• Title/Summary/Keyword: magnetometer

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Characterization of step-edge dc SQUID magnetometer fabricated on sapphire substrate (사파이어 기판 위에 제작된 step-edge dc SQUID magnetometer의 특성)

  • 임해용;박종혁;정구락;한택상;김인선;박용기
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2002.02a
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    • pp.127-130
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    • 2002
  • Step-edge dc SQUID magnetometers have been fabricated on sapphire substrate. Ce$O_{2}$ buffer layer and $YBa_{2}$$Cu_{3}$ $O_{7}$(YBCO) films were deposited in-situ on the low angle (~$35^{\circ}$)steps formed on the substrates. Typical 5-$\mu$m-wide junction has $R_{N}$ of 4 $\Omega$ and $I_{c}$ of 60 $\mu$A with $I_{c}$$R_{N}$ product of 240 $\mu$V at 77 K. According to applied bias current, depth of voltage modulation was changed and maximum voltage was measured 100~300 fT/$\checkmark$ Hz at 100 Hz, and about 1.5 pT/$\checkmark$ Hz at 1 Hz. For ac bias reversal method, field noise was decreased in the 1/f region. The QRS peak of magneto-cardiogram was measured 50 pT in the magnetically shielded room.

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Rat Magnetocardiograms Measured by YBCO SQUID Magnetometer (YBCO SQUID를 이용한 실험쥐의 심자도 측정)

  • Ahn, San;Kim, I.S.;Song, J.H.
    • Progress in Superconductivity
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    • v.12 no.2
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    • pp.124-128
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    • 2011
  • We have developed a high-$T_C$ SQUID magnetometer system to measure magnetocardiograms of laboratory rats. White noise of the measurement system was about 50 fT/$Hz^{1/2}$ when measured in a magnetically shielded box. We optimized the measurement position to obtain clear MCG wave from rat's small heart by using grid measurements. With the optimization, the MCG signal was successfully detected with the peak amplitude of about 50 pT. We could observe well defined P-, QRS-, and T-wave from the rat MCG. The results suggest that the developed system has a strong potential to monitor the progress of heart disease model using laboratory rat.

Construction of HTS multi-channel SQUID system

  • Park, W.K.;Lee, H.J.;Moon, S.H.;Lim, S.H.;Kim, D.Y.;Oh, B.;Lee, S.M.
    • 한국초전도학회:학술대회논문집
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    • v.10
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    • pp.169-172
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    • 2000
  • We have constructed a multi-channel SQUID magnetometer system. The system is designed to operate normally with 10 high temperature direct coupled SQUIDs. The main features of the system include a remote control by serial communication, low noise with wide bandwidth and high slew rate by several MHz modulation, signal conditioning and calibration by digital signal processing.

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Real-time Fall Detection with a Smartphone (스마트폰을 이용한 실시간 낙상 감지)

  • Hwang, Soo-Young;Ryu, Mun-Ho;Kim, Je-Nam;Yang, Yoon-Seok
    • Journal of Information Technology Services
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    • v.11 no.sup
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    • pp.113-121
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    • 2012
  • In this study, a real-time fall detection system based on a smartphone equipped with three-axis accelerometer and magnetometer was proposed and evaluated. The proposed system provides a service that detects falls in real time, triggers alarm sound, and sends emergency SMS(Short Message Service) if the alarm is not deactivated within a predefined time. When both of the acceleration magnitude and angle displacement of the smartphone attached to waist belt are greater than predefined thresholds, it is detected as a fall. The proposed system was evaluated against activities of daily living(walking, jogging, sitting down, standing up, ascending stairs, and descending stairs) and unintended falls induced by a proprietary pneumatic-powered mattress. With the thresholds of acceleration magnitude 1.7g and angle displacement $80^{\circ}$, it showed 96.5% accuracy to detect the falls while all the activities of daily living were not detected as fall.

Development of High-Field ESR System Using SQUID Magnetometer and its Application to Measurement under High Pressure

  • Sakurai, T.;Fujimoto, K.;Okubo, S.;Ohta, H.;Uwatoko, Y.
    • Journal of Magnetics
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    • v.18 no.2
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    • pp.168-172
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    • 2013
  • We have developed a high-field and high-frequency ESR system using a commercially available magnetometer equipped with the superconducting quantum interference device (SQUID). This is magnetization detection type ESR and ESR is observed as a change of the magnetization at the resonance condition under irradiation of the electromagnetic wave. The frequency range is from 70 to 315 GHz and the maximum magnetic field is 5 T. The sensitivity is estimated to be $10^{13}$ spins/G. The advantage of this system is that the high-field ESR measurements can be made very easily and quantitatively. Moreover, this high-field ESR can be applied to the measurements under pressure by using a widely used piston-cylinder pressure cell.