• Title, Summary, Keyword: magnetic property

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A Measurement System for Two-Dimensional DC-Biased Magnetic Property

  • Enokizono, Masato;Takahashi, Syuichi;Ikariga, Atsushi
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • v.2B no.4
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    • pp.143-148
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    • 2002
  • Up to now, DC-biased magnetic properties have been measured in one dimension (scalar). However, scalar magnetic properties are insufficient to clarify DC-biased magnetic properties because scalar magnetic properties can only impossibly consider the phase difference between the magnetic flux density B vector and the magnetic field strength H vector. Thus the magnetic field strength H and magnetic flux density B in magnetic materials must be directly measured as a vector quantity (two-dimensional). This paper presents measurement system to clarify the two-dimensional DC-biased magnetic properties.

A Study of Electromagnetic Properties on Magnetic Fluids (Magnetic Fluid의 전자기적 특성 연구)

  • Min Eui Hong;Koh Jae Gui
    • Korean Journal of Materials Research
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    • v.14 no.9
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    • pp.659-663
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    • 2004
  • Magnetite was prepared by wet method and oil-based magnetic fluid also was prepared by its magnetite. Ahead of making magnetite, we investigated the variation of physical properties for changing $Fe^{3+}/Fe^{2+}$. Through the variation of the process mixing time, pH, magnetite content, we made magnetic fluid of magnetite. We examined the magnetic and frequency property by a toroidal mold. In result $Fe^{3+}/Fe^{2+}=1.2$, over the minute mixing time property of magnetite, Ms was 61.98 emu/g. Moreover, the B-H loop result indicated that the magnetic fluid followed paramagnetic behavior.

Availability of 2-Dimensional Vector Magnetic Property for High Flux Density Machines

  • Enokizono Masato
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • v.5B no.1
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    • pp.1-5
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    • 2005
  • The vector magnetic property is defined as the relationship between the magnetic field strength vector H and the magnetic flux density vector B. It is very important for the development of high efficiency and the high-density electric machines. The electrical steel sheet for the machine core shows the remarkable vector behavior by the high magnetic flux density level. In this paper, the magnetic characteristic analysis using E&S2 model is introduced as the useful technology for the design and development.

Nd2Fe14B Synthesis: Effect of Excess Neodymium on Phase Purity and Magnetic Property

  • Jadhav, Abhijit P.;Ma, Haoxuan;Kim, Dong Soo;Baek, Youn Kyung;Choi, Chul Jin;Kang, Young Soo
    • Bulletin of the Korean Chemical Society
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    • v.35 no.3
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    • pp.886-890
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    • 2014
  • The properties of magnetic material of Nd-Fe-B are highly affected by various factors such as particle size, magnetic anisotropy, phase purity and crystal structure. Incorporation of excess neodymium was carried out in various percentages so that it will adjust the proportion of neodymium in the host crystal after reduction treatment and finally help to improve magnetic property of a material. The interdiffusion of Nd-Fe and boron was studied for various compositions and their effect on magnetic property was understood with theoretical concepts. The factors such as amount of hard and soft phase in the reduction treated product is also responsible for the possible exchange coupling between hard and soft phase magnets for better magnetic properties.

Study on Magnetic Property Enhancement of Metal Powders for Magnetic Tape by Using Ultrasonic Dispersion (자기테이프용 Metal Powder의 초음파 분산에 의한 자기적 특성 향상에 관한 연구)

  • Kim, Chang-Gon;Choe, Hyeon-Seung;Jang, Hak-Jin;Yun, Seok-Yeong;Kim, Tae-Ok
    • Korean Journal of Materials Research
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    • v.11 no.11
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    • pp.972-977
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    • 2001
  • It was investigated the effect of ultrasonic treatment on magnetic property of ultra fine magnetic Fe powders ($\alpha$-Fe) for magnetic tape. The properties were characterized with vibrating sample magnetometer (VSM), particle size analyzer (PSA) and scanning electron microscope (SEM). At 4hours ultrasonic treatment of 70 kHz, magnetic properties such as squareness ratio (S.Q. : 0.8868), orientation ratio (O.R. : 2.45) and switching field distribution (S.F. D. : 0.394) before taping were relatively enhanced. Cumulative particle size distribution of less than 5$\mu\textrm{m}$ fine powder was above 90% below 1 hour leaving time after ultrasonic treatment and it was supposed that ultrasonic treatment prevent aggregation. The magnetic values of S.Q. and S.F.D. of tape manufactured at 70 kHz and 4hour ultrasonic treatment were improved from 0.7747, 0.3818 to 0.8037, 0.3706, respectively. Electro-magnetic property used as in-output signal characteristic was improved, which showed that ultrasonic treatment developed the magnetic properties.

