• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1422-1427
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• 2007

MR fluid is a suspension of micrometer-sized magnetizable particles in silicon oil and a functional fluid whose apparent viscosity can be controlled by the applied magnetic field strength. In this paper, a rotary brake using MR fluid called MR brake for tension control of precision machinery such as roll-to-roll printing machinery is presented. First, to obtain the higher performance than conventional powder brake, a MR brake with a modified rotor shape is newly designed and analyzed using FEM. Second, the prototype of MR brake is fabricated with the optimized structural parameters and an experimental apparatus is constructed. Then, basic characteristics of the MR brake are investigated with the different MR fluids. Finally, the validity of the developed MR brake is verified through the comparison with the conventional powder brake.

• Smart Structures and Systems
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• v.17 no.2
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• pp.275-296
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• 2016

This paper focuses on developing a new configuration on magnetorheological (MR) brake damper as prosthetic knee. Prosthetic knee uses magnetic fields to vary the viscosity of the MR fluid, and thereby its flexion resistance. Exerted transmissibility torque of the knee greatly depends on the magnetic field intensity in the MR fluid. In this study a rotary damper using MR fluid is addressed in which a single rotary disc will act as a brake while MR fluid is activated by magnetic field in different walking gait. The main objective of this study is to investigate a prosthetic knee with one activating rotary disc to accomplish necessary braking torque in walking gait via T-shaped drum with arc surface boundary and implementing of Newton's equation of motion to derive generated torque at the inner surface of the rotary drum. For this purpose a novel configuration of a T-shaped drum based on the effects of a material deformation process is proposed. In this new design, the T-shaped disc will increase the effective areas of influences in between drum and MR fluid together and the arc wall crushes the particles chains (fibrils) of the MR fluid together instead of breaking them via strain in a conventional MR brake. To verify the proposed MR brake, results of the proposed and conventional MR brakes are compared together and demonstrated that the resisting torque of the proposed MR brake is almost two times greater than that of the conventional brake.

• 유공압시스템학회:학술대회논문집
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• 2010.06a
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• pp.105-108
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• 2010

In this study, a MR(Magneto-rheological) brake to obtain high torque-to-size ratio instead of conventional powder brake is presented for high-tension control of converting machinery such as coater, slitter and so on. First, to obtain the higher performance than conventional powder brake, a MR brake with a modified rotor shape is newly designed and analyzed by using electromagnetic field analysis. Second, a prototype of the MR brake is fabricated with the optimized structural parameters and an experimental apparatus is constructed. Finally, basic characteristics between current and torque are experimentally investigated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.169-172
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• 2004

This paper proposes a new MR(magneto-rheological) brake utilizing composite modes of MR fluid. Its basic structure and design scheme are almost the same with the conventional MR brake, but for slots in a rotating disk or shell. The slots enable the proposed MR brake to use a new mode, so-called, ‘direct cutting chain mode’as well as shear mode, which results in increasing the braking force(almost 150% compared to the case without slots). Some experimental results show that the proposed MR brake provide the sufficient braking force to be adopted for small portable force feedback devices.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.183-186
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• 1997

This paper presents the new MR rotary brake with a permanent magnet, based on the shear operating mode. Due to the permanent magnet, the MR rotary brake can give the nominal resistance to the external disturbance and give the fail safe capacity to the system even when the power supply is accidentally cut off. As we apply the positive or negative current to the electric magnet coil, the resistance torque of the MR rotary brake can be reduced to the value less than the nominal resistance or increased up to the magnetic saturation point.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.1
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• pp.34-41
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• 2009

In this paper, a novel MR brake with permanent magnet is developed. This system consists of rotary disk, permanent magnet, spring and MR fluid. Permanent magnets are attached to the rotary disk and moves in the direction of radius. The magnets are linked to rotor axis by spring. As rotation speed increases, the magnets move outward from the center of the system by centrifugal force in the MR fluid. A proper design of stator or case makes the system have unique torque characteristics. The research is performed like following procedures. First, the electromagnetic characteristic of the system is analyzed using Maxwell. Next, torque is calculated using the results of the electromagnetic analysis. Finally, the performance of various types of the brake systems are investigated and compared with each other.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.67-68
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.105-106
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• 2007

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.7
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• pp.2878-2885
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• 2012

In this study, the training and sporting equipment for leg rehabilitation featuring the MR fluids is proposed. The compact MR fluid brake is designed and manufactured to apply to the rehabilitation training and sporting mechanism. The resistance characteristic of the MR fluid brake is controllable by varying the magnetic field around the fluid. Under consideration of spatial limitation, design parameters which are related with the magnetic strength are determined to maximize to a torque using finite element method. The FE analysis is performed using a commercial code, ANSYS Workbench. The proposed brake device is manufactured, and its field-dependant torque is experimentally evaluated. When the electric current is supplied, the torque of the MR fluid brake is increased and the response is very fast. Depending on the strength of the current supply, torques of the MR fluid brake also increase similar to Bingham property of MR fluid.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.5
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• pp.459-467
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• 2012

In this work, the configuration of a haptic gripper featuring magnetorheological(MR) brakes is proposed and an optimal design of the MR brakes for the haptic griper is performed considering the required braking torque, the uncontrollable torque(zero-field friction torque) and mass of the brakes. Several configurations of MR brake is proposed such as disc-type, serpentine-type and hybrid-type. After the configurations of the MR brakes are proposed, braking torque of the brakes is analyzed based on Bingham rheological model of the MR fluid. The zero-field friction torque of the MR brakes is also analyzed. An optimization procedure based on finite element analysis integrated with an optimization toolbox is developed for the MR brakes. The purpose of the optimal design is to find optimal geometric dimensions of the MR brake structure that can produce the required braking torque and minimize the mass of the MR brakes. In addition, the uncontrollable torque of the MR brakes is constrained to be much smaller than the required braking torque. Based on the developed optimization procedure, optimal solution of the proposed MR brakes are achieved and the best MR brake is determined. The working performance of the optimized MR brake is then investigated.