• Journal of the Korean Society of Food Science and Nutrition
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• v.17 no.2
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• pp.144-148
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• 1988

Differential scanning calorimerty(DSC) was used to study gelatinization phenomena of defatted rice, corn, wheat, potato starch and nondefatted rice and wheat starch at heating rate $5{\sim}15^{\circ}C/min$. Gelatinization temperature of defatted rice and wheat starch indicated $4{\sim}5^{\circ}C$ lower temperature than nondefatted starch. More rapid heating rate resulted in a increasing of the gelatinization enthalpy for various starches. A linear relation was observed between water content, heating rate and gelatinization temperature. From the linear relationship existing between water content and gelatinization enthalpy, minimum water content for the gelatinization were 41, 38, 33 and 30% of rice, potato, wheat and corn starch, respectively.

• Journal of the Mineralogical Society of Korea
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• v.31 no.1
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• pp.13-22
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• 2018

Aluminum silicates ($Al_2SiO_5$) undergo phase transitions among kyanite, andalusite, and sillimanite depending on temperature and pressure conditions. The minerals are often used as an important indicator of the degree of metamorphism for certain metamorphic rocks. In this study, we have applied classical molecular dynamics (MD) simulations and density functional theory (DFT) to the aluminum silicates. We examined the crystal structures as a function of applied pressure and the corresponding stabilities based on calculated enthalpies at each pressure. In terms of the lattice parameters, both methods showed that the volume decreases as the pressure increases as observed in the experiment. In particular, DFT results differed from experimental results by much less than 1%. As to the relative stability, however, both methods showed different levels of accuracy. In the MD simulations, a transition pressure at which the relative stability between two minerals reverse could not be determined because the enthalpies were insensitive to the applied pressure. On the other hand, in DFT calculations, the relative stability relation among the three minerals was consistent with experiment, although the transition pressure was strongly dependent on the choice of the electronic exchange-correlation functional.

• Food Science and Preservation
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• v.12 no.1
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• pp.54-61
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• 2005

The absorption characteristics and their physical properties of hot air, vacuum and freeze dried soybean curd powder were investigated. Absorption conditions were at 5, 15, and 25 t with $0.11\~0.93$ water activities. Equilibrium moisture content and the monolayer moisture content determined by prediction models showed highest value in the freeze dried soybean curd powder due to porous structure. Absorption energy decreased with increasing water activity was not affected by drying method. In the comparisons of the isothermal absorption models, Oswin model generally was the best fit model for isothermal adsorption of soybean curd powder.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.2189-2205
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• 1991

Thermodynamic properties of binary nonazeotropic refrigerant mixtures are estimated by using a modified Carnhan-Starling equation of state. In this study, pure component refrigerants such as R14, R23, R13, R13 B1, R22, R12, R134a, R152a, R142b, RC318, R114, R11, R123 and R113 are chosen and the thermodynamic properties of enthalpy and entropy are calculated in terms of relevant variables. The modified Carnahan-Starling equation of state is compared with the carnahan-Staring-De Santis equation of sate. Results show that the relative errors become slightly smaller with the equation of state proposed in this study. Correlations are obtained for the mixtures of which the vapor liquid equilibruim data are available to us in the literature. Those mixtures are R14/R23, R23/R12, R13/R12, R13/R11, R13B1/R22, R13B1/RC318, R12/RC138, R12/R114 and R12/R11. The binary interaction coefficients are found under the condition of minimizing the pressure deviations at the vapor liquid equiblibrium state and the estimation of the vapor liquid equilibrium for the refrigerant mixtures is done. Pressure-enthalpy and temperature-entropy diagrams are plotted for the refrigerant mixtures of specific composition.

• Korean Journal of Food Science and Technology
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• v.25 no.4
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• pp.334-339
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• 1993

Physicochemical properties such as amylose content, swelling power, gelatinization and DSC of legume starches were investigated. The granule shape of legume starches was oval. The size of cowpea and mung bean were smaller than kidney bean and red bean. The amylose content of mung bean and kidney bean was larger and were $25{\sim}29%$. Swelling power of kidney bean starch was much lower than other starches in all temperature range. In gelatinization temperature by Brabender amylogram, red bean starch was low, but kidney bean starch was rather high. Amylographic hot-paste viscosity and set back of cow pea, mung bean and red bean starches were high. But those of kidney bean starch were very low. DSC results Indicated kidney bean starch gelatinized in higher temperature. From above results, row pea and mung bean starches were similar in granule size and shape, solubility and swelling power, amylogram, and DSC thermogram. But kidney bean starch was very different and red bean starch was slightly different with the physicochemical properties of cow pea and mung bean starches.

