• Journal of Powder Materials
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• v.16 no.4
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• pp.249-253
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• 2009

3-D shape soft magnetic composite parts can be formed by general compaction method of powder metallurgy. In this study, the results on the high density nanostructured Fe-Si/Fe composite prepared by a warm compaction method were presented. Ball-milled Fe-25 wt.%Si powder, pure Fe powder and Si-polymer were mixed and then the powder mixture was compacted at various temperatures and pressures. Pore free density of samples up to 95% theoretical value has been obtained. The warm compacted sample prepared at 650 MPa and 240$^{\circ}C$ had highest compaction properties in comparison with other compacts prepared at 300, 400 MPa and room temperature and 120$^{\circ}C$. The magnetic properties such as core loss, magnetization saturation and coercivity were measured by B-H curve analyzer and vibration sample magnetometer.

• Journal of the Korean Magnetics Society
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• v.20 no.5
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• pp.178-181
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• 2010

Search coil magnetometer has been used for detection of ac magnetic field with high sensitivity. To reduce demagnetizing factor of core and increase S/N ratio of search coil magnetometer, the core was divided by two parts and coil was wound on each cores. Two coils were connected serially and put into amplifier as differential mode. Constructed 120 mm length search coil magnetometer shows linearity of 0.03%, sensitivity of 9.3 mV/nT, and resolution of 20 pT at 1 Hz.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.3
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• pp.234-239
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• 2010

An inductive coupler, which feeds communication to the electric power transmission line, is required to establish Power Line Communication(PLC). The electro-magnetic property of magnetic core and design technology for coupler are very important to manufacture an inductive coupler for power transmission line. The magnetic core with superior electro-magnetic property was manufactured by using nanocrystalline alloy and an inductive coupler, which can operate at the maximum 2,000 A current, was designed and manufactured by establishment of current saturation, signal out winding, and electromagnetic simulation in this study. Communication speed of 14 Mbps in 600 meter communication distance of the real electric power transmission line was obtained by using the inductive coupler and application possibility of the inductive coupler for the electric power transmission line was certified.

• Journal of Magnetics
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• v.20 no.4
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• pp.444-449
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• 2015

Soft magnetic composites (SMCs) are especially suitable for the construction of low-cost, high-performance motors with 3-D magnetic fields. The main advantages of SMCs is that the iron particles are insulated by the surface coating and adhesive used for composite bonding, the eddy-current loss is much lower than that in laminated steels, especially at higher frequencies, and the hysteresis loss becomes the dominant component of core losses. These properties enable machines to operate at higher frequencies, resulting in reduced machine size and weight. In this paper, 3-D topologies are proposed that enable the application of SMCs to effectively reduce losses in high-speed permanent magnet (PM) motors. In addition, the electromagnetic field characteristics of the motor topologies are evaluated and compared using a non-linear finite element method (FEM) based on 3-D numerical analysis, and the feasibility of the motor designs is validated.

• Journal of Sensor Science and Technology
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• v.21 no.5
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• pp.339-344
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• 2012

This article describes a novel method for the detection of amyloid-${\beta}$($A{\beta}$) peptide that utilizes a photo-sensitive field-effect transistor (p-FET). According to a recent study, $A{\beta}$ protein has been known to play a central role in the pathogenesis of Alzheimer's disease (AD). Accordingly, we investigated the variation of photo current generated from p-FET with and without intracellular magnetic beads conjugated with $A{\beta}$ peptides, which are placed on the p-FET sensing areas. The decrease of photo current was observed due to the presence of the magnetic beads on the channel region. Moreover, a similar characteristic was shown when the Raw 264 cells take in magnetic beads treated with $A{\beta}$ peptide. This means that it is possible to simply detect a certain protein using magnetic beads and a p-FET device. Therefore, in this paper, we suggest that our method could detect tiny amounts of $A{\beta}$ for early diagnosis of AD using the p-FET devices.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.2
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• pp.121-128
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• 1998

