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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 27, Issue 6 - Dec 1989
Volume 27, Issue 5 - Oct 1989
Volume 27, Issue 4 - Aug 1989
Volume 27, Issue 3 - Jun 1989
Volume 27, Issue 2 - Apr 1989
Volume 27, Issue 1 - Feb 1989
Selecting the target year
Prof. Chai-sung Lee and Chemical Engineering in Korea
Lee, Wha-Young ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 357~357
Professor Chai-sung Lee, Who had introduced the chemical engineering discipline for the first time into this country, is retiring from Seoul National University at the end of August this year. As the very pioneer of the chemical engineering profession in Korea, he has been serving in various aspects and capacities for the development of the profession. It was by him that the formal chemical engineering curriculum was established at Seoul National University early in 1950's. He was also the man who give birth to the Korean Institute of Chemical Engineers in 1962. It was through his leadership that the Third Pacific Chemical Engineers' Congress, held at Seoul in 1983, was a great success and ever since it became a model for an international academic conference in Korea. During his tenure of 43years at Seoul National University, perhaps the longest in the history of the University, he has surely set a standard not only as a teacher but also as a researcher that can hardly be surpassed. He also served as the Dean of Engineering for four years late in 1970's to make major contributions toward the development of engineering discipline. It is now only natural that we dedicate a special issue of Hwahak Konghak in honor of Professor Chai-sung Lee on this occasion of his retirement from Seoul National University, in recognition of his dedication to the development of the chemical engineering profession. He is now retiring but it is only from the professorship. All of us are quite certain that Professor Lee's professional activities will not be affected at all to make him as busy as ever.
Sensitivity Analysis and Sequential Parameter Estimation in Immobilized Enzyme Reactor System
Lee, Jung-Heon ; Yoo, Young-Je ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 366~366
Accurate estimation of the kinetic parameters is essential for on-line optimization and control in bio-catalytic reactor system. Fructose production from glucose using immobilized enzyme was chosen as a model system and deactivation constant which is the most sensitive among the kinetic parameters was estimated from the measurements of product concentration. The effects of sensitivity on the sequential parameter estimation were analyzed under the operating conditions of both constant temperature and varying temperature. By considering the parameter sensitivity on Kalman filtering, estimated values showed reduced fluctuations in the initial period of operations where the sensitivity was low and better convergence to the true value as the sensitivity increased.
The Analysis of Thermal Instability and Heat Transfer Prediction in a Horizontal Fluid Layer Heated from Below
Choi, Chang-Kyun ; Lee, Jong-Dae ; Hwang, Sun-Tak ; Yoo, Jae-Soo ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 374~374
In the present study the onset of natural convection in an initially quiescent, horizontal fluid layer heated isothermally from below has been analysed, by employing the propagation theory. The stability analysis under the linear theory has been conducted deterministically for the limiting cases of extremely small and infinite Prandtl numbers. A new heat transfer correlation connecting the theoretical critical conditions on thermal instability to turbulent thermal convection has been suggested as a function of both the Rayleigh number and the Prandtl number. It is found that the resulting new correlation agrees well with experimental data of mercury, air, water and silicon oil.
n-Hexane Conversion on Acid-leached and/or Steam-treated Mordenites
Lee, Myung-Sup ; Choi, Ko-Yeol ; Lee, Yeong-Sub ; Ha, Baik-Hyon ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 382~382
Hydrogen mordenite[HM(10)], aluminum-deficient mordenite [HM(22)] (
), and their steam-treated mordenites [
, which is washed with hydrogen chloride solution after steam-treating, and
] were prepared and characterized by measuring nitrogen adsorption capacities, XRD analysis, NMR studies, and IR studies on ammonia adsorption and hydroxyl bands. Catalytic reaction of n-hexane with hydrogen was carried out on these samples. HM(10) and HM(22) revealed fast deactivation rate, but elimination of IR
band from these samples by steam-treating reduced the deactivation rate. The quantity of ammonia adsorption was reduced by steam-treating and acid-leaching, but the quantity showed on correlation with the activity of the n-hexane conversion. Isomerization selectivity was much improved by steam-treating.
showed high selectivity for 3-methyl pentane and $>C_6$, respectively.
