• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.2
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• pp.31-37
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• 2008

In this paper, we analyzed the dynamic behavior of magnetic fluid in a circular pipe with multiple permanent magnets. Magnetic fluid react on magnetic field against the normal fluid. In other words, magnetic fluid flow has the electromagnetism and fluid mechanics. So magnetic fluids has studied about the fluids properties and experiment. In this paper we studied the magnetic fluids velocity and pressure distribution for the novel type actuator. Because the velocity and pressure distribution is the important element of the magnetic fluids flow. First, we analyzed the Maxwell equation for the multiple permanent magnet and then concluded the governing equations for the magnetic fluid flow using the equation of Navier-Stokes. And, we simulated the dynamic behavior of magnetic fluid flow using the FEM(Finite Element Method). And we illustrated the relation between magnetic field and dynamic behavior of magnetic fluid flow.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1830-1835
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• 2005

It is important to estimate the distribution of intensity of a magnetic field for application of magnetic method to industrial nondestructive evaluation. Magnetic camera provides the distribution of a quantitative magnetic field with homogeneous lift-off and same spatial resolution. And it is possible to interpret the distribution of the magnetic field when the dipole model is introduced. This study introduces the numerical and experimental considering of the quantitative evaluation of several size and shapes of the cracks using the magnetic field images of the scan type magnetic camera.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.609-612
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• 2001

To investigate the magnetic field distribution of power line, we used amorphous wire sensor. And we discuss extremely low frequency magnetic field distribution dependent upon arrangement of power line and shielding pipe made from iron or alumimum materials by both measurement and FEM(Finite Element Method) analysis. Appling current of single phase 60 [Hz] 15 [A] is supplied to copper wire coated enamel resign. As the results, we confirmed that linear characteristics of amorphous wire sensor is very excellent and measurement value agrees with FEM calculation. Magnetic field distribution due to shielding materials is changed by permeability and conductivity.

• Journal of the Korean Society for Precision Engineering
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• v.9 no.2
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• pp.29-35
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• 1992

The distribution of magnetic flux density of electro-magnetic chucks may clarify the clamping characteristics which are strongly related to the machining efficiency and machining accuracy in a surface grinder. Therefore the distribution of the normal and the tangential components of magnetic flux density has been analyzed theoretically. It appears that the normal and the tangential components of magnetic flux density increase as the ratio of the separator width to the pitch e/p decreases. The results seem to increase the uniformity and stability of normal component of magnetic flux density for the decreased e/p.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.826-830
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• 2004

Fault tolerant control method for 6-pole homopolar magnetic bearings are presented. If some of the coils or power amplifiers suddenly fail, the remaining coil currents change via a novel distribution matrix such that the same magnetic forces are maintained before and after failure. Lagrange multiplier optimization with equality constraints is utilized to calculate the optimal distribution matrix that maximizes the load capacity of the failed bearing. Some numerical examples of distribution matrices are provided to illustrate this control method.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.3-5
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• 1997

The relation between electric current and magnetic field under three overhead transmission lines being operated was studied. It was examined for a difference each other in comparison with calculated value and measured value for current, magnetic field. With magnetic field equations made out, The magnetic field distribution around transmission lines had made to figure out with easy by load electric current value. Additionally, we are going to describe the distribution curve of magnetic exposure volume for KEPCO's T/L.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.3
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• pp.506-513
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• 2007

This paper proposes a rotary magnetic position sensor which has a sinusoidally magnetized permanent magnet with a small number of poles. To make the sinusoidal magnetic flux density distribution from the permanent magnet, a magnetizing future is optimized by the DOE(Design of Experiments) method. The magnetization process is analyzed using the Preisach model and 2 dimensional finite element method. The magnetic flux density distribution from the magnetized permanent magnet is very similar to ideal sine wave. The simulation result of the magnetic flux density distribution is compared with the experimental one. Also the availability of the proposed rotary type magnetic position sensor is confirmed by position calculation technique.

• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.312-314
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• 2000

The electric wave propagation characteristics of electromagnetic field by induction current shows a nonlinear distinction in the metal but linear on air. This paper is written about the magnetic transmission distinction in the metalic tube, which wrapped the center axis by the same direction. The electromagnetic field made by the transmission signal is transferred from the transmission coil area toward the receiving coil by the magnetic diffusion. So, it is different magnetic flux around the coil with one in the remote field area. Analyzing such a complex magnetic characteristic, we verified this theory by the vector analysis and presented eddy current mechanism and analytical model about magnetic distribution in the remote field area. This magnetic distribution rate in metal body will be very useful in the nondestructive inspection of the eddy current in remote field which is recently rising as a new technology.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.6_1
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• pp.659-667
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• 2021

This paper develops the theory for a novel fault-tolerant, permanent magnet biased, 4-active-pole, double plane, homopolar magnetic bearing. The Lagrange Multiplier optimization with equality constraints is utilized to calculate the optimal distribution matrices for the failed bearing. If any of the 4 coils fail, the remaining three coil currents change via a novel distribution matrix such that the same opposing pole, C-core type, control fluxes as those of the un-failed bearing are produced. Magnetic flux coupling in the magnetic bearing core and the optimal current distribution helps to produce the same c-core fluxes as those of unfailed bearing even if one coil suddenly fails. Thus the magnetic forces and the load capacity of the bearing remain invariant throughout the failure event. It is shown that the control fluxes to each active pole planes are successfully isolated. A numerical example is provided to illustrate the new theory.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.13-18
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• 2004

It is important to estimate the distribution of intensity of a magnetic field for application of magnetic method to industrial nondestructive evaluation. Magnetic camera provides the distribution of a quantitative magnetic field with homogeneous lift-off and same spatial resolution. Leakage magnetic flux near the crack on the specimen could be amplified by 3-dimensional magnetic fluid and zoom in and out of measurement area. This study introduces the experimental consideration of the effects of lens for concentrating of magnetic flux. The experimental results showed that the magnetic fluid has sufficient lens effect for magnetic camera and effect of improvement in probability of detection.