• Title/Summary/Keyword: Magnetic Object

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Design and Development of the Magnetic Tomography System Using Two Poles Perpendicular Magnetic Field (2극 수직자계를 이용한 Magnetic Tomograpy의 설계와 제작)

  • 박은식;박관수
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.52 no.2
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    • pp.61-67
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    • 2003
  • This paper describes a development of magnetic tomography system using two poles perpendicular magnetic field. In the system, the relative permeabilities of the object are detected by Hall sensors located along with tube circumference. The signals according to the size and position of the object could be separated in case the relative permeability of the object are over 10. Moreover, the size and location of the object could be determined in real time.

Efficient Experimental Design for Measuring Magnetic Susceptibility of Arbitrarily Shaped Materials by MRI

  • Hwang, Seon-ha;Lee, Seung-Kyun
    • Investigative Magnetic Resonance Imaging
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    • v.22 no.3
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    • pp.141-149
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    • 2018
  • Purpose: The purpose of this study is to develop a simple method to measure magnetic susceptibility of arbitrarily shaped materials through MR imaging and numerical modeling. Materials and Methods: Our 3D printed phantom consists of a lower compartment filled with a gel (gel part) and an upper compartment for placing a susceptibility object (object part). The $B_0$ maps of the gel with and without the object were reconstructed from phase images obtained in a 3T MRI scanner. Then, their difference was compared with a numerically modeled $B_0$ map based on the geometry of the object, obtained by a separate MRI scan of the object possibly immersed in an MR-visible liquid. The susceptibility of the object was determined by a least-squares fit. Results: A total of 18 solid and liquid samples were tested, with measured susceptibility values in the range of -12.6 to 28.28 ppm. To confirm accuracy of the method, independently obtained reference values were compared with measured susceptibility when possible. The comparison revealed that our method can determine susceptibility within approximately 5%, likely limited by the object shape modeling error. Conclusion: The proposed gel-phantom-based susceptibility measurement may be used to effectively measure magnetic susceptibility of MR-compatible samples with an arbitrary shape, and can enable development of various MR engineering parts as well as test biological tissue specimens.

Magnetic field distribution in steel objects with different properties of hardened layer

  • Byzov, A.V.;Ksenofontov, D.G.;Kostin, V.N.;Vasilenko, O.N.
    • Advances in Computational Design
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    • v.7 no.1
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    • pp.57-68
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    • 2022
  • A simulation study of the distribution of magnetic flux induced by a U-shaped electromagnet into a two-layer massive object with variations in the depth and properties of the surface layer has been carried out. It has been established that the hardened surface layer "pushes" the magnetic flux into the bulk of the magnetized object and the magnetic flux penetration depth monotonically increases with increasing thickness of the hardened layer. A change in the thickness and magnetic properties of the surface layer leads to a redistribution of magnetic fluxes passing between the poles of the electromagnet along with the layer and the bulk of the steel object. In this case, the change in the layer thickness significantly affects the magnitude of the tangential component of the field on the surface of the object in the interpolar space, and the change in the properties of the layer affects the magnitude of the magnetic flux in the magnetic "transducer-object" circuit. This difference in magnetic parameters can be used for selective testing of the surface hardening quality. It has been shown that the hardened layer pushes the magnetic flux into the depth of the magnetized object. The nominal depth of penetration of the flow monotonically increases with an increase in the thickness of the hardened layer.

Quantitative Approach to the Magnetic Force of a Cylindrical Permanent Magnet Acting on a Ferromagnetic Object (원형 막대자석이 강자성 물체에 작용하는 자기력에 대한 정량적 접근)

  • Hyun, Donggeul;Shin, Aekyung
    • New Physics: Sae Mulli
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    • v.68 no.11
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    • pp.1249-1261
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    • 2018
  • The quantitative representation for the magnetic force of a cylindrical permanent magnet acting on a ferromagnetic cylindrical object was derived on the basis of magnetization theories, and the Gilbert and Ampere models of magnetism. The magnetic force derived in this study is directly proportional to the remanent magnetization magnetic field, the cross-sectional area of the permanent magnet, the saturation magnetic field, and the cross-sectional area of the ferromagnetic object and is inversely proportional to the square of the quantity related to the distance between the permanent magnet and the ferromagnetic object. The magnetic forces of an AlNiCoV cylindrical permanent magnet and a Ferrite cylindrical permanent magnet, both with a radius of 0.4 cm and a length of 7 cm, acting on ferromagnetic objects at distances farther than the radius were calculated to be less than 3.6711 N and 0.1857 N, respectively.

Magnetic Resonance Imaging of a Current Density Component

  • Oh, Suk-Hoon;Park, Tae-Seok;Han, Jae-Yong;Lee, Soo-Yeol
    • Journal of Biomedical Engineering Research
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    • v.25 no.3
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    • pp.183-188
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    • 2004
  • Magnetic resonance current density imaging (MRCDI) is a useful method for measuring electrical current density distribution inside an object. To avoid object rotations during the conventional MRCDI scans, we have reconstructed current density component images by applying a spatial filter to the magnetic field data measured both inside and outside the object. To measure the magnetic field outside the object with MRI, we immersed the object in a water tank. To evaluate accuracy of the current density imaging, we have made a conductivity phantom with a corresponding finite element method model. We have compared the experimentally obtained current density images with the ones calculated by the finite element method. The average errors of the reconstructed current density images were 6.6 ∼ 45.4 % when the injected currents were 1 ∼ 24 mA. We expect that the current density component imaging technique can be used in diverse biomedical applications such as electrical therapy system developments and biological electrical safety analysis.

