• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.314-315
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• 2008

We have studied a property change of organic light-emitting diodes (OLED)s due to a surface reformation of indium-tin-oxide(ITO) substrate. An ITO is widely used as a transparent electrode in light-emitting diodes, and the OLEDs device performance is sensitive to the surface properties of the ITO. The ITO surface reformation could reduce the Schottky barrier at the ITO/organic interface and increase the adhesion of the organic layer onto the electrode. We have studied the characteristics of OLEDs with a treatment by a wet processing of the ITO substrate. The self-assembled monolayer(SAM) was used for wet processing. The characteristics of OLEDs were improved by SAM treatment of an ITO in this work. The OLEDs with a structure of ITO/TPD(50nm)/$Alq_3$(70nm)/LiF(0.5nm)/Al(100nm) were fabricated, and the surface properties of ITO were investigated by using seneral characterization techniques. Self-assembled monolayer introduced at the anode/organic interface gave an improvement in turn-on voltage, luminance and external quantum efficiency compared to the device without the SAM layer. SAM-treatment time of the ITO substrate was made to be 0/10/15/20/25min. The current efficiency of the device with 15min. treated SAM layer was increased by 3 times and the external quantum efficiency by 2.6 times.

• Archives of Plastic Surgery
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• v.38 no.1
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• pp.81-84
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• 2011

Purpose: Nerve injury is one of the complication which can develop after brow lift. Peripheral nerve ending which is stretched from supraorbital nerve and supratrochlear nerve can be injured and symptoms such as pain, dysesthesia may appear. Usually, developed pain disappeared spontaneously and does not go on chronic way. We experienced a case that a patient complained chronic pain after brow lift which was not controlled by conservative management such as medications, local nerve block and report a successful surgical treatment of chronic pain after brow lift. Methods: A 24-year-old male who received brow lift with hairline incision at local hospital was admitted for chronic pain at the right forehead. The pain was continued for 3 months even though fixed thread was removed. Local nerve block at trigger point with mixed 1 mL 2% lidocaine and 1 mL Triamcinolone acetonide was done and oral medications, Gabapentine and carbamazepine, were also applied but there was no difference in the degree of pain. Therefore the operation was performed so that careful dissection was carried out at right supraorbital neurovascular bundle and adhered supraorbital nerve was released from surrounding tissues and covered with silastic sheet to prevent adhesion. Results: The pain was gradually relieved for a week. The patient was discharged without complications. No evidence of recurrence has been observed for 2 years. Conclusion: The pain developed after brow lift was engaged with nerve injury and sometimes remains chronically. Many kinds of conservative management to treat this complication such as medications, local nerve block have been reported and usually been used. But there are some chronic cases that conservative treatment do not work. In sum, we report 1 case of successful surgical treatment for relief of intractable pain developed after brow lift surgery.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.255-255
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• 2011

Zinc oxide based thin films have been extensively studied in recent several years because they have very interesting properties and zinc oxide is non-poisonous, abundant and cheap material. ZnO films are employed in different applications like transparent conductive layers in solar cells, protective coatings and so on. Wide industrial application of the ZnO films requires of development of cheap, effective and scalable technology. Typically used technologies don't completely satisfy the industrial requirements. In the present work, we studied effect of the deposition parameters on the structure and properties of ZnO films deposited by DC arc plasmatron. The varied parameters were gas flow rates, precursor composition, substrate temperature and post-deposition annealing temperature. Vapor of Zinc acetylacetone was used as source materials, oxygen was used as working gas and argon was used as the cathode protective gas and a transport gas for the vapor. The plasmatron power was varied in the range of 700-1500 watts. Flow rate of the gases and substrate temperature rate were varied in the wide range to optimize the properties of the deposited coatings. After deposition films were annealed in the hydrogen atmosphere in the wide range of temperatures. Structure of coatings was investigated using XRD and SEM. Chemical composition was analyzed using x-ray photoelectron spectroscopy. Sheet conductivity was measured by 4-point probe method. Optical properties of the transparent ZnO-based coatings were studied by the spectroscopy. It was shown that deposition by a DC Arc plasmatron can be used for low-cost production of zinc oxide films with good optical and electrical properties. Increasing of the oxygen content in the gas mixture during deposition allow to obtain high-resistive protective and insulation coatings with high adhesion to the metallic surface.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.252.2-252.2
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• 2013

