• Bulletin of the Korean Chemical Society
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• v.22 no.1
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• pp.43-45
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• 2001

This study simplifies the phenomenological theory of viscosity previously proposed by the present authors. This simplified theory has only two thermodynamic properties and one parameter, as opposed to its predecessor, which has many, allowing for easy calculation of the liquid viscosities. The viscosity of liquid metals, an excellent test for checking the validity of the liquid theory, can be calculated using the equation based on the simplified theory. The calculated results by the current theory turn out to be good for the liquid metals, including sodium, potassium, rubbidium, cesium, lead and mercury.

• Bulletin of the Korean Chemical Society
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• v.23 no.11
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• pp.1524-1526
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• 2002

It is very difficult to measure the fluid viscosity at the critical point, there are seldom found experimental values of fluid viscosity at the critical point. Few theories can explain the critical viscosity quantitatively. A theory of viscosity previously proposed by authors10 is applied to the fluid at the critical point. This theory can be simplified as a simple form with no adjustable parameters, allowing for easy calculation. Viscosities at the critical point for some substances have been calculated, and calculated results are satisfactory when compared with the observed values.

• Bulletin of the Korean Chemical Society
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• v.29 no.1
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• pp.33-37
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• 2008

A phenomenological theory of viscosity previously proposed by the present authors8 is applied to the corresponding state theory for the viscosity of liquid. Through the process of the formulation of the corresponding state equation, we can find the simple viscosity equation with no parameters in a reduced form. The liquid viscosities of various substances can be calculated using this equation when we know only the values of the molecular weight and critical constant of substances. A corresponding state equation for the viscosity of liquid from this theory may be applicable to predicting viscosities of various substances under varying temperature and pressure. As a result, this equation may be widely applied to chemical engineering.

• Korea-Australia Rheology Journal
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• v.17 no.1
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• pp.27-32
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• 2005

We determine the effective viscosity of suspensions with bidisperse particle size distribution by modifying an effective-medium theory that was proposed by Acrivos and Chang (1987) for monodisperse suspensions. The modified theory uses a simple model that captures some important effects of multi-particle hydrodynamic interactions. The modifications are described in detail in the present study. Estimations of effective viscosity by the modified theory are compared with the results of prior work for monodisperse and bidisperse suspensions. It is shown that the estimations agree very well with experimental or other calculated results up to approximately 0.45 of normalized particle volume fraction which is the ratio of volume faction to the maximum volume fraction of particles for bidisperse suspensions.

• Bulletin of the Korean Chemical Society
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• v.10 no.4
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• pp.372-374
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• 1989

The new viscosity theory is applied to the abnormal behavior of the viscosity near the critical point. This theory suggests that the viscosity is equal to the product of the absolute pressure(kinetic pressure + internal pressure) and the collision time. We can find this abnormal behavior to be due to the large collision time near the critical point. The agreements between theoriticals and experimentals of the critical enhancement are satisfactory.

• Korea-Australia Rheology Journal
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• v.12 no.1
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• pp.69-76
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• 2000

We have derived the translation diffusion coefficient and the intrinsic viscosity formula adopting the Kholodenko's theory using 3＋1 dimensional Dirac propagator in the Kirkwood and Riseman scheme. We also performed static light scattering experiments and intrinsic viscosity measurement of dilute solutions of polyimides with different rigidities. In the framework of Kholodenko's theory, we can easily measure the persistence length of polyimide. We prepared five different polyamic acids and polyimides with different degree of imidization by controlling imidization temperatures. From experimental results, we obtained molecular weights and persistence lengths according to the Kholodenko's plot. The molecular weight and the intrinsic viscosity decreased and then increased with the imidization temperature but the persistence length increased monotonically and then leveled off. The persistence lengths calculated from intrinsic viscosities showed very good agreement with those from light scattering experiments.

• Journal of the Korean Chemical Society
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• v.48 no.3
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• pp.243-248
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• 2004

Brake theory of viscosity, which can sucessfully calculate the viscosity of real gases, dense gases and liquids, is extended to the binary gas mixture. Adjustable parameters are not involved, but the calculated results are good agreements with the experimental values at high pressure as well as low pressure. Corresponding state equation for viscosity can be obtained by using the Redlich-Kwong equation, so that we hope this equation may be useful for the supercritical fluid in engineering applications at high pressure around the critcal point.

• Bulletin of the Korean Chemical Society
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• v.11 no.1
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• pp.28-31
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• 1990

By using Pak's theory of liquid, a phenomenological theory of viscosity proposed by the authors is applied to liquids under high pressures. The calculated viscosities for various simple substances are in good agreements with those of the observed values over wide pressure ranges.

• Journal of the Korean Chemical Society
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• v.15 no.6
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• pp.303-312
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• 1971

Dependence of the flow behavior of aqueous suspension of Black Hills bentonite on the concentration and the types of electrolytes was stydied. The flow properties were measured with a Couette-type totational viscometer. On addition of monovalent cations, the apparent viscosity determined from the reproducible flow curves (shear rate vs. shear stress) decreased followed by a rise as the ionic concentration further increased. Addition of multivalent cations (di- and tri-) resulted in the viscosity which increased to a maximum then decreased to a constant value. Anions of different chatges produced essentially the same relationship between viscosity and electrolyte concentration. The flow behavior of the electrolyte-containing suspensions was rationalized in terms of the Derjaguin-Landau-Verwey-Overbeek theory of colloidal stability and the generalized theory of viscosity.

• 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.