v.7 no.1
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• pp.135-144
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• 2001

Objectives : This study was carried out to research the protective effects of Sagunja-Tang(SA) through in vivo experiments, and tried to investigate the relation between oxidation of renal tissues and deficiency of Qi. Methods : Acute renal injury which initiated from free radical induced by $HgCl_2$, were applied to mice and metabolic data were obtained. In order to measure the degree of renal injury, serum level of creatinine, blood urea nitrogen(BUN), total protein(TP) and glucose were measured. Besides, serum level of alanine aminotransferase(AST), aspartate aminotransferase(ALT) were measure too. Lipid peroxidation of renal cortex was examined by measuring malondialdehyde(MDA), a product of lipid peroxidation. Results : SA had protective effects on acute renal injury caused by decrease of glomerular filtration which was initiated by subcutaneous injection of $HgCl_2$. SA protected acute liver injury too. Conclusions : Through this study, we found that SA have healing effects on renal injury of $HgCl_2$ induced oxidative stress that is similar to deficiency of Qi. And further studies have to be followed to certify the mechanisms.

• Journal of the Korean institute of surface engineering
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• v.47 no.6
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• pp.347-353
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• 2014

We present a synthesis of single-walled carbon nanotubes(SWNTs) for enhancement of parallel-alignment and density using chemical vapor deposition with methane feed gas. As-purchased ST-cut quartz substrates were heat-treated and line-patterned by electron-beam lithography in order to grow SWNTs with parallel alignment. We investigated the effects of various synthesis parameters such as catalyst oxidation, reduction, and synthesis conditions in order to enhance both tube density and degree of parallel alignment. The condition of $1{\AA}$ of Fe catalyst film, atmospheric oxidation at $750^{\circ}C$ for 10 min, reduction under 400 Torr for 5 min, and growth at $865^{\circ}C$ under 300 Torr yields $33tubes/10{\mu}m$, which is the highest tube density with parallel alignment. Based on the results of atomic force microscope and Raman spectroscopy, it was found that SWNTs have diameter range of 0.8-2.0 nm. We believe that the present work would contribute to the development of SWNTs-based flexible functional devices.

• Applied Biological Chemistry
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• v.41 no.4
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• pp.213-217
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• 1998

An assay for cytochrome P450 monooxygenase activity by determination of the products of organophosphate oxidation via inhibition of acetylcholinesterase was described. Extracts from strains of Oryzaephilus surinamensis selected for resistance to chlorpyrifos-methyl (QVOS 102), fenitrothion (VOS F) and malathion (VOS 3), and a standard susceptible strain VOS 48, were incubated with an organophosphate in the presence of a NADPH-generating system and acetylcholinesterase. The degree of inhibition of the acetylchoinesterase activity was converted to manooxygenase activity using standard curves for the inhibition of acetylcholiesterase by chlorpyrifos-methyl-oxon, fenitrooxon and malaoxan. Activity was detectable in VOS 48 and was present at different increased levels with the different organophosphates in the three resistant strains, suggesting that different forms of P450 might be involved in organophosphate oxidation in these insects. The assays were carried out using crude insect homogenates and much smaller samples of insect material than the standard aldrin to dieldrin assay. It should be possible to use the method for determination of monooxygenase activity in single insert.

• Journal of the East Asian Society of Dietary Life
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• v.25 no.1
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• pp.146-152
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• 2015

Seasoned laver is the highest consumed item among processed laver foods. However, it easily undergoes quality deterioration during processing and storage by lipid oxidation. The purpose of this study was to develop onion seasoned laver with strengthened functional properties through evaluation of storage characteristics. Proximate composition, color index, acid value, thiobarbituric acid (TBA) production, and sensory evaluation of seasoned laver with 0, 15 and 30% onion powder were analyzed during storage periods of 0, 12 and 24 weeks. The lightness, redness, and yellowness of 30% onion seasoned laver significantly increased according to storage period. The acid value and TBA production significantly increased in control laver without onion powder, with no significant difference in 30% onion seasoned laver according to storage period. Sensory preference of onion seasoned laver was better than that of control laver in terms of taste, texture, and overall acceptability. To sum up these results, seasoned laver with 30% onion powder showed superior color degree, acid value, TBA production and sensory preference in proportion to added amount.

