• Korean Journal of Materials Research
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• v.9 no.10
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• pp.1037-1040
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• 1999

Magnetic characteristics of some anisotropic mischmetal- FeB- (Co,Ti,Al) permanent magnets have been investigated. The magnets were fabricated by using hot-pressed and die-upsetting. Hot-pressed $\textrm{(MM)}_{12.5}\textrm{Fe}_{71.9}\textrm{Co}_{5.0}\textrm{Al}_{2.0}\textrm{B}_{8.6}$ permanent magnet showed $\textrm{H}_{c}$=4.27 kOe, $\textrm{B}_{r}$=4.75 kG, $\textrm{(BH)}_{max}$=3.82 MGOe, and die- upset magnet showed $\textrm{H}_{c}$=3.10 kOe, $\textrm{B}_{r}$=5.58 kG, $\textrm{(BH)}_{max}$=5.34 MGOe, respectively. Hot-pressed $\textrm{(MM)}_{12.5}\textrm{Fe}_{77.9}\textrm{Ti}_{1.0}\textrm{B}_{8.6}$ permanent magnet showed $\textrm{H}_{c}$=3.75 kOe, $\textrm{B}_{r}$=4.64 kG, $\textrm{(BH)}_{max}$=2.78 MGOe, and die- upset magnet showed $\textrm{H}_{c}$=3.29 kOe, $\textrm{B}_{r}$=5.01 kG, $\textrm{(BH)}_{max}$=3.54 MGOe, respectively. X-ray diffraction and transmission electron microscopy revealed that the higher energy products in the die-upset magnets results from alignment of the c-axis along the die-upsetting direction. The magnetic anisotropy in hot-pressed MM-FeB- Al magnet is increased by the substitution of Co for Fe.

• Journal of the Korean Magnetics Society
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• v.26 no.5
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• pp.154-158
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• 2016

A CRDM (Control Rod Drive Mechanism) is an electromagnetic device which drives a control rod assembly linearly to regulate the reactivity of a nuclear core. An RPIS (Rod Position Indication System) is used as a position indicator for a control rod assembly of a CRDM of SMART, and an RPIS consists of permanent magnets and reed switches. SMART is designed for the maximum coolant temperature of $350^{\circ}C$, and the permanent magnets are installed inside of the reactor. The reed switches and electrical circuit are installed outside of the reactor on the other hand. Test coil for a reed switch is test equipment for quality verification of a reed switch, and a test coil consists of a coil and core. In this study, magnetic property of test coil and permanent magnet on a reed switch is compared by using finite element electromagnetic simulation.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.2
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• pp.146-153
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• 2005

In a permanent magnet brushless dc motor, cogging torque is produced by the magnetic attraction between the rotor mounted permanent magnets and the stator teeth. This always produces a pulsating torque ripple resulting in vibration and acoustic noise, which is detrimental to the motor performance. This paper deals with the analytical prediction of cogging torque and the various cogging torque minimization techniques as applied to a permanent magnet brushless dc motor.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.185-187
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• 2006

The line-start permanent magnet synchronous motor has a high efficiency and an advantage in constant speed operation regardless of the effect of load variation. However it is difficult to predict the performance of characteristics accurately, because of the unbalanced starting torque with the initial starting position of the rotor and the generation of a break torque. In this paper the dynamic characteristics of the line-start permanent magnet synchronous motor are described and compared with those of the squirrel-cage induction motor through the simulation to find the characteristics of the permanent magnets and the rotor bars in the line-start permanent magnet synchronous motor.

• Journal of Electrical Engineering and Technology
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• v.3 no.3
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• pp.379-384
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• 2008

This paper examines permanent magnet eddy current couplings and brakes. Specifically, the effect of permanent magnet magnetization patterns on the magnetic field and force production is investigated. The eddy current couplings and brakes employ high energy-product neodymium-iron-boron (NdFeB) permanent magnets that act on iron-backed copper drums to provide torque transfer from motor to load without mechanical contact. A 2-dimensional finite element modeling is performed to predict the electromagnetic behavior and the torque-speed characteristics of permanent magnet type eddy current couplings and brakes under constant speed operation.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.50-52
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• 2001

The BLDC(Brushless DC) motor with the permanent magnet has many merits such as high efficiency and efficiency. These characteristics of the BLDC motor makes them one of the most popular motors in the world today. The C type ferrite magnet is many used in BLDC motor for high performance, especilly low price. Many papers have been written on the analysis of the BLDC motor with C type ferrite magnet. But, most of these target models are contained symmetric distribution of permanent magnet. In this paper, investigations are made on different distribution of permanent magnets for a understanding of the effects of unequal permanent magnet location on the unbalanced cogging torque. Motor torque and cogging torque are obtained by using the 2 dimensional finite element method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.8
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• pp.1390-1396
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• 2007

The line-start permanent magnet synchronous motor has a high efficiency and an advantage in constant speed operation regardless of the effect of load variation. However, it is difficult to predict the performance of characteristics accurately, because of the unbalanced starting torque with the initial starting position of the rotor and the generation of a break torque. In this paper the dynamic characteristics of the line-start permanent magnet synchronous motor are described and compared with those of the squirrel-cage induction motor through the simulation to find the characteristics of the permanent magnets and the rotor bars in the line-start permanent magnet synchronous motor. Finally this paper gives the comparison between the simulation results and the experimental results.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.86-88
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• 2005

The line-start permanent magnet synchronous motor has a high efficiency and an advantage in constant speed operation regardless of the effect of load variation. However it is difficult to predict the performance of characteristics accurately, because of the unbalanced starting torque with the initial starting position of the rotor and the generation of a break torque. In this paper the dynamic characteristics of the line-start permanent magnet synchronous motor arc described and compared with those of the squirrel-cage induction motor through the simulation to find the characteristics of the permanent magnets and the rotor bars in the line-start permanent magnet synchronous motor.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.930-932
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• 2005

The line-start permanent magnet synchronous motor has a high efficiency and an advantage in constant speed operation regardless of the effect of load variation. However it is difficult to predict the performance of characteristics accurately, because of the unbalanced starting torque with the initial starting position of the rotor and the generation of a break torque. In this paper the dynamic characteristics of the line-start permanent magnet synchronous motor are described and compared with those of the squirrel-cage induction motor through the simulation to find the characteristics of the permanent magnets and the rotor bars in the line-start permanent magnet synchronous motor.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.947-951
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• 2007

This paper is concerned with a new concept for the damper without neither a coil spring nor fluid. The new damper concept consists of the permanent magnets and the cylinder of the conducting material. The opposite pole magnets produces the repulsive forces and this is substituted for the coil spring. The relative motion between the magnets and conducting cylinder produces eddy currents thus resulting in the electromagnetic force, which turns out to be the damping force thus and is substituted for a damping fluid. This damper is called the eddy current damper(ECD). The important advantage of the proposed ECD is that it does not require the damping fluid and any external power and is non-contacting and relatively insensitive to temperature. In the present study, the proposed ECD was constructed and experiments were performed to investigate its dynamic characteristics. The experiments shows that the proposed ECD has the excellent damping ability.