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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 :
Volume & Issues
Volume 31, Issue 6 - Dec 1993
Volume 31, Issue 5 - Oct 1993
Volume 31, Issue 4 - Aug 1993
Volume 31, Issue 3 - Jun 1993
Volume 31, Issue 2 - Apr 1993
Volume 31, Issue 1 - Feb 1993
Selecting the target year
Study on the Etching Reaction of Silicon with Carbon Tetrafluoride in Electron Cyclotron Resonance Plasma Etching System
Yun, Min-Hee ; Kim, Chong-Bae ; Nahm, Kee-Suk ; Lee, Sang-Mok ; Park, Won-Il ; Lee, Kee-Bang ;
Korean Chemical Engineering Research, volume 31, issue 3, 1993, Pages 255~255
The etching reaction of silicon with
was studied in a home-made ECR(electron cyclotron resonance) plasma etching system. Experimental data for the etch rates of p-Si(100) and n-Si(100) were measured and analyzed with varying etch time, etching pressure,
flow rate, the partial pressure of
and etching temperature to investigate the characteristics of the etching system. The etch rates were almost the same for both p- and n-type Si(100) and increased with the increases in etching pressure and
flow rate, while the etch rate decreased because polymer film was formed on the Si surface at high pressure and reactive species were pumped away at high flow rate of
. The etch rate became maximum when the amount of
was about 15% and showed uniformity. The etching profile showed anisotropic etching at low pressure and isotropic etching at high pressure.
The Reaction of Dolomite with
Lee, Gun-Jik ; Kim, Won-Bae ; Kim, Jae-Young ; Yoo, Young-Hong ;
Korean Chemical Engineering Research, volume 31, issue 3, 1993, Pages 263~263
Calcium and magnesium were widely distributed over the world and the use have been increased gradually. Under these circumstances, the reaction of dolomite with
was carried out to develop a new process for the extraction of calcium and magnesium and to find the fundamental data for the reaction mechanisms from the reaction products. The overall reaction mechanism was as follows :
. And the optimum condition for the reaction of dolomite with
was as follows; reaction temp. :
, reaction time : 30 min, weight ration(
) : 8.0,
gas flow rate :
, particle size(av.) :
. Under the above condition, dissolved magnesium and calcium was 85.48%, 99.63% reapectively.
Design of Multiloop PI Controller
Lee, Jie-Tae ; Choi, Jin-Young ;
Korean Chemical Engineering Research, volume 31, issue 3, 1993, Pages 272~272
A procedure designing of a multi-loop PI controller, combining the IMC-PID tuning method and recent stability conditions, has been proposed. It competes with the well-known BLT method in simplicity and computation. Furthermore it is robust for the controller gain variations between zero and two times. Some simulations show that its control performances are better than those of the BLT method.
A Study of Methanol Conversion to Light Olefins over ZSM-5 Catalyst
Jeong, Jong-Hun ; Lee, Jun-Won ; Rhee, Hyun-Ku ;
Korean Chemical Engineering Research, volume 31, issue 3, 1993, Pages 279~279
From the experimental results of methanol conversion over HZSM-5 catalyst, it was observed that around
methanol was only dehydrated to DME(dimethylether) and the aromatization was promoted by the autocatalytic reaction of light olefins around
. When water was added to the reaction mixture, the selectivities to light olefins and aromatics were found to increase and the degree of deactivation to decrease due to the steam distillative effect exerted by water present in the pore. In case of HZSM-5 catalysts modified by metal impregnation, it was noticed that the
acid sites decreased because of the partial ion-exchange of
ions by metal ions and that redistribution of acid sites occurred since metal ions and metal-oxides gave rise to an increase in the Lewis acid sites. Also, it is evident that the crystalline metal oxide formed on the catalyst surface during the course of calcination played the role of pore-plugging. For these reasons, the metal impregnated HZSM-5 catalysts showed lower activity and lower rate of deactivation in comparison to the HZSM-5. In particular, the modified catalysts gave substantially higher selectivities to light olefins at the level of 100% conversion of methanol.
Heat Transfer Characteristics of Membrane Water Wall in a Fluidized Bed Coal Combustor
Park, Yeong-Seong ; Son, Jae-Ek ;
Korean Chemical Engineering Research, volume 31, issue 3, 1993, Pages 287~287
Heat transfer characteristics of membrane water wall have been determined in a pilot-scale fluidized bed coal combustor. The effects of fluidizing velocity(2.2-3.2 m/s) and bed temperature(
) on individual heat transfer coefficient and heat flux have been determined. The heat transfer coefficients of the in-bed membrane water wall increase with bed temperature, while it exhibits a maximum value with fluidizing gas velocity. Also, the heat transfer coefficients of membrane water wall were slightly lower than those of typical horizontal and vertical tube located in a fluidized bed. The heat transfer coefficients of free-board membrane water wall appeared to be 30-40% of those of in-bed membrane water wall and they increase with fluidizing velocity and bed temperature.
