• Toxicological Research
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• v.34 no.1
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• pp.49-53
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• 2018

Cyclohexanone ($C_6H_{10}O$, CAS No. 108-94-1) is a colorless oily liquid obtained through the oxidation of cyclohexane or dehydrogenation of phenol. It is used in the manufacture of adhesives, sealant chemicals, agricultural chemicals, paint and coating additives, solvent, electrical and electronic products, paints and coatings, photographic supplies, film, photochemicals, and as an intermediate in nylon production. Owing to the lack of information on repeated inhalation toxicity of cyclohexaone, in this study, we aimed to characterize the subacute inhalation toxicity. B6C3F1 mice were exposed to 0, 50, 150, and 250 ppm of cyclohexanone for 6 hr/day, 5 days/week for 4 weeks via whole-body inhalation in accordance with the OECD Test Guideline 412 (subacute inhalation toxicity: 28-day study). Mortality, clinical signs, body weights, food consumption, hematology, serum biochemistry, organ weights, as well as gross and histopathological findings were evaluated between the control and exposure groups. No mortality or remarkable clinical signs were observed during the study. No adverse effects on body weight, food consumption, hematology, serum biochemistry, and organ weights, gross or histopathological lesions were observed in any male or female mice in any of the exposure groups, although some statistically significant changes were observed in organ weights. We concluded that no observable adverse effect level (NOAEL) is above 250 ppm in mice exposed to cyclohexanone for 6 hr/day for 5 days/week.

• New & Renewable Energy
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• v.4 no.1
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• pp.11-18
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• 2008

In-situ lithiated NiO has been manufactured as a conventional cathode material of molten carbonate fuel cell (MCFC), however this material has a weakness for commercialization of MCFC because NiO is spontaneously dissolved into the electrolyte under MCFC operating conditions, resulting in short circuit between cathode and anode. In this research, therefore, $Co(OH)_2$-coated Ni powder was prepared by precipitation method with controlling pH at low temperature and atmospheric pressure. Modified cathode was fabricated by a conventional tape casting method and sintered at 700$^{\circ}C$ in a $H_2/N_2$ atmosphere, Based on characterization result, Pore size distribution and porosity was suitable for the cathode of MCFC. According to the result of dissolution, Ni solubility of modified cathode was 33% lower than that of conventional cathode. In addition, modified electrode showed a good performance from the single cell operation.

• Journal of the Korean institute of surface engineering
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• v.39 no.3
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• pp.129-136
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• 2006

The high velocity oxy-fuel sprayed coatings of 38Ni-23Co-20Cr-11Al-3Y-5Ta, 25Ni-34Co-20Cr-11Al-3Y-2Re and 32Ni-34.5Co-22Cr-11Al-0.5Ir (in wt%) were oxidized at 1000 and $1100^{\circ}C$ in air in order to find the alloying effect of Ta, Re and Ir on the oxidation properties of the NiCoCrAlY-base coatings. The primary phase of the coatings was $Ni_3Al$. The oxides formed on the coatings consisted primarily of ${\alpha}-Al_2O_3$, together with some $CoCr_2O_4,\;CoAl_2O_4$, and $Al_5Y_3O_{12}$. Tantalum oxidized to $Ta_2O_5$ and $Ta_2O_{22}$. However, no oxides of Re and Ir were detected by XRD owing to their thermodynamic inertness and/or their small amount.

