• Title, Summary, Keyword: Magnetization distribution

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Magnetic Anisotropy Energy Distribution and Magnetization of CoPt Nanoparticles Encaged in Protein Shell

  • Lee, T.H.;Suh, B.J.;Jang, Z.H.
    • Journal of Magnetics
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    • v.22 no.1
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    • pp.1-6
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    • 2017
  • Magnetic properties of CoPt nanoparticles (average size = 2.1 nm) encapsulated in synthesized protein shell have been investigated with SQUID (Superconducting Quantum Interference Device) magnetometer and analyzed by the recently developed non-equilibrium magnetization calculation by our group [T. H. Lee et al., Phys. Rev. B 90, 184411 (2014)]. Field dependence of magnetization measured at 2 K was successfully analyzed with modified Langevin function. In addition, small hysteresis loops having the coercive field of 890 Oe were observed at 2 K. Temperature dependence of magnetization has been measured with zero field cooled (ZFC) and field cooled (FC) protocol with slightly modified sequence in accordance with non-equilibrium magnetization calculation. The analysis on the M vs. T data revealed that the anisotropy energy barrier distribution is found to be very different from the log-normal distribution found in a size distribution. Zero temperature coercive field and Bloch coefficient have also been extracted from the analysis and the validity of those values is checked.

Identification of Unknown Remanent Magnetization in the Ferromagnetic Ship Hull Utilizing Material Sensitivity Information Combined with Magnetization Modeling

  • Kim, Nam-Kyung;Jeung, Gi-Woo;Yang, Chang-Seob;Chung, Hyun-Ju;Kim, Dong-Hun
    • Journal of Magnetics
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    • v.16 no.2
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    • pp.114-119
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    • 2011
  • This paper presents a magnetization modeling method combined with material sensitivity information to identify the unknown magnetization distribution of a hull and improve the accuracy of the predicted fields. First, based on the magnetization modeling, the hull surface was divided into three-dimensional sheet elements, where the individual remanent magnetization was assumed to be constant. For a fast search of the optimum magnetization distribution on the hull, a material sensitivity formula containing the first-order gradient information of an objective function was combined with the magnetization modeling method. The feature of the proposed method is that it can provide a stable and accurate field solution, even in the vicinity of the hull. Finally, the validity of the method was tested using a scale model ship.

Analysis of 3-Dimensional Magnetic Field Distribution in CPM Considering Magnetization Vector Distribution and Design of CPM (자화 벡터 분포를 고려한 CPM의 3차원 자계 분포 해석 및 설계)

  • Lee, Cheol-Gyu;Gwon, Byeong-Il;Park, Seung-Chan;U, Gyeong-Il
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.51 no.10
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    • pp.545-553
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    • 2002
  • This paper is about the analysis of 3-dimensional magnetic field distribution in CPM(Convergence Purity Magnet) considering magnetization vector and the optimum design of CPM. The magnetization vector of CPM is obtained using 2-dimensional magnetization FEA(Finite Element Analysis) coupled with Priesach model. Using this magnetization vector of CPM, we analysed the 2-dimensional and 3-dimensional magnetostatic field of CPM and know that these analysis results are not equal. From experimental result, we know that the 3-dimensional analysis is accurate because the magnetic field distribution in CPM cannot be considered correctly by 2-dimensional analysis because of the shape of CPM. Finally, the optimum designing of CPM which control accurately the electron beam deflection in CRT(Cathode Ray Tube) was possible using 3-dimensional magnetic field analysis result.

A Study on Characteristic of Spindle Motor by Unsymmetric Magnetization Distribution in Permanent Magnet (비대칭 착자에 따른 스핀들 모터 특성에 관한 연구)

  • Park, Jae-Young;Bae, Jae-Nam;Kim, Ki-Chan;Lee, Ju
    • Proceedings of the KIEE Conference
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    • pp.38-40
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    • 2008
  • Distribution of Permanent magnet used in the spindle motor on the ODD is arranged by magnetizer. In general, permanent magnet is putted between yoke and back yoke of magnetizer so that symmetric magnetization distribution. But the magnet has unsymmetric magnetization distribution because of eccentricity of the yoke in mass production. So, in this paper we discuss the effect of asymmetric magnetization distribution on back EMF and cogging torque of the spindle motor.

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Comparison of Three Modeling Methods for Identifying Unknown Magnetization of Ferromagnetic Thin Plate

  • Choi, Nak-Sun;Kim, Dong-Wook;Yang, Chang-Seob;Chung, Hyun-Ju;Kim, Hong-Joon;Kim, Dong-Hun
    • Journal of Electrical Engineering and Technology
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    • v.6 no.6
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    • pp.799-805
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    • 2011
  • This study presents three different magnetization models for identifying unknown magnetization of the ferromagnetic thin plate of a ship. First, the forward problem should be solved to accurately predict outboard magnetic fields due to the magnetization distribution estimated at a certain time. To achieve this, three different modeling methods for representing remanent magnetization (i.e., magnetic charge method, magnetic dipole array method, and magnetic moment method) were utilized. Material sensitivity formulas containing the first-order gradient information of an objective function were then adopted for an efficient search of an optimum magnetization distribution on the hull. The validity of the proposed methods was tested with a scale model ship, and field signals predicted from the three different models were thoroughly investigated with reference to the experimental data.

