• Title/Summary/Keyword: Magnetic Properties

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Electromagnetic Properties of Bi System Superconductor for Magnetic Levitation Car Maglev

  • Lee, Sang-Heon
    • Journal of Electrical Engineering and Technology
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    • v.2 no.1
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    • pp.102-105
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    • 2007
  • Effects of $Ag_2O$ doping on the electromagnetic properties in the BiSrCaCuO superconductors. The electromagnetic properties of the $Ag_2O$ doped and undoped BiSrCaCuO superconductor were evaluated to investigate the contribution of the pinning centers to the magnetic effect. It was confirmed experimentally that a large amount of magnetic flux was trapped in the $Ag_2O$ doped sample than that in the undoped one, indicating that the pinning centers of magnetic flux are related closely to the occurrence of the magnetic effect. It is considered that the area where normal conduction takes place increases by adding $Ag_2O$ and the magnetic flux penetrating through the sample increases. The results suggested that Ag acts to increase the pinning centers of the magnetic flux, contributing to the occurrence of the electromagnetic properties.

THE MAGNETIC SEPARATION OF Nd-Fe-B POWDERS

  • Cui, Li-Ya;Zheng, Da-Li;Zhu, Jing-Han;Zhao, Wei-Hong;Ding, Shu-Lin
    • Journal of the Korean Magnetics Society
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    • v.5 no.5
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    • pp.672-678
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    • 1995
  • The magnetic separation of Nd-Fe-B powders prepared by melt-spun and HDDR processes was investigated. The experiments show that the ununiform melt-spun powders can be separated into various standards by means of magnetic separation method. The magnetic powders with higher properties were obtained by the use of suitable separating field. For example, the properties of ununiform melt-spun powders are Br=7.95 kG, iHc=9.93 kOe and (BH)max=10.2 MGOe before separating. Through separating in different magnetic fields, the powders obtained with a separating field of 780 Oe has the optimum properties of Br=7.7 kG, iHc=11.0 kOe and (BH)max=15.3 MGOe. The magnetic properties of the HDDR magnetic powder are hardly separated by the magnetic separation method.

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Magnetic Properties of BiPbSrCaCuO System (Bi계 초전도체의 자기적 효과)

  • 이상헌
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2002.02a
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    • pp.355-357
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    • 2002
  • The relationship between magnetic properties of BiPbSrCaCuO superconductor and externally applied magnetic field was studied to develop a magnetic field polarity sensor. The behavior was related to the magnetic flux trapped in the superconductor, which penetrates through the material by the external magnetic field. Some portion of the superconductor was changed to a normal state by the trapped magnetic flux. Electrical characteristics of the superconductor with trapped magnetic flux were extremely sensitive to the external magnetic field and showed different responses depending on the direction of the magnetic field.

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What is Magnetic Fluid\ulcorner (자성 유체의 특성 및 응용)

  • Lee, Hyo-Suk
    • Korean Journal of Materials Research
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    • v.12 no.4
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    • pp.264-268
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    • 2002
  • Magnetic fluid is a very stable colloid that is attracted by magnetic force as wholly. The magnetic fluids is composed with 10 nm magnetic materials such as magnetite, iron etc., which is dispersed homogeneously in solvent by coating surfactant on their surface. Also this colloid is not separated into magnetic particles and solvent even under magnetic field, centrifugal force, gravity. Due to these properties, the magnetic fluids is used in high vacuum seal, exclusion seal, damper, etc. I would like to introduce the specific properties and applications of the magnetic fluids.

2-Dimensional Magnetic Properties of Electrical Steel Sheet Under Rotating Magnetic Field (회전자계하 전기강판의 2차원 자기적 특성 분석)

  • Ha, Kyung-Ho;Kim, Ji-Hyun;Kwon, Oh-Yeoul;Cha, Sang-Yoon;Kim, Jae-Kwan;Takahashi, Norio
    • Proceedings of the KIEE Conference
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    • 2008.07a
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    • pp.621-622
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    • 2008
  • This paper deals with the magnetic properties under the rotational magnetic field on the electrical steel sheet by using Single Sheet Tester with two excitation coils. Actually, the magnetic flux of stator cores in running motors have the behaviour of rotating and alternating flux. In order to improve motor characteristics, it is require to estimate these magnetic properties. When the magnetic field vectors are rotating around in the plane of the sheet during one period of cycle, the magnetization properties and the core loss are measured and then, the results are compared with the magnetic properties obtained by the alternating magnetic fields.

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Enhanced magnetic properties of FeCo alloys by engineering crystallinity and composition (FeCo의 결정성 및 조성 제어를 통한 자기 특성 향상)

  • Kim, Dan-Bi;Kim, Ji-Won;Eom, Nu-Si-A;Park, Seong-Heum;Im, Jae-Hong
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2018.06a
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    • pp.32.1-32.1
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    • 2018
  • Novel soft magnetic materials can be achieved by altering material properties such as morphology, composition, crystallinity, and grain size of soft magnetic alloys. Especially, magnetic properties (i.e., saturation magnetization, coarcivity) of soft magnetics are significantly affected by grain boundaries which act as a control of magnetic domain wall movement. Thus, we herein develop a two-step electroless plating method to control morphology and grain size of FeCo films for excellent magnetic properties. Accordingly, the chemical composition to control the degree of polarization of FeCo alloys was altered by electroless deposition parameters; for example, electrolyte concentration and temperature. The grain size and crystallinity of FeCo alloys was dramatically affected by the reaction temperature because the grain growth mechanism dominantly occurs at $90^{\circ}C$ where as the neucleation only happens at $50^{\circ}C$. By simply controlling the temperature, the micron-sized FeCo grains embedded FeCo film was synthesized where the large grains allow high magnetization originated from larger magnetic domain with low corecivity and the nano-sized grains allow excellent soft magnetic properties due to the magnetic correlation length.

