• Journal of Magnetics
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• v.5 no.4
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• pp.116-119
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• 2000

Magnetic field dependence of magnetization reversal in Co/Pt multilayers was quantitatively investigated. Serial samples of Co/Pt multilayers were prepared by dc-magnetron sputtering under various Ar pressures. Magnetization reversal was monitored by magnetization viscosity measurement and direct domain observation using a magneto-optical microscope system, and the wall-motion speed V and the nucleation rate R were determined using a domain reversal model based on time-resolved domain reversal patterns. Both V and R were found to be exponentially dependent on the applied reversing field. From the exponential dependencies, the activation volumes for wall motion and nucleation could be determined, based on a thermally activated relaxation model, and the wall-motion activation volume was found to be slightly larger than the nucleation activation volume.

• Journal of the Korean Chemical Society
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• v.45 no.6
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• pp.603-607
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• 2001

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.1029-1030
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• 2010

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.2
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• pp.286-292
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• 1995

Proximate composition, dimension, water uptake and volume increase rates of three cultivars of Korean kidney beans, Pink(PKB), Red(RKB) and White(WKB) were compared. Significant differences in the proximate composition and calorie were not observed among samples. Hull removed samples showed the lowest ash content and the highest calorie. The rates of water uptake increased as the soaking temperature increased from 10~4$0^{\circ}C$. The moisture gain of the kidney beans during soaking showed a similar pattern to volume increase. Water uptake and volume increase rates were in the decreasing order of PKB, RKB and WKB. Moisture and volume gains held a linear relation with the square root of soaking time regardless soaking temperatures. The activation energies of water uptake and volume increase were 3033~3087 and 3077~ 3161 kcal/mole, respectively. The log time to reach a fixed moisture content showed a linear relation with soaking temperature regardless soaking temperatures. The z-values calculated from weight and volume changes decreased in proportions to the increase of hydration. The z-values of weight and volume to reach 50% hydration were 50.5~56.6$^{\circ}C$ and 48.4~61.2$^{\circ}C$, respectively.

• Korean Journal of Materials Research
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• v.21 no.3
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• pp.161-167
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• 2011

The stress-strain responses and oxidation properties of cold-rolled Zr-1.5Nb-O and Zr-1.5Nb-O-S alloys were studied. The U.T.S. (ultimate tensile strength) of cold-rolled Zr-1.5Nb-O-S alloy with 160 ppm sulfur (765 MPa) were greater than that of Zr-1Nb-1Sn-0.1Fe alloy (750 MPa), achieving an excellent mechanical strength even after the elimination of Sn, an effective solution strengthening element. The addition of sulfur increased the strength at the expense of ductility. However, the ductile fracture behavior was observed both in Zr-Nb-O and Zr-Nb-O-S alloys. The beneficial effect of sulphur on the strengthening was observed in the cold rolled Zr-1.5Nb-O-S alloys. The activation volume of cold-rolled Zr-1.5Nb decreased with sulfur content in the temperature region of dynamic strain aging associated with oxygen atoms. Insensitivity of the activation volume to the dislocation density and the decrease of the activation volume at a higher temperature where the dynamic strain aging occurs support the suggestion linking the activation volume with the activated bulge of dislocations limited by segregation of oxygen and sulfur atoms. The addition of sulfur was also found to improve the oxidation resistance of Zr-Nb-O alloys.

• Carbon letters
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• v.10 no.4
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• pp.293-299
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• 2009

Potassium hydroxide activated carbons were prepared from Egyptian petroleum cokes with different KOH/coke ratios and at different activation temperatures and times. The textural properties were determined by adsorption of nitrogen at $-196^{\circ}C$. The adsorption of iodine and methylene blue was also investigated at $30^{\circ}C$. The surface area and the non-micropore volume increased whereas the micropore volume decreased with the increase of the ratio KOH/coke. Also the surface area and porosity increased with the rise of activation temperature from 500 to $800^{\circ}C$. Textural parameter considerably increased with the increase of activation time from 1 to 3 h. Further increasing of activation time from 3 to 4 h was associated with a less pronounced increase in textural parameters. The adsorption of iodine shows the same trend of surface area and porosity change exhibited by nitrogen adsorption, with KOH/coke ratio and temperature of activation. Adsorption of methylene blue follows pseudo-first-order kinetics and its equilibrium adsorption follows Langmuir and D-R models.

