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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Korean Chemical Engineering Research
Journal Basic Information
Journal DOI :
The Korean Institute of Chemical Engineers
Editor in Chief :
KIM JAE JEONG
Volume & Issues
Volume 33, Issue 6 - Dec 1995
Volume 33, Issue 5 - Oct 1995
Volume 33, Issue 4 - Aug 1995
Volume 33, Issue 3 - Jun 1995
Volume 33, Issue 2 - Apr 1995
Volume 33, Issue 1 - Feb 1995
Selecting the target year
Leach Rate Expression Based on Equilibrium Concept and Realistic Boundary Conditions and Model Validation
Kim, Chang-Lak ; Cho, Chan-Hee ; Choi, Heui-Joo ; Lee, Myung-Chan ; Kim, Jhin-Wung ;
Korean Chemical Engineering Research, volume 33, issue 2, 1995, Pages 139~139
A model equation for nuclide leaching from cementitious waste form is formulated based on diffusion, sorption equilibrium, and the continuity boundary conditions of concentration and flux on the waste form surface. Nuclide release unrelated to diffusive transport mechanism is reflected in the model as a wash-off fraction which depends on the surface conditions of the waste form. This leaching model is validated by comparison with the results of leaching experiments in various environments including land water, sea water and soils. It is expected that this leaching model will be used satisfactorily in analyzing various leaching experimental results.
Hydrodesulfurization of Dibenzothiophene over Molybdenum Nitride Catalysts
Lee, Jihn-Koo ; Park, Hea-Kyung ; Kim, Moon-Chan ; Kim, Kyung-Lim ;
Korean Chemical Engineering Research, volume 33, issue 2, 1995, Pages 147~147
catalysts were prepared by topotactic reaction method. The catalysts characterization and hydrodesulfurization of n-decane containing 0.5 mol% dibenzothiophene was studied in a fixed bed continuous flow reactor. The XRD and BET studies showed that the extent of the crystallinity and the surface area of the prepared
catalysts increased when the temperature ramping rate was lowered and the packing weight was reduced. After stabilized in the incipient stage of the reaction the nitride catalysts showed constant hydrodesulfurization activity and the surface area showed very little change. The acidity and the hydrodesulfurization activity increased in the order of $Mo_2N
Cell Performances of Proton Exchange Membrane Fuel Cell as to Operation Conditions
Rho, Yong-Woo ; Cho, Won-Ihl ; Kho, Young-Tai ; Lee, Jin-Hong ; Mok, Young-Il ;
Korean Chemical Engineering Research, volume 33, issue 2, 1995, Pages 157~157
The performance of proton exchange membrane fuel cell was investigated to optimize the fabrication method of membrane/electrode assembly, and to find appropriate operation conditions such as pressure, temperature and inlet gas humidification, It is the membrane electrolyte that has decisive effect on the cell performance. The optimum condition for humidification could be found by varying the inlet gas temperatures. Gas temperature
for oxygen and
for hydrogen higher than that of cell temperature was found to the optimum humidification condition irrespective of the cell temperature. Increase in temperature and/or pressure generally resulted in enhanced cell performance. The cell performance operated at 1 atm, however, exhibited an interesting temperature dependence. Enhanced performance with increasing temperature was observed up to
, whereas cell temperature showed no appreciable effect on the cell performance above
. This observation might be attributed to the increased vapor pressure, with increasing temperature, which dilutes inlet gas composition. Cells operated at higher pressure did not show this behavior where the effect of increased vapor pressure becomes relatively insignificant.
Theoretical Analysis of Mass Transfer in Perstraction Using Regular Arrays of Hollow Fibers
Lee, Ho-Won ; Kim, Woo-Sik ;
Korean Chemical Engineering Research, volume 33, issue 2, 1995, Pages 165~165
The purpose of this study is to clarify perstraction(permeation-extraction) factors and to analyze separation mechanism in perstraction using hollow fiber modules. The analytical solution on the concentration profiles in hollow fiber modules has been obtained. Also, using this solution, separation mechanism was analyzed by comparing the mass transfer rate changes according to the changes in perstraction factors such as the properties of hollow fibers, distribution coefficient, potting density, and the thickness, porosity and tortuosity of the hollow fibers. The analyses based on concentration profiles show that the mass transfer rate depends mainly on the solute diffusion in the membrane phase, and it has maximum values when the ration of diameter to pitch is between 0.8-0.9. While hydrophilic membrane shows faster mass transfer rates in the system with the distribution coefficient less than 1, hydrophobic membrane shows faster mass transfer rates when the distribution coefficient is above 1.
The Fluid Mixing Characteristics of Internal Loop Bubble Column
Park, Chan-Jin ;
Korean Chemical Engineering Research, volume 33, issue 2, 1995, Pages 177~177
To study the characteristics of mixing of liquid in gas-liquid flow with solid particles which can be applied in the wet FGD process and carbon dioxide wet removal process, Residence Time Distribution Curves obtained in the circulating slurry flow were analyzed. Mixing time of liquid was reduced with the increase of superficial gas velocity and concentration of solid particles due to coalescence of bubbles, and it had the same tendency with the size of particles at low gas flow rate. Such tendencies could be well explained by the equation from Kolmogoroff's isotropic turbulence theory with Bodenstein numbers.
