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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 32, Issue 6 - Dec 1994
Volume 32, Issue 5 - Oct 1994
Volume 32, Issue 4 - Aug 1994
Volume 32, Issue 3 - Jun 1994
Volume 32, Issue 2 - Apr 1994
Volume 32, Issue 1 - Feb 1994
Selecting the target year
Effects of Catalyst Structure on Asphaltene Hydrodesulfurization
Rhee, Young-Woo ; Guin, James A. ;
Korean Chemical Engineering Research, volume 32, issue 1, 1994, Pages 1~1
The effects of catalyst pore structure on the catalyst activity observed in the catalytic hydrodesulfurization reactions of asphaltenes were studied. In the simplified model, effective diffusivity and surface area were calculated using important physical properties of catalyst and the experimental hydrodesulfurization activity was analyzed based on this calculation. The existence of a maximal point in catalyst activity observed in the reaction could be explained in terms of the trade-off between the effective diffusivity and surface area.
Cell Performances as to Manufacture and Operation Conditions of Unit Cell for PAFC
Kim, Yeong-Woo ; Lee, Ju-Seong ;
Korean Chemical Engineering Research, volume 32, issue 1, 1994, Pages 10~10
Unit cell performance(current density) was investigated as to various conditions. First of all, as increasing the catalyst contents up to 6w/o, the current density was increased, but decreased the utilization ratio of catalyst was. As thickness of electrode increased up to 0.2mm, the current density was increased but
gain was not good. The decrease of cell performance during at least 200hr was mainly due to the exhaustion effect of electrolyte. We anticipated that as the differences of cathodic gas pressure from anodic on increased, the cell performances were to increased unless the exhaustion of electrolyte. Z & paralleltype gas supply method was better one than those of I & cross-type and Z & counter-type.
Characteristics of the Freeboard Combustion in a Fluidized-Bed Coal Combustor II. Mathematical Modeling
Park, Yeong-Seong ; Ghim, Young-Sung ; Son, Jae-Ek ; Maeng, Ki-Suck ;
Korean Chemical Engineering Research, volume 32, issue 1, 1994, Pages 18~18
A mathematical model for the carbon combustion reaction in the freeboard of a fluidized bed combustor using domestic anthracite coal was developed by using the entrainment mechanism of unburned carbon particle and applying the related reaction kinetics. The extent of carbon combustion, gas composition and temperature distributions in the freeboard can be determined from the proposed model. It was also found that among the kinetic parameters, the surface reaction rate constant gives significant effects on the temperature and gas compositions in the freeboard, while the CO combustion reaction rate constant gives a dominant effect on CO composition in the freeboard.
A study on Separation of Cd(II) by Hollow Fiber Supported Liquid Membrane
Whang, Duk-Ki ; Park, Dong-Won ;
Korean Chemical Engineering Research, volume 32, issue 1, 1994, Pages 28~28
The extraction of cadmium(II) in aqueous HCl solution was carried with TOA(tri-n-octylamine) dissolved in aromatic organic solvents using HFSLM(hollow fiber supported liquid membrane). Hollow fiber module with constant volume was utilized to measure mass transfer coefficients of the extraction with aqueous solutions containing
of hydrochloric acid,
of cadmium(II) and o-xylene diluted organic solutions containing
of TOA at
. The experimental value of the overall mass transfer coefficient in the concentration of HCl 1mol/dm3 was
, which was accordant with theoretical value, and the mass transfer coefficient was increased with increasing initial concentration of HCL in aqueous solution and with increasing velocity of inner fibers.
Optimization of Pretreatment Conditions for Enzymatic Hydrolysis of Lignocellulosic Biomass
Lee, Jin-Suk ; Lee, Jun-Pyo ; Cho, Jae-Kyung ; Lee, Young-Woo ; Hong, Jong-Jun ; Park, Soon-Chul ;
Korean Chemical Engineering Research, volume 32, issue 1, 1994, Pages 36~36
For the development of large-scale enzymatic hydrolysis of lignocellulosics, the influence of various parameters has been studied. Steam explosion and delignification by NaOH have been adopted as a pretreatment process. Optimum pretreatment condition based on both cellulose yield and saccharification rate and yield were determined to be 6min for steam explosion at
and 0.2% NaOH for delignification. With the addition of
-glucosidase, the rate and extent of hydrolysis were increased significantly. Optimum enzyme loading was determined to be 15IU/g substrate with supplementation of
-glucosidase. The addition of surfactant(0.1%) increased the hydrolysis yield by 10%.