• Bulletin of the Korean Chemical Society
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• v.33 no.5
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• pp.1523-1526
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• 2012

In this work, we prepared activated multi-walled carbon nanotubes/polyacrylonitrile (A-MWCNTs/C) composites by film casting and activation method. Electrochemical properties of the composites were investigated in terms of serving as MWCNTs-based electrode materials for electric double layer capacitors (EDLCs). As a result, the A-MWCNTs/C composites had much higher BET specific surface area, and pore volume, and lower volume ratio of micropores than those of pristine MWCNTs/PAN ones. Furthermore, some functional groups were added on the surface of the A-MWCNTs/C composites. The specific capacitance of the A-MWCNTs/C composites was more than 4.5 times that of the pristine ones at 0.1 V discharging voltage owing to the changes of the structure and surface characteristics of the MWCNTs by activation process.

• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.279-286
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• 2000

Magnetic field dependence of magnetization reversal in Co/Pt multilayers has been quantitatively investigated. Serial samples of Co/Pt multilayers have been prepared by dc-magnetron sputtering under various Ar pressure. Magnetization reversal was monitored by magnetization viscosity measurement and direct domain observation using a magneto-optical microscope system, and the wall-motion speed and the nucleation rate R were determined using a domain reversal model based on time-resolved domain reversal patterns. Both and R were found to be exponentially dependent on the reversing applied field. From the exponential dependencies, the activation volumes of the wall motion and nucleation could be determined based on a thermally activated relaxation model, and the wall-motion activation volume was revealed to be slightly larger than the nucleation activation volume.

• Bulletin of the Korean Chemical Society
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• v.31 no.5
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• pp.1209-1214
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• 2010

Reactions of 2-methyl-2-chloroadamantane (1) in a variety of pure and binary solvents have been studied at various temperatures and pressures up to 80 MPa. The sensitivity (m) to changes in solvent ionizing power of the Grunwald-Winstein equation, and the activation volume (${\Delta}V^{\ddag}$) are calculated from the specific rates. An excellent linear relationship (R = 0.997) for 1, log (k/$k_0$) = $0.80Y_{Cl}$ + 0.11, and the activation volume, ${\Delta}V^{\ddag}$ = -15.2 ~ -10.2 $mL{\cdot}mol^{-1}$ were observed. These values are similar to those for solvolyses of 1-adamantyl halides over the full range of solvents, suggesting that the unimolecular mechanism involving ion pairs is rate-determining. These observations are also compared with those previously reported for the corresponding 1-adamantyl derivatives and chloroformate esters.

• Journal of Environmental Science International
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• v.9 no.4
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• pp.345-349
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• 2000

Activated carbons were prepared from Korean coal by steam activation in this study. The variation of pore structure of the activated carbons were investigated according to different carbonization temperatures. Yield, surface area, pore volume and pore structure of this activated carbon were compared with those of activated carbon prepared without carbonization. The investigated carbonization temperature ranged from 700${\circ}C$ to 1,000${\circ}C$. Carbonization was carried out in nitrogen atmosphere for 70 minutes and activation was performed by steam at 950${\circ}C$ for 210 minutes. Surface area and pore volume of the resulting activated carbons increased with carbonization temperature. Also pore volume increased by 20% compared to the activated carbon without carbonization. Especially, in mesopore region, the activated carbon carbonized at 900${\circ}C$ had more pores by 60% than that of activated carbon carbonized at other temperature.