• 한국소음진동공학회논문집
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• 제18권3호
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• pp.307-314
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• 2008

The paper presents control performance of a magnetorheological(MR) fluid-based haptic knob which is applicable to in-vehicle comfort functions. As a first step, MR fluid-based haptic knob is devised to be capable of both rotary and push motions with a single device. Under consideration of spatial limitation, design parameters are optimally determined to minimize a reciprocal of control torque using finite element analysis. The proposed haptic knob is then manufactured and its field-dependent torque is experimentally evaluated. Subsequently, in-vehicle comfort functions are constructed in virtual environment and make them communicate with the haptic knob. Control performances such as reflection force are experimentally evaluated via simple feed-forward control strategy.

• 한국융합학회논문지
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• 제8권12호
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• pp.291-298
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• 2017

최근 차량내부에서는 운전과 직접적인 관련이 적은 다양한 편의장치들이 도입되고 있으며, 이러한 장치들의 조작환경을 하나로 통합하려는 노력이 시도되고 있다. 본 논문은 자동차 내의 다양한 편의장치에 대한 통합 조작환경을 구축하기 위해 자기유변유체(magnetorheological fluid; MR 유체)를 이용한 햅틱장치를 제안하고자 한다. 이를 위해 먼저 차량 편의 조작장치들이 갖는 회전과 상하 수직 운동을 동시에 구현할 수 있는 메커니즘을 고안하고 햅틱 기능을 부여하기 위해 MR 유체를 도입함으로써 하나의 장치로 다기능 조작이 가능한 햅틱 장치를 고안한다. 장치에서 발생하는 반향력에 대한 모델링에 근거하여 MR 햅틱 장치의 자료를 설계하고 시작품을 제작한다. 그리고 완성된 장치의 회전 및 수직 운동에 대한 응답 성능시험을 수행하여 제안된 모델을 검정한다. 또한 힘 반향 성능을 구현하기 위해 장치의 반향력 모델을 이용한 역모델 보상기(inverse model compensator)를 설계한다. 마지막으로 실제 자동차의 여러 편의 기능의 작동과정을 고려하여 햅틱 반향력 맵을 구축하고 제어기와 연동하여 제작된 햅틱 장치의 힘반향(force-feedback) 제어 성능을 평가한다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.998-999
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• 2014

This paper proposes a method for damping force modeling of magnetorheological (MR) damper featuring bypass hole. After describing configuration and of the MR damper, a damping force modeling of the MR damper is derived based on Bingham model of MR fluid. MR damper consists of piston, accumulator, gap, bypass hole and coil. Damping force is consists of spring force induced by accumulator, viscous force induced at gap and bypass hole, and controllable force induced at gap.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 봄 학술발표회 논문집
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• pp.149-156
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• 2002

This paper examines the ASCE first generation benchmark problem for a seismically excited cable-stayed bridge, and proposes a new semi-active control strategy focusing on inclusion of effects of control- structure interaction. In this study, magnetorheological (MR) fluid dampers, which belong to the class of controllable fluid dampers, are proposed as the supplemental damping devices, and a clipped-optimal control algorithm, shown to perform well in previous studies involving MR fluid dampers, is employed. The dynamic model for MR fluid dampers is considered as a modified Bouc-Wen model, which is obtained from data based on experimental results for large-scale dampers. Numerical results show that the performance of the proposed semi-active control strategy using MR fluid dampers is quite effective.

• Journal of Magnetics
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• 제22권2호
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• pp.281-285
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• 2017

To suppress the wall slip effect and improve the yield stress measurement precision of magnetorheological fluid, measurement disks with different grooves are first manufactured. Then, the influence of groove characteristics on the yield stress of magnetorheological fluid is investigated by the method of experiments. Finally, the optimization wall grooves of measurement disks are obtained, and the yield stress of a self-prepared magnetorheological fluid is measured. Results indicate that the groove type and groove width have a slight influence on the shear yield stress, whereas the measured yield stress increases with enhanced groove density, and the optimized groove depth is 0.3 mm. The measured shear yield stress of self-prepared MR fluid can be improved by 18 % according to the optimized grooved disks, and the maximum yield stress can reach up to 65 kPa as the magnetic flux density is 0.5 T.