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Annealing Effect of Co/Pd Multilayers on Magnetic Properties During Interdifusion

  • Kim, Jai-Young;Jan E. Evetts
    • Journal of Magnetics
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    • v.2 no.4
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    • pp.147-156
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    • 1997
  • An artificially modulated magnetic Co/Pd multilayer is one of the promising candidates for high density magneto-optic (MO) recording media, due to a large Kerr rotation angle in the wavelength of a blue laser beam. However, since multilayer structure, as well as amorphous structure, is a non-equilibrium state in terms of free energy and a MO recording technology is a kind of thermal recording which is conducted around Curie temperature (Tc) of the recording media, when the Co/Pd mulilayer is used for the MO recording media, changes in the magnetic properties are occurred as the amorphous structure do. Therefore, the assessment of the magnetic properties in the Co/Pd multilayer during interdiffusion is crucially important both for basic research and applications. As the parameter of the magnetic properties in this research, saturation magnetization and perpendicular magnetic anisotropy energy of the Co/Pd multilayer are measured in terms of Ar sputtering pressure and heat treatment temperature. Form the results of the research, we find out that the magnetic exchange energy between Co and Pd sublayers strongly affects the changes in the magnetic properties of the Co/Pd multilayers during the interdiffusion in ferromagnetic state. This discovery will provide the understanding of the magnetic exchange energy in the Co/Pd multilayer structure and suggest the operating temperature range for MO recording in the Co/Pd multilayer for the basic research and applications, respectively.

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Effect of Silica Coating on Particle Shape and Magnetic Properties of Iron Powder(I) (실리카 피착이 철립말의 입자형태 및 자기특성에 미치는 영향 (제1보))

  • 오재희;김종식;류병환
    • Journal of the Korean Ceramic Society
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    • v.22 no.6
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    • pp.21-28
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    • 1985
  • The properties of magnetic recording materials largely depend on their shape magnetic anisotropy. The control of their shape and size distribution is very important for improving magnetic properties. The silica-coated goethite$(SiO_2$/$\alpha$-FeOOH=1.5wt%) having acicular shape was prepared. The sillica-coated goethite was heat-treated at 40$0^{\circ}C$~1,00$0^{\circ}C$ 1hr and then reduced at 50$0^{\circ}C$ 2hr. When the silica-coated goethite was heat-treated at 80$0^{\circ}C$ its acicular shape was maintained and its magnetic properties were improved(Hc: 1,325 Oe $\sigma$m:138.8 emu/g, Rs:0.56) However the acicular shape of the paricles was broken for non-coated hematite obtained by dehydration at 80$0^{\circ}C$ They were sintered and showed poor magnetic properties.

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Electromagnetic Properties of Bi System Superconductor for Neutron Irradiation

  • Lee, Sang-Heon;Choi, Yong
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09b
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    • pp.1239-1240
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    • 2006
  • Effects of $Ag_2O$ doping on the electromagnetic properties in the BiSrCaCuO superconductors. The electromagnetic properties of $Ag_2O$ doped and undoped BiSrCaCuO superconductor were evaluated to investigate the contribution of the pinning centers to the magnetic effect. It was confirmed experimentally that a large amount of magnetic flux was trapped in the $Ag_2O$ doped sample than that in the undoped one, indicating that the pinning centers of magnetic flux are related closely to the occurrence of the magnetic effect. It is considered that the area where normal conduction takes place increases by adding $Ag_2O$ and the magnetic flux penetrating through the sample increases. The results suggested that Ag acts to increase pinning centers of magnetic flux, contributing to the occurrence of the electromagnetic properties.

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Synthesis of SiAlON Ceramics with Novel Magnetic Properties

  • Karunaratne, Baththanamudiyanselage Samarakoon Bandara;Ko, Jae-Woong;Park, Young-Jo;Kim, Hai-Doo
    • Journal of the Korean Ceramic Society
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    • v.46 no.5
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    • pp.525-527
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    • 2009
  • This paper presents a study on the magnetic behaviour of selected doped SiAlONs with various compositions including Y, Yb, Sm, Gd, and Er. The resulting crystalline phases were confirmed by X-ray diffraction. The magnetic hysteresis data for the samples were collected at room temperature using a vibrating sample magnetometer. The study revealed that doped SiAlONs experience an appreciable level of magnetic hysteresis. Although the parameters corresponding to hysteresis loops in doped SiAlONs are less than those of common ferrites, their magnetic properties of SiAlONs may open up new potential areas of application as the host SiAlON ceramics have excellent structural properties.