• Food Science and Biotechnology
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• 제15권5호
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• pp.756-762
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• 2006

Freeze concentration of milk was carried out through the controlled recrystallization of ice in a multi-stage freeze concentrator. Rheological characteristics of ice slurries were analyzed to determine efficient concentration levels for the freeze concentration process. It was determined that efficient concentration level was 17% of total solids in the first and 27% in the second stage. Physicochemical properties were compared between freeze concentrated and evaporated milk. Freeze concentrated milk was more similar in color appearance to control milk than was evaporated milk. pH significantly decreased in evaporated milk than in freeze concentrated milk. pH of freeze concentrated milk resulted in similar value to control. These results indicated the advantages of freeze concentration as a non-thermal milk processing technology in terms of physicochemical properties. Consequently, we investigated the influence of ice recrystallization on the rheological characteristics of ice slurries and physicochemical properties of freeze concentrated milk.

• 한국정밀공학회지
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• 제10권1호
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• pp.134-141
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• 1993

Electro-Rheological(ER) fluids undergo a phase-change when subjected to an external electic field, and this phase-change typically manifests itself as a many-order-of-magnitude change in the rheological behavior. This phenomenon permits the global stiffness and energy- dissipation properties of the beam structures to be tuned in order to synthesize the desired vibration characteristics. This paper reports on a proof-of-concept experimental investigation focussed on evaluation the vibration properties of hollow cantilevered beams filled with an ER fluid. and consequently deriving an empirical model for predicting field-dependent vibration characteristics. A hydrous-based ER fluid consisting of corn starch and silicone oil is employed. The beams are considered to be uniform viscoelastic materials and modelled as a viscously-damped harmonic oscillator. Natural frequency, damping ratio and elastic modulus are evaluated with respect to the electric field and compared among three different beams: two types of different volume fraction of ER fluid and one type of different particle concentration of ER fluid by weight. Transient and forced vibration responses are examined in time domain to demonstrate the validity of the proposed empirical model and to evaluate the feasibility of using the ERfluid as an actuator in a closed-loop control system.

• Smart Structures and Systems
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• 제2권1호
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• pp.61-80
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• 2006

The concept of structural vibration control is to absorb vibration energy of the structure by introducing auxiliary devices. Various types of structural vibration control theories and devices have been recently developed and introduced into mechanical systems. One of such devices is damper employing controllable fluids such as ElectroRheological (ER) or MagnetoRheological (MR) fluids. MagnetoRheological (MR) materials are suspensions of fine magnetizable ferromagnetic particles in a non-magnetic medium exhibiting controllable rheological behaviour in the presence of an applied magnetic field. This paper presents the modelling of an MRfluid damper. The damper model is developed based on Newtonian shear flow and Bingham plastic shear flow models. The geometric parameters are varied to get the optimised damper characteristics. The numerical analysis is carried out to estimate the damping coefficient and damping force. The analytical results are compared with the experimental results. The results confirm that MR damper is one of the most promising new semi-active devices for structural vibration control.

• Elastomers and Composites
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• 제44권3호
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• pp.323-328
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• 2009

고분자 용융 같은 물질의 유변학적인 성질은 전단 흐름에서 복잡한 비 뉴톤 유동 현상을 보인다. 이들 유동성질은 유동단위와 유동부분 사이의 상호작용의 특성에 의하여 결정된다. poly(vinyl alcohol) hydrogel의 비 뉴톤유동 곡선을 cone-plate 레오메타로 여러 온도와 여러 농도 조건에서 얻었다. PVA hydrogel의 유동 곡선을 비 뉴톤 유동식에 적용시켜 유동 파라메타를 얻었다. 유동현상은 전단 속도가 증가함에 따라 전단박화의 틱소트로피 현상을 나타내었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 추계학술대회 논문집
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• pp.92-93
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• 2013

In this study, Shock Absorption performance of Magneto-rheological elastomer(MRE) is identified through the drop impact test. Magneto-rheological materials are divided into two groups by MR fluid in fluid state and MR elastomer in solid state like rubber. The stiffness characteristics of Magneto-rheological material can be changed as magnetic field is applied. The impact loads in MR elastomer were measured under weight of impactor. Experiment results are shown through the experiments to confirm the effect of shock absorption of MR elastomer. Thus, the MR elastomer can be applied to shock absorber used in area that shock occurs.

• 한국공작기계학회논문집
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• 제12권1호
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• pp.78-83
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• 2003

Electro-rheological(ER) fluids are suspensions in which rheological properties show an abrupt change with variation of electric fields. We modeled the parallel-plates relating to ER-Valve system and yielded shear stress according to the strength of electric field. The purpose of the present study is to examine the flow characteristics of ER fluids according to the strength of electric field between parallel-plates. Then the steady relationship between pressure drop and flow rate of the ER fluids between parallel-plates under application of an electric fields was measured. The pressure drop and flow rates of ER fluids under the application of electric fields for steady flow were measured. For the experiment, we used the ER fluids, 35w% zeolite having hydrous particles and differential pressure gauge. This test reviewed experiment for the special changes of ER fluids in the steady flow condition.

• 한국기계가공학회지
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• 제2권3호
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• pp.48-55
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• 2003

This study investigates the effect of temperature and electric field strength on the Bingham characteristics of Electro-Rheological(ER) fluids which change their Yield shear stress and viscosity by temperature and electric field strength. It is found that under constant temperature the Yield sheal stress and viscosity of ER fluids proportionally increase with the applied electric field strength, and under constant applied electric field strength the Yield shear stress and viscosity of ER fluids decrease with the increasing temperature. These results are considered to be applied to the fluid and pneumatic power industry.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.328.1-328
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• 2002

MR(Magneto-rheological) fluid is smart fluid that can change its characteristics when magnetic fields are applied. Recently, many researches are going on this MR fluid for the application in a variety of areas including automobile shock absorbers. This paper describes the design procedure of a MR damper and the analysis results of its dynamic characteristics. MR fluid in the magnetic field shows initial yield shear stress and increasing resistive viscousity with final saturation thereafter. (omitted)

• Korea-Australia Rheology Journal
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• 제11권3호
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• pp.197-218
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• 1999

Rheological techniques are frequently used to characterize particulate suspensions and polymer systems. Experimental data frequently show that similar trends and characteristics are found in both systems. Using common examples and illustrations of the rheological behaviour, we attempt to bring together these separate fields and investigate the common links in the different systems. In many cases the similar rheological behaviour observed in these different systems can be related to the same basic physical principles.

• 한국응용과학기술학회지
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• 제32권3호
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• pp.386-393
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• 2015

콜로이드 분산계와 같은 복잡한 물질의 유변성질은 전단 흐름이 일어날 때 비뉴톤 유동현상을 나타낸다. 이들 유변성질은 유동단위의 성질과 유동 세그먼트 사이의 상호작용에 의하여 영향을 받는다. 유동곡선을 이론적인 틱소트로피식에 적용하여 여러 틱소트로피 유동 곡선에 대한 유동파라메타, 완화시간, $({\beta}_2)_0$, 구조적인 요인, $C_2$, 전단 모듈러스, $X_2/{\alpha}_2$을 구하였다. 유변 파라메타의 변화는 비뉴톤 유동, 점도, 유동 세그먼트의 유동 활성화 에너지와 직접적인 관계가 있다.