• 대한기계학회논문집A
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• 제24권2호
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• pp.347-354
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• 2000

This paper presents performance characteristics of a semi-active suspension featuring continuously variable ER (electro-rheological) dampers. These are evaluated through the field test of a passeng er car. Four ER dampers (two for front and two for rear part) are manufactured and their field-dependent damping properties are experimentally investigated. The damping force responses to step input fields are also identified by employing small size of high voltage amplifiers which are made adaptable to the field test. A skyhook controller considering the vertical, pitch and roll motions is formulated and incorporated with a car to be tested. The field test is then undertaken in order to evaluate both comfortability and steering stability showing bump, dive and squat responses.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.451-456
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• 2002

This paper describes the properties of Temperature-Viscosity characteristics of hydrous and anhydrous ER fluids containing starch and titanium particle in silicone oil. ER effects arise from electrostatic forces between the starch particles and titanium particles dispersed in the electrically insulating silicone oil induced when electric field is applied. ER fluids under electric field have been found to provide resonable estimates of ER fluid viscosity variation characteristics. Yield shear stress of the ER fluids were measured on the couette cell type rheometer as a function of electric fields. The outer cup is connected to positive electrode(+) and bob becomes ground(-). The electric field is applied by high voltage DC power supply. In this experiment shear rates were increased from 0 to 200/equation omitted/ in 2 minutes.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.576-579
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• 2005

MR (Magneto Rheological) fluids are well known as a smart fluid and their application researches to control vibration have been conducted by many researchers. However, their dynamic properties have not been identified clearly yet. Therefore, the MR effect is investigated by using a rotational viscometer and a single degree of freedom system with an MR damper. The results obtained from the experimental study show that stiffness and viscous damping coefficients of the system with an MR damper are changed according to the variation of the applied current.

• 한국정밀공학회지
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• 제23권1호
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• pp.105-112
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• 2006

The nonlinear damping force model is made to identify the properties of the ER (electro-rheological) fluid suspension damper. The instrumentation is carried out to measure the damping force of the ER damper. The higher order spectral analysis method is used to investigate the nonlinear frequency coupling phenomena with the damping force signal according to the sinusoidal excitation of the damper. The distinctive higher order nonlinear characteristics are observed. The nonlinear damping force model, which has the higher order velocity terms, is proposed with the result of higher order spectrum analysis. The higher order terms coefficients, which vary according to the strength of the electric field, are calculated using the least square method.

• 한국정밀공학회지
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• 제19권11호
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• pp.37-45
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• 2002

This paper presents the field-dependent Bingham characteristics and damping force control of an electro-rheological (ER) fluid under squeeze mode operation. The squeeze force of the ER fluid due to the imposed electric field is analyzed and an appropriate size of the disk-type electrode is devised. On the basis of the theoretical model of the ER fluid under squeeze mode operation, the yield stress and response speed of the ER fluid are distilled from the time responses of squeeze force to the step electric potentials. Measured squeeze forces under various excitation conditions are compared with the predicted ones from Bingham model and time constant obtained at the transient response test. In addition, the controllability of the field-dependent damping force of the ER fluid under squeeze mode is experimentally demonstrated by implementing simple PID controller.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.616-619
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• 2004

This study has focused on the possibility for recycling of tailings from the Sangdong tungsten mine as powder. The experimental tests for entrapped water ratio were carried out in accordance with the specificed method by Okamura. The rheological measurements of cement paste were conducted by using a commerically digital Brookfield viscometer (Model LVDV-II+) equipped with cylindrical spindles. The results of this study, in case of cement paste mixed with tailings, entrapped water ratio was decreased with increasement of mixing ratio. Thickness of pseudo water film was increased, and mean plastic viscosity was decreased with increasing replacement.

• Journal of Advanced Marine Engineering and Technology
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• 제25권6호
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• pp.1211-1219
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• 2001

The electro-rheological(ER) fluids for smart hydraulic system are a class of colloidal dispersion which exhibit large reversible Changes in their rheological behavior when they are subjected to external electrical fields. This paper presents experimental results on material properties of an ER fluids subjected to electrical fatigues. As a first step, ER fluid is made of methyl cellulose(MC) choosing 25% of particle weight-concentration. Following the construction of test mechanism for durability estimation, the dynamic yield shear stress and the current density for the ER fluids of MC component are experimentally distilled as a function of electric field. In addition, the surface roughness of the employed electrode are evaluated as a function of the number of the electric-field cycles.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2004년도 학술대회지
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• pp.323-329
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• 2004

The electrical and rheological properties pertaining to the electrorheological (ER) behavior of chitosan derivatives, chitosan, chitosan ammonium salt and chitosan phosphate suspensions in silicone oil were investigated. Chitosan derivative suspensions showed a typical ER response (Bingham flow behavior) upon application of an electric field. However, chitosan phosphate suspension exhibited an excellent shear yield stress compared with chitosan and chitosan ammonium salt suspensions. The difference in behavior results from the difference in the conductivity of the disperse phases due to the difference of their polarizability. The shear stress for the chitosan, chitosan ammonium salt and chitosan phosphate suspensions exhibited a linear dependence on the volume fraction of particles and 1.18 ,1.41 and 1.67 powers of the electric field. On the basis of the experimental results, the newly synthesized chitosan derivative suspensions found to be an ER fluid.

• KSTLE International Journal
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• 제5권2호
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• pp.49-51
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• 2004

The electrical and rheological properties pertaining to the electrorheological (ER) behavior of chitosan derivatives, chitosan, chitosan ammonium salt and chitosan phosphated suspensions in silicone oil were investigated. Chitosan derivative suspensions showed a typical ER response (Bingham flow behavior) upon application of an electric field. However, chitosan phosphate suspension exhibited an excellent shear yield stress compared with chitosan and chitosan ammonium salt suspensions. The difference in behavior results from the difference in the conductivity of the disperse phases due to the difference of their polarizability. The shear stress for the chitosan, chitosan ammonium salt and chitosan phosphate suspensions exhibited a linear dependence on the volume fraction of particles and 1.18, 1.41 and 1.67 powers of the electric field. On athe basis of the experimental results, the newly synthesized chitosan dervative suspensions found to be an ER fluid.

• 한국미생물·생명공학회지
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• 제17권5호
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• pp.475-480
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• 1989

Pseudomonas delafieldii이 배양액으로부터 분리한 다당류 용액의 물성을 검토하였다. 본 다당류는 매우 점도가 높은 의가소성 물질로 1% 용액의 겉보기 점도는 42sec$^{-1}$에서 1769mpaㆍs이었다. 이 용액은 pH에 대한 안정성은 있으나 열 안정성은 보이지 않았다. 이 용액의 유동 활성에너지는 4.44kacl/mole 이고, 농도의존성은 double 1logarithm으로 포현되었다.