Extensional Behavior of Isotropic Pitch During the Melt Spinning
Yun, Yo-Rim ; Joo, Chang-Whan ; Rhee, Bo-Sung ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 389~389
A newly developed method for the measurement of extensional viscosity was introduced to investigate the extensional behavior of pitch during melt spinning. The confidence of this method was confirmed with the 3.6% of tolerance limit. The theoretical equation based on the viscoelastic model to calculate the extensional viscosity was proposed and its results were compared with experimental data. The spinnabilily of the isotropic pitch would be depended more viscous rather than elastic effect sinces the extensional viscosity found was of pitch independent of drawing ratio. During the melt spinning of pitch, measured force was rhelogical force by the extension. Therefore, innertia, gravity, air drag force was negligible.
Hydrogenolysis of Methyl Formate to Methanol
Kim, Young-Gul ; Lee, Jae-Sung ; Kim, Jae-Chang ; Lee, Si-Hoon ; Kim, Kwang-Man ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 396~396
The catalytic hydrogenolysis of methyl formate to methanol was studied. Copper chromite catalysts with 42-78wt% of copper oxide content were used. The selectivities and activities of the catalysts were measured as a function of reaction temperature, pressure, amounts of water content, and pretreatment conditions of catalysts such as reduction temperatures and reduction time. The selectivity to methanol was always higher than 99% above 50 bar of hydrogen pressure and
. The catalysts was easily deactivated above
. The activity depended greatly upon the reduction states of catalysts. This was believed to be due to the differences in the amounts of
species in catalysts, known to be an active species in the reaction. The conclusion was supported by XRD results of the catalysts treated at different conditions.
Adsorption of Methylene Chloride and Freon-12 on the Some Adsorbents
Kang, Suk-Ho ; Lee, Tae-Jin ; Bae, Kwang-Soo ; Ahn, Hee-Kwan ; Kim, Yoon-Kap ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 404~404
The adsorption isotherms for halogenated hydrocarbons such as methylene chloride and Freon-12 on five kinds of adsorbents(two activated carbons, two molecular sieves, and
)were measured with the BET adsorption and the pressurized adsorption apparatus. The BET multilayer model is shown to fit well the experimental adsorption isotherms. The adsorption capacity is in the order of S-AC>K-AC>MS-13X>
>MS-5A at the same equilibrium adsorption pressure. Enthalpy of adsorption which is estimated from the constant C of BET multilayer model seems to be related to the reversibility of adsorption and the strength of adsorption. Activated carbons used seems to be the best adsorbent among the other ones, comparing with the terms of the adsorption capacity and the adsorption strength.
Properties of Highly-loaded
Catalysts Prepared by Repeated Metal Impregnation
Ha, Heung-Ryong ; Chung, Jong-Shik ; Lim, Tae-Hoon ; Moon, Sang-Heup ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 410~410
Catalysts of high metal loading supported on the carrier of pre-adjusted pore structure may be prepared by repeated impregnation of the carrier with metal salt solution. However, when
catalysts were prepared by the repeated impregnation method, the catalysts showed uneven metal distribution and many cracks within the pellets. The problem could be solved by treating the catalysts in oxygen between impregnation steps. Low oxidation temperature was helpful to obtaining small nickel particles dispersed on the carrier, but the temperature effect became insignificant when nickel loading was higher than 20wt%. As the nickel content of the catalyst increased by repeated impregnation, the nickel particles grew larger, blocking the entrance of some micro-pores or reducing the average pore size, which eventually affected the catalytic activity. In this study, the rates of benzene hydrogenation decreased drastically when the catalysts contained more than 15wt% of nickel. At this nickel content, the average nickel size approached
, which was the size of the most abundant pores in the catalysts.
Relationships between the Viscoelastic Behavior and Compatibility in Mixtures of Molten Polymers
Han, Chang-Dae ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 416~416
The rheological behavior of compatible polymer blends in the molten state is different from that of incompatible polymer blends. Experimental data are first presented and then explained by phenomenological arguments for incompatible polymer blends, and by molecular/thermodynamic arguments for compatible polymer blends.
Effect of Boron-Incorporation on the Acid-Base Property of Alkalimetal Exchanged Zeolite X
Mun, Se-Gi ; Kim, Hyeong-Jin ; Seo, Gyo-Taek ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 422~422
Infrared spectroscopy and temperature-programmed desorption have been used to investigate the acid-base properties of alkali cation exchanged X zeolites incorporated with boron. Boron led to decrease the acidity of fresh catalyst rapidly and to lower the acidity-decay during the reaction, side-chain alkylation of toluene with methanol. But boron can not affect the basicity, significantly. In conclusion, it seems reasonable that the role of boron is to help the activation of methyl group of toluene, which accelerates the side-chain alkylation of toluene selectively.