• Korean journal of food and cookery science
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• v.12 no.2
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• pp.186-192
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• 1996

Retrogradation of non-waxy rice (NWR) and waxy rice (WR) cakes (45% moisture) stored at 5$^{\circ}C$, $25^{\circ}C$ and -2$0^{\circ}C$ was studied by differential scanning calorimetry (DSC) and enzymatic ($\beta$-amylase-puuulanase) method. With DSC, endotherms did not appear with rice cakes stored at room ($25^{\circ}C$) and deep freezing (-2$0^{\circ}C$) temperatures but did with samples stored at low temperature (5$^{\circ}C$), showing accelerated retrogradation by low temperature. Onset temperature (To) and peak temperature (Tp) did not change under 14 days at 5$^{\circ}C$ but enthalpy values ($\Delta$H) increased rapidly within one day and increased steadily until 5th day of storage, then equilibrated. Higher $\Delta$H were obtained with WR cakes than NWR cakes. It was suggested that more amylopectin recrystallization occured with WR than NWR. Degrees of gelatinization of rice cakes determined by enzymatic method increased in the following order: 5$^{\circ}C$ < $25^{\circ}C$ < -2$0^{\circ}C$. In contrast with DSC results, dogrees of gelatinization of NWR cakes, were relatively lower than that of WR cakes. However, increased retrogradation extents (melting enthalpies) caused reduced enzyme susceptibilities to $\beta$-amylase-pullulanase system, among NWR or WR cakes stored at 5$^{\circ}C$. The degrees of retrogradation of rice cakes stored at 5$^{\circ}C$ were higher than those stored at $25^{\circ}C$ and -2$0^{\circ}C$ without regard to the kind of rice. The higher sensitivity of the enzymatic method was obtained than that of DSC method when the degrees of retrogradation of rice cakes were determined during storage under this experiment conditions.

• Journal of the Korean Chemical Society
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• v.39 no.5
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• pp.384-392
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• 1995

Steady-state sublimation vapour pressures of anhydrous bismuth trichloride have been measured by the continuous gravimetric Knudsen effusion method from 370.6 to 488.8 K. Additional effusion measurements have also been made from 438.2 to 495.7 K by the torsion effusion method. Based on a correlation of ${\Delta}_H0298$.15 and ${\Delta}_H0298$.15, a recommended p(T) equation has been obtained for BiCl3(s); log(p/Pa)=－C/(T/K)－2.838log(T/K)－8.097${\times}$10-2(K/T)2＋22.588, where p is in Pa, T in Kelvin and ${\Delta}_H0298$.15 in kJmo1-1 and C=(${\Delta}_H0298$.15＋5.9988)/1.9146${\times}$10-2. Condensation coefficients and their temperature dependence have been derived from the effusion measurements.

• Korean journal of food and cookery science
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• v.13 no.5
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• pp.585-591
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• 1997

The proximate composition and physicochemical properties of three cultivars of Korean kidney bean sediments, Pink (PKB), Red (RKD) and White (WKB) were compared. No significant differences in the proximate composition and calorie were noticed among three samples. Sediment granule was oval/round and rough in all samples. The amylograms showed no peak and continuous increase of viscosity during heating. The water-binding capacities of the sediments were 322.4∼355.0%. The swelling power and solubility were 5.93∼6.68% and 3.76∼5.28%, respectively. The percent transmittances of the sediment suspension decreased linearly from 50$^{\circ}$∼75$^{\circ}C$. The gelatinization temperature and gelatinization enthalpy determined by DSC (Differential Scanning Caloriemeter) were much lower than those of starches.

• Journal of the Korean Chemical Society
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• v.24 no.2
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• pp.150-154
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• 1980

Kinetic studies of the reaction of benzyl benzenesulfonate with pyridine in acetone were carried out by the electric conductivity method under 1 to 2000 bars and at 20 to $40^{\circ}C$. The rate increases with increasing pressure and temperature. The activation enthalpy $({\Delta}H^{\neq}),\;entropy\;({\Delta}S^{\neq})$ and activation volume $({\Delta}V^{\neq})$ of the reaction are obtained by the above experiment. The isokinetic relationship between $({\Delta}H^{\neq})\;and\;({\Delta}S^{\neq})$ for pressure change in the reaction was shown, and its isokinetic temperature was $342^{\circ}K$. From all of the above results it was found that this reaction precedes on the $S_N2$ reaction mechanism in which the rate of the reaction was determined by $C{\cdots}N$ bond formation at transition state.

• Korean Journal of Food Science and Technology
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• v.35 no.2
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• pp.211-216
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• 2003

Absorption characteristics of hot air-. vacuum-, and freeze-dried ginger powder were investigated. Monolayer moisture content as determined by GAB equation was $0.257{\sim}0.540\;H_2O/g$, showing higher significance than BET equation. Absorption enthalpy was calculated based on different drying methods and water activities. Absorption energy decreased with increasing water activity but was not affected by drying method. Isotherm curves showed a typical sigmoid form. Among models applied for predicting equilibrium moisture content, Caurie model was the best fit model for ginger powder, showing the lowest prediction deviation of $1.2{\sim}5.4%$, followed by Henderson then Bradley models. The prediction model equations for the moisture content were established by in(time), water activity, and temperature.