• Journal of Microbiology and Biotechnology
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• v.30 no.8
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• pp.1227-1234
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• 2020

In this study, yeast cell immobilization was carried out in a packed bed reactor (PBR) to investigate the effects of the volumetric capacity of carriers as well as the different fermentation modes on fuel ethanol production. An optimal volumetric capacity of 10 g/l was found to obtain a high cell concentration. The productivity of immobilized cell fermentation was 16% higher than that of suspended-cell fermentation in batch and it reached a higher value of 4.28 g/l/h in repeated batches. Additionally, using this method, the ethanol yield (95.88%) was found to be higher than that of other tested methods due to low concentrations of residual sugars and free cells. Continuous ethanol production using four bioreactors showed a higher productivity (9.57 g/l/h) and yield (96.96%) with an ethanol concentration of 104.65 g/l obtained from 219.42 g/l of initial total sugar at a dilution rate of 0.092 h^-1. Furthermore, we reversed the substrate-feed flow directions in the in-series bioreactors to keep the cells at their highest activity and to extend the length of continuous fermentation. Our study demonstrates an effective method of ethanol production with a new immobilized approach, and that by switching the flow directions, traditional continuous fermentation can be greatly improved, which could have practical and broad implications in industrial applications.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.12
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• pp.1484-1493
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• 2004

In this study, it induced to a conclusion below by experiment consideration to regarding an effective supercooling ends method of the flow cooling water in a tube of continuous ice making method and the static cooling water in a tube of continuous ice making method which used magneticfluid in a dynamic type ice storage system. Continuous ice making in a tube of the flow cooling water was shortened about 12 minutes until supercooling ends that case which gave vertical eccentricity rotation magnetic field 120rpm than did not provide magnetic field by experimental result that was tested to supercooling ends effect from shape control of magneticfluid. Continuous ice making method in a tube of the static cooling water compared with and reviewed the case that was not provided with the magnetic field and exposed cooling surface instantaneously by magnetic field. It confirmed that supercooling degree $\Delta$ $T_{c}$, $\Delta$ $T_{s}$, and $\Delta$ $T_{w}$ became lower because of heat transfering increasing by the occurrence of natural convection between after cooling starting progress time 1∼3 minutes if it did not give a magnetic field, and peformed the supercooling ends when natural convection occurred confirmed that refrigerating capacity was better. That relation $\Delta$ $T_{c}$, and $t_{e}$/($\Delta$ $T_{c}$-$\Delta$ $T_{s}$) after convection occurred, was not depended on $T_{b}$ and initial temperature if the depth of water and thickness of magneticfluid were regular and it was possible to verify conjecture of tp from $\Delta$ $T_{s}$ and $\Delta$ $T_{c}$.lar and it was possible to verify conjecture of tp from $\Delta$ $T_{s}$ and $\Delta$ $T_{c}$.c}$.>.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.1
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• pp.1-10
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• 2005

An aerodynamic shape optimization technique has been developed for helicopter rotor blades in hover based on a continuous adjoint method on unstructured meshes. The Euler flow solver and the continuous adjoint sensitivity analysis were formulated on the rotating frame of reference for hovering rotor blades. In order to handle the repeated evaluation of the design cycle efficiently, the flow and adjoint solvers were parallelized using a domain decomposition strategy. A solution-adaptive mesh refinement technique was adopted for the accurate capturing of the tip vortex. Applications were made for the aerodynamic shape optimization of Caradonna-Tung rotor blades and UH60 rotor blades in hover. The results showed that the present method is an effective tool to determine optimum aerodynamic shapes of rotor blades requiring less torque while maintaining the desired thrust level.

• Journal of Environmental Science International
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• v.9 no.6
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• pp.463-468
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• 2000

Ther effect of UV on the mortality rate of toxic dinoflagellate Amphidinium Carterae causing a red tide in the coastal area of korea was investigated in the batch and continuous-scale reactor equipped with ultraviolet irradiation-apparatus. Degussa P(sub)25 titanium oxide, a photocatalyst proved to be effective of the mortality of Amphidinium Carterae supplied with photocatalyst and UV radiation were greater than 95% in 2 minutes of UV radiation and the rate were higher than that by UV-radiation without titanium dioxide in the batch and continuous-flow scale reactor, The mortality time of Amphidinium Carterae increased with the cell density under UV-illumination in the batch scale reactor. The mortality rate in the density of $5.0$\times$10^4$ cell/mL at the same experimental condition was more than 90% in 4 minutes in the continuous flow scale reactor. The percentage of 99.9$\pm$0.1% of Amphidinium Carterae in the density of $0.5$\times$10^4$ cells/mL was died in 20 minutes when the phytoplankton was illuminated with UV-radiation without photocatalyst.

