• 한국초전도학회:학술대회논문집
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• v.9
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• pp.27-32
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• 1999

We developed a 40-channel superconducting quantum interference device (SQUID) system for neuromagnetic measurements. The main features of the system are use of double relaxation oscillation SQUID (DROS), and planar gradiometer for measuring tangential field components. The DROSS with high flux-to-voltage transfers enabled direct readout of the SQUID output by room-temperature electronics and simple flux-locked loop circuits could be used for SQUID operation. The pickup coil is an integrated first-order planar gradiometer with a baseline of 40 mm. The average noise of the 40 channels is around 1.2 fT/cm/${\sqrt{Hz}}$ at 100 Hz, corresponding to the field noise of 5 fT/${\sqrt{Hz}}$ at 100 Hz, operated inside a magnetically shielded room. The 40-Channel system was applied to measure auditory-evoked neuromagnetic fields.

• JSTS:Journal of Semiconductor Technology and Science
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• v.3 no.1
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• pp.21-26
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• 2003

4H-SiC Schottky rectifiers were exposed to pure Ar discharges in a planar coil Inductively Coupled Plasma system, as a function of source power, of chuck power and process pressure. The reverse breakdown voltage ($V_B$) decreased as a result of plasma exposure due to the creation of surface defects associated with the ion bombardment. The magnitude of the decrease was a function of both ion flux and ion energy. The forward turn-on voltage ($V_F$), on-state resistance ($R_{ON}$) and diode ideality factor (n) all increased after plasma exposure. The changes in all of the rectifier parameters were minimized at low power, high pressure plasma conditions.

• Progress in Superconductivity
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• v.2 no.1
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• pp.20-26
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• 2000

A 40-channel superconducting quantum interference device (SQUID) system was constructed for measuring neuromagnetic fields. Main features of the system are the use of double relaxation oscillation SQUIDs (DROSs), and planar gradiometers measuring magnetic field components tangential to the head surface. The DROSs with high flux-to-voltage transfers enabled direct readout of the SQUID output by room-temperature dc preamplifiers and simple flux-locked loop circuits could be used for SQUID operation. The pickup coil is an integrated first-order planar gradiometer with a baseline of 40 mm. Average noise level of the 40 channels is around 1.2 $fT/cm/{\surd}Hz$ at 100 Hz, corresponding to a field noise of 5 $fT/{\surd}Hz$, operated inside a magnetically shielded room. The SQUID insert was designed to have low thermal load, minimizing the loss of liquid helium. The constructed system was applied to measure auditory-evoked neuromagnetic fields.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.1
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• pp.16-24
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• 2001

This paper presents an electromagnetic microactuator using the copper coil electroplated on the p+silicon diaphragm. The microactuator generates a vertical motion of the diaphragm using the radial direction, we propose a new actuator structure with twin magnets. The microactuator field in the radial direction, we propose a new actuator structure with twin magnets. The microactator shows a values of resonant frequency and quality factor in the ranges of 10.51${\pm}$0.22kHz and 46.6${\pm}$3.3, respectively. The twin magnet microactuator generates the maximum peak-to-peak amplitude of 4.4$\mu\textrm{m}$ for the AC rms current of 26.8mA, showing 2.4 times larger amplitude than the single magnet microactuator.

• Journal of Magnetics
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• v.13 no.2
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• pp.37-42
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• 2008

In this paper, design parameters of high Q (> 50), high current inductor for on-chip power module were optimized by 4 Xs 3 Ys DOE (Design of Experiment). Coil spacing, coil thickness, ferrite thickness, and permeability were assigned to Xs, and inductance (L) and Q factor at 10 MHz, and resonance frequency ($f_r$) were determined Ys. Effects of each X on the Ys were demonstrated and explained using known inductor theory. Multiple response optimizations were accomplished by three derived regression equations on the Ys. As a result, L of 125 nH, Q factor of 197.5, and $f_r$ of 316.3 MHz were obtained with coil space of $127\;{\mu}m$, Cu thickness of $67.8\;{\mu}m$, ferrite thickness of $130.3\;{\mu}m$, and permeability 156.5. Loss tan ${\delta}=0$ was assumed for the estimation. Accordingly, Q factor of about 60 is expected at tan ${\delta}=0.02$.