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Finite Element Analysis of BLDC Motor Characteristic according to Magnetic Property Measurement Methods (자성 측정 방법에 따른 BLDC 전동기의 전자계 특성해석)

  • Kim, Ji-Hyun;Ha, Kyung-Ho;Kwon, Oh-Yeoul;Cha, Sang-Yoon;Kim, Jae-Kwan
    • Proceedings of the KIEE Conference
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    • pp.697-698
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    • 2008
  • This paper deals with finite element characteristic analysis of brushless DC motor according to magnetic property measurement methods. Magnetic property data for non-oriented (NO) electrical steel for electric motors are measured by the Epstein test which is considered as the international standards. Data from Epstein test may result in discrepancy from motor characteristic tests due to innate anisotropic property of NO electrical steel. Finite element analysis were performed for a BLDC motor by various measurement methods such as Epstein test, Ring test and single sheet test (SST), and calculated results were compared with considering anisotropic property conditions.

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Position Control of Capsule Filled with Magnetic Fluid for Targeted Drug Delivery System (지적투약시스템을 위한 자성유체 캡슐의 위치 제어)

  • Ahn Chang-ho;Nam Yun-Joo;Park Myeong-Kwan
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.8
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    • pp.1166-1173
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    • 2004
  • In this paper, in order to apply magnetic fluid with superparamagnetic property as the substitute of ferromagnetic materials, physical properties of magnetic fluid are investigated. A targeted drug delivery system using a capsule filled magnetic fluid is proposed where a magnetic fluid capsule and cylinders are considered as a drug and vital organs, respectively. The dynamic governing equation of this system first is derived. Fluid viscosity, clearance between a cylinder and a magnetic fluid capsule, and levitation height with respect to different cylinder height are considered as major parameters to evaluate dynamic characteristics of the system. The experiments and simulations for the position control of the magnetic fluid capsule in various cylinders are conducted using PID controller. The results show that magnetic fluid with the superparamagnetic property can be applied to a targeted drug delivery system.

Effect of Magnetic Property Modification on Current-Induced Magnetization Switching with Perpendicular Magnetic Layers and Polarization-Enhancement Layers

  • Kim, Woo-Jin;Lee, Kyung-Jin;Lee, Taek-Dong
    • Journal of Magnetics
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    • v.14 no.3
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    • pp.104-107
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    • 2009
  • The effects of the magnetic property variation on current-induced magnetization switching in magnetic tunnel junction with perpendicular magnetic anistoropy (PMA) and the soft magnetic polarization-enhancement layers (PELs) inserted between the layers with PMA and the MgO layer was studied. A micromatnetic model was used to estimate the switching time of the free layer by different applied current densities, with changing saturation magnetization ($M_s$) of the PELs, interlayer exchange coupling between PMA layers and PELs. The switching time could be significantly reduced at low current densities, by increasing $M_s$ of PELs and decreasing interlayer exchange coupling.

SINTERED $Al_{2}O_{3}$-TiC SUBSTRATE FOR THIN FILM MAGNETIC HEAD

  • Nakano, Osamu;Hirayama, Takasi
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • pp.6-6
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    • 1998
  • In 1957, the first magnetic disk drive compatible with a movable head was introduced as an external file memory device for computer system. Since then, magnetic disks have been improved by increasing the recording density, which has brought about the development of a high performance thin film magnetic head. The thin film magnetic head has a magnetic circuit on a ceramic substrate using IC technology. The physical property of the substrate material is very important because it influences the tribology of head/disk interface and also manufacturing process of the head. $Al_{2}O_{3}$-TiC ceramics, so called ALTIC, is known to be one of the best substrate materials which satisfies this property requirement. Even though the head is not in direct contact with the disk, frequent instantaneous contacts are unavoidable due to its high rotating speed and the close gap between them. This may cause damage in the magnetic recording media and, thus, it is very important that the magnetic head has a good wear resistance. $Al_{2}O_{3}$-TiC ceramics has an excellent tribological property in head/disk interface. Manufacturing process of thin film head is similar to that of IC, which requires extremely smooth and flat surface of the substrate. The substrate must be readily sliced into the heads without chipping. $Al_{2}O_{3}$-TiC ceramics has excellent machineability and mechanical properties. $Al_{2}O_{3}$-TiC ceramics was first developed at Nippon Tungsten Co. as cutting tool materials in 1968, which was further developed to be used as the substrate materials for thin film head in collaboration with Sumitomo Special Metals Co., Ltd. in 1981. Today, we supply more than 60% of the substrates for thin film head market in the world. In this paper, we would like to present the sintering process of $Al_{2}O_{3}$-TiC ceramics and its property in detail.

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Reclaiming property of magnetic adsorbent for oil spill recovery and pollution control (환경오염방지 유출오일 회수용 자기흡착제의 재생회복 특성)

  • Soh, Dea-Wha;George, Ksandopulo;Lim, Byong-Jae;Nina, Mofa;Tlek, Ketegenov
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.296-299
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    • 2001
  • Data on the oil spill recovery from the water surface by light floating electromagnetic plants using a new magnetic adsorbent are given. The feasibility scope for further oil recovery from such gathered mixtures(oil + adsorbent), reuse of this magnetic adsorbent and its property reclaiming and recycling were shown. The basic conception of the oil spill recovery and efficiency of this method were set forth.

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