• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.3
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• pp.130-135
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• 2014

In this paper, a new estimation method is proposed to calculate steering rack axial force using a 3 dimensional tire mesh model when a car is standing on the road. This model is established by considering changes of camber angle and contact patch between the tires and the ground according to steering angle. The steering rack bar axial force is estimated based on the static equilibrium equations of forces and moments. A tire friction force is supposed to act on the center point of the contact patch, and the proportional coefficient of friction depending on contact patch is suggested. Using the proposed estimation method, rack axial force sensitivity analysis is evaluated according to changes of suspension geometry. Then optimal motor power of Motor Driven Power Steering(MDPS) is evaluated using suggested rack forces.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.480-485
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• 2009

This paper presents dynamic modeling and control analysis of a military vehicle suspension featuring MR valve structure. Firstly, the dynamic model of the suspension system which is included gas spring, MR valve and gas chamber is established with respect to the disturbance. Secondly, the friction model of the suspension system is derived by considering experiment result of the MR suspension system. And then, response characteristics of the damping force with respect to the magnetic field and friction force with the proposed friction model are provided to show the feasibility of practical application. In addition, control performance of the proposed MR suspension system is evaluated with quarter vehicle.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.1
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• pp.58-65
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• 2010

This paper presents dynamic modeling and control analysis of a military vehicle suspension featuring MR valve structure. Firstly, the dynamic model of the suspension system which is included gas spring, MR valve and gas chamber is established with respect to the disturbance. Secondly, the friction model of the suspension system is derived by considering experiment result of the MR suspension system. And then, response characteristics of the damping force with respect to the magnetic field and friction force with the proposed friction model are provided to show the feasibility of practical application. In addition, control performance of the proposed MR suspension system is evaluated with quarter vehicle.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.938-944
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• 1994

Active damping has been shown to offer increased suspension performance in terms of vehicle isolation, suspension packaging, and road-tire contract force. Many semi-active damping strategies have been introduced to approximate the response of active damping with the modulation of passive damping parameters. This study investigates the characteristics of semi-active suspension control through the simulation of passive, skyhook active, and semi-active damping models. A quarter car model is studied with the conrolled damping replacing both passive and active damping. A new semi-active scheme is suggested to eliminate the abrupt changes in semi-active damping force. It is shown that the new strategy performs almost identically to the so called "force controlled" semi-active law without steep changes in damping force or body acceleration.eleration.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.57-64
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• 2010

In this paper, a novel Bearingless Switched Reluctance Motor(BLSRM) with the shoe rotor pole in order to minimize the torque ripple and the suspension force ripple at an overlap position is proposed. For reduction the torque ripple and the suspension force ripple at an overlap position, the fringing flux is used for the main flux. This configuration of the rotor pole results in more average torque with high suspension force. In addition, this paper is compared the transient characteristics using the inductance look-up table. The torque, radial force and flux density are analyzed by finite element method.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.473-478
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• 2005

Active suspension system improves ride quality with optimized suspension force, generated by electric, hydrolic or pneumatic power and controlled by micro-processor under various operation condition of train, while Semi-Active susepsion system provides optimized and controlled characteristics of suspensions such as damping coefficient without external energy. The benefits fo Semi-Active suspension are no required power source and to be made compact with lower cost. Train with narrow gauge could be more unstable than one for normal or wide gauge, and it could be more vibrated than others one by external force such as aerodynamic force and track irregularity. So, the reduced ride quality could be improved with appling with Semi-active suspension system. In this report, the Semi-Active suspension system for narrow gauge train shall be proposed and to prepare the Roller Rig test of this train, integration of system, development of control algorithm and confirmation of its performance with simulation tool would be taken.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.2
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• pp.60-69
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• 2005

In electrostatic suspension system of thin plates like a silicon wafer or an aluminum disk for hard disk applications, the lateral restoring force exerted on a suspended object plays an important role since the lateral motion of the suspended object, owing to the inherently stable restoring forces, can be passively stabilized without any active control of it. This paper reports about the measurement apparatus of the lateral restoring force originating from a relative translation of the suspended object with respect to the electrodes-for-suspension. An approximate calculation of the lateral force in disk-shaped objects, the structure of the measurement apparatus, a measurement method, stabilization condition and the guideline in designing the measurement apparatus are described. Experimental results obtained by using a 3.5-inch aluminum disk as a suspended object are presented as well in order to assess the magnitude of lateral force and stiffness, and also verify the usefulness of the measurement apparatus.

• Structural Engineering and Mechanics
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• v.56 no.6
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• pp.939-957
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• 2015

In this paper, a new approach based on the continuum model is proposed to estimate the main cable tension force of suspension bridges from measured natural frequencies. This approach considered the vertical vibration of a main cable hinged at both towers and supported by an elastic girder and hangers along its entire length. The equation reflected the relationship between vibration frequency and horizontal tension force of a main cable was derived. To avoid to generate the additional cable tension force by sag-extensibility, the analytical solution of characteristic equation for anti-symmetrical vibration mode of the main cable was calculated. Then, the estimation of main cable tension force was carried out by anti-symmetric characteristic frequency vector. The errors of estimation due to characteristic frequency deviations were investigated through numerical analysis of the main cable of Taizhou Bridge. A field experiment was conducted to verify the proposed approach. Through measuring and analyzing the responses of a main cable of Taizhou Bridge under ambient excitation, the horizontal tension force of the main cable was identified from the first three odd frequencies. It is shown that the estimated results agree well with the designed values. The proposed approach can be used to conduct the long-term health monitoring of suspension bridges.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1219-1224
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• 2007

This is Presents experimental results of a force tracking controller for a quarter-car suspension system. The active suspension system was decomposed into two loops. At the main loop, the desired force signal is calculate by using a standard LQ design process. The Time Delay Control(TDC) design technique is then used to design the force controller such that the desired force signal is achieved in a robust manner when actuator or other plant uncertainties are present. The ADAMS controls module was used to realize the joint simulation of ADAMS and MATLAB, of which the results showed that the TDC strategy is reasonable and feasible.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.6 s.249
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• pp.622-630
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• 2006

This paper is about the magnetic suspension stage based on the Switched Reluctance propulsion principle. Because the previous studies on contact-free stage adopted the Lorentz force for main force generation mechanism they have suffered from thermal problem deteriorating the precision. Thus, the magnetic suspension stage adopting SR principle which can achieve high force density is proposed. The main operating principle and structure for achieving high resolution and long travel range are represented. The magnetic force analysis of each actuator, providing back data for dynamic modeling and controller design are carried out. By conducting basic experiments, the feasibility of the proposed system is shown. In addition the problems which should be improved and their solutions are represented.