• Structural Engineering and Mechanics
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• 제17권3_4호
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• pp.493-526
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• 2004

Semiactive control systems have received considerable attention for protecting structures against natural hazards such as strong earthquakes and high winds, because they not only offer the reliability of passive control systems but also maintain the versatility and adaptability of fully active control systems. Among the many semiactive control devices, magnetorheological (MR) fluid dampers comprise one particularly promising class. In the field of civil engineering, much research and development on MR fluid damper-based control systems has been conducted since this unique semiactive device was first introduced to civil engineering applications in mid 1990s. In 2001, MR fluid dampers were applied to the full-scale in-service civil engineering structures for the first time. This state-of-the-art paper includes a detailed literature review of dynamic models of MR fluid dampers for describing their complex dynamic behavior and control algorithms considering the characteristics of MR fluid dampers. This extensive review provides references to semiactive control systems using MR fluid dampers. The MR fluid damper-based semiactive control systems are shown to have the potential for mitigating the responses of full-scale civil engineering structures under natural hazards.

• 한국소음진동공학회논문집
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• 제23권2호
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• pp.160-166
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• 2013

This paper proposes a driver supportive device with haptic cue function which can be applicable for vehicles adopting manual transmission system to transmit gear-shifting information to a driver by kinesthetic forces. This haptic cue function is implemented on accelerator pedal by utilizing magnetorheological(MR) fluid and clutch mechanism. In order to achieve this goal, an MR clutch mechanism is devised to be capable of rotary motion of accelerator pedal. The proposed MR clutch is then optimally designed and manufactured under consideration of spatial limitation of vehicles. After transmission torque is experimentally evaluated according to field intensity. The manufactured MR clutch is integrated with accelerator pedal and electric motor to establish the haptic cue device. Control performances are experimentally evaluated via a simple feed-forward control algorithm.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.957-962
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• 2008

This paper presents vibration control performances and stability evaluations of railway vehicle featuring controllable magnetorheological (MR) damper. The MR damper model is developed and then incorporated with the governing equations of motion of the railway vehicle which includes vehicle body, bogie and wheel-set. A cylindrical type of MR damper is devised and its damping force is evaluated by considering fluid viscosity and MR effect. Design parameters are determined to achieve desired damping force level applicable to real railway vehicle. Subsequently, computer simulation of vibration control and stability analysis is performed using Matlab Simulink.

• 한국소음진동공학회논문집
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• 제18권7호
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• pp.732-740
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• 2008

This paper presents vibration control performances and stability evaluations of railway vehicle featuring controllable magnetorheological(MR) damper. The MR damper model is developed and then incorporated with the governing equations of motion of the railway vehicle which includes vehicle body, bogie and wheel-set. A cylindrical type of MR damper is devised and its damping force is evaluated by considering fluid viscosity and MR effect Design parameters are determined to achieve desired damping force level applicable to real railway vehicle. Subsequently, computer simulation of vibration control and stability analysis is performed using Matlab Simulink.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.464-467
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• 2005

Among several polishing techniques for micro structures, polishing process using magnetorheological(MR) fluid has advantages in the finishing process of 3-D micro structures because abrasives in the fluid can reach surfaces with complex feature and play their role. Although many researchers have been trying to reveal its polishing mechanism of the MR polishing, it has not been successful because in-situ measurement of state variables is difficult and process parameters are complex. In fact, one of the key factors for applying process control methodologies, such as Run-to-Run control, is the measuring and monitoring of slurry quality because the process strongly depends on the fluid property. Therefore, it is necessary to maintain consistent slurry quality to guarantee the process repeatability. The proposed equipment achieves the longer life cycle of MR fluid and reduces the variability of products. A new method to measure the material removal rate in MRF polishing process is also proposed and discussed.