• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.448-460
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• 2018

Copper nanoparticle-doped and graphitic carbon nanofibers-covered porous carbon beads were used as an efficient catalyst for treating synthetic phenolic water by catalytic wet air oxidation (CWAO) in a packed bed reactor over 10-30 bar and $180-230^{\circ}C$, with air and water flowing co-currently. A mathematical model based on reaction kinetics assuming degradation in both heterogeneous and homogeneous phases was developed to predict reduction in chemical oxygen demand (COD) under a continuous operation with recycle. The catalyst and process also showed complete COD reduction (>99%) without leaching of Cu against a high COD (~120,000 mg/L) containing industrial wastewater.

• Korean Chemical Engineering Research
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• v.53 no.4
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• pp.440-444
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• 2015

Effects of operating variables on the solid circulation rate were investigated in a three-phase circulating fluidized bed, of which inside diameter was 0.102m and height was 3.5m, respectively. Gas velocity, primary and secondary liquid velocities, particle size and height of solid particles piled up in the solid recycle device were chosen as operating variables. The solid circulation rate increased with increasing primary and secondary liquid velocities and height of solid particles piled up in the solid recycle device, but decreased with increasing particle size. The value of solid circulation rate decreased only slightly with increasing gas velocity in the riser. The values of solid circulation rate were well correlated in terms of dimensionless groups within the experimental conditions.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.482-487
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• 1988

A sequential-clustered integrator based on GEAR method is developed for the purpose of dynamic simulation of chemical processes. And a single simulator structure capable of employing various integration approaches is designed and its efficiency and flexiblity is evaluated. Sequential integration method is superior to simultaneous method for the process without recycle, but simultaneous method is very powerful for the coupled process with recycle.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.11a
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• pp.235-239
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• 2001

In recent years, as Chemical Mechanical Planarization(CMP) has been routinely utilized in integrated circuit(IC) fabrication, the consumption of slurry, main consumable in a CMP process, is greatly increased. Thus the reprocess of CMP slurries has been actively considered in the industry to reduce cost-of-consumable (COC). The main purpose of this study was to recycle the used oxide slurry using filters as a new method. As a result, Ultra Fine(UF) Filter could distinguish silica from the used oxide slurry and Reverse Osmosis(RO) Filter could distinguish Deionized(DI) Water and chemistry from chemistry solution. The tetraethylorthosilicate removal rate was almost the same as the number of recycle polishing was increased, when it was modified by slightly adding new SS-12 slurry. The microscratch didnt found as the number of recycle polishing was increased.

• Proceedings of the Membrane Society of Korea Conference
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• 1999.10a
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• pp.39-39
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• 1999

Membrane separation technology has become a more attractive technology on waste water treatment and water recycle in recent years. On this application, membrane does not take main part of treatment, such as decomposition or handling of organic matter in the waste water, but it is very important supporting method in the total system. Activated sludge is most popular method as main part. In the system , membrane works as a separator to obtain clear water after biological treatment, by which the permeate could be released, recycled or applied to further additional treatment, instead of conventional sedimentation, coagulation and sand filtration. We would like to introduce our system cases for waste water treatment and water recycle, in which membrane separation technology works. In most of cases, membranes are applied to solid- liquid separation of activated sludge. Our experiences will be introduced as following items.

• Korean Chemical Engineering Research
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• v.48 no.2
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• pp.198-204
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• 2010

Solids flow characteristics have been determined in a pressurized solids recycle systems of silica sand particles for the application in a pressurized CFB(PCFB). The solids recycle system is composed of a downcomer(0.10 m i.d. 2.25 m high) and a loop-seal(0.10 m i.d.). The silica sand($d_p=240{\mu}m$, ${\rho}_s=2582kg/m^3$) particles were transported at room temperature and system pressure($P_{sys}$) up to 0.71 MPa using air. Solids mass flux($G_s$) increases with increasing system pressure at constant aeration rate. Pressure gradient, solids velocity and actual gas velocity increase with increasing $P_{sys}$ at constant aeration rate. The Pressure drop number($\Phi$) on pressure gradient in downcomer has been correlated with Transportation number(Tr). Pressure drop across the loop-seal increases with increasing of $G_s$ irrespective of variation of $P_{sys}$. The obtained $G_s$ and Transportation number(Tr) have been correlated with the experimental variables.

• Microbiology and Biotechnology Letters
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• v.13 no.1
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• pp.33-39
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• 1985

The effects of initial concentration, flow rate, and recycle ratio on the removal efficiency of phenol were studied in a tapered fluidized bed reactor packed with activated carbon which was attached with Candida tropicalis. The optimum conditions of Candida tropicalis were showed that pH was 7.0 and temperature was $30^{\circ}C$, and the specific growth rate of Candida tropicalis was satisfied with the Monod equation up to 500 mg/L of phenol, and beyond it the inhibition of substrate was found. According to the increases of initial concentration and flow rate, the removal efficiency was decreased, as the recycle ratio was increased, the removal efficiency was increased. In the case of flow rate of 10mL/sec and the recycle ratio of 2, the removal efficiency was 90% above for the all of initial concentration. The removal rate of phenol was the first order reaction in this system, and the rate equation of reaction was as follows.

• Plant Journal
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• v.13 no.3
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• pp.26-29
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• 2017

In this research, the composition of the feed stream is optimized in pressure swing distillation for separating of methanol-acetone. It is well known that the composition of feed stream in pressure swing distillation system has a great influence on the feasibility to separate mixture. The workscope of this study is to show better separation efficiency at specified pressure by controlling the composition of feed stream with recycle of two products. Based on the base case without recycle flow, two processes are designed that methanol and acetone are recycled to feed stream, respectively. Each processes are compared with total annual cost and as a result, the base case without recycle flow are most favorable.

• Membrane and Water Treatment
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• v.2 no.2
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• pp.75-89
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• 2011

The predicting equations for mass transfer rate in cross-flow rectangular dialyzers with double flow and recycle, have been derived by mass balances. The recycling operation has two conflicting effects. One is the desirable effect of the increase in fluid velocity, resulting in an increased mass transfer coefficient. The other is the undesirable effect of the reduction in concentration difference due to remixing, resulting in decreased mass-transfer driving force. In contrast a single-pass device without recycling, considerable improvement in mass transfer is achieved if the cross-flow rectangular dialyzer of same size is operated with double pass and external recycling. It is concluded that recycle can enhance mass transfer, especially for larger reflux ratio.

• Elastomers and Composites
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• v.32 no.5
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• pp.325-329
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• 1997

Microbial treatment of the powdered waste tire was studied to recycle the waste tires. Chemoautotrophic acidophilic, iron-oxidizing bacterium was employed to unvulcanize the powdered tires. Biotreated rubber powder was compared to a untreated and a chemically treated powder. The results showed sulfur content of rubber powder(1.33%) were decreased to 1.22% by chemical treatment and 1.12% by microbial treatment for 20 days, 0.88%, for 30 days. One of the problems of the powdered utilization of the waste tires is that rubber powder leads to decrease mechanical properties when it is compounded with other virgin polymers. When tee biotreated powder was compounded with natural rubber, the mechanical properties were less decreased when untreated or chemically treated powder. Therefore, the microbial treatment can be one of useful methods to recycle the waste tire.