• Proceedings of the Membrane Society of Korea Conference
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• 1996.06a
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• pp.121-147
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• 1996

Since 1980, the water quality of ultra-pure water has been rapidly improved, and presently ultra-pore water producing equipment for 64Mbit is in operation. Table 1 shows the degree of integration of DRM and required water quality exlmple. The requirements of the ultra-pure water for 64Mbit are resistivity: 18.2 MQ/cm or higher, number of particulates: 1 pc/ml or less (0.05 $\mu$m or larger). bacteria count: 0.1 pc/l or less. TOC (Total Organic Carbon, index of organic snbstance) : 1ppb or less, dissolved oxygen: 5ppb or less, silica: 0.5ppb or less, heavy metal ions: 5ppb or less. The effect of metals on the silicon wafer has been well known, and recently it has been reported that the existence of organic substance in ultra-pure water is closely related to the device defect, drawing attention. It is reported that if organic substance sticks to the natural oxidation film, the oxide film remaims on the organic substance attachment in the hydrofluoric acid treatment (removal of natural oxidation film). The organic substance forms film on the silicon wafer, and harmful elements such as metals and N.P.S., components contained in the organic substance and the bad effect due to the generatinn of silicon carbide cannot be forgotten. In order to remove various impurities in raw water, many technological develoments (membrane, ion exchange, TOC removal, piping material, microanalysis, etc.) have been made with ultra-pure water producing equipment and put to practical use. In this paper, technologies put to practical use in recent ultra-pure vater producing equimeut are introduced.

• Herbal Formula Science
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• v.9 no.1
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• pp.375-385
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• 2001

Objectives : This study was carried out to research the protective effects of Sagunja-Tang(SA) through in vivo experiments, and tried to investigate the relation between oxidation of liver tissues and deficiency of Qi. Methods : Acute liver injury which initiated from free radical induced by $CCl_4$, were applied to mice and metabolic data were obtained. In order to measure the degree of liver injury, serum level of alanine aminotransferase(AST), aspartate aminotransferase(ALT), creatinine, blood urea nitrogen(BUN), total protein(TP) and glucose were measured. Lipid peroxidation of liver slice was examined by measuring malondialdehyde(MDA), a product of lipid peroxidation. Results : SA had protective effects on $CCl_4$ induced acute liver injury by decreasing serum level of ALT. Kidney injury was induced by injection of $CCl_4$ too, and SA protected kidney injury by decreasing serum level of creatinine and BUN. Conclusions : Through this study, we found that SA have healing effects on liver and kidney injury of $CCl_4$ induced oxidative stress that is similar to deficiency of Qi. And further studies have to be followed to certify the mechanisms.

• Journal of Welding and Joining
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• v.19 no.2
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• pp.191-199
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• 2001

The oxidation and recrystallization behaviors of Ni-base single crystal superalloy, CMSX-2 were investigated to determine the condition of the preparation for transient liquid phase (TLP) bonding operations. The faying surfaces of CMSX-2 were worked by the shot peening, fine cutting and mechanical polishing treatments and the degree of working of treated surfaces was evaluated by the hardness test and X-ray diffraction method CMSX-2 was heat-treated at 1,173∼1.589k for 3.6ks in vacuum of 4mPa. The mechanically polished surface was slightly oxidized after heat treatment even in the vacuum atmosphere of 4mPa. The thickness of an oxide film increased with increasing the heating temperature and the surface roughness of the faying surface. Recrystallization occurred at the surface after heat treatment at above 1,423K when the hardness was increased more than Hv600 by the shot peening treatment while the mechanically polished or fine cut surfaces didn't recrystallized. Based on these results, it was clearfied that the mechanically polishing with fine abrasive grit could be used for the preparation of faying surface of CMSX-2 before bonding operation.