• Korean Chemical Engineering Research
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• v.51 no.2
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• pp.226-232
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• 2013

To produce biobutanol, fermentation processes using clostridia that mainly produce acetone, butanol and ethanol are used. In this work, a dynamic model describing the metabolic reactions in an acetone-butanol-ethanol (ABE)-producing clostridium, Clostridium acetobutylicum ATCC824, was proposed. To estimate the 58 kinetic parameters of the metabolic network model with experimental data obtained from a batch fermentor, we used an efficient optimization method combining a genetic algorithm and the Levenberg-Marquardt method because of the complexity of the metabolism of the clostridium. For the verification of the determined parameters, the developed metabolic model was evaluated by experiments where genetically modified clostridium was used and the initial concentration of glucose was changed. Consequently, we found that the developed kinetic model for the metabolic network was considered to describe the dynamic metabolic state of the clostridium sufficiently. Thus, this dynamic model for the metabolic reactions will contribute to designing the clostridium as well as the fermentor for higher productivity.

• Applied Chemistry for Engineering
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• v.26 no.4
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• pp.477-482
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• 2015

This study examined the adsorption characteristics of heavy metal ions ($Cr^{6+}$, $As^{3+}$) in an aqueous solution using recycled aggregate (RA) and recycled aggregate (RA)/steel slag (SS) composites. The RA and SS are favorable for the absorbent because it contains about 91% and 86.9%, respectively, which are some of the major adsorbent ingredients (CaO, $SiO_2$, $Al_2O_3$ and $Fe_2O_3$) for heavy metal. Kinetic equilibrium of $Cr^{6+}$ and $As^{3+}$ in RA and RA/SS composites reached within 180 min and 360 min, respectively. The kinetic data presented that the slow course of adsorption follows the Pseudo first and second order models. The equilibrium data were well fitted by the Freundlich model and showed the affinity order of $As^{3+}$ > $Cr^{6+}$. The results of $As^{3+}$ also showed that the adsorption capacity slightly increased with increasing pH from 6 to 10. Meanwhile, the adsorption capacity of $Cr^{6+}$ was slightly decreased. From these results, it was concluded that the RA and RA/SS composites can be successfully used for removing the heavy metals ($Cr^{6+}$ and $As^{3+}$) from aqueous solutions.

• Journal of Energy Engineering
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• v.8 no.2
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• pp.333-340
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• 1999

A numerical study of turbulent condensing vapor jet submerged in subcooled liquids has been conducted. A physical model of the process is presented employing the locally homogeneous flow approximation of two phase flow in conjunction with a $\kappa$-$\varepsilon$-g model of turbulence properties. In this model the turbulence is represented by differential equations for its kinetic energy and dissipation. A differential equation for the concentration fluctuations is solved and a clipped normal probability distribution function is proposed for the mixture fraction. Effects of steam mass flux, pool temperature and nozzle internal diameter on the condensing vapor jet are also analyzed. The model is evaluated using existing data for turbulent condensing vapor jets. The agreement between the predictions and the available experimental data is good.

• Nuclear Engineering and Technology
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• v.26 no.3
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• pp.345-354
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• 1994

Numerical Predictions including secondary flows have been Performed for fully developed turbulent single-phase rod bundle flows. The k-$\varepsilon$ turbulence model(two equation model) for the isotropic eddy viscosity, together with an algebraic stress model for generating secondary velocities, enabled the prediction of mean axial velocities, secondary velocities, and turbulent kinetic energy and turbulent stresses. Comparisons with experiment hate shown that the influence of secondary motion on mean flow and turbulence is dearly evident. The convective transport effects of secondary flow on the velocity field have been identified.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.3
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• pp.1-8
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• 2008

We present a model for simulating high energy laser heating of metal for ignition of energetic materials. The model considers effect of ablation of steel plate with long laser pulses and continuous lasers of several kilowatts and the thermal response of well-characterized high explosives for ignition. Since there is enough time for the thermal wave to propagate into the target and to create a region of hot spot in the high explosives, electron thermal diffusion of ultra-short (femto- and pico-second) lasing is ignored; instead, heat diffusion of absorbed laser energy in the solid target is modeled with thermal decomposition kinetic models of high explosives. Numerically simulated pulsed-laser heating of solid target and thermal explosion of RDX, TATB, and HMX are compared to experimental results. The experimental and numerical results are in good agreement.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.4
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• pp.9-17
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• 2000

The crystal growth and dissolution rates were calculated by solving a model equation, which involved the dissolution of the metastable phase($\beta$-HNIW) and growth of the stable phase($\varepsilon$-HNIW), together with the mass balance equation. The model has been successfully used to simulate available kinetic data for the $\beta$$\longrightarrow$$\varepsilon$ polymorphic transformation via a solution phase. From the effectiveness factor based on the two-step model, it was found that the surface integration contribution to the process was comparatively small, and a diffusion dependency decreased with an increase of the mass fraction of chloroform in the mixed solvents of ethyl acetate and chloroform. Appling these kinetics in process simulation allowed for the prediction of the product size of $\varepsilon$-HNIW.