• Journal of Hydrogen and New Energy
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• v.29 no.2
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• pp.205-211
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• 2018

Performance evaluation of a regenerative pump has been compared with a conventional open channel impeller and a S-shaped continuous impeller designed newly. To analyze flow field for both pumps, analysis code, CFX, is employed. Unstructured grids are used to represent a composite geometryincluding blade, casing and ducts. Throughout the comparisons between numerical simulation and experiments, the predicted efficiency has a good agreement with the experimental one. It is noted that the pump having a S-shaped continuous impeller is about 4.8 percent more efficient than conventional one, which is due to the relatively large pressure increase. Detailed flow field inside the pump is also analyzed and compared.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.4
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• pp.488-493
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• 2008

A mathematical model of molten steel level for continuous casting process is presented, where the molten steel level, input and output flow in the mold, the relation between stopper position and input flow etc. are considered. The mathematical model is implemented and simulated by using MATLAB. Comparing the result of molten steel level from the simulator with that of real plant, the performance of the model is shown to be reasonable. By using this simulator, it is shown that PI controller with variable P gain, adjusted by fuzzy logic system, has better control result than conventional PI controller.

• Journal of Advanced Marine Engineering and Technology
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• v.17 no.4
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• pp.28-37
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• 1993

Flow characteristics within the three-dimensional square cavity are studied experimentally by adopting PIV(Particle Image Velocimetry). A new method for tracking the same particle pairs in the consecutive flow image is suggested resulting in more effective acquisition of the velocity vectors. Two methods for supplying the shearing stress within the cavity are developed by continuous moving belt and 2-dimensional plane Poiseuille flow. The effect of TGL vortex in the case of belt-moving flow is remarkable owing to the distribution of the kinetic energy in the spanwise direction. But, for the plane Poiseuille flow, velocity profiles similar to a forced vortex are obtained and its tendency increases with the Reynolds number.

• Nuclear Engineering and Technology
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• v.47 no.6
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• pp.669-677
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• 2015

A mechanistic model for void fraction prediction with improved interfacial friction factor in nearly horizontal tubes has been proposed in connection with the development of a condensation model package for the passive auxiliary feedwater system of the Korean Advanced Power Reactor Plus. The model is based on two-phase momentum balance equations to cover various types of fluids, flow conditions, and inclination angles of the flow channel in a separated flow. The void fraction is calculated without any discontinuity at flow regime transitions by considering continuous changes of the interfacial geometric characteristics and interfacial friction factors across three typical separated flows, namely stratified-smooth, stratified-wavy, and annular flows. An evaluation of the proposed model against available experimental data covering various types of fluids and flow regimes showed a satisfactory agreement.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.468-473
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• 1998

A mathematical model was developed for a continuous re-actor in which free radical polymerization of methyl methacrylate (MMA) occurred. Elementary reactions considered in this study were initiation, propagation, termination, and chain transfers to monomer and solvent. The reactor model took into account the density change of the reactor contents and the gel effect. A control system was designed for a continuous reactor using extended Kalman filter (EKF) based non-linear model predictive controller (NLMPC) to control the conversion and the weight average molecular weight of the polymer product. Control input variables were the jacket inlet temperature and the feed flow rate. For the purpose of validation of the control strategy, on-line digital control experiments were conducted with densitometer and viscometer for the measurement of the polymer properties. Despite the com-plex and nonlinear features of the polymerization reaction system, the EKF based NLMPC performed quite satisfactorily for the property control of the continuous polymerization reactor.

• Journal of environmental and Sanitary engineering
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• v.16 no.2
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• pp.1-8
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• 2001

The water treatment by electrochemical method was performed to increase the yield of production. Continuous plug flow reactor was operated to treat poultry and domestic wastewaters. Experimental results were compared with experimental results of the wastewater treatment by chemical coagulation, they were increased over 10% in the removal efficiency of COD and the production rate of sludge was reduced by 30%. Ozone utilized to degrade or change the organic chemical structures, which removal efficiency increased to 20% in the electro-coagulation reactor. Economic evaluation was performed to estimate total cost of electro-coagulation reactor in comparison with that of chemical coagulation method. The total cost to treat 1000 ton/day of domestic wastewater was reduced by 50%.