• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1416-1421
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• 2007

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. To show the performance of the system, the research is performed by following procedure. First, the electromagnetic characteristic of the system is analyzed using FEM and commercial code, Maxwell is used for this analysis. Then, torque is calculated using the result of the electromagnetic analysis to validate the performance of the system.

• 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 Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.63-68
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• 2004

Since rotor position information is necessary to drive the SRM, absolute-encoder, resolver and incremental-encoder is used to detect a poor position. But, it is not desirable to use a high priced encoder and high efficient microprocessor under the condition of the simple driving system when precision control is not demanded. In this paper, Only using the reflective type 2 photosensors replace the conventional opto interrupter and slotted disk, which not only remove a slotted disk section but drive 3-phase 6/4 SRM bidirectionally. Moreover, as control circuit only is composed of common analog device economy is maximized.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.1
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• pp.125-132
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• 2007

Within the framework of brake-by-wire technology, this paper presents five types of novel models of electro-mechanical disk brake calipers with self-servo mechanism which provides self-servo effect of boosting a friction force generated between the brake pad and the rotor disk surface. The models have been developed utilizing patent map analysis results of previous invents of electro-mechanical brake calipers. The feasibility of the developed motor-driven brake caliper models have been validated through the dynamic simulation analysis. Among the developed models, the caliper mechanism with separated pressure plate was designed especially in detail and was made as a pilot. The pilot caliper has been installed on the simple test bed constructed with domestic passenger car brake components, and its function and effectiveness have been validated through several types of experimental tests.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.538-541
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• 2004

In turbomachinery rotor, there are small differences in the structural and/or geometrical properties of individual blades, which are referred to as blade mistuning. Mistuning effects of the forced response of bladed disks can be extremely large as often reported in many studies. In this paper, the pattern optimization of intentional mistuning for bladed disks considering with damping and coupling effect is the focus of the present investigation. More specifically, the class of intentionally mistuned disks considered here is limited, for cost reasons, to arrangements of two types of blades (A and B, say) and Genetic Algorithm is used to optimize the arrangement of these blades around the disk to reduce the forced response of blade with different damping and coupling stiffness.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.221-226
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• 2005

In this paper, a dynamic model for the rotor shaft-coupling-blade system is developed. The blades are attached to a disk and driven by an electric motor shaft which is flexible in torsion. We assumed that the shaft torsional flexibility is lumped in the flexible coupling which is usually adopted in rotor systems. The Lagrangian approach with the small deformation theory for both blade-bending and shaft-torsional deformations is employed for developing the equation of the motion. The assumed modes method is used for estimating the blade transverse deflection. The numerical results highlight the effects of both structural damping of the system and the torsional stiffness of the flexible coupling to the dynamic response of the blade. The results showed strong coupling between the blade bending and shaft torsional vibrations in the form of inertial nonlinearif, stiffness hardening and softening.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.9 s.102
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• pp.1023-1029
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• 2005

In this paper, a dynamic model for the rotor shaft-coupling-blade system was developed. The blades are attached to a disk and driven by an electric motor shaft which is flexible in torsion. We assumed that the shaft torsional flexibility was lumped in the flexible coupling which is usually adopted in rotor systems. The Lagrangian approach with the small deformation theory for both blade-bending and shaft-torsional deformations was employed for developing the equation of the motion. The Assumed Modes Method was used for estimating the blade transverse deflection. The numerical results highlight the effects of both structural damping of the system and the torsional stiffness of the flexible coupling to the dynamic response of the blade. The results showed strong coupling between the blade bending and shaft torsional vibrations in the form of inertial nonlinearity, stiffness hardening and softening.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.236-240
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• 2005

This paper deals with friction-induced vibration of disc brake system under constact friction coefficient. A linear, finite element model to represent the floating caliper disc brake system is proposed. The complex eigenvalues are used to investigate the dynamic stability and in order to verify simulations which are based on the FEM model, The comparison of experimental and analytical results shows a good agreement and the analysis indicates that mode coupling due to friction force and geometric instability is responsible fur disc brake squeal. And the Front brake system reduced the squeal noise using design of experiment method(DOE). This helped to validate the FEM model and establish confidence in the simulation results. Also they may be useful during real disk brake model.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1549-1554
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• 2000

HDD structure is excited by the dynamic motion of disk-spindle motor components. Those excitations which are generated at stator and magnet rotor, at bearings and from disk dynamics, are transmitted through motor spindle and flange to HDD cover and base. The operational deflection shape measurement can show the structural excitation patterns at the most influent frequency on the acoustic noise level. One of those components is the axial excitation along spindle, and the other is the local orbital excitation at contact area of motor flange and base. To make a reduction of those structural transmission excitations, the structure of spindle motor is modified to the direction of reinforcement at transmission path without change of bearings, magnet and coil. Some excitation of spindle motor component carrying out essential function is unavoidable. So it is the efficient way of HDD noise improvement to control the structural transmission of excitation.

• 한국전산유체공학회:학술대회논문집
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• 1999.11a
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• pp.167-173
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• 1999

An Euler-based CFD tool has been developed for the performance evaluation of a thrust reverser mounted on a high bypass ratio turbofan engine. The computational domain surrounded by the ground and non-reflection boundary includes the whole nacelle configuration with a deployed thrust reverser. The numerical algorithm is based on the modified Godunovs scheme to allow the second order accuracy in both space and time. The grid system is generated by using eleven multi-blocks, of which the total cell number is 148,400. The thrust reverser is modeled as if it locates at the nacelle simply in all circumferential direction. The existence of a fan and an OGV(Outlet Guide Vane) is simulated by adopting the actuator disk concept, in which predetermined radial distributions of stagnation pressure ratio and adiabatic efficiency coefficient are used for the rotor type disk, and stagnation pressure losses and flow outlet angles for the stator type disk. All boundary conditions including the fan and OGV simulation are treated by Riemann solver. The developed solver is applied to a turbofan engine with a bypass ratio of about 5.7 and the diameter of the fan cowl of 83 inch. The computational results show that the Euler-based inviscid method is very useful and economical to evaluate the performance of thrust reversers.