Metal Distribution Effects on CO Hydrogenation of Reduced Ni/Y- Zeolite Catalysts
Ihm, Son-Ki ; Lee, Dong-Keun ; Lee, Jin-Ho ; Choi, Seon-Yub ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 430~430
The influence of nickel metal distribution on the properties of Ni/Y-zeolite catalysts for CO hydrogenation was investigated. The studies using TPR/TPO, TEM, X-ray line broadening and FMR have shown the existence of a bidispersion of nickel metal particles; i.e., small particles were restricted inside the zeolite pores, and large particles were formed outside the zeolite crystal. CO hydrogenation reaction was performed in a differential reactor operating at atmospheric pressure,
ratio of 3. Nickel metal distribution affected the activity and hydrocarbon product distribution significantly. With increasing fraction of nickel metal inside the zeolite pores the activity continued to decrease, while the production of the long chain and olefinic hydrocarbons was enhanced significantly. Especially when all the nickel metals were restricted within the pores of zeolite, a bimodal hydrocarbon product distributions for
were observed. This was ascribed to the dimerization of the primarily formed ethene to butene on the active species of
Adaptive Predictive Control for Nonlinear Processes
Yeo, Yeong-Koo ; Park, Won-Hee ; Song, Hyung-Keun ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 438~438
An adaptive predictive controller for SISO bilinear processes without time delay and with stable inverses is defined based upon a classical recursive identification algorithm. For the case with no disturbance both the control error and the identification error converge to zero. For the case with a bounded disturbance the control error is bounded and the identification converges. For the case with a constant disturbance the control error converges to zero and the identification converges.
Effect of Oil Viscosity on Ultrafiltration Flux
Rho, Yong-Woo ; Kim, Hwa-Yong ; Park, Won-Hee ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 446~446
The effect of oil viscosity on flux in membrane separation process was studied in the stirred batch cell. Membranes used in our experiment were FS-81PP and FSM-2.0PP from Denmark DDS Co. and test solutions were the mixtures of base lube oils. It was found that the relationship between the inverse flux(1/Jv)and the kinematic viscosity of oil(
) can be shown as
where A and B are the characteristic parameters of the membrane under given operation conditions. It was also found that the effect of temperature can be interpreted as the change in oil viscosity.
Mathematical Modeling and Simulation of the Membrane-Extractive Butanol Fermentation
Jeon, Yeong-Jung ; Lee, Yun-Yeong ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 451~451
A mathematical model of the membrane-extractive butanol fermentation process, which has been developed as a method of in situ product recovery to solve the problems of butanol fermentation caused by the severe product inhibition, was proposed and the model was solved by a computer-assisted numerical method. The results indicate that the best way of improving the butanol productivity is to use a feed with high glucose concentration. On the other hand, only marginal advantages are obtained by increasing the membrane area and/or the extractant flow rate beyond certain limits. It is also shown that a solvent with distribution coefficients as high as those of oleyl alcohol is acceptable for this process.
An Experimental and Theoretical Study on the Circulation of Suspension in a Solid-Suspended Bubble Column with a Draft Tube
Park, Chan-Jin ; Do, Dong-Seop ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 459~459
The characteristics of circulation of slurry suspension by bubble-agitation in a bubble column with a draft tube have been studied in a 8.90cm
high acryl column. The circulation time and the degree of dispersion of fluid were measured by the analysis of Residence Time Distribution which were obtained by the pulse in-put of tracer. Static pressure gradient and local gas holdup in the riser and downcomer sections were calculated using the measured pressure profile in each section. The circulation time of suspension was diminished compared with that of solid-free liquid in the bubbly and transition flow regimes. An energy balance was made over the circulating fluid in the bubble column as the control volume and from which a polynomial equation with a velocity of the suspension as a variable was obtained. The velocities of suspension calculated from the steady-state numerical simulation of the polynomial equation which is dependent on the local gas holdup of each section of bubble column. physical properties of suspension, the ratio of the cross-sectional area of inner to outer column and the length of the draft tube, could explain the characteristics of circulation of suspension in a solid-suspended bubble column with a draft tube very well.
