• Journal of the Korean Magnetics Society
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• v.24 no.3
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• pp.86-89
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• 2014

Anisotropic bonded magnet is composed of magnetic powder and organic binder. organic binder in bonded magnet, serves to orientation of the powder. organic binder is composed of polymer resin, lubricant, hardener and coupling agent, etc.in this study, selection of the various components to producing an organic binder and by adjusting the composition ratio and concentrate, apply to bonded magnet for producing an organic binder that suitable for magnetic powder. so evaluation of magnetic properties and mechanical properties, the organic binder ratio and component was confirmed to suitable for bonded magnet.

• Proceedings of the Korean Magnestics Society Conference
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• 2013.12a
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• pp.95-95
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• 2013

The NdFeB magnet can be classified into the sintered magnet and bonded magnet. The former has superior magnet characteristics but the degree of freedom in shape is highly restricted, whereas the latter has a high degree of freedom, but its magnet characteristics are inferior to the former. When a NdFeB magnet is used at the elevated temperature, part of Nd must be replaced with a high priced Dy to increase its coercive force. For these reasons, a Dy free and high performance NdFeB bonded magnet is desired strongly. The author successfully developed a Dy free NdFeB anisotropic bonded magnet based on discovery of new phenomena called as d-HDDR reaction and its mass production process such as a thermally balanced hydrogen reaction furnace, micro capsuled powder, compression molding / injection molding under magnetic field, magnetic die and so on. Applied to DC brush seat motor for automotive use, the motor has become 50% small in size and weight. The commercialization of a half sized motor for automotive use has been realized up to the market share of 30%. At present, its commercialization is extending to various types of motors such as power tool, ABS motor, wiper motor, window motor, electric bike power motor, and compressor motor. It is expected that the applications will be increasingly enlarged to EV motor, wind generator, EPS motor, washing machine, and glass cutting machine. This innovative technology has realized Dy free high performance magnet and mudt make big contribution to not only rare element strategies but also energy conservation.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.10
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• pp.652-658
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• 2000

In many cases, ferrite magnets of ferrite bonded magnets used in inner-rotor type small brushless DC(BLDC) motors do not have rotor core. The magnetization directions of permanent magnets do not have only parallel or radial direction. In this case, the characteristics of magnets are different from cored type ones which have uniform magnetization direction. In this paper, the magnetization directions and intensities of a ferrite magnet and a ferrite bonded magnet are analyzed by finite element analysis for magnetization procedure. The characteristics of inner-rotor type BLDC motor are analyzed by using the analyzed results. The validity of the method is verified by comparing the analyzed results with measured ones.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.12
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• pp.2173-2178
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• 2010

The magnetization directions of a polar magnetized ferrite bonded magnet are analyzed by finite element method (FEM). The influence of the width of SmCo magnets for magnetic field generation is investigated. The surface flux densities of the polar anisotropic magnets are analyzed and compared according to the pole number and thickness of the magnets. And the electromotive force (EMF) values of brushless DC motors with the magnets are investigated. The validity of the analysis method is verified by comparing the analyzed results with measured ones.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.12
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• pp.988-995
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• 2010

In this study the (Alnico, Sm-Co) bonded magnets were fabricated by mixing the Sm-Co added alnico alloy powders with epoxy resin and binder, appropriately. Also, the hybrid ring magnets of (Alnico, Sm-Co)/Sr-ferrite were fabricated by coupling the Sr-ferrite composite layer with an (Alnico, Sm-Co) magnet. The magnetic properties of (Alnico, Sm-Co) ring magnets were varied with the amount of Sm-Co powders. The addition of Sm-Co powders increased a remanent induction($B_r$) and coercive force($_BH_C$), while decreasing a surface flux density and repulsive distance. The surface flux density and repulsive distance for the (Alnico, Sm-Co) ring magnet increased with a magnetizing voltage up to about 160 V and reached an apparent saturation point. Also, the measurements of temperature and moisture characteristics showed that the surface flux densities of N-S poles and repulsive distance decreased a little within 4% after 10 days passed.

• Electrical & Electronic Materials
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• v.10 no.5
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• pp.440-446
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• 1997

This research has been performed for the fabrication of high quality ferrite plastic magnet. The magnetic properties of S $r_{5.9}$F $e_2$ $O_3$ ferrite bonded magnets by injection moulding with a variety of applied magnetic field were investigated. 0.3wt% CaCO3, 0.2wt% $SiO_2$, 0.5wt% $Al_2$ $O_3$and 0.5wt% N $a_2$ $SiO_3$are added in order to improve the magnetic properties of Sr-ferrite plastic magnets during the powder fabrication. For carbon coating on chemical compound specimen, 5wt% polyvinyl alcohol is added, and then calcinated under $N_2$ environment of 12$25^{\circ}C$. The particle size is distributed from 0.9~1.2${\mu}{\textrm}{m}$ which approximates to the single domain. The obtained Sr ferrite powder is well mixed with silane coupling and calcium stearate of 1wt%. Nest, the specimen is pelleted after kneading each of them with polyamidel2 as a binder. When the temperature of injection and mould were 25$0^{\circ}C$ and 8$0^{\circ}C$ respectively at injection pressure of 200kgf/$\textrm{cm}^2$, the degree of orientation was 85.3% under the applied magnetic field of 12kOe. As the results, when the packing density of Sr ferrite powder was 90wt%, the magnetic properties of Sr ferrite bonded magnet were follows : $_{B}$ $H_{c}$=2.41kOe, Br=3.1kG, (BH)$_{max}$=2.21MgOe. Especially, the Sr-ferrite bonded magnet with 10wt% N $d_2$F $e_{14}$B additive were as follows : $_{B}$ $H_{c}$=2.57kOe, Br=3.14kG and (BH)$_{max}$=2.39MGOe.GOe.GOe.GOe.e.

• Proceedings of the Korean Magnestics Society Conference
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• 1998.05a
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• pp.86-87
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• 1998

• Proceedings of the Korean Magnestics Society Conference
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• 1994.10a
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• pp.48-49
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• 1994

• Proceedings of the Korean Magnestics Society Conference
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• 2005.12a
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• pp.88-88
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• 2005

• Journal of the Korean Magnetics Society
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• v.21 no.4
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• pp.147-150
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• 2011

Since their discovery in the early 1980's, the market for bonded rare earth magnets has shown steady growth. Today these magnets are widely used for our daily life such as computer peripherals, automotive, consumer electronics, and office automation. However, the price increases of rare-earths started from the $2^{nd}$ half of 2010 became even worse in 2011. During $2^{nd}$ quarter of 2011, almost all of rare-earths showed unprecedented vertical price increases, and it brought significant impact to the related industry in terms of the price and supply. This will ask the fundamental change in the policy of the bonded rare earth industry to expand its market share, which has been highly dependent on the replacement of ferrite magnets via relatively higher performance compared to the price at certain applications. In order to achieve the sustainable growth of bonded rare-earth magnets in the future, it needs to change the current paradigm and setup the new business model. This article includes a brief summary of the rare earth price trend and the applications of the rare-earth bonded magnets. The efforts to improve the performance and diversify the applications for future growth have been also presented.