The Acidity and Shape-selectivity of Silicon Oxide Deposited HZSM-5 Catalysts Compared with Those of Boric Oxide Impregnated HZSM-5 Catalysts
Kim, Moon-Hyuck ; Kim, Hyoung-Jin ; Moon, Sei-Ki ;
Korean Chemical Engineering Research, volume 31, issue 3, 1993, Pages 295~295
In order to control the pore-opening size of HZSM-5, boric acid was impregnated on the HZSM-5 catalyst and silicon methoxide was used for Chemical Vapor Deposition(CVD) method. The catalysts were characterized by temperature programmed desorption of ammonia, infrared spectroscopy and adsorption experiments using water, p-xylene and o-xylene as adsorbate. Every result was compared with that of parent HZSM-5 catalyst. It was found that silicon oxide was deposited only on the external surface of the catalysts without changing the internal structure, while in the impregnated catalysts boron oxide was incorporated in the framework of a catalyst and occurred the change of the internal structure of a catalyst. The phenomena of pore-opening size control was tested by the alkylation of toluene with methanol and sorption experiments. From the results of reaction experiments over a series of silicon oxide deposited sample(SiHZSM-5), the yield and selectivity of p-xylene were increased with the contents of deposited silicon oxide. From the results of reaction experiments over a series of boron impregnated samples(BHZSM-5), the selectivity of p-xylene was increased as the above, but the yield of p-xylene was decreased as the contents of impregnated boron oxide was increased. In the aspect of the structural stability and activity of a catalyst, the CVD(chemical vapor deposition) by silicon methoxide was an more effective method to have control of the pore-opening size of a catalyst than the impregnation method by boric acid.
CNDO/2 MO Studies of
and CO Gas Penetration through the
of the Cation Saturated A-Zeolite
Kim, Young-Hoon ; Kim, Myung-Chul ; Kim, Dong-Hyun ; Hoe, Nam-Ho ; Kim, Jong-Taik ;
Korean Chemical Engineering Research, volume 31, issue 3, 1993, Pages 303~303
Penetration of gas molecules through the
of A-zeolite was studied theoretically. Total potential energies of the gas penetrating the system were calculated by means of CNDO/2 MO theory with the 8-R window model. Potential curves for the
and CO molecules indicated high possibilities of their penetration and those for the
illustrated the difficulties of their going through the plane. Cation position was flexible as spring to allow intruding molecules but required certain amount of activation energies according to the cation gas molecule interaction. The dislocation of the cations within the 8-R window due to the foreign gas penetration were visualized by the variation of distance between cation to
atom and the extent of the dislocation of cations and their characteristics were very dependent on the constituents of the gas molecule.
Liquid-Liquid Interfacial Area and Mass Transfer Characteristics in Liquid-Liquid Three-Phase Fluidized Beds
Kim, Sang-Done ; Lee, Dong-Hyun ; Kim, Dong-Yoon ; Hahn, Poong-Woo ;
Korean Chemical Engineering Research, volume 31, issue 3, 1993, Pages 311~311
The effects of the dispersed(0.01-0.03 m/s) and continuous phase velocities(0.02-0.08 m/s) and particle size(1-3 mm) on liquid-liquid interfacial area(a) and mass transfer coefficient(
) have been determined in a
Q.V.F. Pyrex glass column. Liquid-liquid interfacial area increases with increasing dispersed velocity, but it decreases with the continuou phase velocity in liquid-liquid three-phase fluidized beds. Mass transfer coefficient increases with increasing the continuous and dispersed phase velocities. The mass transfer coefficient of continuous phase in terms of Sherwood number in liquid-liquid three-phase fluidized beds has been correlated with Schmidt and particle Reynolds numbers based on the energy dissipation rate in the bed.
Extraction Rates of Vindoline and Catharanthine from Catharanthus roseus with Supercritical Carbondioxide
Song, Kyu-Min ; Hong, Won-Hi ; Lee, Huen ; Kwak, Sang-Soo ; Liu, Jang-Ryul ;
Korean Chemical Engineering Research, volume 31, issue 3, 1993, Pages 318~318
Vindoline and catharanthine were extracted from the pretreated leaves of Catharanthus roseus using supercritical carbon dioxide and their mass transfer coefficients were determined in various conditions of temperature and pressure. Extraction yields of vindoline and catharanthine were compared with the reduced density of supercritical carbon dioxide and the relational parameters were calculated in each given temperature. Defining the mass transfer coefficient of vindoline and catharanthine between solid phase and fluid phase, the mass transfer was studied by steady state analysis. Sherwood number obtained by this method was expressed as a function of Reynolds and Schmidt number.