The Characteristics of Hydrodynamics and Mass Transfer in Three Phase Fluidized Column with Draft Tube
Lee, Sung-Hee ; Choi, Ho-Sang ; Park, Young-Tae ; Doh, Kap-Soo ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 472~472
An experimental study was carried out to investigate the characteristics of hydrodynamics and mass transfer in a three phase fluidized column with the draft tube. The gas holdup and the mass transfer coefficient were measured by conducting experiment for air-water-glass bead systems. The overall gas holdup increased with the gas velocity and tended to decrease with the particle size, and the overall volumetric mass transfer coefficient increased with the gas velocity and the size of the draft tube, and showed a tendency to decrease with increasing liquid velocity and solid particle size. dependences of the overall gas holdup and the overall volumetric mass transfer coefficient on each experimental variable were given by the following empirical equations:
Effects of Domestic Diatomite Filter Aid on the Characteristics of Cake Filtration
Yun, Seok-Ho ; Na, Jong-Bok ; Jo, Won-Seon ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 482~482
Variations of porosity and specific local filtration resistance in cake filtration were studied in a filter cell. samples used were slurries of
, Talc(I) and Talc(II) and diatomite filter aids, which were used by body feed-ing and precoation. From the experimental result, the porosity of filter cake decreased and the specific local filtration resistance in-creased with increasing pressure. The addition of filteraids increased the porosity of filter cake and it resulted in de-creasing the specific local filtration resistance.
Fischer-Tropsch Synthesis over
Ryu, Seung-Ho ; Song, Jae-Chun ; Lee, Wha-Young ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 489~489
The Fischer-Tropsch syntheses over silica-supported iron catalysts were carried out in an atmospheric reactor at
. The catalytic activity extended to steady-state value after 10-20 hour reaction. The longer reduction period and the higher reduction temperature made the catalytic activity more stable, and even unreduced catalyst showed similiar activity. K-promoted catalysts showed higher olefin selectivity and increased
production rate with little decrease of activity. The maximum olefin selectivity of 53.5% was obtained at space velocity of
Study on the Mold Filling Process of Short Fiber Filled Composite Systems
Lee, Seong-Jae ; Suh, Dong-Gil ; Lee, Seung-Jong ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 496~496
A numerical algorithm to simulate the mold filling process of short fiber filled(generalized Newtonian) composite systems was developed in the case of planar channel and cylindrical tube geometries. The transient movement of the frontal free surface and the fountain flow phenomena could be well simulated for those geometries. the distribution and orientation of fibers in the Newtonian fluid medium during the filling process were also calculated solving the Jeffery‘s eq’n, and the results showed that the fibers near the wall and the moving front allign parallel to those surfaces.
Ethanol Fermentation in a Three Phase Tower Fermenter with Highly Concentrated Yeast Cells
Kim, Woo-Sik ; Yoo, In-Sang ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 506~506
Two methods for increasing cell concentration in a fermenter were evaluated in terms of ethanol productivity; cell recycling with settling of yeast flocs and immobilization of yeast cells in Ca-alginate gels. A three phase tower fermenter was designed and used through this study. Under aerobic and anaerobic conditions, the characteristics of ethanol fermentation process were investigated for each of the methods. It was found that the maximum dry cell concentration in the three phase tower fermenter with floc recycle system was
. The maximum ethanol yield(96.1%) was obtained at
under anaerobic condition. The maximum ethanol productivity in this system was
. On the other hand, the fermentation using the Ca-alginate immobilized yeast cell was found to be possible at relatively high dilution rates(
) in the three phase tower fermenter. The maximum ethanol yield in this system was 84.7% at
under aerobic condition. The maximum ethanol productivity of
was obtained at
The p-Xylene Selectivity over Modified ZSM-5 Catalysts I. Characteristics of Catalysts and Selectivity
Kim, Jin-Do ; Choi, Nak-Mann ; Rhee, Hyun-Ku ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 513~513
HZSM-5, HFerrosilicate and HBorosilicate were prepared and then modified by impregnation each of several metallic components. These catalysts were examined for their crystal structure, surface characteristics, and acidic properties and also applied for two reactions, alkylation and disproportionation of toluene. The objective here is to make a study of the selectivity enhancement for p-xylene from both reactions. These solid acid catalysts turned out to have one strong and one weak acid sites, which appear to be relate to the
and Lewis acids, respectively. In particular, the strong acid was lowered in its amount and weakened in its strength by metal impregnation as well as by the increase of metal loading. For both reactions the p-xylene selectivity was observed higher over HFerrosilicate than over the other two catalysts. For the three catalysts of H-form, the p-xylene selectivity was markedly enhanced by metal impregnation, the degree being most distinguished over HZSM-5 catalyst. Such enhancement in the p-xylene selectivity may be at-tributed to weakening of the strong acid and pore-blocking caused by metal impregnation.
