• Korea-Australia Rheology Journal
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• v.12 no.3_4
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• pp.151-155
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• 2000

A semiconducting poly(naphthalene quinone) radical (PNQR) was synthesized from Friedel-Craft acylation between naphthalene and phthalic anhydride and used as dispersing particles of a dry-base electrorheological (ER) material in silicone oil. Under an applied electric field (E), the dynamic yield stress (${\tau}_{dyn}$) of this ER fluid, obtained from a steady shear experiment with a controlled shear rate mode, was observed to increase with $E^{1.45}$ Based on this relationship, we propose a universal correlation curve for shear viscosity, which is independent of E using a scaling analysis.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.713-716
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• 2002

Aging effect on the cardiovascular circulation is simulated by lumped parameter model. Aging phenomena can be hemodynamically explained as (1) the increase of flow resistance induced by remodeling of artery vessels and increased viscosity of blood and (2) the reduction of the vessel capacitance caused by arteriosclerosis. Appropriate physiological parameters are evaluated from the clinical data of adults and old men. Simulation results well explain the hypertension with aging of cardiovascular system.

• Korean journal of food and cookery science
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• v.11 no.1
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• pp.33-36
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• 1995

This study attempted to examine the effect on sensory characteristcs and physiochemical properties of Omija jelly in various volume of adding carrageenan. The pH of Omija extract was 3.02. The viscosity was increased and the turbidity was decreased according to the increase concentration Omija extract. the sensory evaluation of Omija jelly was the best with the ratio 0.5% carrageenan.

• Korean journal of food and cookery science
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• v.12 no.3
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• pp.291-294
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• 1996

This study attempted to examine the effect on sensory characteristics and physiochemical properties of Grape jelly in various volume of adding carrageenan. The pH of Grape extract was 3.98. The viscosity was increased and the turbidity was decreased according to the increase concentration Grape jelly. The sensory evaluation of Grape jelly was the best with the ratio 0.5% carrageenan. The sensory evaluation of Grape jelly mold salad showed that the most preferable jelly was the one made by 0.9% carrageenan and 40% fruits(apple, orange and sweet persimmons).

• Journal of Advanced Marine Engineering and Technology
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• v.16 no.5
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• pp.97-110
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• 1992

Rape-seed oil has high viscosity and high rubber content like other vegetable oils. When crude rape-seed oil obtained by a general oil extraction process is used in a diesel engine, automization condition during injection is not good and a large amount of combustion product is doposited in a combustion chamber. The improvement of a diesel engine is required to use rape-seed oil as a diesel engine fuel. In this study, the physical and chemical properties and combustion characteristics of rape-seed oil were investigated. The auxiliary aid was developed to improve automization condition and the effect of the auxiliary injection aid on the performance of a diesel engine was determined. The results are as follows. 1) Oil content of rape-seed is 45%. The exraction rate is 33%. The resuls show higher values compared to those of other vegetable oils. 2) The viscosity of rape-seed oil is 50.8 cSt and nearly 14 times of diesel oil viscosity. 3) The heating value and flash point of rape-seed oil are 9720kcal/Kg and 318$^{\circ}C$, respectively. 4) In case rape-seed oil is used as fuel, brake horse power, specific fuel consumption and brake thermal efficiency are compared to those of diesel oil. The results of rape-seed oil show 3.6%, 12.7% and 3.1% higher values. 5) Particle size of injection fuel with the auxiliary injection aid on the performance of a diesel engine was determined. The results are as follows. 1) Oil content of rape-seed is 45%. The extraction rate is 33%. The results show higher values compared to those of other vegetable oils. 2) The viscosity of rape-seed oil is 50.8 cSt and nearly 14 times of diesel oil viscosity. 3) The heating value and flash point of rape-seed oil are 9720kcal/Kg and 318.deg.C, respectively. 4) In case rape-seed oil is used as fuel, brake horse power, specific fuel consumption and brake thermal efficiency are compared to theose of diesel oil. The results of rape-seed oil show 3.6%, 12.7% and 3.1% higher values. 5) Particle size of injection fuel with the auxiliary injection aids is 100.mu.m smaller than that od injection fuel without the aid. 6) Brake horse power and brake thermal efficiency with the auxiliary injection aid increase 5.07% and 6.07%, respectively. However, specific fuel consumption decreases 3.85% with the auxiliary injection aid.

• Journal of Pharmaceutical Investigation
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• v.29 no.4
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• pp.295-307
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• 1999

Using a Rheometries Fluids Spectrometer (RFS II), the dynamic viscoelastic properties of aqueous poly(ethylene oxide) (PEO) solutions in small amplitude oscillatory shear flow fields have been measured over a wide range of angular frequencies. The angular frequency dependence of the storage and loss moduli at various molecular weights and concentrations was reported in detail, and the result was interpreted using the concept of a Deborah number De. In addition, the experimentally determined critical angular frequency at which the storage and loss moduli become equivalent was compared with the calculated characteristic time (or its inverse value), and their physical significance in analyzing the dynamic viscoelastic behavior was discussed. Finally, the relationship between steady shear flow and dynamic viscoelstic properties was examined by evaluating the applicability of some proposed models that describe the correlations between steady flow viscosity and dynamic viscosity, dynamic fluidity, and complex viscosity. Main results obtained from this study can be summarized as follows: (1) At lower angular frequencies where De<1, the loss modulus is larger than the storage modulus. However, such a relation between the two moduli is reversed at higher angular frequencies where De>l, indicating that the elastic behavior becomes dominant to the viscous behavior at frequency range higher than a critical angular frequency. (2) A critical angular frequency is decreased as an increase in concentration and/or molecular weight. Both the viscous and elastic properties show a stronger dependence on the molecular weight than on the concentration. (3) A characteristic time is increased with increasing concentration and/or molecular weight. The power-law relationship holds between the inverse value of a characteristic time and a critical angular frequency. (4) Among the previously proposed models, the Cox-Merz rule implying the equivalence between the steady flow viscosity and the magnitude of the complex viscosity has the best validity. The Osaki relation can be regarded to some extent as a suitable model. However, the DeWitt, Pao and HusebyBlyler models are not applicable to describe the correlations between steady shear flow and dynamic viscoelastic properties.

