• Title, Summary, Keyword: bias magnetic field

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Dynamic Magneto-mechanical Behavior of Magnetization-graded Ferromagnetic Materials

  • Chen, Lei;Wang, Yao
    • Journal of Magnetics
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    • v.19 no.3
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    • pp.215-220
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    • 2014
  • This study investigates the dynamic magneto-mechanical behavior of magnetization-graded ferromagnetic materials Terfenol-D/FeCuNbSiB (MF). We measure the dynamic magneto-mechanical properties as a function of the DC bias magnetic field ($H_{dc}$). Our experimental results show that these dynamic magneto-mechanical properties are strongly dependent on the DC bias magnetic field. Furthermore, the dynamic strain coefficient, electromechanical resonance frequency, Young's moduli, and mechanical quality factor of Terfenol-D/FeCuNbSiB are greater than those of Terfenol-D under a lower DC bias magnetic field. The dynamic strain coefficient increases by a factor of between one and three, under the same DC bias magnetic field. In particular, the dynamic strain coefficient of Terfenol-D/FeCuNbSiB at zero bias achieves 48.6 nm/A, which is about 3.05 times larger than that of Terfenol-D. These good performances indicate that magnetization-graded ferromagnetic materials show promise for application in magnetic sensors.

Yoke Topology Optimization of the Bias Magnetic System in a Magnetostrictive Sensor (자기변형 센서 바이어스 자기계의 요크 위상최적설계)

  • Kim, Yoon-Young;Kim, Woo-Chul
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.7
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    • pp.923-929
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    • 2004
  • A magnetostrictive sensor is a sensor measuring elastic waves. Because of its unique non-contact measurement feature, the sensor receives more attentions in recent years. These sensors have been mainly used to measure longitudinal and torsional waves in ferromagnetic waveguides, but there increases an interest in using the sensor for flexural wave measurement. Since the performance of the sensor is strongly influenced by the applied bias magnetic field distribution, the design of the bias magnetic system providing the desired magnetic field is critical. The motivation of this investigation is to design a bias magnetic system consisting of electromagnets and yokes and the specific objective is to formulate the design problem as a bias yoke topology optimization. For the formulation, we employ linear magnetic behavior and examine the optimized results for electromagnets located at various locations. After completing the design optimization, we fabricate the prototype of the proposed bias magnetic system, and test its performance through flexural wave measurements.

Demagnetization Performance According to Vertical and Horizontal Magnetic Bias Fields

  • Kim, Young-Hak;Kim, Ki-Chan;Shin, Kwang-Ho;Yoon, Kwan-Seob;Yang, Chang-Seob
    • Journal of Magnetics
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    • v.16 no.4
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    • pp.453-456
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    • 2011
  • Demagnetization for a tube sample which was made of a galvanized steel sheet was performed by applying a magnetic field with a decrement to remove the remanent magnetization of the material. An orthogonal fluxgate magnetic field sensor was used to measure a magnetic field created from a ferromagnetic material. To evaluate the remanent magnetization, the measured magnetic fields were separated into two magnetic field components by the remnant magnetization and the induced one. The horizontal and the vertical bias fields should be controlled separately during demagnetization to remove the horizontal and the vertical components of the remanent magnetization of the tube sample.

Bias Estimation of Magnetic Field Measurement by AHRS Using UKF (UKF를 사용한 AHRS의 자기장 측정 편차 추정)

  • Ko, Nak Yong;Song, Gyeongsub;Jeong, Seokki;Lee, Jong-Moo;Choi, Hyun-Taek;Moon, Yong Seon
    • Journal of Ocean Engineering and Technology
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    • v.31 no.2
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    • pp.177-182
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    • 2017
  • This paper describes an unscented Kalman filter approach to estimate the bias in magnetic field measurements. A microelectromechanical systems attitude heading reference system (MEMS AHRS) was used to measure the magnetic field, together with the acceleration and angular rate. A magnetic field is usually used for yaw detection, while the acceleration serves to detect the roll and pitch. Magnetic field measurements are vulnerable to distortion due to hard-iron effect and soft-iron effect. The bias in the measurement accounts for the hard-iron effect, and this paper focuses on an approach to estimate this bias. The proposed method is compared with other methods through experiments that implement the navigation of an underwater robot using an AHRS and Doppler velocity log. The results verify that the compensation of the bias by the proposed method improves the navigation performance more than or comparable to the compensation by other methods.

Bias Field Effect of SmCo Films on Soft Magnetic Properties of CoZrNb Films (SmCo박막의 바이어스자계가 CoZrNb박막의 연자성특성에 미치는 효과)

  • Shin, K.H.;Kim, Y.H.
    • Journal of the Korean Magnetics Society
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    • v.13 no.5
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    • pp.198-203
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    • 2003
  • To investigate whether the use of hard magnetic film is available to generate bias magnetic field for a magnetoimpedance sensor, the magnetic properties of SmCo hard magnetic films were investigated as a function of their compositions. The saturation magnetization decreased with Sm content increasing in SmCo films. And, the coercive force increased in the extent of Sm content of 28 at%, but decreased as Sm content increased moreover. The bias field effect of SmCo film to amorphous CoZrNb film was investigated with the magnetization corves, permeabilities, and magnetic domain structures of SmCo/CoZrNb multilayers. The bias field of about 60 Oe was observed in the film with 3 mm ${\times}$ 0.5 mm, which can be constructed as a MI sensor, and this result strongly indicates that the bias field generated from a hard magnetic film is adequate to enhance the sensitivity of a MI sensor with hard/soft magnetic multilayer structure.