Extraction Characteristics of Evening Primrose Oil with Supercritical Carbon Dioxide
Lee, Byung-Chul ; Kim, Jae-Duck ; Hwang, Kyung-Yub ; Lee, Youn-Yong ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 522~522
Solubilities of evening primrose oil(EPO) in supercritical carbon dioxide were measured at temperatures of
and pressures of 100 to 300 bars. Solubilities of EPO were found to increase with increasing pressure at constant temperature. When pressure was kept constant, solubilities of EPO decreased with increase in temperature at pressures of 100 to 200 bars, while they increased with higher temperatures at 300 bar. Solubilities at 250 bar were of a constant value. The effects of temperature and pressure on the extraction yield coincided with the tendency in solubility. Under the range covered in this study the highest yield of extraction was 21wt% at the temperature of
and the pressure of 300bar with the flow rate of carbon dioxide of
(STP). Loading of oil in supercritical carbon dioxide was constant until the extraction yield based on available oil was less than about 50%, and then it decreased sharply. The average loadings increased with increase in residence time. Mass transfer parameter,
, increased linearly with the superficial velocity of carbon dioxide in the extractor.
The Combustion of Copper Sulfide Concentrate Particles in a Turbulent Gas Jet
Son, Hong-Yong ; Seo, Gyeong-Won ; Han, Yun-Bong ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 531~531
Experimental measurements and mathematical model predictions for flash combustion of copper sulfide particles in a turbulent gas jet are described. A mathematical model has been developed to describe the process taking place in an axisymmetric flash-furnace shaft. The model incorporates turbulent fluid dynamics, chemical reaction kinetics, and heat and mass transfer. The key features include the use of the
turbulence model, incorporating the effect of particles on turbulence, and the four flux-model for radiative heat transfer. The experiments were carried out in a laboratory flash furnace. Gas temperature, sulfur content in the particles,
concentration in the gas phase, and particle dispersion during flash-smelting at different locations were measured for various matte grades. Reasonable agreement was obtained between the measured and predicted values. The predicted results are compared with experimental data obtained from Outokumpu pilot and comercial flash furnaces. Satisfactory agreement is obtained between the predicted and measured data in terms of the gas-phase temperature and the
concentrations along the centerline. The model predictions show that the reaction of sulfide particles is almost completed in the upper zone of the furnace within about 1m of the burner and the double-entry burner system with radial feeding of the concentrate-laden distribution air gives better performance than the single-entry burner system.
A Thermodynamic Model for Strong Electrolytes-Mixed Solvent Systems I. Activity Coefficients of Electrolytes
Kim, Ho-Dong ; Lee, Chul-Soo ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 548~548
A model by Cruz and Renon was extended to concentrated mixed strong electrolytes-mixed solvents systems. Calculation was simplified by using solvent volume instead of system volume. Also a systematic method was developed for the determination of parameters applicable to mixed electrolytes-mixed solvents systems. Comparison of calculated activity coefficients of electrolytes and of standard Gibbs free energy of solution with experimental values showed good agreements for NaCl-Methanol-Water, KCl-Methanol-water and NaCl-KCl-Water systems.
A Refocus on the Draw Resonance Theory
Hyun, Jae-Chun ; Oh, Joo-Seok ; Lee, Seung-Jong ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 556~556
The draw resonance theory published by one of the present authors, has been numerically restudied to confirm the correctness of the originally proposed kinematics(based on the concept of the waves traveling times) for the onset of draw resonance instability in melt spinning. It also has been found that the draw resonance criterion should include not only the two traveling times, i.e., the throughput wave traveling time and the fluid element travel-ing time(based on the threadline velocity), but also the phase difference(time difference)between the fluctuations of the threadline force and the threadline cross-sectional area. Using the simple model of Newtonian fluids into the revised draw resonance criterion, we have got the value of 20.21, for
(critical draw ratio at the onset of draw resonance), which is the same value obtained by other researchers who employed direct numerical simulation methods without the concept of kinematics of the traveling waves.
