• Archives of Pharmacal Research
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• v.8 no.2
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• pp.91-98
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• 1985

Dependence of the flow behavior of aqueous suspension of Young-Il bentonite on the concentration and the type of electrolytes was studied. Viscosity measurements were made was Rion Viscotester, using No. 3 rotor at 62.5 R. P. M. at 25.deg.C. As electrolyte concentration increased, the apparent viscosity was observed to increase. Changes in viscosity were in general agreement with predicted results based on the Hofmeister sequence and the Schulze-Hardy rule. The observed electrolyte effect on the apparent viscosity was discussed in terms of the Verwey-Overbeek theory.

• Food Science and Biotechnology
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• v.15 no.6
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• pp.871-876
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• 2006

Rheological behavior of commercial hot pepper-soybean paste (HPSP) was evaluated in small amplitude oscillatory and steady shear tests. Storage modulus (G'), loss modulus (G"), and complex viscosity (${\eta}^*$) as a function of angular frequency (${\omega}$), and shear stress (${\sigma}$) as a function of shear rate (${\gamma}$) data were obtained for 5 commercial HPSP samples. HPSP samples at $25^{\circ}C$ exhibited a non-Newtonian, shear-thinning flow behavior with high yield stresses and their flow behaviors were described by power law, Casson, and Herschel-Bulkley models. Time-dependent flow properties were also described by the Weltman, Hahn, and Figoni & Shoemaker models. Apparent viscosity over the temperature range of $5-35^{\circ}C$ obeyed the Arrhenius temperature relationship with activation energies (Ea) ranging 18.3-20.1 kJ/mol. Magnitudes of G' and G" increased with an increase in ${\omega}$, while ${\eta}^*$ decreased. G' values were higher than G" over the most of the frequency range (0.63-63 rad/sec), showing that they were frequency dependent. Steady shear viscosity and complex viscosity of the commercial HPSP did not fit the Cox-Merz rule.

• The Korean Journal of Rheology
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• v.10 no.4
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• pp.234-246
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• 1998

The objective of this study is to investigate the correlation between steady shear flow (nonlinear behavior) and dynamic viscoelastic (linear behavior) properties for concentrated polymer solutions. Using both an Advanced Rheometic Expansion System(ARES) and a Rheometics Fluids Spectrometer (RFS II), the steady shear flow viscosity and the dynamic viscoelastic properties of concentrated poly(ethylene oxide)(PEO), polyisobutylene(PIB), and polyacrylamide(PAAm) solutions have been measured over a wide range of shear rates and angular frequencies. The validity of some previously proposed relationships was compared with experimentally measured data. In addition, the effect of solution concentration on the applicability of the Cox-Merz rule was examined by comparing the steady flow viscosity and the magnitude of the complex viscosity Finally, the applicability of the Cox-Merz rule was theoretically discussed by introducing a nonlinear strain measure. Main results obtained from this study can be summarized as follows : (1) Among the previously proposed relationships dealt with in this study, the Cox-Merz rule implying the equivalence between the steady flow viscosity and the magnitude of the complex viscosity has the best validity. (2) For polymer solutions with relatively lower concentration, the steady flow viscosity is higher than the complex viscosity. However, such a relation between the two viscosities is reversed for highly concentrated polymer solutions. (3) A nonlinear strain measure is decreased with increasing stran magnitude, after reaching the maximum value in small strain range. This behavior is different from the theoretical prediction demonstrating the shape of a damped oscillatory function. (4) The applicability of the Cox-Merz rule is influenced by the $\beta$ value, which indicates the slope of a nonlinear stain measure (namely, the degree of nonlinearity) at large shear deformations. The Cox-Merz rule shows better applicability as the $\beta$ value becomes smaller.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.1127-1132
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• 1991

Pneumatic control system has been used mainly for endpoint position control because of the compressibility, viscosity and low output stiffness of air which causes nonlinear flow characteristics. In this paper, pneumatic position control algorithms using fuzzy rule were developed to achieve faster and more stable response than conventional PI control algorithm. The performances of the proposed algorithms were compared by computer simulations with them of PI controller. From those simulations it was shown that the proposed algorithms are more efficient about settling time, steady state error and overshoot than PI control algorithm.

