• Tribology and Lubricants
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• 제19권2호
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• pp.72-77
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• 2003

Chitosan derivatives, Fluorinated chitosan, and N,N,N-Trimethyl chitosan iodide were synthesized as the disperse phases for the electrorheological fluid. The synthesis of these materials were confirmed by Fourier transform infrared spectroscopy (FT-lR). Chitosan derivative suspensions showed ER effect under the electric field. Especially, N,N,N-Trimethyl chitosan iodide suspension showed better electrorheological and electric properties than Fluorinated chitosan. It is due to difference in electron strength of polar groups composed derivatives. N,N,N-Trimethyl chitosan iodide suspension exhibited a linear dependence on an electric field power of 2.07.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1840-1843
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• 2003

The Magnetorheological fluid has the properties that its viscosity has drastic changed under some magnetic fields therefore, Magnetorheological fluids has been used for micro polishing of the micro part( for example, a aspherical surface in a micro lens). The polishing process may appears as follows. A part rotating on the spindle is brought into contact with an Magnetorheological finishing(MRF) fluids which is set in motion by the moving wall. In the region where the part and the MRF fluid ate brought into contact, the applied magnetic field creates the conditions necessary for the material removal from the part surface. The material removal takes place in a certain region contacting the surface of the part which can be called the polishing spot or zone. The polishing mechanism of the material removal in the contact zone is considered as a process governed by the particularities of the Bingham flow in the contact zone. Resonable calculated and experimental magnitudes of the material removal rate for glass polishing lends support the validity of the approach.

• KSTLE International Journal
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• 제3권1호
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• pp.23-25
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• 2002

The electrorheological (ER) behavior of amino coated chitosan phosphate suspension in silicone oil is investigated. Amino coated chitosan phosphate suspension shows a typical ER response (Bingham flow behavior) upon application of an electric field due to the polarizability of phosphoryl polar group. The shear stress for the suspension exhibits a linear dependence on an electric field power of 1.94. The values of structure factors $A_s$obtains 2 far mine coated chitosan phosphate suspension and it may be due to the formation of multiple chains upon application of the electric field. Throughtout the experimental results, amino coated chitosan phosphate suspension shows good dispersion stability and found to be an anhydrous ER fluid.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.489-494
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• 2002

This paper presents hydraulic model which can capture the hysteric damping force behavior of ER damper. A flow mode rue ER damper is manufactured, and its field-dependent damping forces are measured. Newly proposed hydraulic model which derived from physical hydro-mechanical parameters of ER damper are conventional Bingham model are investigated to represent the field-dependent damping force characteristics of ER damper. After principal parameters of two models are estimated from the measured damping forces data, the force vs velocity hysteresis cycles are then reconstructed. The results show that the proposed hydraulic model can capture the hysteresis behavior of ER damper accurately.

• 한국건축시공학회지
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• 제11권4호
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• pp.387-395
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• 2011

In the construction of tall-building, concrete pumping influences the success of the project. In order to establish pumping technology for high speed construction of tall building, study for quantitative evaluation of flow characteristics and pumpability should be conducted. So in this study, the characteristics including the inner pipe pressure, rheological properties of concrete and mortar through the continuous pumping test were evaluated. Then we analyzed the relations between rheological properties and pumpability. In the result of test, there are high correlations between the rheological characteristics which represented by yield stress and plastic viscosity and pressure loss with pipe length. Also, we estimated pressure loss according to conditions of concrete mix and pumping through the evaluation of inner pipe friction.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 춘계 학술논문 발표대회 1부
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• pp.99-101
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• 2011

In order to have pumping technology for high speed construction of tall building, study for quantitative evaluation of flow characteristics and pumpability should be conducted. So, this study evaluate the characteristics among the inner pipe pressure, fresh concrete properties and separated mortar through the continuous pumping test. Then it consider of relations between rheological properties and pumpability. In the result of test, it found that there are high interrelationship between the rheological characteristics which represented plastic viscosity and pressure lose by pipe length.