Microbial Desulfurization of Coal by Sulfur Oxidizing Bacteria Thiobacillus ferrooxidans
Ryu, Hee-Wook ; Chang, Yong-Keun ; Kim, Sang-Done ;
Korean Chemical Engineering Research, volume 31, issue 3, 1993, Pages 325~325
To remove pyritic sulfur from coal, chemoautotrophic, acidophilic, iron-oxidizing bacterium Thiobacillus ferrooxidans was employed. Coal samples used in all the experiments were an anthracite coal obtained from the Han Yang Mining Company. The effects of various process variables(such as coal pulp density, salt concentration, particle size and initial cell density) on the pyritic sulfur removal rate has been determined. About 80-98% of pyrite(
) in coal could be removed by T. ferrooxidans within 11-15 days in a shake flask. The maximum pyritic sulfur removal rate increases linearly between 10 and 50%(w/v) of the pulp density and reaches a maximum level at 70%(w/v) of pulp density(1,117 mg-S/L day). The optimum operating conditions are found to be a pulp density of 70%(w/v), particle size less than 0.42 mm, and initial cell concentration of
Kinetics of Toluene Alkylation with Ethylene over H-ZSM-5
Suh, Dong-Jin ; Park, Tae-Jin ;
Korean Chemical Engineering Research, volume 31, issue 3, 1993, Pages 333~333
Alkylation of toluene with ethylene over H-ZSM-5 catalyst was carried out in a fixed-bed differential reactor at
under atmospheric pressure. A typical Langmuir-Hinshelwood-Hougen-Watson(LHHW) kinetic expression was postulated, and the kinetic parameters were estimated by a nonlinear regression method. The results of model discrimination by using initial rate and thermodynamic criteria indicate that a noncompetitive adsorption model with surface reaction control scheme is the most suitable one for this reaction.
Effects of Prandtl Numbers on Natural Convection and Heat Transfer in a Horizontal Fluid Layer Heated Uniformly from Below
Lee, Jong-Dae ; Choi, Chang-Kyun ;
Korean Chemical Engineering Research, volume 31, issue 3, 1993, Pages 338~338
The onset of natural convection in an initially quiescent fluid layer heated uniformly from below has been analysed by employing the propagation theory. The stability criteria for finite Prandtl numbers
have been obtained deterministically as a function of both the Rayleigh number and the Prandtl number. A new heat transfer correlation connecting the theoretical critical condition has been suggested. It is found that this correlation agrees reasonably well with the extant experimental data.
CO Hydrogenation and Effects of Water over Zirconia Catalyst
Koh, Dong-Jun ; Chung, Jong-Shik ; Kim, Young-Gul ;
Korean Chemical Engineering Research, volume 31, issue 3, 1993, Pages 346~346
Zirconia catalyst was prepared by precipitation method, and the CO hydrogenation and the effects of water on the methanol synthesis were studied. Zirconia exhibited a high selectivity toward butenes and produced hydrocarbons, methanol and dimethyl ether. Water appeared to play an important role in the methanol synthesis. Preadsorbed water promoted the formation of hydrocarbons but inhibited the methanol synthesis. When water was added to the reactant, however, it resulted in increased rates of methanol and hydrocarbon generation. Water is believed to participate in the methanol synthesis and to replenish surface OH groups.
Solubilities of Stearic Acid, Palmitic Acid, Myristic Acid and Their Binary Mixtures in Supercritical Carbon Dioxide
Cho, Yong-Sang ; Yang, Hyun ; Choi, Byung-Oh ; Kang, Jung-Won ; Lee, Chul-Soo ;
Korean Chemical Engineering Research, volume 31, issue 3, 1993, Pages 352~352
Solubilities of pure stearic acid, palmitic acid, myristic acid and their binary mixtures in supercritical carbon dioxide were experimentally determined. Flow method was employed in the experiment. The mixed solute data showed that the solubility of the less soluble component increased in the presence of the more soluble component and that the solubility of the more soluble component remains almost constant. Solubility data of pure and mixed solute were fitted using Peng-Robinson equation of state and equations based on the lattice model of You and Lee.
A Study on Propylene Polymerization over
Han, Taek-Kyu ; Choi, Hong-Ki ; Kim, Jae-Ha ; Chung, In-Jae ; Woo, Seong-Ihl ;
Korean Chemical Engineering Research, volume 31, issue 3, 1993, Pages 361~361
The highly active and stereospecific
was prepared by precipitation method from
, 2-ethyl hexanol(EH), and phthalic anhydride(PA). Propylene polymerizations were carried out in a slurry reactor under atmospheric pressure using the MPDT catalyst cocatalyzed with TEA(triethylaluminum) in the absence of phenyl triethoxy silane(PTES) and in the presence of PTES as external electron donor(EED) to study the effect of TEA and PTES concentration on the activity and stereospecificity. The effect of polymerization temperature on the isotactic index(I.I.) and the activity was studied. The influence of the hydrogen addition on the I.I. and the molecular weight was also observed. In the absence of PTES, maximum average polymerization
was obtained at the mole ration of TEA/Ti of
was, however, obtained at the TEA/Ti ratin of 50 in the presence of PTES. Isotacticity decreased as the TEA/Ti molar ratio is increased in the absence of PTES. In contrast, I.I. was higher than 96% in the presence of PTES in spite of increasing the TEA/Ti molar ratio. The increase of temperature above
decreased the isotactic index as well as the activity. The addition of hydrogen enhanced the activity and decreased the isotactic index(I.I.) of the polypropylene to a small extent. MPT(
) catalyst without DIBP slightly increased isotactic index in the presence of PTES. The characteristics of MDT(
) catalyst without PA were also compared with those of MPDT catalyst.