ZnO nanostructures have a lot of interest for decades due to its varied applications such as light-emitting devices, power generators, solar cells, and sensing devices etc. To get the high performance of these devices, the factors of nanostructure geometry, spacing, and alignment are important. So, Patterning of vertically- aligned ZnO nanowires are currently attractive. However, many of ZnO nanowire or nanorod fabrication methods are needs high temperature, such vapor phase transport process, metal-organic chemical vapor deposition (MOCVD), metal-organic vapor phase epitaxy, thermal evaporation, pulse laser deposition and thermal chemical vapor deposition. While hydrothermal process has great advantages-low temperature (less than $100^{\circ}C$), simple steps, short time consuming, without catalyst, and relatively ease to control than as mentioned various methods. In this work, we investigate the dependence of ZnO nanowire alignment and morphology on si substrate using of nanosphere template with various precursor concentration and components via hydrothermal process. The brief experimental scheme is as follow. First synthesized ZnO seed solution was spun coated on to cleaned Si substrate, and then annealed $350^{\circ}C$ for 1h in the furnace. Second, 200nm sized close-packed nanospheres were formed on the seed layer-coated substrate by using of gas-liquid-solid interfacial self-assembly method and drying in vaccum desicator for about a day to enhance the adhesion between seed layer and nanospheres. After that, zinc oxide nanowires were synthesized using a low temperature hydrothermal method based on alkali solution. The specimens were immersed upside down in the autoclave bath to prevent some precipitates which formed and covered on the surface. The hydrothermal conditions such as growth temperature, growth time, solution concentration, and additives are variously performed to optimize the morphologies of nanowire. To characterize the crystal structure of seed layer and nanowires, morphology, and optical properties, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and photoluminescence (PL) studies were investigated.

• Polymer(Korea)
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• v.25 no.4
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• pp.587-593
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• 2001

In this work, red mud (RM) was chemically modified by 0.1, 1, and 5 M H3PO4 solution to prepare epoxy/RM nanocomposites. The effect of chemical treatment on pH, acid-base values, specific surface area, and porosity of RM surface was analyzed. To estimate the mechanical interfacial properties of epoxy/RM nanocomposites, the critical stress intensity factor (K$_{IC}$) was measured. From the experimental results, it was clearly revealed that the porosity, specific surface area, and acid values of RM surface were developed as the increase of the treatment concentration due to the increase of acidic functional group, including hydroxyl group on RM surface. The mechanical interfacial properties of epoxy/treated-RM nanocomposites were higher than those of epoxy/RM as-received due to an improvement of interfacial bonding between basic matrix and RM surface.

• Journal of Conservation Science
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• v.24
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• pp.37-42
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• 2008

Stability of the moving historic sites have something to do with the degree of easiness of work as well as physical property of polymer product. These agents should be able to use without the effect of outer environments like water or low temperature and must have stability during progress of working the peel off Urethane pre-product from Epoxy surface. So, we synthesized low viscosity epoxy resin and hardener with best physical quality and separation media for the moving of historical sites. These products have very good tension strength, adhesion strength, low viscosity and various physical properties that the users want. Particularly, separation media products have good separation of Urethane pre-products surface and Epoxy final product surface.

• Journal of the Korean Applied Science and Technology
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• v.12 no.1
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• pp.47-54
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• 1995

Water pollution, which is caused by surfactants, is increased by insolubility and excessive uses of detergents. The detergency properties of nine kinds of amphoteric surfactants derived from imidazoline were investigated and compared with sodium lauryl sulfats(SLS) of petrochemical surfactant by using detergent formulations. Several physico-chemical properties were measured to investigate the effective factors on detergency. From the comparision of these compounds with SLS, it was found that 1-(2-hydroxyethyl)-1- (3-sulfonatedpropyl)-2-undecyl-2-imidazolinum [IV] has the most outstnading characteristics of detergency and various fundamental properties. Therefore, this result is expected to do its environmental stability as a nonpolluting detergent. Detergency process of surfactants were discussed in relation to physico-chemical treatments. Performance improvement on detergency is made work of adhesion to soil as small as possible. Therefore these results show that contamination is easily removed and industrial applications may be respected.