Modification of Cation Exchange Membrane Using the Polyelectrolyte
Chun, Kyoung-Yong ; Kim, Han-Sung ; Han, Jeong-Woo ; Joe, Yung-Il ;
Korean Chemical Engineering Research, volume 32, issue 1, 1994, Pages 42~42
Commercial cation exchange membrane was modified using poly(1-alkyl-4-vinylpyridinium iodide) as polyelectrolyte. And the electrochemical properties and permselectivity between
of the modified membrane were investigated. Ion exchange capacity, water content and specific conductivity of the modified membrane was lower than the original membrane(CL-25T). The smaller the molecular weight of polyelectrolyte was, the larger the adsorbed amounts were for same dipping time. As the adsorbed amounts were larger, permselectivity was increased, but specific conductance and ion flux were decreased. Permselectivity was also increased with the formular weight of alkyl group, and specific resistance of
, was proportional to permselectivity.
Manufacture of Graphite-Copper Composite Powder by the Electroless Plating Method
Lee, Jin-Young ; Han, Choon ; Ju, Jae-Baek ; Oh, Jong-Ki ;
Korean Chemical Engineering Research, volume 32, issue 1, 1994, Pages 51~51
The possibility of manufacturing the graphite-copper composite powder by the electroless plating method as well as effects of related variables on the deposition process have been examined. For the continuous coating of the copper layer, the activation of the surface of graphite particle was necessary and at least one minute of activation time was needed. Although initial concentrations of copper ions were found important on the initial reaction rate, the gave the same conversion at the final stage. Since the uniform coating could be achieved when the initial concentration of copper ion was higher than 0.25M/l, the thickness of copper layer could be controlled with the initial concentrations of copper ions. As the size of graphite particles became smaller, the amount of deposition was increased due to the larger surface area and active sites for the reduction of copper ions. Although the reaction occurred in the solution with the stoichiometric amounts of reactants, it could be accomplished with only a small amount of K-Na tartrate because of its repetitive participations during the reaction. An empirical equation was developed for the understanding and prediction of reaction rates, which gave the satisfactory results compared with the experimental data.
Effects of Bubble Breaking by Floating Material on Pressure Fluctuations in a Continuous Bubble Column
Kang, Yong ; Min, Byung-Tae ; Ko, Myung-Han ; Kim, Sang-Done ;
Korean Chemical Engineering Research, volume 32, issue 1, 1994, Pages 58~58
Effects of floating material on the bubble breaking were investigated by analyzing the pressure fluctuations in a bubble column operating continuously. The gas and liquid velocities, height from the distributor, and amount of floating material added in the column were selected as experimental variables. The variations of the mean value, standard deviation, skewness, kurtosis and spectral density function from the pressure fluctuations were determined with the variations of experimental variables. From the results of this study, the addition of floating material into the bubble column could improve the qualities of uniformity and stability of bubble flowing in the column.
Fractal Analysis of Pressure Fluctuations in a Gas-Liquid-Solid Fluidized Bed
Kang, Yong ; Min, Byung-Tae ; Ko, Myung-Han ; Kim, Sang-Done ;
Korean Chemical Engineering Research, volume 32, issue 1, 1994, Pages 65~65
To investigate the hydrodynamic characteristics of gas-liquid-solid fluidized beds considering the phase contact and flow phenomena of individual phase, fractal analysis has been adopted to manipulate the pressure fluctuation signal from the fluidized bed. The pressure fluctuation signals were measured in a gas-liquid-solid fluctuation signal from the fluidized bed. The pressure fluctuation signals were measured in a gas-liquid-solid fluidized bed of
acryle column. The size of fluidized particles was in the range of
, and the gas and liquid flow rates were in the range of
, respectively. The pressure fluctuation signals which were measured at a steady state were analyzed in terms of Rescaled Range analysis(R/S analysis) based on the concept of fractional Brownian motion, yielding the Pox diagram where the Hurst exponent and eventually local fractal dimension could be obtained. From the fractal analysis of the signals, the hydrodynamic charateristics of gas-liquid-solid fluidized beds could be described by means of the Hurst exponent; the Hurst exponent decreased with an increase in the gas flow rate, but it increased with an increase in the fluidized particle size. However, it exhibited a maximum with an increase in the liquid flow rate.
A Study on the Cavitation Erosion of Polymeric Materials
Kim, Ki-Ju ; Kim, Dong-Sup ;
Korean Chemical Engineering Research, volume 32, issue 1, 1994, Pages 72~72
The cavitation erosion tests of polymeric materials were made by using a magnetostriction vibratory apparatus in pure water. The results were as following : (1)The erosion rate of polymeric materials depends on the test time and increases as the amplitude of the vibration is increased. (2)Alicyclic epoxy resin and orthophthalic unsaturated polyester resin shows brittle fracture caused by the formation and growth of cracks while polypropylene and polyetherether ketone(PEEK) shows ductile fracture caused by plastic deformation and tearing. (3) It is also noted that the erosion resistance of the brittle materials shows a good correlation with fracture toughness, and that of the ductile materials is also correlated well with the degree of crystallinity.