A new magnetic ballast was designed and developed to get high luminous efficiency. The core material of new magnetic ballast was G-9 and its shape of core is modified. The diameter of the coil was upgraded to 0.5[mm], and a new power-saving circuit was designed for the semiconductor ignition starter. The experimental results of the ballast showed reduction of the electric loss in the magnetic ballast about 1.7Watt (0.5[%]). The luminous efficiency was increased by 6.2 lm/Watt (7.6[%]) and the ballast efficiency factor(BEF) of 1.09(7.6[%]). The prototype was tested through national standard testing procedure. A high efficient energy-using equipment (the second grade in the efficiency of energy consumption) was certified. The saving power of 1.7[W] was shown by lighting appratus for fluorescent lamps. The result will be used for the high efficient magnetic ballast technology.nology.

• Journal of Power Electronics
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• v.18 no.1
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• pp.309-322
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• 2018

The technology of inductive power transfer has been proved to be a promising solution in many applications especially in electric vehicle (EV) charging systems, due to its features of safety and convenience. However, loosely coupled transformers lead to the system efficiency not coming up to the expectation at the present time. Therefore, at first, the magnetic core losses are calculated with a novel magnetic-circuit model instead of the commonly used finite-element-method (FEM) simulations. The parameters in the model can be obtained with a one-time FEM simulation, which makes the calculation process expeditious. When compared with traditional methods, the model proposed in the paper is much less time-consuming and relatively accurate. These merits have been verified by experimental results. Furthermore, with the proposed loss calculation model, the system is optimized by parameter sweeping, such as the operating frequency and winding turns. Specifically, rather than a predesigned switching frequency, a more efficiency-optimized frequency for the series-parallel (SP) compensation topology is detected and a detailed investigation has been presented accordingly. The optimized system is capable of an efficiency that is greater than 93% at a coil separation distance of 200mm and coil dimensions of $600mm{\times}400mm$.

• Journal of Electrical Engineering and Technology
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• v.10 no.2
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• pp.545-550
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• 2015

High Temperature Superconducting (HTS) synchronous generators can be designed with either an air-core type or iron-core type. The air-core type has higher efficiency under rated rotating speed and load than the iron-core type because of the iron losses which may produce much heat. However, the total length of HTS wire in the air-core type is longer than the iron-core type because the generated magnetic flux density of the air-core type is low. This paper deals with designs of 10 MW air-core and iron-core HTS wind power generators for wind turbines. Fully air-core, partially iron-core, and fully iron-core HTS generators are designed, and various stator winding methods in the three HTS generators are also considered, such as short-pitch concentrated winding, full-pitch concentrated winding, short-pitch distributed winding, and full-pitch distributed winding. These HTS generators are analyzed using a 3D finite elements method program. The analysis results of the HTS generators are discussed in detail, and the results will be effectively utilized for large-scale wind power generation systems.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1024-1026
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• 2003

This paper deals with the characteristic analysis of round shape core of transformer compared with conventional EI core transformer. The round shape has specific configuration to reduce leakage magnetic flux. Characteristics such as B-H characteristic curve and in-rush current, etc. are compared.

• Journal of the Korean Magnetics Society
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• v.11 no.6
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• pp.239-244
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• 2001

Recently, RF inductor having researched by many workers, we fabricated and investigated properties of RF inductors. In order to improve the Q-factor (Quality), we try to apply the patterned Fe$_{78.81}$Ta$_{8.47}$N$_{12.71}$ soft magnetic thin film of 5000 which shows magnetic anisotropy of 30 Oe. Thus, patterned magnetic film was artificially increased magnetic anisotropy lead to increasing of ferro-magnetic resonance frequency up to GHz band. Coil as part of inductor was fabricated by lift off process. The dimension of RF inductor was designed 47un, rectangular shape, and measured properties. In the case of Ti/Ag air core type inductor shows Q of 9, inductance of 8.4 nH at 2 GHz. Magnetic film employed inductor shows inductance of 9 nH and FMR resonance frequency was 700 MHz.