• Journal of the Korean Ceramic Society
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• v.48 no.6
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• pp.571-576
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• 2011

Activity carbon (AC), Cu and $Cu_2O$ modified $TiO_2$ composites (Cu/$Cu_2O$-AC/$TiO_2$) were prepared using a sol-gel method. The characteristics of the composites were evaluated using Brunauer-Emmett-Teller (BET) surface area measurements, X-ray diffraction (XRD), energy dispersive X-ray (EDX) analysis and scanning electron microscope (SEM) analysis. A methyl orange (MO) solution under visible light irradiation was used to determine the photocatalytic activity. The degradation of MO was determined using UV/Vis spectrophotometry. $Cu_2O$, Cu and the cooperative effect of the AC increased the photo-absorption effect, thus increasing in photocatalytic activity.

• Journal of the Korean Ceramic Society
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• v.50 no.3
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• pp.226-230
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• 2013

We performed high pressure high temperature (HPHT) sintering for the 20 nm MgO powders at the temperatures from $600^{\circ}C$ to $1200^{\circ}C$ for only 5 min under 7 GPa pressure condition. To investigate the microstructure evolution and physical property change of the HPHT sintered MgO samples, we employed a scanning electron microscopy (SEM), density and Vickers hardness measurements. The SEM results showed that the grain size of the sintered MgO increased from 200 nm to $1.9{\mu}m$ as the sintering temperature increased. The density results showed that the sintered MgO achieved a more than 95% of the theoretical density in overall sintering temperature range. Based on Vickers hardness test, we confirmed that hardness increased as temperature increased. Our results implied that we might obtain the dense sintered MgO samples with an extremely short time and low temperature HPHT process compared to conventional electrical furnace sintering process.

• Journal of Environmental Health Sciences
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• v.31 no.6
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• pp.483-488
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• 2005

The waste seashells were used for the removal of hydrogen sulfide from a hot gas stream. The sulphidation of waste seashells with $H_{2}$S was studied in a thermogravimetric analyzer at temperature between 600 and $800^{circ}C$. The desulfurization performance of the waste seashell sorbents was experimentally tested in a fixed bed reactor system. Sulfidation experiments performed under reaction conditions similar to those at the exit of a coal gasifier showed that preparation procedure and technique, the type and the amount of seashell, and the size of the seashell affect the $H_{2}$S removal capacity of the sorbents. The pore structure of fresh and sulfided seashell sorbents was analyzed using mercury porosimetry, nitrogen adsorption, and scanning electron microscopy (SEM). Measurements of the reaction of $H_{2}$S with waste seashells show that particles smaller than 0.631 mm can achieve high conversion to CaS. According to TGA and fixed bed reactor results, temperature had influenced on $H_{2}$S removal efficiency. As desulfurization temperature increased, desulfurization efficiency increased. Also, maximum desulfurization efficiency was observed at $800^{circ}C$. Desulfurization was related to calcinations temperature.

• The Journal of Korean Academy of Prosthodontics
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• v.25 no.1
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• pp.41-54
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• 1987

The purposes of this study were to evaluate the color differences those can exist between different brands of porcelain with identical shade designation, and to find their causes. For these purposes the following experiments were executed: The color of each opaque and layered porcelain specimen was determined by spectral reflectance measurements with a spectrophotometer. The compositions of each opaque porcelain powder were analyzed by qualitative, and quantitative analysis. Microscopic structures of each opaque porcelain were observed by scanning electron microscope. The results were as follows: 1. Identical shade of different brands of porcelain produced significantly different colors. 2. Color differences among the three brands were found under different light sources. 3. Color differences among the three brands were mostly a result of differences in kinds and amounts of opacifying agents and fluxes and microstructure of porcelain systems. 4. When porcelain systems have similar compositions and firing cycles, they produced similar colors.

• Fashion & Textile Research Journal
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• v.16 no.3
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• pp.456-461
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• 2014

The objective of this study is to give PP(polypropylene) fabric a good affinity for water. Oxygen plasma was treated to PP fabrics in a commercial glow discharge reactor with different RF power, discharge pressure, and reaction time. The PP fiber surfaces were characterized by the measurement of contact angle and ESCA. A JEOL scanning electron microscope was used to observe the surface morphology of fibers. The spontaneous water uptake amount of PP fabrics was determined by the demand wettability test. To determine the effect of aging on the surface properties of $O_2$ plasma treated PP, all the above measurements of the samples were carried out after 1, 7, 30, 60, and 150 days. The results are as follows. The PP fiber surfaces treated by $O_2$ plasma treatment have a chemical composition that consisted of various oxygen containing polar groups. Consequently, the contact angles of the treated PP fibers decreased, which improved the water uptake rate of PP fabrics. Surface roughness of the treated PP affected the fabric wettabiity as well. Wettability of the treated PP decreased and leveled off with aging. The $O_2$ plasma treatment is a simple and effective method to increase the water uptake rate of PP fabrics.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.35-39
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• 2008

