• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.5
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• pp.824-830
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• 1996

In order to minimize the deterioration of osmotic dried apple quality, the characteristics of mass transfer during osmotic dehydration such as solid gain(SG), weight reduction(WR) and moisture loss(ML) were investigated. Moisture and solid transfer were analyzed by Fick's law. The highest (equation omitted)E value was observed with severe browning at $60^{\circ}C.$ The concentration effect on (equation omitted)E were higher at high temperatures than at low temperatures. SG, WR and ML increased as immersion temperature, sugar concentration and immersion time increased. Higher concentration of sucrose led to more sucrose absorption resulting increase in SG. Diffusion coefficients of moisture increased with immersion temperature and sugar concentration. As concentration increased, diffusion coefficients of solids increased at $20^{\circ}C$ while it decreased at $40^{\circ}C$ and $60^{\circ}C.$ Arrhenius equation was appropriately explain the effect of temperature on diffusion coefficients. Moisture and solid diffusion showed high activation energy in 20 。Brix solution, compared with in 40 and 60 。Brix.

• Proceedings of the Korea Water Resources Association Conference
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• 1999.05a
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• pp.342-347
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• 1999

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2012.05a
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• pp.309-310
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• 2012

• Journal of the Korean Chemical Society
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• v.43 no.6
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• pp.656-662
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• 1999

We have obtained retention data of benzene, toluene, ethylbenzene, phenol, and acetophenone at 25, 30, 35, 40, 45 and 50 $^{\circ}C$ in 30/70, 40/60, 50/50, 60/40, 70/30, and 80/20 (v/v %) methanol/water eluents using a $C_18$ phase with a high ligand density. We drew van't Hoff plots from the data, and computed enthalpies and entropies of solute transfer from the mobile to the stationary phase. The cavity formation effect was found the major factor that governs the solute distribution between the mobile and stationary phases. The hydrophobic effect became significant in highly aqueous mobile phases. We also concluded that the Shodex C18-5B stationary phase was a polymer-like phase with a high ligand density, and followed a partially adsorption-like mechanism.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2009.11a
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• pp.261-262
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• 2009

• 순환기질환의공학회:학술대회논문집
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• 2004.11a
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• pp.30-31
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• 2004

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.05a
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• pp.114-114
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• 1994

• Journal of the Korean Chemical Society
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• v.38 no.3
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• pp.221-223
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• 1994

We tried to apply the linear solvation energy comparison method to solute retention in normal phase liquid chromatography. Correlation coefficients of regression of lnk' collected in a fixed eluent against solute polarity indices have proven to be lower than those obtained from reversed phase liquid chromatography data. This event can be attributed to complexity of solute retention process in normal phase liquid chromatography. We concluded from the regression results that each specific polarity of the stationary phase is greater than that of the mobile phase and that the difference in each polarity between the stationary phase and the mobile phase decreases as the volume fraction(${\phi}$) of the more polar solvent in the mobile phase increases. Correlations of lnk' of a single solute against solvent polarity indices have proven to be meaningless owing to covariance among the solvent polarity indices. Instead, a good linear relationship between lnk' and solvent ${\pi}^*$ was observed, and its linearity is better than that between lnk' and ${\phi}$.

• The Journal of Engineering Geology
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• v.18 no.4
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• pp.381-391
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• 2008

The eigenvalue technique is introduced to overcome the problem of truncation errors caused by temporal discretization of numerical analysis. The eigenvalue technique is different from simulation in that only the space is discretized. The spatially discretized equation is diagonized and the linear dynamic system is then decoupled. The time integration can be done independently and continuously for any nodal point at any time. The results of eigenvalue technique are compared with the exact solution and FEM numerical solution. The eigenvalue technique is more efficient than the FEM to the computation time and the computer storage in the same conditions. This technique is applied to the solute transport analysis in nonuniform flow fields around underground storage caverns. This method can be very useful for time consuming simulations. So, a sensitivity analysis is carried out by using this method to analyze the safety of caverns from nearly located contaminant sources. According to the simulations, the reaching time from source to the nearest cavern may takes 50 years with longitudinal dispersivity of 50 m and transversal dispersivity of 5 m, respectively.

• Economic and Environmental Geology
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• v.41 no.6
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• pp.719-729
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• 2008

In this study, the speciation, adsorption, and transport of uranium in groundwater environments were simulated using geochemical models. The retarded transport of uranium by adsortption was effectively simulated using 3-D groundwater flow and reactive transport models. The results showed that most uranium was adsorbed(up to 99.5%) in a neutral pH(5.5$pCO_2(10^{-3.6}atm)$ condition. Under the higher $pCO_2(10^{-2.5}atm)$ condition, however, the pH range where most uranium was absorbed was narrow from 6 to 7. Under very low $pCO_2(10^{-4.5}atm)$ condition, uranium was mostly absorbed in the relatively wide pH range between 5.5 and 8.5. In the model including anion complexes, the uranium adsorption decreased by fluoride complex below the pH of 6. The results of this study showed that uranium transport is strongly affected by hydrochemical conditions such as pH, $pCO_2$, and the kinds and concentrations of anions($Cl^-$, ${SO_4}^{2-}$, $F^-$). Therefore, geochemical models should be used as an important tool to predict the environmental impacts of uranium and other hazardous compounds in many site investigations.