• Journal of the Korean Magnetics Society
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• v.25 no.3
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• pp.67-73
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• 2015

This is a basic research for improving soft magnetic property of Fe based nano crystalline alloy powder core. The main study is done around characteristics of permeability, core loss, and DC bias depending on amount of insulation coating agent and particle size. First, $Fe_{73.5}Si_{13.5}B_9Nb_3Cu_1$ amorphous alloy ribbon was fabricated by using the planar flow casting (PFC) device. Then, heat treatment and ball milling were done to obtain alloy powder. The amount of polyether imide (PEI) added to it was varied by 0.5, 1.0, 2.0, 2.5 wt% to have compression molding into $16ton/cm^2$. After going through crystalline heat treatment, the made toroidal nano crystalline powder core ($OD12.7mm^*ID7.62mm^*H4.75mm$) had smaller permeability as amount of insulation coating agent decreases. However, it was found out that core loss and DC bias characteristics have been improved. The reason for this results were expected to be because green density of power core decreases as amorphous alloy powder particles become smaller as amount of alloy powder insulation coating agent increases, it was determined that 1 wt% of insulation coating agent is appropriate. Also, for powder core made based on alloy powder size with amount of insulation coating agent fixed at 1 wt%, effective permeability and core loss were outstanding as particle size became bigger. However, characteristics of DC bias became worse as applied DC field increases. This is expected to be due to insulation effect, residual pores, or molding density of powder core resulting from thickness of coating on surface of alloy powder.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.240-241
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• 2007

연자성 분말의 독특한 특성은 3D 등방성 강자성체 이며, 이 때문에 3차원적 자속(flux)를 활용할 수 있어 전기 강판(sillicon steel)에 비해 3차원 성형시 유리한 장점을 가지고 있다는 점이다.[1] 따라서 본 논문에서는 연자성 분말 (Soft Magnetic Composites)의 3차원 성형시 각 성형 형태에 따른 압분 시료의 전기적, 기계적 특성에 대한 연구를 하였다. 연자성 분말의 코어 형상을 크게 ' '형으로 구분하여 압분 코어를 만든 후 압분 코어의 Overhang 각도 및 코어 Teeth의 길이에 따른 파라미터에 변화를 주어 철손 및 경도, 밀도를 측정 하였다. 이 논문에서 우리는 3차원 코어 성형시 전기적, 기계적 특성이 가장 우수한 코어 성형 조건을 연구해 낼 수 있었다.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.43-44
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• 2007

SMC(Soft Magnetic Composite) 재질은 일반 실리콘 강판에 비해 코어의 3차원 형상을 자유롭게 제작 할 수 있으며, 고속 회전시에 발생하는 철손을 감소시킬 수 있어 모터 코어용으로 많은 제작이 이루어지고 있다. 따라서 본 논문에서는 고속 회전용 청소기용 BLDC 모터의 코어를 SMC 재질로 제작 Back-EMF를 측정하였다. 코어의 형상은 크게 3차원 형상을 고려한 3가지로 타입으로 구분하여 제작하였고, 각 형상별로 모터를 제작하여 특성을 측정하였다. 본 논문에서는 SMC 분말을 이용한 코어 성형시 3차원 형상에 따른 모터의 Back-EMF의 특성을 보여준다.

• Korean Journal of Materials Research
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• v.3 no.3
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• pp.300-309
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• 1993

Abstract In this work. gasification of graphite cores from nickel-coated graphite composite powders was carried out to munufacture the hollow nickel metal powders which can be used as a raw materials for porous nickel metal strips. Graphite cores were gasified by $H_2O-H_2$ mixture gases at the temperature between $800^{\circ}C$ and $900^{\circ}C$ and nearly all removed from the composite powders within 1 hour. The hollow nickel metal powders prepared from 82.2wt. % Ni-17.8wt. % C composite powders which have the graphite cores of 21${\mu}$m average size were pressed and sintered at $1150^{\circ}C$ for 1 hour in vacuum furnace. The porosities of green and sintered compacts were 45% and 30%. respectively, and pores were distributed very homogeneously in the sintered compact. It was confirmed that pore distribution and porosity in porous materials can be easily controlled by using hollow powders as a raw materials.