• Solar Energy
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• v.18 no.3
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• pp.15-24
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• 1998

There are mainly 3 heat losses from solar collector; top, bottom, and edge heat loss. Usually edge heat loss is small so that could be neglected. Of the total thermal losses occurring in a flat plate solar collector, top loss heat losses are dominant. Therefore it is necessary to calculate the top loss coefficient accurately in order to find out performance of solar collector. The flat plate solar collector(regenerator in summer) used in this study was made for year-round all conditioning. In order to find out collector efficiency for heating in winter without a system change, outdoor experiment was done. The top loss coefficient of this collector was about 3 to $4.5W/m^2^{\circ}C$. Futhermore use of selective coating in trickling surface can improve a performance of flat plate solar collector.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.3
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• pp.33-38
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• 2021

Recently, rollable and foldable displays are attracting great attention in the flexible display market due to their excellent form factor. To predict and prevent the mechanical failure of the display panels, it is essential to accurately understand the mechanical properties of brittle SiN_x thin films, which have been used as an insulating film in flexible displays. In this study, tensile properties of the ~130 nm- and ~320 nm-thick SiN_x thin films were successfully measured by coating a ~190 nm-thick organic nano-support-layer (PMMA, PS, P3HT) on the fragile SiN_x thin films and stretching the films as a bilayer state. Young's modulus values of the ~130 nm and ~320 nm SiN_x thin films fabricated through the controlled chamber pressure and deposition power (A: 1250 mTorr, 450 W/B: 1000 mTorr, 600 W/C: 750 mTorr, 700 W) were calculated as A: 76.6±3.5, B: 85.8±4.6, C: 117.4±6.5 GPa and A: 100.1±12.9, B: 117.9±9.7, C: 159.6 GPa, respectively. As a result, Young's modulus of ~320 nm SiN_x thin films fabricated through the same deposition condition increased compared to the ~130 nm SiN_x thin films. The tensile testing method using the organic nano-support-layer was effective in the precise measurement of the mechanical properties of the brittle thin films. The method developed in this study can contribute to the robust design of the rollable and foldable displays by enabling quantitative measurement of mechanical properties of fragile thin films for flexible displays.

• International Journal of Highway Engineering
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• v.13 no.4
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• pp.19-28
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• 2011

This study developed a solar radiation reflection pavement, so called a cool pavement, to lessen the urban heat island effect by coating a pavement surface with acrylic resins mixed with light-colored pigments. From a laboratory test, simulating solar heating process in pavements, the cool pavement reduced more than $12^{\circ}C$ of pavement temperature at $60^{\circ}C$ compared to a control porous pavement. With the increase of the mixing ratio of the pigments to acrylic resins, the temperature reduction effect increased, but its workability became worse due to higher viscosity. As a result, an appropriate mixing ratio was determined as 15%. The cool pavement had better durability than the control pavement: One quarter of Catabro loss and twofold dynamic stability. Its adhesion was also higher enough not to be debonded under traffic loading. In-situ noise and friction tests conducted in two field sites showed that the cool pavement reduced its noise level by 3.7dB in average and increased its friction level by 30% compared to the control pavement. The permeability of the cool pavement was little lower than the control pavement, but higher enough to satisfy the minimum requirement for porous pavements.

• Journal of the Korean institute of surface engineering
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• v.36 no.4
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• pp.296-300
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• 2003

Extended cylindrical magnetron sputtering system with rotating 600-mm long and 90-mm diameter graphite cathode and pulsed power supply voltage generator were developed and fabricated. Time-dependent Langmuir probe characteristics as well as carbon films thickness were measured. It was shown that ratio of ions flux to carbon atoms flux for pulsed magnetron discharge mode was equal to $\Phi_{i}$ $\Phi$sub C/ = 0.2. It did not depend on the discharge current in the range of $I_{d}$ / = 10∼60 A since both the plasma density and the film deposition rate were found approximately proportional to the discharge current. In spite of this fact carbon film structure was found to be strongly dependent on the discharge current. Grain size increased from 100 nm at $I_{d}$ = 10∼20 A to 500 nm at $I_{d}$ = 40∼60 A. To deposit fine-grained hard nanocrystalline or amorphous carbon coating current regime with $I_{d}$ = 20 A was chosen. Pulsed negative bias voltage ($\tau$= 40 ${\mu}\textrm{s}$, $U_{b}$ = 0∼10 ㎸) synchronized with magnetron discharge pulses was applied to a substrate and voltage of $U_{b}$ = 3.4 ㎸ was shown to be optimum for a hard carbon film deposition. Lower voltages were not sufficient for amorphization of a growing graphite film, while higher voltages led to excessive ion bombardment and effects of recrystalization and graphitization.