• 한국소음진동공학회논문집
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• 제12권11호
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• pp.882-889
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• 2002

This paper presents vibration control performance of a squeeze mode ER mount for high static load. After experimentally investigating the field-dependent damping force under the squeeze mode motion, a squeeze mode ER mount which can support 200 kg of static load is designed and manufactured. Displacement transmissibility of the proposed ER mount is experimentally evaluated in frequency domain with respect to the intensity of the electric field, and a sky-hook control algorithm is designed to attenuate unwanted vibration. Vibration isolation capabilities of the flow mode ER mount and rubber mount are compared to those of the proposed squeeze mode ER mount.

• 한국건축시공학회지
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• 제8권2호
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• pp.99-106
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• 2008

To improve concrete tensile strength and bending strength, New plan that have more economical and simple manufacture process is groped. By an alternative plan, chemical pre-stressed concrete is presented. In this study, we analyzed the rheological properties of cement paste with the kind and replacement ratio of k-type CSA type expansive additives that is used mainly in domestic. and we suggested that the algorithm of a mixing plan in the chemical pre-stressed concrete and from this, we presented the basic report for the right mixing plan. From the results, Flow increased more or less according to use of expansive additives. This phenomenon was observed by increasing paste amount that shows as substitution for expansive additives that specific gravity is smaller than that of cement. As linear regression a result supposing paste that mix expansive additives by Bingham plastic fluid. The shear rate and shear stress expressed high interrelationship. therefore, flow analysis of quantitative was available. The plastic viscosity following to replacement ratio of expansive additives is no change almost, the yield value is decreased in proportion to the added amount of expansive additives. Through this experiment, we could evaluate rheological properties of cement paste using the expansive additives. Hereafter by an additional experiment, we must confirm stability assessment of material separation by using the aggregate with the kind and replacement ratio of expansive additives.

• Applied Biological Chemistry
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• 제29권4호
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• pp.339-345
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• 1986

발아 옥수수로 부터 분리한 전분의 리올로지 특성을 생옥수수 전분과 비교검토하면서 조사하였다. 발아전분의 유동형태는 생전분과 마찬가지로 빙햄 의가소성 거동을 보였으나 발아전분 호화액의 점조도지수 및 항복응력은 생전분보다 낮은 값을 보였고, 유동거동지수는 비슷한 값을 보였다. 정조도지수의 온도 의존성은 발아전분이 생전분보다 낮았으나 농도 의존성은 변화가 없었다. 발아전분의 시간 의존특성은 생전분과 마찬가지로 틱소트로픽 거동을 보였으나 발아로 인하여 생전분에 비하여 전단하의 구조붕괴가 컸으며 탄성적 성질은 약한 특성을 나타내었다.

• 한국지반공학회논문집
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• 제27권10호
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• pp.81-92
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• 2011

팽윤성 점토의 전단강도 및 유변학적 특성은 점토입자의 크기, 양이온 교환능력, 점토광물학적 조성과 형상 등에 영향을 받는다. 본 연구는 고운 분말가루의 와이오밍(Wyoming) 벤토나이트에 대해 염화나트륨 0g/L 와 30g/L 농도로 24시간 수화시킨 후 염분농도에 따른 물성-강도특성 및 유변학적 특성변화를 살펴봄으로써, 유변학적 특성, 유변화적 모델들의 적용성 및 흙 입자의 구조변화에 따른 항복응력-점도와의 상관관계를 설명하고자 한다. 실험결과에 따르면, 팽윤성 점토는 전단담화(shear thinning)와 항복응력과 소성점도로 표현가능한 Bingham 유체 거동을 보이는 것으로 조사되었다. 염분농도가 낮고 함수비가 높아질수록 벤토나이트는 완전소성거동에 가깝게 나타나며, 전단변형률속도에 따른 변화의 폭이 미미한 것으로 조사되었다. 반면, 염분농도가 높아질수록 전형적인 전단담화거동을 보이며, 전단변형률속도를 증가시킬수록 염분농도에 따른 벤토나이트의 전단강도의 차이는 커진다. S=0g/L에 대해 Carreau, Herschel-Bulkley 및 멱수법칙 모델이, S=30g/L에 대해서는 이중선형, Herschel-Bulkley 및 멱수법칙 모델 등이 흐름특성을 가장 잘 표현한다. 이것은 염분농도에 따른 흙 입자간 구조적 배열과 형상이 입자간 발생하는 인력인 능-능(EE), 능-면(EF), 및 면-면(FF) 구조를 변화시키고 역학적 특성에 영향을 미치기 때문이다.