• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.529-532
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• 2007

In order to characterize the thermal conductivity and viscosity of grout materials used for backfilling ground heat exchangers, nine bentonite grouts and cement grouts being adapted in the United State have been considered in this study. The bentonite grouts indicate that the thermal conductivity and viscosity increase with the content of bentonite or filler (silica sand). In addition, material segregation can be observed when the viscosity of grout is relatively low. The saturated cement grouts appear to possess much higher thermal conductivity than the saturated bentonite grouts, and the reduction of thermal conductivity in the cement grouts after drying specimens is less than in case of the bentonite grouts. Maintaining the moisture content of grouts is a crucial factor in enhancing the efficiency of ground heat exchangers.

• 한국식생활문화학회지
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• 제24권4호
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• pp.419-425
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• 2009

This study examined the effects of added amounts of shrimp powder on the physical and sensory properties of Jook for elderly foodservice operation. According to the amylograph data, the composite shrimp flour-wheat flour samples increased the gelatinization temperature, with increasing shrimp-flour content; moreover, initial viscosity at $95^{\circ}C$, viscosity at $95^{\circ}C$ after 15 minutes, and maximum viscosity were reduced. As the level of shrimp powder in samples increased, L-values decreased, and a-values and b-values increased. In addition, the Jook had higher viscosity and lower spreadability values as the amount of shrimp powder increased. Sensory characteristics, such as nutty taste, color, viscosity, and overall preference increased significantly with the addition of shrimp powder. In conclusion, to enhance the quality of Jook, a 3% addition of shrimp powder would be the most beneficial.

• International Journal of Vascular Biomedical Engineering
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• 제4권2호
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• pp.7-12
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• 2006

The present study investigated the effects of the osmotic environment on the rheological properties of erythrocytes and their suspensions. In an iso-osmotic medium, erythrocytes forming a biconcave discocyte under resting conditions, exhibited high deformability. In a low-osmotic medium, the deformability of erythrocytes, which swelled and exhibited a spherical shape, significantly decreased at a high shear stress and the high-shear viscosity of the cell suspension was slightly higher than that of normal blood. Hyper-osmotic stress, however, which caused to form echinocytes, decreased cell deformability but exhibited smaller viscosity in low shear rates than iso-osmotic blood viscosity. These results showed a close relation with the aggregability measurements, in that hypertonic blood showed lower aggregability than the hypotonic and isotonic RBC suspensions. These findings indicate that the physicochemical environment has a strong influence on the rheological properties of the erythrocyte and its suspensions.

• 에너지공학
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• 제8권2호
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• pp.293-297
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• 1999

Direct comparisons are made between curvature-corrected eddy viscosity models and the present experimental data. The results show that the curvature effects can be quantified through a curvature parameter R$\sub$c/ or S$\sub$c/ and a non-equilibrium value of p/$\varepsilon$. The data reveal a significant dependence of the eddy viscosity on the curvature and strain history for a fluid in a stabilizing curvature field, S$\sub$c/>1.0. Especially, experimental result shows that the eddy viscosity coefficient ratio at S$\sub$c/=3 changes from 10 to -10 although shear rate preserved constant. It is therefore suggested that proper curvature modifications, particularly the strain history effect, must be introduced into current eddy viscosity models for their application to turbulent flows subjected to curvature straining field for a non-negligible period of time.

• Journal of Mechanical Science and Technology
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• 제18권6호
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• pp.1036-1041
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• 2004

A newly designed pressure-scanning slit viscometer is developed to combine an optical device without refraction while measuring blood viscosity over a range of shear rates. The capillary tube in a previously designed capillary viscometer was replaced with a transparent slit, which is affordable to mount optical measurement of flowing blood cells. Using a pressure transducer, we measured the change of pressure in a collecting chamber with respect to the time, p(t), from which the viscosity and shear rate were mathematically calculated. For water, standard oil and whole blood, excellent agreement was found between the results from the pressure-scanning slit viscometer and those from a commercially available rotating viscometer. This new viscometer overcomes the drawbacks of the previously designed capillary viscometer in the measuring whole blood viscosity. First, the pressure-scanning slit viscometer can combine an optical instrument such as a microscope. Second, this design is low cost and simple (i.e., ease of operation, no moving parts, and disposable).