• Journal of the Korean Applied Science and Technology
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• v.33 no.4
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• pp.802-812
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• 2016

Silicone foam is very useful as flame resistant material for many industrial areas such as high performance gasketing, thermal shielding, vibration mounts, and press pads. A silicone foam was prepared through simultaneous crosslinking and foaming by hydrogen condensation reaction of a vinyl-containing polysiloxane (V-silicone) and a hydroxyl-containing polysiloxane (OH-silicone) with hydride containing polysiloxane (H-silicone) in the presence of platinum catalyst and imorganic filler at room temperature. This is more convenient process for silicone foam manufacturing than the conventional separated crosslinking and foaming systems. Funtionalized silicones we used in this experiment were consisted with a V-silicone containing 1,0 meq/g of vinyl groups and a viscosity of 20 Pa-s, an OH-silicone with 0.4 meq/g of hydroxyl groups and a viscosity from 50 Pa-s, and an H-silicone containing 7.5 meq/g of hydride groups and a viscosity of 0.06 Pa.s. The effects of compositions of functionalized silicones and additives, such as catalyst and filler on the structure and mechanical properties of silicone foam were studied. 0.5 wt% of Pt catalyst was enough to accelerate the foaming rate of silicone resins. The addition of OH-silicone with lower viscosity accelerates the initial foaming rate and decreases the foam density, but the addition of V-silicone with lower viscosity reduces the tensile strength as well as the elongation. The final foam density, tensile strength, and elogation of silicone foam prepared under the SF-3 condition increase maximum to $0.58g/cm^3$, $3,51kg_f/cm^2$, and 176 %, repectively. We found out the filler alumina also played an important role to improve the mechanical properties of silicone foams in our foaming system.

• Korean Journal of Food Science and Technology
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• v.27 no.4
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• pp.576-581
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• 1995

To obtain the basic information for the effective use of collagen, the flow behavior of collagen extracted from skin tissue was studied. The viscosity of collagen varied with sex, age and the kinds of collagen by extraction method. Regardless of the kinds of collagen, the viscosity of collagen extracted from $6{\sim}12$ week old rat was relatively high. In case of the same age, the viscosity showed higher in female than in male rat and in acid soluble collagen than in insoluble collagen. The solution of the collagen showed the characteristics of Bingham plastic and thixotropic fluid, and the viscosity varied distinctly with temperature, pH, ethanol concentration and collagen concentration. As collagen concentration increased to 6%, the consistency of acid soluble- and insoluble collagen showed a tendency to increase linearly(r = 0.972 for acid soluble collagen, r = 0.957 for insoluble collagen). In that range of collagen concentration, the increasing velocity of consistency was higher in acid soluble collagen than in insoluble collagen. The consistency of collagen solution was decreased according to temperature rising. In case of acid soluble collagen, the consistency is decreased abruptly between $30{\sim}40^{\circ}C$. According to pH variation, the consistency of acid soluble collagen showed biphasic phenomenon, though the consistency of insoluble collagen was found not to be influenced by pH. The consistency of acid soluble- and insoluble collagen according to ethanol concentration showed high between $40{\sim}60%$ of ethanol concentration.

• Journal of the Korean Society of Food Science and Nutrition
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• v.15 no.2
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• pp.119-127
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• 1986

The rheological properties of mayonnaise were studied with cylindrindrical viscometer. It was observed that mayonnaise showed pseudoplastic behavior, yield stress and time dependent characteristics. In the initial period of shear time, the decay of viscosity of mayonnaise was followed by a second-order kinetic equation. The influence of temperature on viscosity could be described by Arrhenius equation. The apparent viscosity of mayonnaise markedly increased with an rise in the concentration of egg yolk; and the emulsion was most stable at the concentration of 12%. At the concentration of $65{\sim}75%$ oil, the apparent viscosity was increased; the maximum value was reached at 75% oil, and above 75% oil, the remarkable decreased was observed. The size of oil drops was decreased with an increase in oil concentration of 75% oil. The apparent viscosity of mayonnaise was increased with an rise in water contents, while being decreased with one in the concentration of vinegar.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.6
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• pp.465-481
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• 2022

Rock grouting is important to improve the waterproof efficiency and mechanical strength of rock medium with joint for utilizing the underground rock space such as tunnel. The grouting materials typically has been used the cement materials, which represent Bingham fluid model. This model can express the relationship of viscosity and yield strength. In addition, it is dependent with elapsed time. The grouting injection performance can be deteriorated with an increase of viscosity and yield strength in the grouting process if the time dependence is ignored. Therefore, in this study, the characteristics of viscosity and yield strength were investigated according to water-cement ratio and time dependence in the laboratory test. Numerical simulation was carried out to investigate the grouting performance according to the time dependence of characteristics in terms of the viscosity model. Given the results, the grouting injected distance and cumulative grout volume were significantly decreased when the time dependence of grouting material was considered. This study, considering the characteristics according to the time dependence of viscosity and yield strength, will be meaningful to the design of grouting injection in field applications.