Controlled Drug Release by Polymeric Matrix Formulation by Coating and Swelling
Byun, Young-Rho ; Chang, Ho-Nam ; Kim, Young-Ha ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 561~561
In order to avoid a thermal instability and a reaction of drug with solvents, a method was devised to load a drug in a polymer matrix by swelling. Using p-HEMA hydrogel as polymer matrix, the release mechanism of a model drug, citidine diphosphate coline(CNS stimulant),was studied. Also analyzed was the difference in the pH-related release mechanism of p-HEMA which has a non-ionic polymer chain and polyacrylate which has negative ions on the polymer side chain. For p-HEMA, ist break-point on the drug release curve occured due to swelling and degree of swelling did not change pH. On the other hand, swelling polyacrylate differed pH: the higher the pH, the higher the degree of swelling and faster the release rate. A formulation with a bioerodible coating membrane of polylactide was introduced to the co-polymer of HEMA and methylmethacrylate. The difference in the drug release mechanism and changes relative to the polymer thickness in this system was observed. The formulation allows the bioerodible membrane to suppress the initial rate of drug release mechanism, which led to the sustained release pattern.
A New Optimization Strategy of Chemical Processing System by the Combined Sequential Modular and Two-Tier Approach
Cho, In-Ho ; Yoon, En-Sup ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 568~568
By structural comparison of process optimization strategies based on Simultaneous Modular Ap-proach, they can be classified into two groups : the Sequential Module Based Approach and the Two-Tier Approach. The Sequential Module Based Approach needs rigorous models and a set of accurate solutions are guranteed. However it re-quires a large amount of computation time. In the Two-Tier approach composed of rigorous and simplified models, optimization calculation uses simplified models, therefore comparatively smaller amount of computation time is required but the obtained solutions may not be accurate. These optimization problems were somewhat improved by the alter-nate application of the two strategies. In this study improved optimization strategy is suggested, in which Jacobian Matrix is modified to accomodate the strong points of above-mentioned strategies. The results of case study show that this approach is superior to the other strategies.
Rheological Analysis of an Injection Mold Filling Process of a Viscoelastic fluid
Lee, Ki-Jun ; Jung, Kwang-Sik ; Suh, Moon-Ho ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 579~579
Numerical simulation of free surface flow phenomena is presented for the system where a polymeric melt flows into a vertical rectangular cavity which has an inlet gate. The numerical technique combines a modified version of marker and cell method with DuFort-Frankel finite difference approximation to the equations of motion. The Leonov model is introduced for the viscoelastic fluid and compared with the Carreau model analysis for inelastic fluid. The low density polyethylene is used as sample material and the free surface profiles of the flow are simulated with time. The jet-like behavior in the flow front of the polymeric melt appears when both the Gravity number and the Weissenberg number are small. The ratio of gravitational to viscous force plays prevailing role than the elastic force itself. Thus the overall flow pattern is mainly a function of the Gravity number than the Froude number as speculated. The numerical predictions of surface profiles and the velocities of the advancing front are in good agreement with the experimental data.
by Cupric Oxide Supported on Zeolite
Shin, Chang-Sub ; Lee, Tae-Hee ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 588~588
from flue gas was experimented by using cupric oxide supported on zeolite. Experimental results showed that CuO/Zeolite is a good reactant for the removal of
and NO from flue gas and the optimum reaction temperature is
. Removal efficiency of
was not decreased even after repeated cycles of removal and regeneration and it was increased with temperature but decreased at above
because of the thermal decomposition of
. In case of simultaneous removal of
and NO, the efficiency of the removal and the regeneration of
was not changed by the NO reaction and in particular the removal efficiency of NO was approximately 100 percent. The reaction of CuO/Zeolite with
could be well explained by the grain model using 1st order chemical reaction control and the reaction rate constant was obtained as k(cm/s)=7.92exp[-12,540(cal/mol)/RT].
Active Skin Layer Formation Control of Microporous Asymmetric Polysulfone Hollow Fiber Membranes
Kwon, Taeg-Min ; Lee, Soon-Hong ; Kim, Jae-Jin ; Kim, Un-Young ;
Korean Chemical Engineering Research, volume 27, issue 4, 1989, Pages 595~595
Hollow fiber membranes were spun from the mixture of 18wt% polysulfone, 67wt% solvent N,N-dimethylacetamide(DMA)and 15wt% additive(polyvinylpyrrolidone or 2-methoxyethanol) with a take-up winder under the condition of 50% relative humidity, 60cm air gap, 10m/min spinning speed and external coagulant water. Bore coagulant such as water made inner skinned membranes and weak coagulant such as glycerine or 98wt% DMA+5wt% water made outer skinned membranes. The hollow fiber membrane spun with 95wt% DMA+5wt% water solution as bore coagulant showed the rejection as high as 95% against PEG M.W.20,000 (2,000ppm)solution and then its ultrafiltration flux was as great as