• 한국기계기술학회지
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• 제13권2호
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• pp.85-91
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• 2011

Computational results with pseudoplastic fluid flows for fully developed non-Newtonian laminar flows have been obtained. Those consist of the product of friction factor and Modified Reynolds number and Nusselt numbers with respect to the shear rate parameter in an annular pipe. The numerical results of the product of friction factor and Reynolds numbers and the Nusselt numbers for both Newtonian region and the power law region were compared with previously published asymptotic results, respectively. In the present calculations, the product of friction factor and Newtonian Reynolds numbers for pseudoplastic fluid at power law region in annular pipe is 180% less than that for Newtonian fluid. For power law fluids with different power law flow indices, the difference of the product of friction factor and power law Reynolds number between previous and the present results at the power law region is within 0.20%. The solutions also show the effect of the shear rate parameter on the Nusselt number and about 11% increase of Nusselt number at the power region.

• 동력기계공학회지
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• 제13권2호
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• pp.30-35
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• 2009

Numerical Calculations for dimensionless pressure drop (friction factor times Reynolds number) have been obtained for fully developed laminar flow of MPL(Modified Power Law) fluid in isosceles triangle pipes. The solutions are valid for Pseudoplastic fluids over a wide range from Newtonian behavior at low shear rates through transition region to power law behavior at higher shear rates. The analysis identified a dimensionless shear rate parameter which for a given set of operating conditions specifies where in the shear rate range a particular system is operating, i.e., Newtonian, transition or power law region. The numerical calculation data of the dimensionless pressure drop for the Newtonian and power law regions are compared with previously published asymptotic results presenting within 0.16 % in Newtonian region and 2.98 % in power law region.

• 한국식품영양학회지
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• 제12권2호
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• pp.204-208
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• 1999

In order to obtain data for use of algin in drink making process solution properties of algin have been investigated at various condition of algin concentration temperature pH and various food additives. At same revolution velosity viscosities of algin were increased as algin concentration raised. Algin solution showed dilatnat type flow in concentration of 0.25% to 0.4% but pseudoplastic type flow in above 0.5% showed dilatant type flow in concentration of 0.25% to 0.4% but pseudoplastic type folw in above 0.5% A maximum viscosity of algin was observed at pH 5.5 and its viscosities were also decreased as the tem-perature increased and heating at 8$0^{\circ}C$ above. Organic acids affected on the viscosity of algin with pH dependently and gel formed in pH below 3.0 Sweetners have no effect to the viscosity of algin. How-ever addition of NaCl and KCL upto 1.0% decreased a little its viscosity and CACl2 MgCl2 and FeCl3 increased the viscosity of algin Glutamic acid decreased the viscosity of algin.

• 한국수산과학회지
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• 제40권2호
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• pp.68-72
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• 2007

The flow properties of sulfated polysaccharides purified from the ascidian Halocynthia roretzi tunic were investigated. The sulfated polysaccfarides produced aqueous solutions of low apparent viscosity with pseudoplastic flow behavior. The respective activation energies of TCA-treated and TCA-nontreated solutions were $2.2248{\times}10^4\;and\;1.442{\times}10^4J/kg{\cdot}mol$ at a 150L/s shear rate. The viscosity of the sulfated polysaccharides solution was increased by the addition of sugar, while it was not changed by the addition of NaCl.

• 한국식품영양학회지
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• 제13권1호
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• pp.78-82
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• 2000

For the purpose of investigation of the food processing fittness of the sea mustard aqueous extracts, the steady shear flow have been measured over a wide range of shear rate using a Brookfield digital viscometer(SPDL21). The rheological behaviors of the sea mustard aqueous extracts which were extracted at 10$0^{\circ}C$ for 2 hours exhibited pseudoplastic behavior with yield stress. In the test of the relationship between temperature and apparent viscosity of samples at 10 rpm decreased along with the increment of temperature. The sea mustard aqueous extracts appeared greatly temperature dependent characteristics(Ea=1.51 ㎉/mole).

• 한국세라믹학회지
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• 제34권11호
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• pp.1173-1181
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• 1997

Effects of particle size distribution of alumina ceramics on behaviors of tape casting were investigated with emphases on the rheological characteristic of slurry, green density, green sheet strength, and sintering density. For the control of particle size distribution of alumina, the commercial grade low soda alumina, which had different mean particle size of 3.58 ${\mu}{\textrm}{m}$ and 0.42 ${\mu}{\textrm}{m}$, were chosen and blended together. As results, the mixing of 80 wt% fine powder and 20 wt% coarse powder(designated to FC20) led to the increase of packing density and strength of green sheet, and made it easy to handle during processing without lowering of sintering density. Besides, the pseudoplastic behavior of slurry decreased with increase of the fraction of coarse alumina powder.