• Proceedings of the Korean Magnestics Society Conference
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• 2010.06a
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• pp.159-160
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• 2010

• Proceedings of the Korean Magnestics Society Conference
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• 2012.05a
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• pp.123-124
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• 2012

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.4
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• pp.607-616
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• 2022

A new axial flux permanent magnet machine with soft magnetic composited cores is proposed for electric vehicle application in this paper. The windings and soft magnetic composited cores can be designed to form a very compact structure, and; thus, the torque density can be improved greatly. To obtain the a good flux concentrating ability, two toroidally wound internal stator machines are designed and analyzed, and the designed motor is with NdFeB magnet for high-performance electric vehicle application. The 3-D finite-element method is used to analyze the electromagnetic parameter and performance, for performance comparison, a commercial axial flux permanent magnet machine is used. The proposed motor reduced weight about 5.8%, produced torque higher than about 8Nm for existing motor.

• Journal of the Korean Magnetics Society
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• v.24 no.3
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• pp.76-80
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• 2014

Toroidal cores made of metallic powder requires large magnetic field strength up to few decade kA/m to obtain major hysteresis loop. To overcome thermal heat generation problem from large exciting current during measurement, we have employed a real time hysteresis loop tracer which can digitize and calculate B-H signals in personal computer as real time. For example, when we magnetize specimen at 10 Hz frequency, we could display hysteresis loops 10 times per second. Using the real time hysteresis loop tracer, we could measure major hysteresis loop of toroidal shape metallic powder core at maximum flux density or maximum magnetic field strength to be measured within 5 second not to significant increasement of specimen temperature due to the heat dissipation from coil windings. For the constructed hysteresis loop tracer, we could measure hysteresis loop at magnetic field strength higher than 50 kA/m for the toroidal shape specimen.

• Proceedings of the Korean Magnestics Society Conference
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• 2011.06a
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• pp.111-113
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• 2011

변압기, 전동기 등의 에너지 효율을 향상시키기 위해 400 Hz 이상의 주파수에서 사용하는 자성코어 부품의 수요가 증가함에 따라 Si함량이 높은 연자성 코어에 대한 관심이 증가하고 있으며 냉간압연이 어려운 Fe-6.5wt.%Si의 경제적이고 생산성이 높은 분말 성형공정, 주파수에 따른 철손인자들의 영향 및 미세구조 제어에 대한 연구가 체계적이고 지속적 수행되고 있으며 흥미로운 연구결과가 도출되고 있다.

• Journal of the Korean Magnetics Society
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• v.20 no.1
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• pp.13-17
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• 2010

Fe-3, 4.2 and 6.8% Si compressed cores were fabricated, and then electrical resistivity, AC and DC magnetic properties, microhardness, and other properties were analyzed in order to know whether best soft magnetic properties could be also obtained in an Fe-Si compressed core with the well-known composition of Fe-6.5% Si. With increasing the silicon content, eddy current loss and hysteresis loss decreased and increased, respectively, so that a minimum total loss was not obtained in the well-known Fe-6.8 % Si cores, but obtained in the Fe-4.2 % Si cores. Also electrical resistivity of the cores and hardness of the particles increased monotonously with silicon content so that compaction ratio of the cores decreased. B2 and $DO_3$ ordered phase could be observed only in Fe-6.8% Si powder. A minimum loss and highest permeability of the Fe-4.2 % Si cores can be explained by the ratio of specific electrical resistivity of insulator to that of magnetic particles, micro-hardness, compaction ratio and demagnetization coefficient of the Fe-Si powder particles with silicon content.