A New Model of Magnetic Force in Magnetic Levitation Systems

  • Lee, Y.S.;Yang, J.H.;Shim, S.Y.
    • Journal of Electrical Engineering and Technology
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    • v.3 no.4
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    • pp.584-592
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    • 2008
  • In this paper, we propose a new model of the magnetic control force exerted on the levitation object in magnetic levitation systems. The model assumes that the magnetic force is a function of the voltage applied to an electromagnet and the position of a levitation object. The function is not explicitly expressed but represented through a 2D lookup table constructed from the experimentally measured data. Unlike the conventional model that reveals only local characteristics of the magnetic force, the proposed model shows global characteristics satisfactorily. Specially devised measurement equipment is utilized in order to gather the data required for model construction. An experimental procedure to construct the model is presented. We apply the proposed model to designing a sliding mode controller for a lab-built magnetic system. The validity of the proposed model is illustrated by comparing the performances of the controller adopting the conventional model with that of the controller adopting the proposed model.

Control and Display Device of Underground Object Detect system (지하매설물 탐지시스템의 제어 및 표시장치)

  • 서정만;정순기
    • Journal of the Korea Society of Computer and Information
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    • v.6 no.3
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    • pp.35-43
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    • 2001
  • Imposing electromagnetic field using transmitter of buried metal object in skill that detect underground object sensing person atonement in being widowed on the land being magnetized upside numerical value of buried metal object searching way used most widely current by skill be. This paper proposed about mode and detection system of underground object that sense the changed magnetic and judge real radish buried metal object sign of the cook because this treatise forms magnetic in land and design and composition of display device. Also, through simulation of detection system of underground object, showed that can measure radish judgment sign of the cock of underground object

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A Multi-physics Simulation and Measurement for Buoyancy of Nonmagnetic Solid Object Submerged in Magnetic Liquid (자성유체에 잠긴 비자성체 부상현상의 다중물리수치해석 및 실험)

  • Choi, Hong-Soon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.1
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    • pp.43-48
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    • 2013
  • In this paper, magnetic buoyancy force on nonmagnetic solid object submerged in magnetic liquid was simulated and measured. For the evaluation of the force, a multi-physics approach of hydrostatic equilibrium considering magnetic body force as well as gravity is presented. The magnetic body force should be regarded as an additional forcing term in the momentum equation of hydrodynamics. It is also shown that the virtual air-gap based Kelvin's force formula is a useful method for the calculation of force distribution in the magnetic liquid. The experimental result which was performed by a load-cell measurement system agreed quantitatively well with the numerical one.

A Study on the Shape Evaluation using Non-contact Electromagnetic Measurement System (비접촉식 전자기 측정 시스템에서 자성물체의 형상판정에 관한 연구)

  • Kim, Jae-Min;Yun, Seung-Ho;Won, Hyuk;Park, Gwan-Soo
    • Journal of the Korean Magnetics Society
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    • v.20 no.2
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    • pp.45-51
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    • 2010
  • We suggest the algorithm that it detects volume and shape according with a variation of magnetic field in non-contact electromagnetic measurement system. It is possible to assess an object shape through a variation of magnetic field. The basic idea is compared a length difference with a variation of magnetic field in a detected object and a circle which modeled equivalent area. And the shape is detected to many calibration process that it is similar to signal pattern between a length difference and a variation of magnetic field in object and equivalent circle. This is the shape detection algorithm that use only the variation of magnetic field. In this paper, it has application to the shape detection algorithm about the object as hexagon, pentagon, rectangle, trigon. we can detect the object shape easily because the shape detection algorithm is only used to the variation of magnetic field.

Improved Metal Object Detection Circuits for Wireless Charging System of Electric Vehicles

  • Sunhee Kim
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.17 no.8
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    • pp.2209-2221
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    • 2023
  • As the supply of electric vehicles increases, research on wireless charging methods for convenience has been increasing. Because the electric vehicle wireless transmission device is installed on the ground and the electric vehicle battery is installed on the floor of the vehicle, the transmission and reception antennas are approximately 15-30 cm away, and thus strong magnetic fields are exposed during wireless charging. When a metallic foreign object is placed in the magnetic field area, an eddy current is induced to the metallic foreign object, and heat is generated, creating danger of fire and burns. Therefore, this study proposes a method to detect metallic foreign objects in the magnetic field area of a wireless electric vehicle charging system. An active detection-only coil array was used, and an LC resonance circuit was constructed for the frequency of the supply power signal. When a metallic foreign object is inserted into the charging zone, the characteristics of the resonance circuit are broken, and the magnitude and phase of the voltage signal at both ends of the capacitor are changed. It was confirmed that the proposed method has about 1.5 times more change than the method of comparing the voltage magnitude at one node.