Manufacture of Ultrafine Iron-Cobalt Alloy Powders Using Gas Phase Reaction
Park, Kyun-Young ; Jang, Hee-Dong ; Kim, Won-Baek ;
Korean Chemical Engineering Research, volume 32, issue 1, 1994, Pages 79~79
Ultrafine iron-cobalt alloy powders having diameters less than 0.1 micron were manufactured by hydrogen reduction of vapor mixtures of iron(II) chloride and cobalt(II) chloride. The effects of the following variables on chemical, morphological and magnetic properties of the powders were experimentally investigated : composition of iron and cobalt in the alloy powder, concentration of the metal chlorides in the vapor, flow rates of hydrogen and carrier gas(argon), conditions for the post-formation of oxide films on the powder surface, and the magnetic field applied where the powder is formed. Particle size distribution, chemical compositions of impurities, crystal structure and magnetic properties of the powders were measured using ICP, PIXE, XRD, EDS, XPS, TEM and VSM. The average particle size of the powder was in the range of 0.025 to 0.045 micron. Most of oxygen and chlorine, major impurities in the powder, were observed to exist on the surface of the powder. By applying a magnetic field where the powder is being formed, the curved chain of iron-cobalt alloy particles was straightened, and a higher coercive force was obtained. The maximum coercive force of the iron-cobalt powders was 1,466 oersted. The saturation magnetization of the powder ranged from 130 to 180 emu/g.
An Investigation on Performance of Oxygen Electrode with Silver Catalyst for Alkaline Fuel Cell
Cho, Jeong-Yoon ; Kim, Ji-Hyuk ; Kim, Yeong-Woo ; Kim, Hyung-Jin ; Lee, Ju-Seong ;
Korean Chemical Engineering Research, volume 32, issue 1, 1994, Pages 86~86
Double-layered porous oxygen electrode was manufactured with silver catalyst made by reduction of the silver salt and PTFE powder. The optimum PTFE powder content in catalyst layer was 15wt%. Ag-Bi-Ni-Ti catalyst containing dopants of 2wt% Bi, Ni, Ti showed the best catalytic activity, and this electrode exhibited stable electrode performance. In order to increase the porosity of catalyst layer, ammonium bicarbonate(ABC) was added. The electrode performance was improved by addition of ABC, and the optimum amount of ABC to catalyst layer was 2wt%.
Phase Behaviors and Fractionation of Polymer Solutions in Supercritical Fluids
Kim, Sun-Wook ; Lee, Sung-Bong ;
Korean Chemical Engineering Research, volume 32, issue 1, 1994, Pages 95~95
Through the observation of phase behaviors in polystyrene-toluene-
systems by varying
concentrations the LCST and UCST have been determined experimentally. Fractionation of those solutions has been performed utilizing liquid-liquid-liquid phase split phenomena. The experiment shows that only LCST has been detected when the concentration of
is 15.0wt% for the temperature range from
. We also observed UCST as well as LCST at 16.2wt% of
and the dramatic merge of two critical solution temperature curves by increasing
concentration to 16.6wt%. When the concentration of
is 16.6wt%, the fractionated polymer samples have been obtained at different experimental conditions, and those samples have been analyzed in terms of molecular weights and glass transition temperatures.
Analysis of Fluid-Solid System in a Fixed-Bed by Finite Element Method Using Mixed Coordinate II. Experimental Study and Simulation of Activated Carbon Adsorption for Single-Solute Chloroorganics : Parameter Estimation
Park, Pan-Wook ; Yun, Young-Sam ; Kweon, Oh-Sang ; Cho, Tae-Je ; JeungPark, Yong-Ok ;
Korean Chemical Engineering Research, volume 32, issue 1, 1994, Pages 103~103
Experimental studies and perdictive models for adsorption rate and fixed-bed adsorption column were used to investigate the performance of activated carbon in the removal of chloro-organic compounds in aqueous solution. Model equations in batch-reactor and fixed-bed column were solved by the technique of finite element method. Three species, chloroform(CF), monochloroacetaldehyde(MCA) and dichloroacetaldehyde(DCA), were the single solutes studied and activated carbon(Filtsorb : F-400) was used as a adsorbent. Experimental studies for adsorption isotherm, adsorption rate and for concentration history profiles bent. Experimental studies for adsorption isotherm, adsorption rate and for concentration history profiles of effluent from the column were compared with the results obtained from predictive models formulated by finite element method. Since the numerical simulations of the model were in good agreement with experimental data, the parameters estimated by the best fitting could make the models regenerate accurate adsorption rate and breakthrough curves.
Gas Diffusion in the Porous Electrode of Fuel Cell
Lee, Seung-Jae ; Kim, Min-Yong ; Shul, Yong-Gun ; Lee, Tae-Hee ;
Korean Chemical Engineering Research, volume 32, issue 1, 1994, Pages 113~113
For a fuel cell electrode, pore structure and gas diffusion were studied with different electrode fabrication methods and with different carbon papers used as catalyst layer support. And the fuel cell performance of each electrode was examined in the phosphoric acid half cell. Experimental results showed that the gas flow approached to Knudsen flow relatively more in the hot pressed electrode than in the air sintered electrode and that the higher oxygen flux permeated in the electrode gave the better cathode performance.