Effect of Bias Magnetic Field on Magnetoelectric Characteristics in Magnetostrictive/Piezoelectric Laminate Composites

  • Chen, Lei;Luo, Yulin
    • Journal of Magnetics
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    • v.20 no.4
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    • pp.347-352
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    • 2015
  • The magnetoelectric (ME) characteristics for Terfenol-D/PZT laminate composite dependence on bias magnetic field is investigated. At low frequency, ME response is determined by the piezomagnetic coefficient $d_{33,m}$ and the elastic compliance $s_{33}^H$ of magnetostrictive material, $d_{33,m}$ and $s_{33}^H$ for Terfenol-D are inherently nonlinear and dependent on $H_{dc}$, leading to the influence of $H_{dc}$ on low-frequency ME voltage coefficient. At resonance, the mechanical quality factor $Q_m$ dependences on $H_{dc}$ results in the differences between the low-frequency and resonant ME voltage coefficient with $H_{dc}$. In terms of ${\Delta}E$ effect, the resonant frequency shift is derived with respect to the bias magnetic field. Considering the nonlinear effect of magnetostrictive material and $Q_m$ dependence on $H_{dc}$c, it predicts the low-frequency and resonant ME voltage coefficients as a function of the dc bias magnetic field. A good agreement between the theoretical results and experimental data is obtained and it is found that ME characteristics dependence on $H_{dc}$ are mainly influenced by the nonlinear effect of magnetostrictive material.

Analysis of Induced Magnetic Field Bias in LEO Satellites Using Orbital Geometry-based Bias Estimation Algorithm (궤도 기하학 기반 바이어스 추정기법을 이용한 저궤도 위성의 유도자기장 바이어스 분석)

  • Lee, S.H.;Yong, K.L.;Choi, H.T.;Oh, S.H.;Yim, J.R.;Kim, Y.B.;Seo, H.H.;Lee, H.J.
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.36 no.11
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    • pp.1126-1131
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    • 2008
  • This paper applies the Orbital Geometry-based Bias Estimation Algorithm to the magnetometer measurement data of KOMPSAT-1 and 2 and analyzes the induced magnetic field bias caused by the solar panels and electronics boxes in spacecraft bus. This paper reveals that the estimation and correction of the induced magnetic field bias copes with the aging process of magnetometer and makes it possible to carry on the satellite mission by extending its lifetime.

Increment of the Exchange Coupling in Fe-Ni Alloy Thin Films Deposited with a Bias Magnetic Field

  • Han, Kyung-Hunn;Kim, Jung-Gi;Cho, Jae-Hun;Lee, Suk-Mock
    • Journal of Magnetics
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    • v.11 no.2
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    • pp.77-82
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    • 2006
  • The structure and magnetic properties of Fe-Ni films, deposited by DC magnetron sputtering on Si(111) wafer, have been studied. The spin wave stiffness constant is determined by Brillouin light scattering (BLS) and compared with the value obtained from magnetization measurements. The range of exchange interaction was determined as 0.4 atomic distances in the film deposited in a bias magnetic field, which is 1/2 that in the film grown in no bias magnetic field. The results show that the dimensions of exchange coupling increased by the sputtering in the magnetic field.

Topology Optimization of a Bias Magnetic Field for the Performance Improvement of a Magnetostrictive Sensor (마그네토스트릭션 센서 성능 향상을 위한 바이어스 자기장의 위상 최적설계)

  • Cho, Seung-Hyun;Kim, Youngkyu;Kim, Yoon-Young
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.554-558
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    • 2002
  • A magnetostrictive sensor is used to measure stress waves propagating in a ferromagnetic cylinder without physical contact. The performance of a magnetostrictive sensor is affected most significantly by the bias magnetic field applied around the measurement location. The goal of this paper is to carry out the topology optimization of the bias magnet and yoke assembly to maximize the sensor output for traveling bending waves. We will use the multi-resolution topology optimization strategy to find the assembly of the bias magnet and the yoke that is easy to realize. The effectiveness of the present design is confirmed by an actual measurement of the sensor signal with the proposed bias magnet and yoke configuration.

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EM Algorithm-based Segmentation of Magnetic Resonance Image Corrupted by Bias Field (바이어스필드에 의해 왜곡된 MRI 영상자료분할을 위한 EM 알고리즘 기반 접근법)

  • 김승구
    • The Korean Journal of Applied Statistics
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    • v.16 no.2
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    • pp.305-319
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    • 2003
  • This paper provides a non-Bayesian method based on the expanded EM algorithm for segmenting the magnetic resonance images degraded by bias field. For the images with the intensity as a pixel value, many segmentation methods often fail to segment it because of the bias field(with low frequency) as well as noise(with high frequency). Our contextual approach is appropriately designed by using normal mixture model incorporated with Markov random field for noise-corrective segmentation and by using the penalized likelihood to estimate bias field for efficient bias filed-correction.