• Journal of Mechanical Science and Technology
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• 제16권2호
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• pp.255-261
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• 2002

A newly designed mass-detecting capillary viscometer uses a novel concept to continuously measure non-Newtonian fluids viscosity over a range of shear rates. A single measurement of liquid-mass variation with time replaces the now rate and pressure drop measurements that are usually required by capillary tube viscometers. Using a load cell and a capillary, we measured change in the mass flow rate through a capillary tube with respect to the time, m(t), from which viscosity and shear rate were mathematically calculated. For aqueous polymer solutions, excellent agreement was found between the results from the mass-detecting capillary viscometer and those from a commercially available rotating viscometer. This new method overcomes the drawbacks of conventional capillary viscometers meassuring non-Newtonian fluid viscosity. First, the mass-detecting capillary viscometer can accurately and consistently measure non -Newtonian viscosity over a wide range of shear rate extending as low as 1 s$\^$-1/. Second, this design provides simplicity (i. e., ease of operation, no moving parts), and low cost.

• Journal of Mechanical Science and Technology
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• 제16권12호
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• pp.1719-1724
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• 2002

A previously designed capillary viscometer with measuring differential pressure was modified to measure the viscosity of non-Newtonian fluids including unadulterated blood continuously over numerous shear rates in a single measurement. Because of unavoidable experimental noise and a limited number of data, the previous capillary viscometer experienced an inaccuracy and could not directly determine a viscosity without an iterative calculation. However, in the present measurement there are numerous data available near the point of interest so that the numeric value of the derivative, d(In Q)/d(In Q$\sub$w/), is no longer sensitive to the method of differentiation. In addition, relatively low and wide shear rate viscosity measurements were possible because of the present precision pressure-scanning method with respect to time. For aqueous polymer solutions, excellent agreement was found between the results from the pressure-scanning capillary viscometer and those from a commercially available rotating viscometer. In addition, the pressure-scanning capillary viscometer measured the viscosity of unadulterated whole blood without adding any anticoagulants.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.825-828
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• 2000

The objective of the present study is to develop a new device that the viscous characteristics of fluids are determined by applying the unsteady flow concept to the traditional capillary tube viscometer. The capillary tube viscometer consists of a small cylindrical reservoir, capillary tube, a load celt system oat measures the mass flow rate, interfacers, and computer. Due to the small size of the reservoir the height of liquid in the reservoir decreases as soon as the liquid in the reservoir drains out through the capillary and the mass flow rate in the capillary decreases as the hydrostatic pressure in the reservoir decreases resulting in a decrease of the shear rate in the capillary tube. The instantaneous shear rate and. driving force in the capillary tube are determined by measuring the mass flow rate through the capillary, and the fluid viscosity is determined from the measured flow rate and the driving force.

• 한국식품영양과학회지
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• 제20권5호
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• pp.509-512
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• 1991

Rheological property and apparent viscosity(η)of several semi-solid foods were measured with extrusion capillary viscometer. Apparent viscosities of several semi-solid foods ranged from 0.2714 Pa.s to 2.6453 Pa.s Rheological property of spread type semi-solid foods was pseudoplastic (with yield value). Especially, as the moisture content and temperature of Chungkook-jang spread increased, apparent viscosity decreased. On the contrary, as the added soybean oil content of Chungkook-jang spread increased, apparent viscosity also increased.

• 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).

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.489-492
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• 2002

The objective of the present study were to measure the viscosities of non-Newtonian fluids by the transient flow concept in a capillary tube and to apply to hemodynamic studies and pump performance evaluations. The developed capillary tube viscometer could be used to measure the viscosities of the non-Newtonian fluids for a wide range of the shear rate by a run of experiment in a very short time interval. The measured viscosities of water and blood fur different shear rates were good agreement with those of the well established data. The measured viscosities for muddy water varied with the shear rates.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.738-741
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• 2001

The purpose of the present study is to measure the viscosity of liquid in the capillary tube viscometer using the unsteady flow concept. The capillary tube viscometer is consisted of a small cylindrical reservoir, capillary tubes, and the mass flow rate measuring system interfaced with computer. Two capillary tubes with 1.152 and 3.002 mm I.D. are used to determine the diameter effects on the viscosity measurements. The instantaneous shear rate and gravitational driving force in the capillary tube are determined by measuring the mass flow rate through the capillary tube instantaneously. The measured viscosities of water and aqueous Separan solution are in good agreement with the reported experimental data.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.317-320
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• 2002

The effect of vibration on the viscosity of a shear-thinning fluid was investigated with a newly designed pressure-scanning capillary viscometer. The viscometer was designed to measure non-Newtonian viscosity continuously over a range of shear rates at a time. Low frequency vibration was applied perpendicularly to the direction of the flow. The effect of the transversal vibration was investigated for both Newtonian fluids and non-Newtonian fluids. The experimental results showed that the vibration had no effect on the viscosity of the Newtonian fluids. However, the vibration caused a significant reduction of the shear-thinning fluid viscosity. The viscosity reduction was strongly dependent on both vibration frequency and shear rate. In addition, the viscosity reduction was affected by the amplitude of vibration, and, the bigger amplitude applied, the more viscosity reduction occurred.

• 대한기계학회논문집
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• 제14권1호
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• pp.241-250
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• 1990

본 연구에서는 낙구식 점도계를 이용하여 낮은 농도의 용액을 실험할 때 종말 속도측정의 어려움을 해결하기 위하여 레이저와 특수 타이머를 설치하였으며 정확한 특성시간을 결정하기 위하여 실린더 내부의 시험유체를 교란시키지 않고, 떨어뜨린 구 를 회수하는 장치를 제작하였다. 또한 주로 rheogoniometer에 의존하던 영 전단률 점성계수를 측정하기 위하여 속이 빈 알루미늄 구(hollow aluminium ball)의 밀도를 시험 유체와 거의 같은 정도까지 변화시켜가며 종말 속도를 측정하였으며 점탄성 유체 로써 Separan AP-273의 낮은 농도인 300에서 2000wppm까지의 저농도 용액에 대한 특성 시간을 여러모델에 의하여 실험적으로 결정하고 저농도 폴리머 용액에서 퇴화로 인한 점탄성유체의 특성 변화를 분석하였다.

• 한국관광식음료학회지:관광식음료경영연구
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• 제13권1호
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• pp.55-68
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• 2002

Flow properties of doenjang samples at various total solid contents (30, 32, 34, 36, 38, 40%) were evaluated in this study. Flow properties of doenjang samples was determined by using Haake concentric cylinderical viscometer and Instron testing machine with capillary extrusion viscometer, and consistency index(K), and flow behavior index(n) was also determined from power models, and yield stress was derived form Casson models and vanes methods. Doenjang samples showed shear-thinning (pseudoplastic) fluid with small magnitude of flow behavior index(n) (n=0.30-0.55). Casson yield stress was from 2.11 to 64.02(Pa). Vane yield stress was more effective than casson yield stress in property of reactivation. Apparent viscosity was decreased with the increase in temperature and activation energy was in the range of 6.58 to 10.70 kJ/mole. From the capillary extrusion method, K and n was increased with the increase in solid content with good correlation with. The result revealed that capillary extrusion method is useful for measuring the flow properties of doenjang.