• 산업기술연구
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• 제34권
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• pp.11-14
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• 2014

Viscosity and shear stress of the dental impression materials on commercial market(Imprint Garant LB(3M, U.S.A), EXAMIXFINE IT(GC, Japan), Vonflex S LB(Vericom, Korea), S-Silicone LB(Shinwon, Korea)) were measured with increasing shear rate from 50(1/sec) to 100(1/sec). The viscosity of EXAMIXFINE IT was decreased from 20,542(cP) to 14,684(cP), which is the shear thinning property of pseudoplastic as non-Newtonian fluid. Since the pseudoplastic property makes the impression material shear thinning and softly injected from cartridge, EXAMIXFINE IT might be popularly used in dentistry.

• Journal of Magnetics
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• 제21권2호
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• pp.273-280
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• 2016

In this paper, the peristaltic flow of Psedoplastic fluid with variable viscosity in an asymmetric channel is examined. The bionic effects by means of magnetohydrodynamics (MHD) are taken into account. The assumptions of long wave length and low Reynolds number are taken into account. The basic equations governing the flow are first reduced to a set of ordinary differential equation by using appropriate transformation for variables and then solve by using perturbation method. The effect of physical parameters on the pressure rise, velocity and pressure gradient are illustrated graphically. The trapping phenomenon is analyzed through stream lines. A suitable comparison has also been made as a limiting case of the considered problem.

• 한국식품과학회지
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• 제31권3호
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• pp.638-643
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• 1999

본 연구에서는 영양음료 base를 제조할 때 단백질 급원으로 분기대두단백질(soy protein isolate; SPI)과 sodium caseinate를 혼합비를 달리하여 5종의 시료를 제작하였고 각각의 유동특성을 조사하였으며 그 결과는 다음과 같다. $20^{\circ}C$에서 전단속도를 $0\;sec^{-1}$에서 $500\;sec^{-1}$까지 변화시킬때, SPI 비율이 커질수록 시료는 newtonian 유동특성에서 pseudoplastic 유동특성으로 변화되고 비율이 더욱 커짐에 따라 항복력을 동반한 bingham pseudoplastic 유동특성으로 전환되었다. 이는 SPI의 농도가 높아질수록 전체 조직 중 progel의 형성이 많아지고 이것이 유동특성에 변화를 주었기 때문이라고 사료된다. 유동특성과 온도의 관계를 알기 위하여 각 시료를 온도변화에 따라서 겉보기 점도 $(log{\eta}_{app})$와 1/T의 관계를 도시한 결과 겉보기 점도는 모든 시료가 $250\;sec^{-1}$의 전단속도에서 온도가 증가함에 따라 감소되는 경향을 보였으며 SPI의 첨가량이 많은 시료일수록 감소폭이 크게 나타났다. Ea (활성화에너지)는 SPI의 비율이 늘어남에 따라 증가하는 $(0.8035{\sim}1.5947{\times}10^4\;J/kg{\cdot}mol)$ 결과가 나타났다. 이는 SPI의 비율이 높은 시료는 열처리 공정 후 progel화 된 SPI의 함량이 상대적으로 많아지고 이에 따라 겉보기 점도가 증가하고 유동 활성화에너지 외에 분자간 회합등을 절단하는데 소요되는 구조 활성화에너지가 필요하였기 때문이라고 사료된다. 겉보기 점도와 시간의존성의 관계에서는 SPI의 비율이 일정수준 이상일 경우 hysteresis loop를 관찰하였고 전단응력의 변화에 따라 조직붕괴가 심해져 결과적으로 시료의 유동특성이 크게 변함을 알 수 있었다.

• 한국식품과학회지
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• 제33권2호
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• pp.161-165
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• 2001

농도를 달리한 산과 알칼리용매 및 물로 사과박에서 식이섬유를 추출하여 $24.4{\sim}29.3% 범위의 총 식이섬유를 얻었다. 수용성 식이섬유는 산용매로 6.85%, 알칼리용매로 6.55%를 추출하여 모두 물추출 6.0%보다 높았으며, 산과 알칼리용매의 농도가 높을수록 추출수율이 좋았다. 수용성 식이섬유의 galacturonic acid 함량은 0.01M HCl(77.5%)>0.05M HCl(76.8%)>$H_2O(76.1%)$>0.05M NaOH(73.8%)>0.01M NaOH(69.0%)의 순서로 많았으며, 산용매로 추출시 펙틴의 수율이 가장 우수하였다. 추출액의 색도는 추출용매의 농도가 높을수록 그리고 같은 농도에서는 알칼리추출이 산추출보다 높았고, 색도와 수용성 식이섬유 추출수율 간에는 유의성이 없었다. 그리고 각 시료의 유동특성을 조사한 결과, 전단속도를 $1\;sec^{-1}$에서 $600\;sec^{-1}$까지 증가시킬 때의 전단응력은 galacturonic acid 함량이 많을수록 증가하였다. 산과 물추출에 의한 수용성 식이섬유의 물성은 Newtonian 유동특성을 나타낸 반면에 알칼리추출 시료는 pseudoplastic 유동특성에서 알칼리농도가 증가할수록 항복력을 동반한 Bingham pseudoplastic 유동특성으로 전환되는 경향을 보였다. 겉보기점도와 시간의존성의 관계에서는 알칼리 추출시료에서 hysteresis loop이 관찰되었고 thixotropy 성질을 지님을 알 수 있었다.