Analysis of 3-Dimensional Magnetic Field Distribution in C.P.M Considering Magnetization Vector Distribution (자화 벡터 분포를 고려한 C.P.M(Convergence Purity Magnet)의 3차원 자계 분포 해석)

  • Lee, Chol-Gyu;Kwon, Byung-Il;Park, Seung-Chan;Yoon, Tae-Ho
    • Proceedings of the KIEE Conference
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    • pp.241-243
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    • 2000
  • In this paper, we analyze three-dimensional magnetic field distribution of a convergence purity maget(C.P.M) which is used for a cathode ray tube. The magnetization vector distribution of the C.P.M is obtained from the result of magnetization process analysis using the 2D F.E.M. Then the motion of electron beam passing through the inner space of the C.P.M is determined and compared with experimental result.

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Design of the Magnetization System of the Permanent Magnet in Magnetic Sensors (마그네틱 위치 센서용 영구자석의 착자 시스템 설계)

  • Jeong, Seung-Ho;Lee, Chul-Kyu;Kwon, Byung-Il
    • Proceedings of the KIEE Conference
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    • pp.1029-1031
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    • 2005
  • A magnetic position sensor is a apparatus that detect the rotating position by measuring the value of the flux density of the rotating position. In this paper, the magnetization system of the permanent magnet in the magnetic position sensor which detects the rotating position was designed. The permanent magnet was magnetized for the flux density into the hole element to be sinusoidal distribution according to the rotating position. To make the sinusoidal distribution of flux density, the magnetization values according to the position in permanent magnet were varied by adjusting the air gap between the pole of the magnetization fixture and the surface of the permanent magnet.

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Analysis of Cogging Torque in BLDC Motor Taking into account Magnetization Distribution Using 3DEMCN (3차원 등가자기회로망법을 이용한 영구자석의 자화분포에 따른 BLDC 모터의 코깅 토오크 해석)

  • Hwang, D.Y.;Hur, J.;Yoon, S.B.;Hong, J.P.;Hyun, D.S.
    • Proceedings of the KIEE Conference
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    • pp.159-161
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    • 1997
  • This paper presents a method of reducing cogging torque and improving average torque by changing the dead zone angle of trapezoidal magnetization distribution of rotor magnet in ring type. Because brushless d.c. motor has 3D shape of overhang, 3D analysis should be used for computation of its magnet field. In this paper, Three Dimensional Equivalent Magnetic Circuit Network method (3DEMCN) which can calculate an accurate 3D magnetic field has been introduced. The method has an advantage that nonlinear magnetic phenomena can be considered and the cogging torque analyses requesting the rotation of the rotor can be performed by the variation of magnetization distribution without remesh.

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The Development of Rotary Magnetic Position Sensor with Sinusoidal Magnetization Density Distribution (정현적 자화분포를 갖는 위치 검출용 마그네틱 센서 개발)

  • Jeong, Seung-Ho;Rhyu, Se-Hyun;Kwon, Byung-Il
    • Proceedings of the KIEE Conference
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    • pp.107-109
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    • 2005
  • This paper presents the development of the magnetic position sensor for servo motor. The magnetization system is designed for the sinusoidal magnetic flux density distribution from permanent magnet using 2D finite element method and Preisach model. The magnetic position sensor is composed of the permanent magnet and two Hall elements. And the algorithm calculating the rotating position is suggested by the phase difference of outputs of Hall elements.

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Finite Element Analysis of a Inner-Rotor Type BLDC Motor without Rotor Core (회전자 철심이 없는 내전형 BLDC 모터의 유한요소 해석)

  • Chang, Hong-Soon;Jung, In-Soung;Baek, Soo-Hyeon
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.49 no.10
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    • pp.652-658
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    • 2000
  • In many cases, ferrite magnets of ferrite bonded magnets used in inner-rotor type small brushless DC(BLDC) motors do not have rotor core. The magnetization directions of permanent magnets do not have only parallel or radial direction. In this case, the characteristics of magnets are different from cored type ones which have uniform magnetization direction. In this paper, the magnetization directions and intensities of a ferrite magnet and a ferrite bonded magnet are analyzed by finite element analysis for magnetization procedure. The characteristics of inner-rotor type BLDC motor are analyzed by using the analyzed results. The validity of the method is verified by comparing the analyzed results with measured ones.

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