• KSBB Journal
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• v.15 no.1
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• pp.88-95
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• 2000

We have produced new-structured oligosaccharides using immoobilized mixed-enzyme reactor of destransucrase from Leuconostoc mesenteroides B-512FMCM and $\alpha$-amylase from Aspergillus oryzae. The reactors of immobilized mixed-exzyme beads were more efficient for the production of oligosaccharides than that of each immobilized enzyme bead in stirred-tank reactior(STR) or in packed-bed reactor(PCR). In continuous flow reactor, the immobilized mixed-enzyme bead in PBR was more stable than in STR, and 52% of initial yield was maintained for 200 hr. New structured-oligosaccharides (NOS) reduced the change of pH in the culture of Streptococcus mutans. It also showed an inhibitory effect on the growth of Staphylococcus aureus.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.11
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• pp.4649-4655
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• 2010

The aim of this study was to investigate the effect of flowing the industrial wastewater effluents into the K lake which is located in the A city on the eutrophication. The lake was modelled as a continuous stirred-tank reactor. Phosphorus and Chl-a concentration in the lake were calculated to $0.29\;/m^3$과 $4.0\;g/m^3$ at steady state, respectively. Those simulated concentrations were very close to the monitored mean concentration of the lake, indicating that the simulation could be used a tool for characterizing the lake. The non-steady state concentrations of the phosphorus and Chl-a were proposed as a function of time as well. Phosphorus loading ($L_p$) and depth to retention time ratio ($H/{\tau}w$) was calculated in order to analyze the current state of eutrophication. We proposed a strategy to change the lake from eutrophic to permissible oligotrophic state using a graph consisting of two variables, $L_p$ and $H/{\tau}w$.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.542-547
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• 2001

A non-intrusive Planar Laser-Induced Fluorescence(PLIF) technique was applied to study the turbulent mixing process in a Rushton turbine reactor. Instantaneous and ensemble averaged concentration fields are obtained by measuring the fluorescence intensity of Rhodamine B tracer excited by a thin Nd:Yag laser sheet illuminating the whole center plane of the stirred tank. The gray level images captured by a 14-bit cooled CCD camera can be transformed to the local concentration values using a calibration matrix. The dye injection point was selected at the tank wall with three quarter height (3/4H) from the tank bottom to observe the mixing characteristics in upper bulk flow region. There exist distinct two time scales: the rapid decay of mean concentration in each region after the dye infusion reflects the large scale mixing while the followed slow decay reveals the small scale mixing. The temporal change of concentration probability functions conjectures the two sequential processes in the batch type mixing. An inactive column of water existed above the impeller disk, in which the fluid rotates with the shaft but is isolated from the mean bulk flow.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.8
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• pp.1145-1152
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• 2002

A non-intrusive Planar Laser-Induced Fluorescence(PLIF) technique was applied to study the turbulent mixing process in a Rushton turbine reactor. Instantaneous and ensemble averaged concentration fields was obtained by measuring the fluorescence intensity of Rhodamine B tracer excited by a thin Nd:Yag laser sheet illuminating the whole center plane of the stirred tank. The gray level images captured by a 14-bit cooled CCD camera could be transformed to the local concentration values using a calibration matrix. The dye injection point was selected at the tank wall with three quarter. height (3/4H) from the tank bottom to observe the mixing characteristics in upper bulk flow region. There exist distinct two time scales: the rapid decay of mean concentration after the dye infusion reflects the large scale turbulent mixing while the fellowed slow decay reveals the small scale molecular mixing. The temporal change of concentration variance field conjectures the two sequential processes for the batch type mixing. An inactive column of water is existed above the impeller disk, in which the fluid rotates with the shaft but is isolated from the mean bulk flow.

• Journal of environmental and Sanitary engineering
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• v.4 no.1 s.6
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• pp.43-52
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• 1989

A synthetic wastewater composed of powdered baby food and inorganic nutrients was treated by five 3.6L anaerobic reactors in order to test the relationship between solids retention time (SRT) and media surface ratio, and the removal efficiencies of organic substrate. Of the five reactors, four were semi-continuously fed stirred-tank reactors and one continuously-stirred batch reactor. The influent was 7430mg/L in COD, 7120 mg/L $BOD_L$ and 6350mg/L in $BOD_5$, respectively. Operating temperature was $35{\pm}1^{\circ}C$ and pH in the range 6.9 to 7.2. In this experimental study it was found that a linear relationship existed, within the experiment range, between SRT and media surface ratio, and that SRT and removal efficiency increased with increasing media surface ratio. The substrate removal efficiencies were 82.7 to $88.2\%$ in COD, 82.9 to $88.4\%$ in $BOD_L$ and 83.3 to $88.7\%$ in $BOD_5$, respectively.

