• Journal of Conservation Science
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• v.25 no.3
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• pp.233-244
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• 2009

This study was focused on the transducer and suitable contact material for stone cultural heritage, and the correlation of direct-indirect method in rock types for scientific development and quantitative evaluation technique of the ultrasonic measurements. As a result, it was identified the transducer (UTREXTX(RX)54kHz) and contact material (rubber clay) of the type 3 were appropriate for the ultrasonic measurements of stone cultural heritage. The direct-indirect correction factors of type 3 were calculated 1.50 for granite, 1.38 for gabbro, 1.58 for quartz diorite, respectively. This result is the first study for improvement in reliability for the ultrasonic measurements, and it will contribute to establishment of the ultrasonic survey method for stone cultural heritage. Also, complementary studies considering the surface irregularity of rocks and various contact materials will carry out, and the database about correlation of direct-indirect in rock types will establish.

• Journal of Technologic Dentistry
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• v.40 no.2
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• pp.63-69
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• 2018

Purpose: The purpose of this study is to investigate the non-precious metal core materials used in the dental laboratory to fabricate the implant superstructure by CAD / CAM method. And to observe and compare the morphology and distribution of the osteoblasts in relation to implant osseointegration. Methods: In this study, the mandibular right first molar tooth model was selected as an international standard to produce a single core. Using this model, the impression was made with the silicone rubber, the tooth model was scanned, and a single core was designed and 5-axis milling was performed. The materials used were Cobalt-Chromium and Nickel-Chromium, and the cores for dental implant top structures were fabricated according to the procedures of the dental labs. After the fabrication, the marginal area of the core was separated and cell culture experiment was performed. The osteoblast cells used MC3T3-E1, which is currently widely used. For morphological analysis of osteoblasts, cells were posttreated and observed using CLSM (Confocal Laser Scanning Microscope) and compared. Results: The cell adhesion behavior of the specimen surface measured by CLSM was uniformly distributed in specimen A (Cobalt-Chromium) than in specimen B (Nickel-Chromium). The distribution and changes of the cells were different in the two specimens. Conclusion : It is possible to confirm that specimen A (Cobalt-Chromium) is suitable for the living body through adhesion and proliferation of osteoblasts related to implant osseointegration in the non-precious metal superstructure used after implantation. It is considered that it is preferable to use Co-Cr when fabricating the superstructure.

• Journal of Adhesion and Interface
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• v.6 no.3
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• pp.19-25
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• 2005

Synthetic rubber based pressure-sensitive adhesives (PSAs) usually containing SIS or SBS block copolymer, tackifier, plasticizer, and other additives are now widely used on various applications. As these PSAs are physically crosslinked and can be applied without the use of solvent, they are thermally processable and environmentally friendly. However these PSAs cannot be used in high temperature applications and in applications where solvent and chemical resistance properties are required. We developed the PSA adding UV curable system, such as thiol-ene system, to increase adhesion properties at elevated temperature. The adhesion properties such as probe tack, peel strength, shear adhesion failure temperature (SAFT) were evaluated. The probe tack test was conducted with varying probe materials and coating thickness of PSAs. Using the contact angle, the surface property of the cured PSAs was also observed.

• Elastomers and Composites
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• v.35 no.2
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• pp.89-97
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• 2000

Waterborne epoxy resins have been developed in order to meet environmental regulations for reduction of the emission of organic solvents from coating industry As each generation has filled a performance gap in the previous technology, new waterborne epoxy resin has developed. Initially, waterborne epoxy resins were used primarily on masonry, but the subsequent generations have found utility for the protection of metallic substrates as well. Indeed, the third generation systems have been formulated to produce the high performance industrial maintenance primers which possess the desirable combination of good corrosion resistance and low volatile organic compound levels. This paper outlines the important guidelines for formulating waterborne epoxy primers from waterborne epoxy resin that has recently developed in our company. The importance of using the appropriate resin-curing agent system at the optimized epoxy to amine ratio is stressed.

• Elastomers and Composites
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• v.50 no.2
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• pp.103-109
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• 2015

In this study, epoxy/anhydride mixing ratio for the highly silica filled compounds with chromium (III) octoate catalyst was investigated at a low curing temperature ($71^{\circ}C$ for 40 hr) by evaluating the compressive strength with the weight ratio ranges from 0.3/1.0 to 1.0/1.0 of epoxy part (Part A)/anhydride part (Part B). In case of epoxy/anhydride compounds used surface unmodified silica by coupling agent, these compounds need excess anhydride unlike the weight ratio in the conventional epoxy/anhydride compounds. In curing behavior, the epoxy/anhydride compounds containing chromium (III) octoate showed high conversions at $71^{\circ}C$ for 40 hr, even if a dipropylene glycol (DPG) was not used as a polymerization initiator. Also, DPG leads to a poor epoxy network structure. In conclusion, the appropriate weight ratio of Part A/Part B of highly silica filled epoxy/anhydride compounds with chromium (III) octoate catalyst is 0.5/1.0 and the maximum amounts of silica is 1470 phr of epoxy resin.

