• Food Science and Biotechnology
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• v.18 no.1
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• pp.202-206
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• 2009

Drying characteristics of fresh Korean-type rehmannia (jiwhang) noodle was investigated to determine drying kinetic parameters under the experimental conditions of 5 temperatures (30, 40, 60, 80, and $90^{\circ}C$). Drying curve of the noodle showed a biphasic pattern of decrease in drying rate with initial rapid drying followed by slow dehydration as the progress in drying. In all drying conditions, only falling drying rate period was observed and the drying rate of the noodle was greatly influenced by the drying temperature. The effective diffusion coefficients ($D_{eff}$) were determined by the diffusion model and their temperature dependency was determined using an Arrhenius equation. The activation energy ($E_a$) values for the drying of the noodle were 19.94 and 21.09 kJ/mol at the initial and the latter stage of dehydration, which were comparable to those of pasta or Japanese udong dehydration.

• Food Science and Biotechnology
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• v.18 no.5
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• pp.1293-1297
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• 2009

In this study, drying kinetics of onion slices was examined in a laboratory scale vacuum dryer at an air temperature in a range of $50-70^{\circ}C$. Moisture transfer from onion slices was described by applying the Fick's diffusion model, and the effective diffusivity was calculated. Temperature dependency of the effective diffusivity during drying process obeyed the Arrhenius relationship. Effective diffusivity increased with increasing temperature and the activation energy for the onion slices was estimated to be 16.92 kJ/mol. The experimental drying data were used to fit 9 drying models, and drying rate constants and coefficients of models tested were determined by non-linear regression analysis. Estimations by the page and Two-term exponential models were in good agreement with the experimental data obtained.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05b
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• pp.98-101
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• 2005

BSCCO thin films fabricated by using the evaporation method. As a result, although the composition of Bi2212 was set up, the phase of Bi2201, Bi2212 and Bi2223 was formed. The formation area of these stable phases is indicated as inclined line in the direction of the right lower end from the Arrhenius plot of the substrate temperature-oxidation gas pressure, and are distributed in very small area. The activation energy for the phase transformation from the Bi2201 to the Bi2212 is estimated in terms of the Avrami equation.

• Journal of the Korean Ceramic Society
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• v.31 no.3
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• pp.241-248
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• 1994

The ionic conductivity in glassy systems were calculated as functions of temperature and ion concentration using Monte-Carol method considering interaction between neighbouring ion-site occupancies, {{{{ rho }}'s. Also the vacancy availability factor, V, the effective jump frequency factor, W, and the charge correlation factor, fc, have been investigated. The Arrhenius plot could be obtained from the ln {{{{ sigma }}T vs. 1/T* plots and was in exellent agreement with the experimental observations. The effects of the various types of potential well on the ionic conductivity have been considered. The activation energy Eg for ion motion in the glass was 1.3│ε│from the ln {{{{ sigma }}T vs. 1/T* plots.

• Journal of the Korean Applied Science and Technology
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• v.2 no.2
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• pp.31-38
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• 1985

The transesterification reaction between ethanolamine and methyl-methacrylate was kinetically investigated in the presence of various metal acetate catalysts at $110^{\circ}C$. The transesterification was found to obey first-order kinetice with respect to the concentration of ethanolamine and methyl-methacrylate, respectively. By the Arrhenius plot, the activation energy has been calculated as 11.9 Kcal with lead acetate catalyst, 14.7 Kcal without catalyst. The reactivities has highest value where the electronegativity and instability constant (Kij) values for the metal acetate catalysts are about 1.6.

• Journal of the Korean Chemical Society
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• v.14 no.4
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• pp.333-339
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• 1970

1) The copolymerzation of acrylamide $(M_1)$ with styrene $(M_1)$ was studied in absolute methanol solution at $50^{\circ}C$, using azobisisobutyronitrile as a initiator. The monomer reactivity ratios determined at $50^{\circ}C$ were as follows: $r_1=0.2,\;r_2=1.05$ and from these values, Q and e values for acrylamide were calculated as 0.37$(Q_1)$ and 0.45 $(e_1)$. 2) Overall activation energy of copolymer was calculated to 24.3K/cal mol, using the Arrhenius epuation. 3) Measurement of intrinsic viscosity and observation of physical properties were made on the copolymer.

• Journal of the Korean Chemical Society
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• v.11 no.1
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• pp.28-32
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• 1967

The direct acid leaching of domestic Marmatite concentrate at elevated temperatures and pressures was investigated. Almost 100 percent of zinc was extracted from the concentrate liberating free sulfur in 4 hours at $100^{\circ}C$ when the oxygen partial pressure was 5 atm. in sulfuric acid solution. By applying the Arrhenius equation to leach reaction in the range of $60^{circ}$ to $100^{\circ}C$ at the same oxygen partial pressure, 15.7 kcal per mole of activation energy was calculated. At the initial stage of leaching, the rate of reaction increased linearly by increasing temperature and pressure. The concentration of sulfuric acid gave minor effect to leaching velocity in the range of 5 to 20 percent. The particle size should be under 270 mesh for 100 percent extraction of zinc.

• Macromolecular Research
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• v.14 no.3
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• pp.338-342
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• 2006

The kinetic features of polymerization with an active site comprising cobalt dihalides ($CoX_2$, where X=Cl, Br, I) activated by methylaluminoxane (MAO) were investigated in 1,3-butadiene polymerization. The catalytic system exhibited the characteristic features of living polymerization. The initiation ($k_i$) and propagation ($k_p$) rate coefficients were estimated using the kinetic model for slow initiation previously reported by Shiono et al. The energy of activation fur the propagation reaction was calculated to be 27-30 $kJmol^{-1}$. The marked changes in reaction rate observed with different halides could be adequately described in terms of variations in the initiation process, with the same Arrhenius curve fitting propagation rate coeffcients estimated from all three halides, suggesting that the halide does not participate in the growing chain end.

• Macromolecular Research
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• v.8 no.4
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• pp.147-152
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• 2000

The activity of periodic acid as an initiator for the polymerization of acrylamide in aqueous medium was investigated. The rate of polymerization was found to be proportional to the monomer concentration to the 1.5th power in the range of 1.41-5.64 mol/L. The reaction order to the periodic acid concentration was 0.49, which indicated a bimolecular mechanism for the termination reaction in the range of 0.5-4.0$\times$10$\^$-2/ mol/L. Propagation rate increased with raising the temperature according to an Arrhenius expression resulting in the exhibition of an apparent activation energy of 87.8 kJ/mol in the temperature range of 60-80$\^{C}$. The addition of hydroquinone as a radical scavenger stopped the polymerization of acrylamide initiated by periodic acid. These results support that the polymerization proceeds via a radical chain mechanism .

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.7
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• pp.760-765
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• 1992

The material properties and the TFT characteristics fabricated on SiOS12T substrate by LPCVD using SiHS14T gas were investigated. The deposition rate showed Arrhenius behavior with an activation energy of 31Kcal/mol. And the transition temperature form amorphous to crystalline deposition was observed at 570$^{\circ}C$-580$^{\circ}C$. The strong(220) texture was observed as the deposition temperature increases. XRD analysis showed that the film texture of the as-deposited polycrystalline silicon does not change after annealing at 850$^{\circ}C$. The fabricated TFT's based on the as-deposited amorphous film showed superior electrical characteristics to those of the as-deposited polycrystalline films. It is considered that the different electrical characteristics result from the difference of flat band voltage(VS1FBT) due to the interface trap density between the gate oxide and the active channel.