A study on Modeling of Tube Furnace Reactor for Manufacture of Ultrafine
Hyun, Bong-Su ; Kim, Kyo-Seon ;
Korean Chemical Engineering Research, volume 33, issue 2, 1995, Pages 183~183
The results of numerical model for a tube furnace reactor were proposed to manufacture ultrafine
powders. The model equations such as continuity, energy balance and mass balance equations, and the 0th, 1st, and 2nd moment equations of aerosols were considered. The phenomena such as
nucleation rate and the coagulation, diffusion and thermophoresis of
powders were included in the aerosol dynamic equations. It is found that the
particle concentration becomes higher, as the furnace temperature decreases and also as the inlet
concentration and the total gas flow rate increase. On the other hand, the
particle size increases, as the furnace temperature and the inlet
concentration increase and also as total gas flow rate decreases.
Analysis of Chromatographic Response Curve Behavior with Capillary Condensation
Song, Dong-Ik ;
Korean Chemical Engineering Research, volume 33, issue 2, 1995, Pages 192~192
A mathematical model has been introduced for the bed packed with porous particles in which capillary condensation has occurred. Estimation methods for the parameters related to capillary condensation were suggested using the results for the computation of the pore size distribution obtained from the experimental data during desorption process. Variations of the chromatographic response curve were predicted with the degree of capillary condensation. As the degree of capillary condensation increases, response becomes faster and the peak value of the normalized response curve increases within about 30%, Sensitivity test revealed that Peclet number is the most sensitive parameter and partition coefficient becomes sensitive when it is approximately greater than 1. Sensitivity of the gas phase effective diffusivity was found to be very small and the optimum experimental condition for the determination of the reliable effective diffusivity was examined.
Aromatization of n-Hexane over Modified HZSM-5 Catalysts 2. Aromatization over Ga/Hzsm-5
Lee, Jun-Won ; Rhee, Hyun-Ku ;
Korean Chemical Engineering Research, volume 33, issue 2, 1995, Pages 204~204
HZSM-5 catalyst was synthesized and modified by impregnating Ga. The modified catalyst was then applied for the aromatization of n-hexane to give rise to a substantial improvement in the selectivity to aromatics. The aromatics were observed even over Ga/HZSM-5 of high Si/Al ratio. The aromatics turned out to be the secondary product in contrast to their bing tertiary product over HZSM-5. With respect to the aromatics formation the primary and major product was found to be toluene over Ga/HZSM-5 of low Si/Al ratio whereas it was benzene over Ga/HZSM-5 of high Si/Al ratio. Evidently, this feature was related to the ratio of the amount of propylene to that of
-hydrocarbons in the reaction mixture. The hydrogen production was significantly increased by the introduction of Ga regardless of the formation of aromatics. By virtue of the Ga's role of hydrogen scavenger more olefins were formed by cracking reactions and the dehydrocyclization seemed to be promoted. Apparently, this gave rise to the enhancement of the aromatizing activity. From these results the reaction pathways were deduced for the n-hexane conversion over bifunctional Ga/HZSM-5 catalyst and compared with those over HZSM-5 catalyst.
A Theoretical Study on MEK-Water Separation by Azeotropic Distillation
Kim, Hyung-Kyu ; Yi, Jung-Seok ; Han, Choon ; Na, Byung-Ki ; Chung, Yon-Soo ; Song, Hyung-Keun ;
Korean Chemical Engineering Research, volume 33, issue 2, 1995, Pages 213~213
MEK(methyl ethyl ketone) cannot be separated from water by normal distillation because of the presence of minimum boiling azeotrope. However it can be separated by azeotropic distillation by adding entrainer. The best entrainer was selected by considering the ratio between infinite dilute activity coefficients of each component for suggested entrainers and relative volatilities. From this method, acetone was selected as the best entrainer for the MEK-Water system. When the distillation tower was simulated by the UNIFAC equilibrium model for this MEK-Water-Acetone system, the minimum reflux ratio was observed as 0.6. Also, the optimum feed-plate was calculated at each reflux ratio for various amounts of entrainer. Results indicated the number of ideal plates decreases with the amount of entrainer. As the best results, 13 ideal plates were required to obtain 95 mole% of MEK as the bottom product from 70 mole% of MEK of the MEK-Water solution when the reflux ratio and the ratio of entrainer to feed were 0.85 and 2, respectively. In this case, the optimum feed-plate location, which required the minimum number of ideal plates, was the eighth.
Performance Characteristics of Phosphoric Acid Fuel Cell Electrode by Acceleration Test
Kim, Chang-Soo ; Song, Rak-Hyun ; Shin, Dong-Ryul ;
Korean Chemical Engineering Research, volume 33, issue 2, 1995, Pages 225~225
The effects of polytetrafluoroethylene(PTFE) contents and sintering temperature of electrocatalyst on the electrode performance for phosphoric acid fuel cell have been studied by an acceleration test of cathode half cell, and measurement of the phosphoric acid absorption of catalyst layer and support. The acid absorption in catalyst layer was saturated after 10 hours, but that of electrode support layer was continuously increased. While the performance of electrode showed maximum in the low PTFE contents at the initial stage of acceleration test, the maximum performance was shifted to 45 wt% PTFE contents after 24 hours acceleration test. These phenomena were discussed with oxygen gain characteristics and microstructure variation caused by phosphoric acid absorption into electrode.