• Elastomers and Composites
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• v.48 no.3
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• pp.232-240
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• 2013

Microcapsules having healing agent were prepared in which 2,6-dimethylphenol (DMP) as a healing agent forms the core and melamine/formaldehyde resin forms the shell. Microcapsule-contained asphalts showed better mechanical properties than non-contained ones. And as the rest time passed the impact strength of microcapsule-contained asphalt was getting higher than that of asphalt without the microcapsule. As the rest time of 15 days passed, the original strength was restored. This tells that microcapsule-contained asphalt had the ability of self-healing. X-ray photos proved that DMP on asphalt fracture surface, which were burst out of the microcapsules when cracks occurred on asphalt, were polymerized to polyphenyleneoxide and this PPO covered the crack and healed the damage.

• Journal of Microbiology and Biotechnology
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• v.28 no.8
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• pp.1360-1366
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• 2018

The fungi associated with termites secrete enzymes such as laccase (multi-copper oxidase) that can degrade extracellular wood matrix. Laccase uses molecular oxygen as an electron acceptor to catalyze the degradation of organic compounds. Owing to its ability to transfer electrons from the cathodic electrode to molecular oxygen, laccase has the potential to be a biocatalyst on the surface of the cathodic electrode of a microbial fuel cell (MFC). In this study, a two-chamber MFC using the laccase-producing fungus Galactomyces reessii was investigated. The fungus cultured on coconut coir was placed in the cathode chamber, while an anaerobic microbial community was maintained in the anode chamber fed by industrial rubber wastewater and supplemented by sulfate and a pH buffer. The laccase-based biocathode MFC (lbMFC) produced the maximum open circuit voltage of 250 mV, output voltage of 145 mV (with a $1,000{\Omega}$ resistor), power density of $59mW/m^2$, and current density of $278mA/m^2$, and a 70% increase in half-cell potential. This study demonstrated the capability of laccase-producing yeast Galactomyces reessii as a biocatalyst on the cathode of the two-chamber lbMFC.

• Elastomers and Composites
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• v.46 no.3
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• pp.231-236
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• 2011

The polyacrylate/multi-walled carbon nanotube (MWNT) composites were prepared and investigated for the application as a counter electrode in solar cell. The electrical conductivity of the composites was increased with increasing MWNT content and with the thickness of the sheet. The surface resistivity value of the composite at 50 wt% loading of MWNT was 0.36 ${\Omega}$/sq. The thermal decomposition temperature of the composites was also increased with the MWNT contents, and the increase of $15^{\circ}C$ was observed at the composite of polyacrylate/MWNT (50/50, w/w). The increase of storage modulus of the composites was observed, especially at the higher temperature compared to polyacrylate. The dimensional change of polyacrylate decreased over $20^{\circ}C$, but that of the composite increased linearly with the temperature. The morphology of the composites stands for the good dispersion of MWNT into the polyacrylate matrix.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.5
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• pp.79-88
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• 2020

This paper propose the method to drive a solar panel cleaning robot efficiently on an inclined panel using vacuum pad pressure. In this method, the rubber pads using the vacuum pressure are used to attach robot body to the panel surface. By applying the linkage mechanism to the vacuum pads, it was possible to reduce robot weight and power consumption and to prevent slipping of the robot. In addition, the use of solenoid valves, proximity sensors, and encoders to detect movement of the robot body and the control of the pad pressure dedicate to the driving of the robot on an inclined panel. In order to move the robot forward, the operation sequence of multiple solenoid valves was completed, and the six vacuum pads mounted to both legs were accurately controlled to form vacuum and atmospheric pressure in right order so that the robot could move forward without slipping. At last, it was confirmed through experiments that straight-forward moving and rotational movement could be performed up to 36 degrees of inclination angle of solar panel.

• Journal of the Korean Electrochemical Society
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• v.3 no.3
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• pp.141-145
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• 2000

Anodically Polymerized conducting Polypyrrole film electrode was employed to Pick up uranyl ion with the type of Gr/ppy, xylenol orange modified electrode. To have Porous and oriented ppy film, NBR was applied as precoating agent. The rate constant of polymerization was $3.22\times10^{-3}s^{-1}$ which was 1.6 times smaller value than bare graphite surface. The deposited amount of uranyl iou on $1.70Ccm^{-2}$ of ppy was $1.55\times10^{-4}g$. The matrix effect in artificial seawater was $6.8\%$. The polymer film electrode has a diffusion controlled process in conduction, but the modified Gr/ppy, $X.O^{4-}UO^+$ type was influenced on the ion doping and electronic conduction of film itself owing to increasing of impedance. The capacitance of electrical double layer was respectively enhanced to 56 and 130 times in Gr/ppy, $X.O.^{4-}$ and Gr/ppy, $X.O^{4-}UO^+$ than Grippy type electrode.