• Journal of Mechanical Science and Technology
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• 제16권3호
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• pp.395-402
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• 2002

This paper shows how to formulate the transient analysis of 2-dimensional Hagen-Poiseuille flow using smoothed particle hydrodynamics (SPH). Treatments of viscosity, particle approximation and boundary conditions are explained. Numerical tests are calculated to examine effects caused by the number of particles, the number of particles per smoothing length, artificial viscosity and time increments for 2-dimensional Hagen-Poiseuille flow. Artificial viscosity for reducing the numerical instability directly affects the velocity of the flow, though effects of the other parameters do not produce as much effect as artificial viscosity. Numerical solutions using SPH show close agreement with the exact ones for the model flow, but SPH parameter must be chosen carefully Numerical solutions indicate that SPH is also an effective method for the analysis of 2-dimensional Hagen-Poiseuille flow.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2003년도 학술대회지
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• pp.215-223
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• 2003

Viscosity index improver (VII) is one of the major additives to the modern multigrade lubricants for the viscosity stability against temperature rise. However, it causes shear thinning effects which make the film thickness lessened very delicately at high shear rate $(over\;10^5\;s^{-1})$ of general EHL contact regime. In order to exactly verify the VII's performance of viscosity stability at such high shear rate, it is necessary to make the measurement of EHL film thickness down to $\~100nm$ with fine resolution for the preliminary study of viscosity control. In this work, EHL film thickness of VII added lubricant is measured with the resolution of $\~5nm$, which will give very informative design tool for the synthesis of lubricants regarding the matter of load carrying capacity at high shear rate condition.

• 대한화장품학회지
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• 제10권1호
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• pp.49-74
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• 1984

Rheology of gels prepared with stearyl dimethyl benzyl ammonium hectorite (SDBAH) and various polar additives in n-butyl acetate was investigated by measuring the viscosity and rheogram. Including generally recognized polar additives, additional studies on the rheogram and viscosity were made with ether-type methyl cellosolve and carbitol, with dimethyl sulfoxide (DMSO) having sulfonyl group, and furthermore with above-mentioned polar additives containing small quantity of water, It was observed that molecular size, dipole moments and dielectric constants of polar additives had a great influence on viscosity increase and rheology of SDBAH gel, and the increase of SDBAH interlayer spacing was important factor in gel formation and viscosity change. It was also shown that thixotropy effect was increased with the increase of polar additive concentration, finally changed to rheopexy from thixotropy as the concentration of polar additives was increased more than about 40% of SDBAH weight. In addition thixotropy changed to rheopexy as the increase of shear rate. It was further found that the aqueous solutions of polar additives (water content, 5-25%) had more effects on rheology than additives without water, and particularly 95clo DMSO solution was the most effective. And the optimum concentration of polar additives showing maximum viscosity in the same SDBAH concentration system was examined.

• 한국식품영양학회지
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• 제7권4호
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• pp.353-360
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• 1994

Effect of pH, calcium, sucrose, heating and mixing ratio of soy and cow milk was studied on the viscosity and the sensory characteristics of cow-soy milk. The viscosity of soymilk was significantly affected by pH with showing maximum at 6.0 and the pH effect was decreased as the ratio of cow talk increased. A addition of sucrose or calcium affected little on the viscosity and a negative linear relationship was found be tween viscosity and an increase in cow milk ratio. Sensory characteristics of grassy and beany odor and taste of soymilk were rapidly decreased and nutty flavor and total acceptability were increased during initial 30 min of boiling. A further increase in boiling affected little on tastes and odors of soymilk. The beany odor and taste linearly decreased and milk flavor Increased as the ratio of cow milk increased. The total acceptability of 50 : 50 was found to be maximum for cow and soy mixed milks.

• Food Science and Biotechnology
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• 제17권1호
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• pp.80-84
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• 2008

The effect of gellan (GE), xanthan (XA), and $\lambda$-carrageenan (LC) on the viscosity, sedimentation, ellagic acid content, and turbidity of grape 'Campbell Early' juice (CEJ) was investigated. CEJ samples with 0.15% each of GE, XA, and LC were tested for the above variables after 0, 5, 10, and 20 days of storage. The samples containing GE (0.15%) showed the least amount of sediment formation, the lowest ellagic acid content and turbidity, and a rise in viscosity. Sedimentation in CEJ decreased with increased viscosity due to the addition of gums which also limited the ellagic acid content and turbidity. GE was the most effective additive for the stabilization of CEJ.