• Elastomers and Composites
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• v.34 no.3
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• pp.222-228
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• 1999

In this work, the effect of chemical treatments on the carbon blacks as-received has been studied in the context of surface, adsorption, microstructure properties, and physical surface free energetics. As an experimental result, the basic chemical treatment leads to an increase in the either dispersive or specific component without significant change the pH and specific surface area. While, acidic chemical treatment do significantly change the surface and adsorption properties, and microstructures of the carbon blacks. In particular, the result given by basic chemical treatment shows an increase of the London dispersive component of the surface free energy which is a major parameter in evaluating the dispersion or specific surface area of the carbon blacks studied. This is probably a major role in evaluating the dispersion the carbon blacks, which are reinforced in elastomer matrix in a composite system.

• Korean Journal of Materials Research
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• v.23 no.5
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• pp.281-285
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• 2013

In the present work, ZnO nanofibers were applied to electrode materials for the detection of cholesterol. ZnO nanofibers were synthesized using the electrospinning technique with zinc acetate as a precursor. Electrospinning-synthesized ZnO nanofibers were uniformly distributed by properly controlling the electrospinning parameters. After the calcination treatment, nanofibers of pure ZnO phase were synthesized. Then, these fibers were successfully placed on Au-coated glass substrates by dispersion of ZnO nanofibers in ethanol, dropping, and drying, in sequence. Cholesterol oxidase was then immobilized onto the surface of the ZnO nanofibers. To enhance the immobilization, Nafion was additionally applied. The sensing performances of the fabricated ZnO nanofibers-based sensors were analyzed by cyclic voltammetry in terms of cholesterol concentration ranging from 100 to 400 mg/dl. In the I-V curves, measured by cyclic voltammetry, the ZnO nanofiber-based sensor showed a proportional current behavior with cholesterol concentrations in phosphate buffered saline solution. The sensitivity was measured and found to be $30.7nA/mM{\cdot}cm^2$, which is comparable to the values reported in the literature. After not only optimizing the shape of the ZnO nanofibers but also improving the adhesion nature between the ZnO nanofibers and the Au conducting layer, these fibers can be a good candidate for electrode materials in devices used to detect low concentrations of cholesterol in blood.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.75-75
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• 2011

Recently, dye-sensitized solar cell (DSSC) attracts great attention as a promising alternative to conventional silicon solar cells. One of the key components for the DSSC would be the nanocrystalline TiO2 electrode, and the control of interface between TiO2 and TCO is a highly important issue in improving the photovoltaic conversion efficiency. In this work, we applied various interfacial layers, and analyzed their effect in enhancing photovoltaic properties. In overall, introduction of interfacial layers increased both the Voc and Jsc, since the back-reaction of electrons from TCO to electrolyte could be blocked. First, several metal oxides with different band gaps and positions were employed as interfacial layer. SnO2, TiO2, and ZrO2 nanoparticles in the size of 3-5 nm have been synthesized. Among them, the interfacial layer of SnO2, which has lower flat-band potential than that of TiO2, exhibited the best performance in increasing the photovoltaic efficiency of DSSC. Second, long-range ordered cubic mesoporous TiO2 films, prepared by using triblock copolymer-templated sol-gel method via evaporation-induced self-assembly (EISA) process, were utilized as an interfacial layer. Mesoporous TiO2 films seem to be one of the best interfacial layers, due to their additional effect, improving the adhesion to TCO and showing an anti-reflective effect. Third, we handled the issues related to the optimum thickness of interfacial layers. It was also found that in fabricating DSSC at low temperature, the role of interfacial layer turned out to be a lot more important. The self-assembled interfacial layer fabricated at room temperature leads to the efficient transport of photo-injected electrons from TiO2 to TCO, as well as blocking the back-reaction from TCO to I3-. As a result, fill factor (FF) was remarkably increased, as well as increase in Voc and Jsc.