• Fire Science and Engineering
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• v.17 no.2
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• pp.43-49
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• 2003

For the inert gases of Ar, $N_2$and $CO_2$, the empirical equations of the gas mixture were correlated in terms of saturated pressure, density and viscosity. They were obtained by regression analysis based on the mixing rule. The empirical equation of saturated pressure was assumed as the first order function of temperature. The empirical form of density was expressed as compressibility factor and saturated pressure while the empirical equation of viscosity was formulated as a power function of temperature. This empirical equations of the physical properties were obtained in the composition of Ar, $N_2$and $CO_2$, 40/50/10(mol. %).

• Bulletin of the Korean Mathematical Society
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• v.48 no.4
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• pp.737-757
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• 2011

This work is concerned with an optimal selling rule for a large position of stock in a market. Selling a large block of stock in a short period typically depresses the market, which would result in a poor filling price. In addition, the large selling intensity makes the regime more likely to be poor state in the market. In this paper, regime switching and depressing terms associated with selling intensity are considered on a set of geometric Brownian models to capture movements of underlying asset. We also consider the liquidation strategy to sell much smaller number of shares in a long period. The goal is to maximize the overall return under state constraints. The corresponding value function with the selling strategy is shown to be a unique viscosity solution to the associated HJB equations. Optimal liquidation rules are characterized by a finite difference method. A numerical example is given to illustrate the result.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.5
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• pp.860-864
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• 2000

The steady and dynamic shear rheological properties of traditional kochujang fermented at three different temperatures (20${^circ}C$, 25${^circ}C$ and 30${^circ}C$) were studied. Flow of kochujang samples showed time dependence, which was quantitatively described by the Weltman model, Kochujang samples were highly shear thinning fluids (n=0.25~0.27) with large magnitudes of Casson yield stresses (1.09~1.21 kPa). Consistency index (K) and apparent viscosity (${\eta}_{a,20}$) increased with increase in fermentation temperature of kochujang. Storage (G') and loss (G") moduli increased with increase in frequency (ω), while complex viscosity (${\eta}^{\ast}$) decreased. Based on dynamic shear data, kochujang samples exhibit structural properties similar to weak gels. The complex and steady shear viscosities at different fermentation temperatures followed the Cox-Merz superposition rule with the application of the shift factor (a=0.011~0.016).

• Journal of applied mathematics & informatics
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• v.35 no.5_6
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• pp.423-438
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• 2017

The aim of this paper is to present two new viscosity rules for nonexpansive mappings in Hilbert spaces. Under some assumptions, the strong convergence theorems of the purposed new viscosity rules are proved. Some applications are also included.

• Journal of the Korean Chemical Society
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• v.16 no.1
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• pp.25-32
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• 1972

The effect on the apparent viscosity of 2 wt. % Veegum suspensions of different types of electrolytes and of different electrolyte concentrations was studied. Measurements were made with a Brookfield Synchro-Lectric Viscometer, using no.3 spindle at 30 R.P.M. at $24^{\circ}C$. As electriolyte concentration increased, the apparant viscosity was observed to increase to a maximum and then to decrease. Changes in viscosity were in general agreement with predicted results based on the Hofmeister sequence and the Schulze-Hardy rule. The observed electrolyte effect on the apparent viscosity was discussed in terms of the Verwey-Overbeek theory.

• Korea-Australia Rheology Journal
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• v.16 no.4
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• pp.169-173
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• 2004

The control of the rheological properties of a fluid during processing is important and can determine the efficiency of the production in addition to the performance of the final product. The vast majority of process fluids are viscoelastic, hence an instrument that measures both the viscous and elastic properties of the material during processing would be of great practical use. However, most in-line instruments commercially available to date are only capable of measuring viscosity at a single shear rate. An in-line rheometer that measures both the viscous and elastic properties of fluids over a wide range of shear rates simultaneously has been described in a previous publication (Glasscock et at., 2003) in which the results of measurements on flowing sunflower oil were presented. Before this instrument can be used in an industrial situation, it must be demonstrated that the generated results are the same as, or bear some fixed relationship to, the results obtained by conventional off-line rheometers. To this end, the present investigation describes the measurements of a standard reference fluid, polyisobutylene dissolved in 2,6,10,14-tetramethylpentadecane, labelled SRM2490 by the National Institute of Standards and Technology (NIST) in the USA. The results obtained using the in-line rheometer show remarkably good correlation for viscosity, using a modified Cox­Merz rule, with the results supplied with the reference material from NIST.