• Carbon letters
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• v.16 no.1
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• pp.45-50
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• 2015

High crystallinity coke-based activated carbon (hc-AC) is prepared using a potassium hydroxide solution to adsorb carbon dioxide ($CO_2$). The $CO_2$ adsorption characteristics of the prepared hc-AC are investigated at different temperatures. The X-ray diffraction patterns indicate that pitch-based cokes prepared under high temperature and pressure have a high crystal structure. The textural properties of hc-AC indicate that it consists mainly of slit-like pores. Compared to other textural forms of AC that have higher pore volumes, this slit-pore-shaped hc-AC exhibits higher $CO_2$ adsorption due to the similar shape between its pores and $CO_2$ molecules. Additionally, in these high-crystallinity cokes, the main factor affecting $CO_2$ adsorption at lower temperature is the pore structure, whereas the presence of oxygen functional groups on the surface has a greater impact on $CO_2$ adsorption at higher temperature.

• Journal of the Korean Ceramic Society
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• v.20 no.4
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• pp.333-339
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• 1983

Semiconducting glaxe of iron system for the recent use as high Voltage porcelain insulators often showed the tendancy of unstable thermal properties. Thus the development of frit including magnetite was studied to cover the defect. In the experimental process melted and quenched frits were ground pelletized and heat-treated at various temperatures in the range of 800-1 $300^{\circ}C$ for various soaking time within 4 hours and then crystallized specimens were obtained. The speciment were studied with optical and electron microscope DTA x-ray diffractometer and electrometer The results obtained were as follows : 1) The optimum condition for the crystal growth of magnetite in the frite was the heat-treatment of $1300^{\circ}C$ for 3hrs and in this case the range of crystal size was $10-11\mu\textrm{m}$ 2) The activation energy for the crystal growth of magnetite was 21.1 kcal/mole. 3) The heat-treament at $1, 250^{\circ}C$ and $1, 300^{\circ}C$ resulted in the good thermal stability and the range of surface resistivity was $3.5{\times}10^4-4.0{\times}10^7$, /TEX> $\Omega$/$cm^2$ which was adguate to semiconducting frit. 4) The conduction mechanism seems to be due to the electron mobility rather than ion mobility and the activa-tion energy for the conduction was 0.07-0.15eV/mole for the heat-treated specimes in the range of 1, 250-1, 300C

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.6
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• pp.827-834
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• 2011

Epoxy/graphite/expanded graphite composites have been prepared in various weight ratios and thermal degradation and electrical properties were estimated in order to use for the bipolar plate materials in PEMFC. Thermogravimetric analysis (TGA) showed that the epoxy/graphite system cured by a curing agent GX-533 was most proper because its weight loss until $80^{\circ}C$ at which PEMFC would be operated was 0.3 wt%, and differential scanning calorimetry (DSC) analysis showed its cure temperature would be sufficient at $80^{\circ}C$. The activation energy for the cure reaction was 132.0 kJ/mol and the pre-exponential factor was $1.76{\times}10^{17}min^{-1}$. Electrical conductivity on the surface of the bipolar plate prepared under a pressure of 200 $kgf/cm^2$ was increased from 4 to 25 $S/cm^2$ by increasing expanded graphite (EG) content from 50 phr to 90 phr. The percolation threshold was initiated around 75 phr and the corrosion rate at 80 phr was 1.903 $uA/cm^2$.

• Biomedical Science Letters
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• v.17 no.1
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• pp.89-93
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• 2011

Asthma is an inflammatory airway disease and is characterized by the releases of inflammatory mediators including chemokines. They are mainly associated with the recruitment, activation and dysregulation of specific inflammatory cells, especially neutrophils in neutrophilic asthma. CC chemokines bind to CC chemokine receptors (CCRs) in the surface of their target cells. The aims of this study are to examine the CCR expression in neutrophils of bronchoalveolar lavage fluid (BALF) of asthmatic patients and to determine the alternation of migration and apoptosis of neutrophils by the BALF. We demonstrate that CCR3 strongly expresses in BALF neutrophils of asthmatic patients as compared to other CCRs and increases during apoptosis of the BALF neutrophils. The migration of asthmatic blood neutrophils increases in response to asthmatic BALF as compared to BALF of normal volunteer. In addition, asthmatic BALF includes the higher levels of IL-8 protein than normal BALF and it has no effect on apoptosis of asthmatic blood neutrophils. Taken together, our results indicate that CCR3 expression may be associated with unknown function of asthmatic BALF neutrophils and BALF may be involved in the recruitment of neutrophils into the airway, but not in the neutrophils apoptosis.

• Elastomers and Composites
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• v.37 no.2
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• pp.124-133
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• 2002

Waste PBT powder was depolymerized by saponification under the mild temperature conditions($80{\sim}110^{\circ}C$) and atmospheric pressure. In depolymerization of PBT, sodium hydroxide was more effective than potassium hydroxide. The depolymerization increased with increasing reaction temperature and decreasing particle size. The reaction kinetics of depolymerization could be expressed by the shrinking unreacted core model without product layer, in which the surface reaction was a rate determining step. The activation energy was 98.1 KJ/mol. The recovery ratio of the TPA obtained from the depolymerized PBT particles of 85.1 and $105{\mu}m$ for 6 hours was about 95%.