• Transactions on Electrical and Electronic Materials
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• v.14 no.3
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• pp.143-147
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• 2013

This paper describes a low frequency driven electromagnetic energy harvester (EMEH) which consists of a thin flame resistant (FR-4) planar spring, NdFeB permanent magnets, and a copper coil. The FR-4 spring was fabricated using a desk computer numerical control (CNC) 3D modeling machine. Mathematical modeling and ANSYS finite element analysis (FEA) were used totheoretically investigate the mechanical properties of the spring mass system. The proposed EMEH generates a maximum power of 65.33 ${\mu}W$ at a resonance frequency of 8 Hz with an acceleration of 0.2 g (1 g = 9.8 $m/s^2$) and a superior normalized power density (NPD) of 77 ${\mu}W/cm^3{\cdot}g^2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.964-967
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• 2002

The effectiveness of silicon nitride SiNx surface passivation is investigated and quantified. This study adopted single-layer antireflection (SLAR) coating of SiNx for efficiency improvement of solar cell. The silicon nitride films were deposited by means of plasma enhanced chemical vapor deposition (PECVD) in planar coil reactor. The process gases used were pure ammonia and a mixture of silane and helium. The thickness and the refractive index on the films were measured by ellipsometry and chemical bonds were determined by using an FT-IR equipment. This films obtained were analyzed in term of hydrogen content, refractive index for gas flow ratio $(NH_3/SiH_4)$, and efficiency of solar cell. The polycrystalline silicon solar cells passivated by silicon nitride shows efficiency above 12.8%.

• Proceedings of the KSMRM Conference
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• 2001.11a
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• pp.104-104
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• 2001

Purpose： In this study, we investigated the possible motor pathways of hemiplegic stroke patients usin combined TMS and BOLD fMRI approach and evaluated the correlation between TMS a fMRI methods. Method： Four subjects, who demonstrated left hemiplegia after stroke, are included. TMS was performed using a Dantec Mag2 stimulator (Dantec Company, USA) in single puls mode with figure eight-shaped coil. Following TMS localization, The BOLD T2＊-weight images were acquired with echo planar imaging sequence (TR = 1.2 sec, TE = 60 msec, and flip angle = 90). Motor activation was studied by means of a repetitive fing flexion-extension task. The stimulation protocol comprised 10 cycles of alternating activati and rest (10 images per cycle). Total 60 cycles were performed and each cycle take abou 1.5 sec. The resulting images were then analyzed with STIMULATE (CMRR, U, o Minnesota) to generate functional maps using a student t-test (p < 0.0005) and cluste analysis.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.11-12
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• 2015

본 논문에서는 무선전력전송 시스템을 위한 차폐제가 부착된 경우의 평판형 원형 코일의 인덕턴스 계산방법을 제안한다. 페라이트와 도체시트로 구성된 차폐제를 영상법을 이용하여 등가의 영상전류로 모델링하였다. 영상전류에 의해 코일에 쇄교되는 자속을 반영하여 코일의 인덕턴스를 계산하였다. 검증을 위해 Maxwell 2D의 시뮬레이션의 결과와 비교하였다. 계산결과는 시뮬레이션과 정확히 일치하였다.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.4
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• pp.269-274
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• 1999

A bending actuator using zigzag type shape memory alloy springs has been fabricated and characterized. The fabricated millimeter-sized actuator has outer diameter of 3.0mm and inner diameter of 2.0mm. The zigzag type spring is more suitable for thin wall type actuator because the zigzag type spring has a planar structure comparing with the coil type spring which has a three-dimensional structure. The measured characteristics of the fabricated bending actuator show the possibility of practical application to micro active bending catheters.