• Korean Chemical Engineering Research
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• v.54 no.5
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• pp.612-620
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• 2016

Aqueous mineral carbonation process, in which $CO_2$ is captured through the reaction with aqueous calcium oxide (CaO) solution, is one of CCU technology enabling the stable sequestration of $CO_2$ as well as economic value creation from its products. In order to enhance the carbon capture efficiency, it is required to maximize the dissolution rate of solid reactants, CaO. For this purpose, the proper design of a reactor, which can achieve the uniform distribution of solid reactants throughout the whole reactor, is essential. In this paper, the effect of internal reactor designs on the solid dispersion quality is studied by using CFD (computational fluid dynamics) techniques for the pilot-scale reactor which can handle 40 ton of $CO_2$ per day. Various combination cases consisting of different internal design variables, such as types, numbers, diameters, clearances and speed of impellers and length and width of baffles are analyzed for the stirred tank reactor with a fixed tank geometry. By conducting sensitivity analysis, we could distinguish critical variables and their impacts on solid distribution. At the same time, the reactor design which can produce solid distribution profile with a standard deviation value of 0.001 is proposed.

• Biotechnology and Bioprocess Engineering:BBE
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• v.1 no.1
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• pp.26-31
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• 1996

Since biosynthesis of lignin peroxidase from Phanerochaete chrysosporium was known to be sensitive to shear, it is interesting to understand the effects of the shear sensitivity for the overproduction of lignin peroxidase. In stirred-tank fermentor, the shear-sensitivity in lignin peroxidase biosynthesis was quantified by using Kolmogorov length scale. It was found that agitation at 80$\mu$m Kolmogorov length scale is advantageous for the production of lignin peroxidase from P. chrysosporium. To overcome the shear sensitivity in lignin peroxidase biosynthesis caused by the agitation,P. chrysosporium was immobilized on various solid carriers. The nylon-immobilized P. chrysosporium was chosen in the present study as a way to overcome the shear sensitivity at the ranges of above 50$\mu$m Kolmogorov length scale. The adhesion force between immobilized cell and carrier can be predicted by thermodynamic approach and used as a criteria to select an adequate carrier materials for immobilization.

• International Journal of Control, Automation, and Systems
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• v.4 no.6
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• pp.669-681
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• 2006

In this work, a new method of design adaptive controllers for SISO systems based on multiple models and switching is presented. The controller selects the model from a given set, according to a switching rule based on output prediction errors. The goal is to design, at each sample instant, a predictive control law that ensures the robust stability of the closed-loop system and achieves the best performance for the current operating point. At each sample the proposed control scheme identifies a set of linear models that best characterizes the dynamics of the current operating region. Then, it carries out an automatic reconfiguration of the controller to achieve the best possible performance whilst providing a guarantee of robust closed-loop stability. The results are illustrated by simulations a nonlinear continuous and stirred tank reactor.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.2
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• pp.197-203
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• 1997

In this paper, we present a GP-PID(Generalized Predictive PID) controller which has the same structure as a generalized predictive control with steady-state weighting. The proposed controller can perform better than the conventional PID controller because it includes intrinsic delay-time compensator. The PID tuning parameters and delay-time compensator are calculated by equating the two degree of freedom PID to a linear form of GPC. The proposed controller is combined with a supervisor for safe start and self-tuning. GP-PID controller has been tested for various numerical models and an experimental stirred tank heater. As a result, it was observed that the proposed controller shows a satisfactory performance for variable delay as well as stochastic disturbance.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.886-889
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• 2017

An active Fault Tolerant Model Predictive Control (FTMPC) using Fuzzy scheduler is developed. Fault tolerant Control (FTC) system stages are broadly classified into two namely Fault Detection and Isolation (FDI) and fault accommodation. Basically, the faults are identified by means of state estimation techniques. Then using the decision based approach it is isolated. This is usually performed using soft computing techniques. Fuzzy Decision Making (FDM) system classifies the faults. After identification and classification of the faults, the model is selected by using the information obtained from FDI. Then this model is fed into FTC in the form of MPC scheme by Takagi-Sugeno Fuzzy scheduler. The Fault tolerance is performed by switching the appropriate model for each identified faults. Thus by incorporating the fuzzy scheduled based FTC it becomes more efficient. The system will be thereafter able to detect the faults, isolate it and also able to accommodate the faults in the sensors and actuators of the Continuous Stirred Tank Reactor (CSTR) process while the conventional MPC does not have the ability to perform it.