In this study, electromechanical properties of carbon nanotube (CNT) thin film on flexible substrates were measured using a micro-tensile machine with functionality of simultaneous measurements of displacement, load and electrical resistance. The CNT thin film of about 100 nm thick was deposited on flexible substrates, polyethylene terephthalate (PET) using spraying and ink-jetting techniques. To investigate the effect of process condition on the electromechanical properties of CNT thin film, sets of CNT samples were fabricated under various heat treatments and microwave process. The microstructures of the CNT thin film before and after tensile test were investigated using Scanning Electron Microscope (SEM), and the failure modes of the CNT thin films were identified to understand their electromechanical behaviors and interaction with the flexible substrates. Based on the experimental results, the use of CNT thin film as flexible electrodes and strain gages is discussed.

• The Journal of the Acoustical Society of Korea
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• v.14 no.6
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• pp.40-47
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• 1995

A system for measurement of ultrasonic velocity, attenuation and complex modulus of materials by using the spectral analysis method of pulses has been constructed and its performances are estimated. The system has a mechanical scanning part of an acoustic microscope with a ZnO plane wave transducer of the resonant frequency of 85MHz. Ultrasonic velocity has been obtained by the intervals of maxima (or minima) on the power spectrum of a pulse train reflected from the surface and bottom of a specimen, and attenuation has been obtained by the power spectra of three pulses reflected from the surface and the bottom of a specimen and the surface of a standard specimen. The measured results for materials such as fused quartz, polyester show that the system has very high accuracy.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.318.1-318.1
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• 2014

Metal nano-crystals have been received much attentions owing to their excellent catalytic property and surface plasmon effect. In the last decade, many studies on synthesizing well-dispersive nanoparticles and on understanding their distinct physical properties have been performed. There were tremendous reports revealing the electrochemical activities and enhancement of surface plasmonic effect were dependent mainly on the size, shape, and composition. So far, most fabrication methods have been based on vacuum based deposition techniques, such as chemical vapor deposition and electron-beam evaporation, and then annealed them to transform into the nanoparticles. Recently, there were several reports regarding to the photoinduced nano-crystal synthesis as an effective way to produce the metal nanoparticles. In this study, we report synchrotron x-ray mediated synthesis of Au nanoparticles on ZnO nanowires. ZnO nanowires were fabricated by hydrothermal method, and then they were dip into a solution having Au clusters. Detailed structural evolution of Au nanoparticles was investigated using scanning electron microscopy and photoluminescence measurements. The results on formation of well-dispersive Au nanoparticles on ZnO nanowires will be presented.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.242.2-242.2
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• 2014

Plasma-polymer thin films (PPTF) have been deposited on a Si(100) wafer and glass under several conditions such as different RF power by using plasma-enhanced chemical vapor deposition (PECVD) system. Ethylcyclohexane, ammonia gas, hydrogen and argon were utilized as organic precursor, doping gas, bubbler gas and carrier gases, respectively. PPTFs were grown up with RF (ratio frequency using 13.56 MHz) powers in the range of 20~60 watt. PPTFs were characterized by FT-IR (Fourier Transform Infrared), FE-SEM (Scanning Electron Microscope), AFM (Atomic Force Microscope), Contact angle and Probe station. The result of FT-IR measurement showed that the PPTFs have high cross-link density nitrogen doping ratio was also changed with a RF power increasing. AFM and FE-SEM also showed that the PPTFs have smooth surface and thickness. Impedance analyzer was utilized for the measurements of C-V curves having different dielectric constant as RF power.

• Macromolecular Research
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• v.14 no.4
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• pp.456-460
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• 2006

The electrical, morphological, and mechanical properties of poly carbonate (PC)/multi-walled carbon nan-otube (MWNT) composites were studied by electrical conductivity, electromagnetic interference shielding efficiency (EMI SE), scanning electron microscopy, and tensile strength measurements. In the electrical property analysis of the PC/MWNT composites, the percolation threshold of the PC/MWNT composites was observed between 1.5 and 2.5 wt% MWNT content. From the electrical conductivity and EMI SE studies, the theoretical values of the EMI SE were in good agreement with the experimental values of the EMI SE. From the morphology of the PC/MWNT composites, it was observed that MWNT is dispersed homogenously in the PC matrix. From the electrical conductivity and morphological studies, it was suggested that the percolation threshold of the PC/MWNT composites is related with the morphological results in that MWNT is apparently interconnected to form an electrical pathway. The mechanical properties of the PC/MWNT composites peaked at the MWNT content of 2.5 wt%.