Preparation of Piezoelectric ZnO Thin Films by RF Magnetron Sputtering Method and Their Surface Analysis
Lim, Sang-Woo ; Shul, Yong-Gun ; Choi, Jei-Woon ; Lee, Jeon-Kuk ; Jung, Heyong-Jin ;
Korean Chemical Engineering Research, volume 33, issue 2, 1995, Pages 235~235
Zinc oxide thin films have been prepared on Si(100), Al/Si and
substrates by radio-frequency magnetron sputtering method under various deposition conditions. We have investigated the growth rate, crystal structure, morphology, chemical state and composition of the zinc oxide thin films. First of all, we investigated these properties at various sputtering pressures,
gas rations and with different substrates. The growth rate strongly depends on the sputtering pressure and
gas ratio, and also depends a little on the kinds of substrates. C-axis orientations were obtained under all the deposition conditions for sputtering pressures above
Torr. Contrary to our expectations, the stoichiometry of the zinc oxide films does not depend on the
gas ratio, but depends strongly on the sputtering pressure. Thus, the oxygen mole fraction in the chamber affects the growth rate and crystallinity, but not the stoichiometry of the zinc oxide films. On the other hand, the sputtering pressure strongly affects the stoichiometry as well as the growth rate and crystallinity. Finally, the growth rate, crystallinity and stoichiometry of the zinc oxide thin films changed slightly with the different substrates. Under a substrate temperature of
and RF power of 200W, we could obtain the stoichiometric zinc oxide films at sputtering pressure of
Torr for all of the substrates.
Liquid-Liquid Equilibria of Azeotropic Ternary Mixtures
Kang, Choon-Hyoung ;
Korean Chemical Engineering Research, volume 33, issue 2, 1995, Pages 243~243
For the azeotropic ternary systems which contain water, acetic acid, and either ethyl acetate, or N-propyl acetate, or N-butyl acetate as the entrainer, the binodal curves and the tie-lines are, respectively, determined using the titration method and the cross-section method at
. With the UNIQUAC model, these experimental equilibrium data are correlated with good accuracy. The UNIQUAC parameters for the binary pair of water and acetic acid are almost entrainer-independent. However those model parameters appear to be influenced by the temperature of phase separation to a considerable extent.
A Unified Correlation for the Bubble Size in Gas Fluidized Beds of Geldart Group A, B, D Particles
Choi, Jeong-Hoo ;
Korean Chemical Engineering Research, volume 33, issue 2, 1995, Pages 251~251
A unified correlation on the bubble size which considered coalescence and splitting of bubbles has been derived in gas fluidized beds of Geldart group A, B and D particles. In addition, correlations has been proposed to describe respectively the bubble flow faction of the excess gas flow rate A(
), the splitting frequency of the single bubble and the equilibrium bubble diameter on the condition that the coalescing rate is equal to the splitting rate in bubbles. The proposed correlation on the bubble diameter agreed satisfactorily to the data reported in the literature.
Separation of Deoxyribonucleotides by Capillary Zone Electrophoresis
Row, Kyung-Ho ;
Korean Chemical Engineering Research, volume 33, issue 2, 1995, Pages 258~258
The effects of the addition of isopropanol as a organic modifier and the effects of concentration of sodium dodecyl sulfate(SDS) in capillary zone electrophoresis are discussed in terms of resolution using the four deoxyribonucleotides of dAmp, dGmp, DTmp, and dCmp. The system is consisted of a
i.d. fused silica tubing(68.5 cm column length), a high-voltage power supply, and an UV detector set at 254nm. The effects of the eight different mobile phases on the column efficiency and resolution were compared to find the optimum mobile phase. The experimental results showed that the mobil phase of phosphate/Tris with 0.05 M SDS was most suitable for the separation of the components and the column efficiency(Number of theoretical plates) and resolution were affected by the separation voltage.
Process Simulation and Vacuum Distillation of Petroleum Atmospheric Residuum with Waste Lube Oils
Hwang, Jong-Sic ; Kim, Hyung-Rak ; Kim, Myung-Soo ;
Korean Chemical Engineering Research, volume 33, issue 2, 1995, Pages 264~264
The removal efficiency of the contaminated constituents existing in the waste automobile lube oils mixed with petroleum atmospheric residues during a re-refining process was investigated by a vacuum TBP distillation. The refined fuel oils and asphalts with higher qualities were obtained by this process and more than 95% of heavy metals, ash and carbon residue contents in the waste lube oils were eliminated to vacuum residues. The increased yield and improved quality of distilled products were identified in the range of 0-20% blending ratio of waste lube oils to atmospheric residues. These experimental results showed the reasonable agreements with the calculated values provided by process simulation using PRO II.