• Cartoon and Animation Studies
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• s.31
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• pp.227-248
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• 2013

With the advancement of computers, opening title sequences in movies are continuously improving. Initially, titles and opening credits were created using what is called the optical method, whereby text was photographed on separate film and then copied onto the movies film negative. In contemporary movie making, however, the title sequence may be seamlessly integrated into the beginning of the movie by an insertion method that not only allows for more diverse technical expression, including the use of both 2D and 3D graphics, but also for its emergence as an independent art form. As such a title sequence, in as little as 50 seconds or up to 10 minutes, is able to convey the films concept while also suggesting more implicit intricacies of plot and thereby eliciting greater interest in the movie. Moreover, according to the directors intent and for a variety of purposes, the title sequence, while maintaining its autonomy, is inseparable from the movie as an organic whole; therefore, it is possible to create works that are highly original in nature. The purpose of this study is to analyze the kinetic typography that appears in title sequences of ten films produced by the Korean entertainment industry in 2012. Production techniques are analyzed in a variety of ways in order to predict the future direction of opening title sequences, as well as present aesthetic and technical models for their creation.

• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.80-87
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• 2010

Lignite of low rank coal and petroleum coke of high sulfur content can be high potential energy sources for coal gasification process because of their plentiful supply. The kinetic study of steam gasification has been performed in an atmospheric thermobalance with wood chip, lignite, bituminous, anthracite, pet-coke. The effects of gasification temperature($600{\sim}850^{\circ}C$) and partial pressure of steam(30~90 kPa) on the gasification rate have been investigated. The modified volumetric reaction model was applied to the experimental data to describe the behavior of carbon conversion and to evaluate the needed kinetic parameters. Lignite and wood chip with high volatile content showed high average gasification rates comparing to other fuel and thus they might be proper fuel for gasification processes. The activation energies for wood chip, lignite, bituminous, anthracite, and pet-coke through Arrhenius plot were found to be 260.3, 167.9, 134.6, 82.2, 168.9 kJ/mol, respectively. The expression of apparent reaction rates for steam gasification of various chars have been proposed as basic information for the design of coal gasification processes.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.544-552
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• 2014

In this study, We have investigated the kinetics on the char-$CO_2$ gasification reaction. Thermogravimetric analysis (TGA) experiments were carried out for char-$CO_2$ catalytic gasification of an Indonesian Roto lignite. $Na_2CO_3$, $K_2CO_3$, $CaCO_3$ and dolomite were selected as catalyst which was physical mixed with coal. The char-$CO_2$ gasification reaction showed rapid an increase of carbon conversion rate at 60 vol% $CO_2$ and 7 wt% $Na_2CO_3$ mixed with coal. At the isothermal conditions range from $750^{\circ}C$ to $900^{\circ}C$, the carbon conversion rates increased as the temperature increased. Three kinetic models for gas-solid reaction including the shrinking core model (SCM), volumetric reaction model (VRM) and modified volumetric reaction model (MVRM) were applied to the experimental data against the measured kinetic data. The gasification kinetics were suitably described by the MVRM model for the Roto lignite. The activation energies for each char mixed with $Na_2CO_3$ and $K_2CO_3$ were found a 67.03~77.09 kJ/mol and 53.14~67.99 kJ/mol.

• Clean Technology
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• v.27 no.2
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• pp.182-189
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• 2021

The adsorption of disperse yellow 3 (DY 3) on granular activated carbon (GAC) was investigated for isothermal adsorption and kinetic and thermodynamic parameters by experimenting with initial concentration, contact time, temperature, and pH of the dye as adsorption parameters. In the pH change experiment, the adsorption percent of DY 3 on activated carbon was highest in the acidic region, pH 3 due to electrostatic attraction between the surface of the activated carbon with positive charge and the anion (OH^-) of DY 3. The adsorption equilibrium data of DY 3 fit the Langmuir isothermal adsorption equation best, and it was found that activated carbon can effectively remove DY 3 from the calculated separation factor (R_L). The heat of adsorption-related constant (B) from the Temkin equation did not exceed 20 J mol^-1, indicating that it is a physical adsorption process. The pseudo second order kinetic model fits well within 10.72% of the error percent in the kinetic experiments. The plots for Weber and Morris intraparticle diffusion model were divided into two straight lines. The intraparticle diffusion rate was slow because the slope of the stage 2 (intraparticle diffusion) was smaller than that of stage 1 (boundary layer diffusion). Therefore, it was confirmed that the intraparticle diffusion was rate controlling step. The free energy change of the DY 3 adsorption by activated carbon showed negative values at 298 ~ 318 K. As the temperature increased, the spontaneity increased. The enthalpy change of the adsorption reaction of DY 3 by activated carbon was 0.65 kJ mol^-1, which was an endothermic reaction, and the entropy change was 2.14 J mol^-1 K^-1.