• 한국전산유체공학회:학술대회논문집
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• 2005.10a
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• pp.31-34
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• 2005

This article has investigated the spatial distribution of the solid particles in polymerization reactors using CFD analysis (FLUENT v. 6.2.1). The suspension of the solids in stirred reactors is affected by a number of parameters including particle diameter, vessel shape, impeller size, impeller speed, and rotating direction of stirrer. The degree of solids suspension in the vessel was quantified with a statistical average value, ${\sigma}^2$. The best stirring conditions were determined based on ${\sigma}^2$, which was found to depend on the vessel bottom shape.

• Transactions of Materials Processing
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• v.10 no.7
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• pp.558-564
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• 2001

An experimental modeling is applied to investigate the formation of forms in molten aluminum By using a specially designed equipment, the effect of process variables, such as the shape of stirrer, stirring velocity and fluid viscosity, on the formation of foams were studied in the glycerine added water. Bubbles formed in water had various diameter from 1 to 10 mm and the number of bubbles was 0 to 20/$cm^2$. It turned out that among various variables the stirring velocity and fluid viscosity played important roles on the formation of bubbles. The results obtained from the model experiment were preyed to be convincible also in the real aluminum foam.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.381-384
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• 2001

The combined stirring method to uniform distribution of particle is consisted of two strring force both electro-magnetic stirring generated from induction heating and mechanical stirring with graphite stirrer. PMMC billets were fabricated with the volume fractions ranged from 0% to 20% and particle sizes ranged from 14$\mu\textrm{m}$ to 25$\mu\textrm{m}$. It is important to control the size of primary ${\alpha}$-AI solid particles because it could become the cause of the particle pushing or capture phenomena from the fact that secondary dendrite arm spacing size depends on the cooling rate during the solidification in hypoeutectic AI-Si alloy.

• Journal of electromagnetic engineering and science
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• v.13 no.3
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• pp.192-194
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• 2013

This paper proposes a validation model using a reverberation chamber for verification of the effectiveness and accuracy of the statistical power balance (PWB) method. The PWB method treats electromagnetic (EM) field distributions in certain environments as a representative value of an "ensemble" average, so a reverberation chamber is utilized as a testing apparatus to experimentally simulate the sets of measurement field "ensemble" inside a complex environment. Measurements are performed with various test conditions for environmental loss using flat absorbers, and front and side doors of the chamber. Comparison between the PWB analysis and the measurement results shows good agreement, indicating the usefulness of this statistical analysis method for stating the electromagnetic field inside the EM zone as a representative value to general structures.

• ALGAE
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• v.20 no.1
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• pp.61-67
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• 2005

Agar was extracted from Gelidium amansii, which was harvested at the shores of Jeju Island in South Korea. As a unique solvent, the ability of dimethyl sulfoxide (DMSO) was used to separate agarose from agar by removing agaropectine and quality of the resultant agarose was characterized for chromatography purposes. Agar sample was agitated by motor-driven stirrer with DMSO in a water bath (at 70$^{\circ}C$ for 2 h) and centrifuged (3,000 rpm for 20 min). Resultant upper agarose layer was gelled, washed, dried and milled. The quality of agarose was evaluated by the analysis of proximate chemical composition, sulfate content, gelling strength and DNA migration. In this study, the separated agarose showed low sulfate amount (0.28%) and showed high gel strength (1190 g ${\cdot}\;cm^{-2}$). The resolution power and the ligase activities gave clear picture about the suitability of the present agarose for practical purposes.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.3
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• pp.375-382
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• 2011

The usages of CFD (Computational Fluid Dynamics) which is simulating turbulent flows in CSTRs (Complete Stirrer Tank Reactors) have been reported. Considering model strategies and simulation techniques, this paper is focused on the turbulence models. The results of this study would suggest multiple reference frameworks relevant to rotational flow simulation. Specifically, the analysis of turbulence dissipation rates referred to this study would solve the relevant environmental engineering problem and would be beneficial to the CFD in CSTRs using mechanical mixer.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.111-114
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• 2004

It is many devices to obtain the globular structure because the globularity of the structure is the key to the low apparent viscosity and also to good rheological properties. In this study, the morphology of the change of primary Al phase in A356 alloy by electro magnetic stirrer was investigated to obtain the globular structure. The parameters are the current, stirring time, pouring temperature individually. The greater current and longer stirring time was to get the finer the primary however in case of over the 80A of current and 60sec of stirring time, the primary Al was merged together and was increased. The effect of pouring temperature has an important effect on the size of primary phase. About the $675^{\circ}C$, the primary Al was very fined.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.431-432
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• 2006

In this study, the effect of the temperature of magnesium slurry was investigated by mechanical stirring method. The evaluations of rheological behavior of AM50A magnesium alloy were measuring of viscosity and microstructures in the semisolid state. The apparent viscosity was investigated at continuous cooling rate using a concentric cylinder viscometer. Measurement of viscosity measures torque that act to stirrer rotating in slurry doing continuous cooling using torque-meter and expressed by POWER-LAW. Microstructures were observed after mechanical stirring that enforce time at steady state temperature of solid fraction.

• Journal of the Korean Wood Science and Technology
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• v.18 no.4
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• pp.79-85
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• 1990

Many kinds of acetosolv lignin including ricestraw and spruce lignin were pyrolyzed. and liquefied in the autoclave reactor using 50% tetralin and m-cresol solution respectively as soluble solvent and Co-Mo as catalyst. In order to promote deoxyhydrogenolysis reaction $H_2$ gas was supplied into the reactor. The ratio between lignin and the soluble solvent are lg and 10cc. The reaction conditions are $200^{\circ}-700^{\circ}C$ of reaction temperature, 10-50 atms of reaction pressure and 100-500rpm of the reactor stirrer. By the deoxyhydrogenolysis liquefaction reaction, the main chemical structures of lignin which are aryl-alkyl-${\beta}$-0-4 ether, phenylcoumaran and biphenyl etc. are easily destroyed into liqufied aromatic compounds and aliphatic compunds linked with aromatic compounds. The percent yield of monomeric phenols on the weight bvase of lignin reacted reached to 12-14% by the chemical analytic GC-MS etc.

• Korea-Australia Rheology Journal
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• v.19 no.3
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• pp.109-115
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• 2007

A new microchip-based aggregometer that uses a stirring-aided disaggregation mechanism in a microchip was developed to measure red blood cell (RBC) aggregation in blood and RBC suspensions. Conventional methods of RBC disaggregation, such as the rotational Couette system, were replaced with a newly designed stirring-induced disaggregation mechanism. Using a stirrer in a microchip, the aggregated RBCs stored in a microchip can be easily disaggregated. With an abrupt halt of the stirring, the backscattered light intensity can be measured in a microchip with respect to time. The time recording of the backscattered light intensity (syllectogram) shows an exponential decreasing curve representing the RBC aggregation. By analyzing the syllectogram, aggregation indices such as AI and M were determined. The results showed excellent agreement with LORCA. The essential feature of this design is the incorporation of a disposable microchip and the stirring-induced disaggregation mechanism.