• Archives of Pharmacal Research
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• v.18 no.3
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• pp.169-172
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• 1995

The changes in blood pressure may relate to the alterations of the responsiveness to vasoconstrictors and vasodilators, and these alterations can arise the modifications in the properties of angiotensin II (AII) receptor. In order to examine the changes of AII receptor in the hypertensive mechanism of renin-dependent hypertensive rats (RHRs; two-kidney, one-ligated type), we compared the equilibrium binding characteristics of $[^3H]$All in adrenal cortex and medulla from RHRs and normotensive rats. The dissociation constants of AII binding in both tissues of RHRs were very similar to those in the respective tissue of normotensive rats. However, the maximum binding was increased from 805 to 1050 fmole/mg protein in the adrenal cortex of RHRs, and decreased from 172 to 126 fmole/mg protein in the adrenal medulla of RHRs. These results imply that the up- and down-regulation of the All receptor population on the cell surface of adrenal glands from RHRs are consorted with the elevation of blood pressure and the activation of renin-angiotensin system.

• Korean Journal of Materials Research
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• v.12 no.9
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• pp.718-723
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• 2002

$Ti_{1-x}$ $Al_{ x}$N thin films as barrier layer for memory devices application were deposited by reactive magnetron sputtering. The crystallinity, micro-structure, oxidation resistance and oxidation mechanism of films were investigated as a function of Al content. Lattice parameter and grain size of thin films were decreased with increasing the Al content Oxidation of the film with higher Al content is slow and then, total oxide thickness is thinner than that of lower Al content film. Oxide layer formed on the surface is AlTiNO layer. Oxidation of $Ti_{1-x}$ /$Al_{x}$ N barrier layer is diffusion limited process and thickness of oxide layer with oxidation time increased with a parabolic law. The activation energy of oxygen diffusion, Ea and diffusion coefficient, D of $Ti_{0.74}$ /X$0.74_{0.26}$N film is 2.1eV and $10^{-16}$ ~$10^{-15}$ $\textrm{cm}^2$/s, respectively. $_Ti{1-x}$ /$Al_{x}$ XN barrier layer showed good oxidation resistance.

• Journal of Environmental Science International
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• v.4 no.1
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• pp.41-52
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• 1995

The effects of reaction temperature, SO2 and CO2 concentration in an air gas stream, particle sizes of limestone on the reactivity and capacity of SO2 removal have been determined in a thermogravimetric analyser(TGA). The apparent reaction order of sulfation reaction of pre-calcined lime(CaO) with respect to SO2 is found to be close to unity. The apparent activation energies are found to be 17,000 kcal/kmol for sulfation of pre-calcined lime and 19,500 kcal/kmol for direct sulfation of limestone(CaCO3). The initial sulfation reaction rate of pre-calcined lime increases with increasing temperature, whereas the sulfur capture capacity exhibits a maximum value at 90$0^{\circ}C$. In direct sulfation of limestone, sulfation reactivity and sulfur capature capacity of sorbent increase with increasing temperature and decreasing CO2 concentration in a gas bulk stream. The main pare of pre-calcined lime is shifted to the larger pore sizes and pore volume decreases with increasing sulfation time and temperature. The surface area of lime decreases with increasing calcination temperature under an air atmosphere, whereas is yearly constant under a CO2(5, 10%) atmosphere in a gas stream.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.05a
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• pp.105-109
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• 1992

ITO film, 1500${\AA}$ of thickness, onto glass and p-InP wafer was prepared by e-beam evaporator. The bet ITO film had the resistivity 5.3${\times}$10$\^$-3/ $\Omega$-cm, the concentration 6.5${\times}$10$\^$20/cm$\^$-3/, the transmittance above 80%, and the optical energy gap about 3.5eV. The higher pressure of injected oxygen, the less reverse bias saturation current and the more open circuit voltage. Under the optimum evaporation conditions, the efficiency was 7.19% and the series resistance, and the shunt resistance were respectively 8.5%, 3${\alpha}$, and 26K$\Omega$. The interdependence between activation energy and pre-exponential factor was found. We found he surface of the p-InP became n-type and consquently supposed that the buried homojunction formation, that is, n+-ITO/n-InP/p-InP was caused by Sn diffusion or loss of phosphorus in the interface layer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.12
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• pp.1091-1098
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• 1998

Thermal stability of the electroless deposited Cu thin film was investigated. Cu/TaN/Si multilayer was fabricated by electroless-depositing Cu thin layer on TaN diffusion barrier layer which was deposited by MOCVD on the Si substrate, and was annealed in $H_2$ ambient to investigate the microstructure of Cu film with a post heat-treatment. Cu thin film with good adhesion was successfully deposited on the surface of the TaN film by electroless deposition with a proper activation treatment and solution control. Microstructural property of the electroless-deposited Cu layer was improved by a post-annealing in the reduced atmosphere of $H_2$ gas up to $600^{\circ}C$. Thermal stability of Cu/TaN/Si system was maintained up to $600^{\circ}C$ annealing temperature, but the intermediate compounds of Cu-Si were formed above $650^{\circ}C$ because Cu element passed through the TaN layer. On the other hand, thermal stability of the Cu/TaN/Si system in Ar ambient was maintained below $550^{\circ}C$ annealing temperature due to the minimal impurity of $O_2$ in Ar gas.