• Journal of the Optical Society of Korea
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• v.10 no.3
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• pp.99-104
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• 2006

We introduce a novel contrast mechanism for imaging superparamagnetic iron oxide (SPIO) nanoparticles (average diameter ${\sim}100nm$) using magneto-motive optical Doppler tomography (MM-ODT), which combines an externally applied temporally oscillating high-strength magnetic field with ODT to detect the nanoparticles flowing through a glass capillary tube. A solenoid cone-shaped ferrite core extensively increased the magnetic field strength ($B_{max}=1\;T,\;{\Delta}|B|^2=220T^2/m$) at the tip of the core and also focused the magnetic force on targeted samples. Nanoparticle contrast was demonstrated in a capillary tube filled with the SPIO solution by imaging the Doppler frequency shift which was observed independent of the flow rate and direction. Results suggest that MM-ODT may be a promising technique to enhance SPIO nanoparticle contrast for imaging fluid flow.

• Journal of Magnetics
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• v.7 no.3
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• pp.101-105
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• 2002

MRAM (Magnetoresistive Random Access Memory) is a promising candidate for a universal memory that meets all application needs with non-volatile, fast operational speed, and low power consumption. The simplest architecture of MRAM cell is a series of MTJ (Magnetic Tunnel Junction) as a data storage part and MOS transistor as a data selection part. This paper is for testing the actual electrical parameters to adopt MRAM technology in the semiconductor based memory device. The discussed topics are an actual integration of MRAM core cell and its properties such as electrical tuning of MOS/MTJ for data sensing and control of magnetic switching for data writing. It will be also tested that limits of the MRAM technology for a high density memory.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.71-71
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• 2009

This paper describes a simple, on-chip CMOS compatible the thin-film inductor applied for the dc-dc converters. A fully CMOS-compatible thin-film inductor with a bottom NiFe core is integrated with the DC-DC converter circuit on the same chip. By eliminating ineffective top magnetic layer, very simple process integration was achieved. Fabricated monolithic thin film inductor showed fairly high inductance of 2.2 ${\mu}H$ and Q factor of 11.2 at 5MHz. When the DC-DC converter operated at $V_{in}=3.3V$ and 5MHz frequency, it showed output voltage $V_{out}=8.0V$, and corresponding power efficiency was 85%.

• Proceedings of the KIEE Conference
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• 2008.11a
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• pp.157-159
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• 2008

This paper describes modeling and analysis of magnetic inrush for a 765kV transformer using EMTP-RV. EMTP-RV generates the core flux and thus helps show the behavior of the core, i.e. hysteresis characteristics. The results of three kinds of the magnetic inrush such as initial inrush, sympathetic inrush, and recovery inrush are included. This modelling can help the design of a protection relay for a transformer.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.145-146
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• 2011

In this paper, a bridgeless flyback power factor correction (PFC) rectifier which uses single magnetic core is proposed. The proposed PFC rectifiers utilize bidirectional switch to handle both positive and negative input voltage without bridge diodes. A transformer with dual output windings enables the rectifier dispense with any additional magnetic component. The operation of the proposed flyback PFC rectifier is analyzed, and its higher efficiency than its conventional counterpart is verified by experiment.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1667-1673
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• 2015

The vibration and noise caused by the dynamic interaction between electromagnetic suspension and the linear synchronous motor stator beneath a flexible guideway remain problems in designing attractive Maglev trains. One possible method to reduce the sources of vibration is to minimize the detent force in the linear synchronous motor that creates variations in both lift force and thrust. This paper proposes lowering detent force by using separated core instead of single united core. The magnet is designed to adapt to the deflected guideway at a speed of 550km/h. This study will analyze the electromagnetic field and control performance, and how they relate to lift forces and dynamic responses.

• Journal of Korea Foundry Society
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• v.15 no.4
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• pp.397-407
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• 1995

The objectives of this study are first, to expand our understanding of relationship between magnetic properties and microstructural features such as grain size and texture, and second to reduce core loss of Fe-6.5%Si strip through optimizing heat treatment conditions. A rapid solidification technique, planar flow casting(PFC), was adopted to produce Fe-6.5%Si strips. The strips were heat treated under various conditions. The results show that heat treatment conditions can change not only grain size but also (200) texture formation on the strip surface. Variation in magnetic properties of Fe-6.5%Si strip is analyzed in terms of the change in grain size as well as (200) texture on the strip surface. The heat treatment conditions of $1100^{\circ}C$ over 2 hr or $1150^{\circ}C$ $1{\sim}2hr$ in $N_2+5%H_2$ appear to minimize core loss of Fe-6.5%Si strips.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.1
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• pp.22-26
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• 2005

This paper proposes the calculation method of magnetic coupling coefficient of the contactless energy transmission system by 3D finite element method with a variation of the secondary core positions. The primary, secondary self and leakage inductances and the capacitances of a resonant circuit are calculated by the finite element analysis results. From these values, the magnetic coupling coefficients are obtained. The secondary voltages and currents according to the secondary core positions are calculated by using the resonant circuit and compared.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.4
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• pp.561-566
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• 2016

In this paper, effective design method of linear induction motor(LIM) for Maglev is proposed in order to maximize system efficiency of Maglev. For the high system efficiency of Maglev, it is important to minimize weight of traction motor. Light weight design by changing materials of core and winding is conducted without changing volume of LIM. For the silicon steel core of primary part for magnetic flux path, iron-cobalt alloy steel with high magnetic saturation characteristic compared to silicon steel is suggested. Moreover, aluminium winding with light weight instead of copper winding is wounded in the widen slot area due to the high magnetic saturation level. For the verification of performance of proposed model, the characteristics are analyzed by using finite element method(FEM).

• ETRI Journal
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• v.25 no.4
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• pp.270-273
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• 2003

This paper presents a simple process to integrate thin-film inductors with a bottom NiFe magnetic core. NiFe thin films with a thickness of 2 to 3${\mu}m$ were deposited by sputtering. A polyimide buffer layer and shadow mask were used to relax the stress of the NiFe films. The fabricated double spiral thin-film inductor showed an inductance of 0.49${\mu}H$ and a Q factor of 4.8 at 8 MHz. The DC-DC converter with the monolithically integrated thin-film inductor showed comparable performances to those with sandwiched magnetic layers. We simplified the integration process by eliminating the planarization process for the top magnetic core. The efficiency of the DC-DC converter with the monolithic thin-film inductor was 72% when the input voltage and output voltage were 3.5 V and 6 V, respectively, at an operating frequency of 8 MHz.