• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.9 no.6
• /
• pp.41-48
• /
• 2000

The Compression molding process is widely used in the automotive industry to produce parts that are large, thin, light-weight, strong and stiff. Compression molded parts are formed by squeezing a glass fiber reinforced polypropylene sheet, known a glass mat thermoplastic(GMT), between two heated cavity surfaces. In this study, the anisotropic viscosity of the Unidirectional Fiber-Reinforced Plastic Composites is measured using the parallel plastometer and the composites is treated as an incompressible Newtonian fluid. The effects of molding parameter and fiber contents ratio on longitudinal/transverse viscosity are also discussed.

• Bulletin of the Korean Chemical Society
• /
• v.3 no.4
• /
• pp.133-139
• /
• 1982

It has been presumed that the molten sulfur above $159^{\circ}C$ consists of an equilibrium mixture of $S_8$ rings and $S_x$ polymers where the number average degree of polymerization, P, is large. But it is known that admixture of halogens with liquid sulfur greatly reduce the viscosity. Constructing a new equilibrium equation, it is possible to evaluate the viscosity when halogens are added to liquid sulfur. Calculated viscosity is in good agreement with experimental values. Using the proposed model, the thermodynamic properties of liquid sulfur are also calculated over a wide range of temperature which the sulfur exists as the polymer.

• Journal of the Korean Mathematical Society
• /
• v.48 no.4
• /
• pp.867-885
• /
• 2011

We study a class of quasilinear wave equations with strong and nonlinear viscosity. By using the perturbation method for semilinear parabolic equations, we have established the fundamental results on existence, uniqueness and continuous dependence on data of weak solutions.

• Journal of Powder Materials
• /
• v.17 no.4
• /
• pp.270-275
• /
• 2010

Ethylene glycol-based Cu nanofluids were prepared by pulsed wire evaporation (PWE) method. The structural properties of Cu nanoparticles were studied by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). The average diameter and Brunauer Emmett Teller (BET) surface area of Cu nanoparticles were about 100 nm and $7.46\;m^2/g$, respectively. The thermal conductivity and viscosity of copper nanofluid were measured as functions of Cu concentration and temperature. As the volume fraction of Cu nanoparticles increased, both the enhanced ratios of thermal conductivity and viscosity of Cu nanofluids increased. As the temperature increased, the enhanced ratio of thermal conductivity increased, but that ratio of viscosity decreased.

• Journal of the Korean Ceramic Society
• /
• v.43 no.4 s.287
• /
• pp.203-206
• /
• 2006

Polyacrylonitrile (PAN) nanofibers, which are pH-sensitive and exhibit soft actuation as a linear actuator and artificial muscles, were prepared by electrospinning to investigate the effect of viscosity on the morphology of PAN fibers. Experimental results revealed that higher viscosity is critical for the formation of unbeaded nanofibers because surface tension is almost constant throughout the experiment. Uniform, smooth, and continuous fibers with diameters of about 700 nm were achieved for the 10 wt% PAN fibers at a flow rate of 0.5 mL/h and an electric field of 0.875 kV/cm.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1996.10a
• /
• pp.266-270
• /
• 1996

The objective of this study is to develop the Non-compacting concrete with mormal strength in practice by using viscosity agent and flyash. In this paper, we present the reference data about not only the properties of Non-compacting concrete at fresh state such as flowability, segregation-resistibility, placebility and so on but, optimum mixing design using viscosity agent and flyash. The test results indicate that optimum dosage of viscosity agent in combination of flyash in 50% of W/C is about 400g/$\textrm{m}^3$ with 20% of the ratio of flyash replacement.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.24 no.3
• /
• pp.389-395
• /
• 1995

The neutral sugar sidechains of apple pectins were hydrolyzed by commercial hemicellulase produced from Aspergillus niger, and the corresponding changes in solution viscosity were investigated in dilute(cc*) pectin solutions. Pectinase activity included in hemicellulases was removed by Epoxy-activated Sepharose 6B affinity chromatography using polygalacturonic acid as a ligand. Enzymatic hydrolysis of sidechains did not affect the specifc viscosity of dilute(0.5%) pectin solutions, while viscosity significantly decreased in concentrated(2.0∼6.0%) region. These results strongly suggest that the sidechains of pectins exists as an entangled state in concentrated solutions. It was also found that in the concentrated region the extent of viscosity reduction was dependent on pectin concentrations.

• 유체기계공업학회:학술대회논문집
• /
• 2003.12a
• /
• pp.367-370
• /
• 2003

In this study the effects of fluid viscosity on the pump performances of a conventional centrifugal pump were experimentally studied. The study aimed to compare the pump characteristics for water and high viscosity fluids. The Working fluids are water, aqueous sugar solution and glycerin solution. The pump characteristics of total head and efficiency with high viscosity fluids were different. The performance curves of efficiency for the sugar and glycerin solutions were decreased up to 8.1% and 12.9% than that of water.

• Journal of computational fluids engineering
• /
• v.18 no.2
• /
• pp.56-65
• /
• 2013

Two compression ramp problems and an impinging shock problem are computed to investigate influence of turbulence models and eddy viscosity on the shock-wave / boundary layer interaction. A Navier-Stokes boundary layer generation code was applied to the generation of inflow boundary conditions. Computational results are validated well with the experimental data and effects of turbulence models are investigated. It is shown that the behavior of turbulence (eddy) viscosity directly affects both the extent of the separation and shock-wave positions over the separation.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1996.04a
• /
• pp.112-116
• /
• 1996

This experimental study was performed to produce high flowing nomal strength concrete using viscosity agent. Test variables were selected to the viscosity agent contents with 4 levels, the cement contents with 5 levels and the coarse aggregate contents with 3 levels, etc. As a result, the high flowing and filling properties of concrete were obtatined by proper amount of viscosity agent and superplasticizer in the normal strength concrete. For the concrete mix proportions, it was found that unit weight of cement was more than 364kg/㎥ and volume of coarse aggregate was less than $280\ell/\textrm{m}^3$ in this study.