• Elastomers and Composites
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• 제51권1호
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• pp.38-42
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• 2016

For improving the heat loss of a refrigerator around door gasket, it is very important to reduce the amount of rubber magnet used, of which thermal conductivity is much higher than the plastics, and enhancing the magnetic properties of rubber magnet itself is crucial for this. In the present study, therefore, a relationship between the optimum conditions of rubber magnet fabrication process and raw material compositions in the ferrite powder/CPE binder compounds was investigated for finding a way to enhance the magnetic properties of rubber magnet. Magnetic attraction forces of a sample rubber magnet was measured as function of distance, and thermal properties of the sample ferrite powder/CPE binder compound were analyzed with TG/DTA thermal analyzer. As a results, a rubber magnet strip with enhanced magnetic properties was expected to be fabricated, of which raw material compound was prepared by compounding with higher ferrite magnetic powder concentration.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권10호
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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.

• 조명전기설비학회논문지
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• 제22권4호
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• pp.121-129
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• 2008

본 논문에서는 페라이트자석을 사용하고 있는 BLDC 전동기를 희토류 자석을 사용하는 전동기로의 설계를 다루고 있다. 최근 전기기기가 소형 경량화 됨에 따라 자석 성능이 우수한 희토류 자석을 이용한 전동기가 많이 사용되고 있다. 그러나 전기제품 메이커들은 기존의 설계를 유지하려는 경향이 있다. 본 연구에서는 전기기기에 취부되는 전동기의 외형을 그대로 하고 내부의 설계만 희토류 자석으로 변경하는 설계를 한다. 설계를 간단히 하기 위해 유한 요소법의 상용 패키지를 반복적으로 사용하였고 코깅 토오크를 줄이기 위해 고정자 요크와 고정자 단의 그루브를 설계하였다.

• 자원리싸이클링
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• 제12권6호
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• pp.19-25
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• 2003

제철소 냉연 공정의 염산 폐액에서 ruthner process 공법으로 제조된 산화철을 사용하여 2차 배소 온도변화에 따른 산화철의 분체 특성을 조사하였고, 산화철과 스트론튬을 건식 혼합 및 가소후 Sr-ferrite 자석을 제조하여 자기적 물리적 특성을 조사하였다. Ruthner proces의 산화철을 2차 배소를 실시한 경우, Cl- 함량이 적고 분체 특성이 안정적인 배소온도는 $800^{\circ}C$ 부근으로, 평균 입자(APS)는 1.5 $mu extrm{m}$, apparent bulk density(ABD)는 1.4 g/$m\ell$ 이며, Cl- 함유량은 0.05% 이하를 나타내었다. Ruthner process에서 제조된 산화철을 vibrating disk mill에서 1차 분쇄를 실시한 경우, Sr-ferrite magnet의 보자력(HcJ)은 229 kA/m에서 251 kA/m로 향상하였다. Sr-ferrite magnet의 소결 온도 변화에 따른 잔류자속밀도와 보자력의 희귀식은 Br≒-0.258HcJ＋494의 함수 관계를 나타내고 있으며, 성형 중 가한 자장 방향과 수직방향에 따른 수축비는 산화철의 2차 배소 온도 $800^{\circ}C$까지는 1.6으로 안정적인 판상형으로 결정 성장을 나타내고 있으나, 그 이상의 온도로 2차 배소한 산화철을 사용한 경우에는 소결에서 결정이 더 커진 것으로 판단된다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1999년도 추계학술발표강연 및 논문개요집
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• pp.51-51
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• 1999

• E2M - 전기 전자와 첨단 소재
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• 제10권5호
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.118-121
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• 1991

The characteristics of magnetizing system considering the anisotropy and the nonlinearity are analyrized using PEM in This paper. The case of magnetizing the ferrite magnet with 12 poles is analyrized. The anisotropy characteristic is considered when ferrite magnet which is widely used as permanent magnet is magnetized. The Nonlinear characteristic of magnetizing yoke aid ferrite is considered because the current is in the saturation region. When the magnetizing current value is over the optimum value, the magnet is magnetized with 24 poles. This is not the case of our expectation. Thus, for the case of our expected magnetizing form, it is the conclusion that the optimum magnetizing current value is selected.

• 한국세라믹학회지
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• 제42권10호
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• pp.672-677
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• 2005

In this study we prepared the Sr-ferrite powders and magnet by a molten salt method using the (NaCl+KCl) salt mixture. Starting materials of $Fe_{2}$$O_{3}$ and Sr$Co_{3}$ were mixed as the molar ratio of 5.70:1, and 0.08 mol$ \% $ $Al_{2}$$O_{3}$, 0.10 mo1$ \% $ Si$O_{2}$ and 0.12 mo1$ \% $ CaO were added as additives. Sr-ferrite powders synthesized at the reaction temperatures of 800$\∼$1200$ ^{\circ}C $ showed the typical M-type hexagonal ferrite phase, and hexagonal plate-like morphology with uniform distribution of 1$\∼$3 $\mu$m particle size. The bulk density of the sintered Sr-ferrite magnet prepared with powders by the molten salt method showed the maximum density of 4.82 g/$cm^{3}$ at the sintering temperature of 1200$^{\circ}C $. The maxima of remanent flux density (Br, 45 emu/g) and coercive force (iHc, 3.75 kOe) occurred at the sintering temperatures of 1150$ ^{\circ}C$ and 1200$^{\circ}C $.

• Journal of Electrical Engineering and Technology
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• 제9권3호
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• pp.942-949
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• 2014

We studied about the rotor design change using a Ferrite ring magnet to reduce material cost in the condition of the same stator core design. However, this design direction has many weak points such as the decrease of BEMF, the low maximum output, the irreversible demagnetization characteristics of a permanent magnet and so on. In order to mitigate such disadvantages, an optimization design of the BLDC motor has been developed by changing each design parameter and by improving the electromagnetic structure. In the proposed water pump SPM BLDC motor using Ferrite magnet, the outer and inner diameter of stator is fixed to the value of the conventional IPM BLDC motor using Nd-Fe-B magnet. The design specification requirements should be satisfied with the same output power and efficiency characteristics in the same dimension. As a result of this study, the design comparison results considering driving performances and material cost are represented. Through the actual experiment with the prototype of the designed motor, the simulations results are verified.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2017년도 임시총회 및 하계학술연구발표회
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• pp.114-114
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• 2017