• Journal of the Korean Applied Science and Technology
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• v.22 no.2
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• pp.142-150
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• 2005

The natural graphite particles A and heat-treated graphite particles B at $1800\;^{\circ}C$ after pitch-coating were used as the anode base materials for lithium ion secondary battery. In order to improve the performance of anode materials, the base anode materials were treated with various acids. With the acid treatments of 62% $HNO_3$ and 95% $H_2SO_4$ aqueous solution, the specific surface area and electrical conductivity of base anode materials were increased, and the initial charge-discharge capacity and cycle performance were improved due to the elimination of structural defects.

• Elastomers and Composites
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• v.34 no.2
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• pp.128-134
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• 1999

Steel tire cords were coated via RF plasma polymerization of acetylene and butadiene gas in order to enhance adhesion to rubber compounds. Adhesion of tire cords was measured by TCAT and T-test as a function of type of gas, plasma powder, treatment time, gas pressure and Ar gas etching. Some samples were subjected to aging study in distilled water at $80^{\circ}C$ for a period of 7 days. After testing, tire cords were analysed by SEM to elucidate the adhesion mechanism. The highest adhesion values were obtained at 20W, 2min and 25mtorr for acetylene plasma polymerization, and l0W, 4min, 25mtorr for butadiene plasma polymerization. However, Ar plasma etching did not affect adhesion, while the adhesion of tire cords increased rather than decreased, contrary to expectations. It was not possible to elucidate failure mode by SEM, owing to the rough surface of the tire and the thin plasma polymer coating layer.

• Journal of Dental Rehabilitation and Applied Science
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• v.22 no.3
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• pp.221-230
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• 2006

Recently, the need for esthetic results has increased the interest for all-ceramic crown prosthesis. Furthermore, the development of zirconium core via CAD/CAM system has allowed the all ceramic restorations to be applied to almost all fixed prosthesis situations. But, the increased strength has been reported to increase in proportion with the bond strength of cement, and recently, the tribochemical system which increases the bond strength through, silica coating and silanization has been introduced. The purpose of this study was to compare the $Rocatec^{TM}$ system and $CoJet^{TM}$ system with the traditional acid etching and silanization method of the irconium based ceramic. The surface character was observed via SEM(X2000), and the bond strength with the resin cement were measured. 50 In-Ceram Zirconia (Adens, Korea) discs were fabricated and embedded in resin, group 1 was treated with glass-bead blasting and cleaning, group 2 was treated with 20% HF for 10 minutes and silanized, group 3 was treated with the $Rocatec^{TM}$ system, and group 4 was treated with the $CoJet^{TM}$ system. Each group was comprised of 10 specimens. The specimens were cemented to a $3mm{\times}5mm$ resin block with Super-Bond C&B. The shear bond strength was measured with the $Instron^{(R)}$ 8871 at a crosshead speed of 0.5mm/min. The results were as follows. 1. According to SEM results, there were little difference between group 1 & group 2, but in group 3 and 4, silica coating was detected and there was increase in surface roughness. 2. The shear bond strength decreased in the order of group 3(46.28MPa), group 4(42.04MPa), group 2(31.56MPa), and group 1(27.46MPa). 3. There was significant differnce between group 1&2 and group 3&4(p<0.05). From the results above, it can be considered that the conventional method of acid etching and silane treatment cannot increase the bond strength with resin cements, and that by applying the tribochemical system of $Rocatec^{TM}$ system and $CoJet^{TM}$ system, we can achieve a stronger all ceramic restoration. Further studies on surface treatments to increase the bond strength are thought to be needed.