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Jeong-su Kim - One of the best experts on this subject based on the ideXlab platform.

  • Analysis of power loss in Ni-Cu-Zn ferrites
    INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference 2005., 2005
    Co-Authors: E. Otsuki, Jeong-su Kim
    Abstract:

    The power loss analysis was carried out for Ni-Cu-Zn ferrite samples with different content of NiO and ZnO. The power loss, Pc/spl nu/ decreases monotonically with increasing temperature and attains to a certain value at around 100/spl sim/120 degrees Celsius. The frequency dependence of Pc/spl nu/ can be explained by Pc/spl nu//spl sim/f, and n is independent of the frequency, f up to 1 MHz. The Pc/spl nu/ decreases with an increase in ZnO/NiO. The Pc/spl nu/ was separated to hysteresis loss, Ph and residual loss, (Pc/spl nu/-Ph). The temperature characteristics and compositional dependence of Pc/spl nu/ can be attributed to the Ph, while (Pc/spl nu/-Ph) is not affected by both temperature and ZnO/NiO. By analyzing temperature and composition dependence of Ph and initial Permeability, u/sub i/ following equations could be formularized. u/sub i/u/sub 0/ = I/sub s//sup 2//(K/sub I/ + bs/sub 0/l/sub s/) (1), Wh = 13.5(I/sub s//sup 2//u/sub i/u/sub 0/) (2), where u/sub 0/ is Permeability of Vacuum, I/sub s/ saturation magnetization, K/sub I/ anisotropy constant, s/sub 0/ internal heterogeneous stress, l/sub s/ magnetostriction constant, b unknown constant. Wh hysteresis loss per one cycle of excitation (Ph = Wh*f). Steinmetz constant of Ni-Cu-Zn ferrites, m = 1.64/spl sim/2.2 is smaller than the one of Mn-Zn ferrites, which suggests the difference of loss mechanism between these materials.

  • Power Loss and Electro-Magnetic Characteristics of Ni-Cu-Zn Ferrites
    Journal of the Korean Institute of Resources Recycling, 2004
    Co-Authors: E. Otsuki, Jeong-su Kim
    Abstract:

    The power loss analysis was carried out for Ni-Cu-Zn ferrite sample with different content of NiO and ZnO. The power loss, Pcv decreases monotonically with increasing temperature and attains to a certain value at around 100~120 degrees Celsius. The frequency dependence of Pcv can be explained by Pcv~f, and n is independent of the frequency, f up to 1 MHz. The Pcv decreases with an increase in ZnO/NiO. The Pcv was separated to hysteresis loss(Ph) and residual loss(Pcv-Ph). The temperature characteristics and compositional dependence of Pcv can be attributed to the Ph, while Pcv-Ph is not affected by both temperature and ZnO/NiO. By analyzing temperature and composition dependence of Ph and initial Permeability, like following equations could be formularized. Wh=13.5(I Where is Permeability of Vacuum, I is saturation magnetization, K is anisotropy constant, is internal heterogeneous stress, is magnetostriction constant, b is unknown constant, and Wh is hysteresis loss per one cycle of excitation (Ph=Whf). Steinmetz constant of Ni-Cu-Zn ferrite, m=1.64~2.2 is smaller than that of Mn-Zn ferrites, which suggests the difference of loss mechanisms between these materials.

Koji Fujiwara - One of the best experts on this subject based on the ideXlab platform.

  • Investigation of measurement method of saturation magnetization of iron core material using electromagnet
    AIP Advances, 2018
    Co-Authors: Takuya Shibataki, Yasuhito Takahashi, Koji Fujiwara
    Abstract:

    This paper discusses a measurement method for saturation magnetizations of iron core materials using an electromagnet, which can apply an extremely large magnetic field strength to a specimen. It is said that electrical steel sheets are completely saturated at such a large magnetic field strength over about 100 kA/m. The saturation magnetization can be obtained by assuming that the completely saturated specimen shows a linear change of the flux density with the magnetic field strength because the saturation magnetization is constant. In order to accurately evaluate the flux density in the specimen, an air flux between the specimen and a winding of B-coil for detecting the flux density is compensated by utilizing an ideal condition that the incremental Permeability of saturated specimen is equal to the Permeability of Vacuum. An error of magnetic field strength caused by setting a sensor does not affect the measurement accuracy of saturation magnetization. The error is conveniently cancelled because the sa...

  • Investigation of measurement method of saturation magnetization of iron core material using electromagnet
    AIP Publishing LLC, 2018
    Co-Authors: Takuya Shibataki, Yasuhito Takahashi, Koji Fujiwara
    Abstract:

    This paper discusses a measurement method for saturation magnetizations of iron core materials using an electromagnet, which can apply an extremely large magnetic field strength to a specimen. It is said that electrical steel sheets are completely saturated at such a large magnetic field strength over about 100 kA/m. The saturation magnetization can be obtained by assuming that the completely saturated specimen shows a linear change of the flux density with the magnetic field strength because the saturation magnetization is constant. In order to accurately evaluate the flux density in the specimen, an air flux between the specimen and a winding of B-coil for detecting the flux density is compensated by utilizing an ideal condition that the incremental Permeability of saturated specimen is equal to the Permeability of Vacuum. An error of magnetic field strength caused by setting a sensor does not affect the measurement accuracy of saturation magnetization. The error is conveniently cancelled because the saturation magnetization is a function of a ratio of the magnetic field strength to its increment. It may be concluded that the saturation magnetization can be easily measured with high accuracy by using the proposed method

E. Otsuki - One of the best experts on this subject based on the ideXlab platform.

  • Analysis of power loss in Ni-Cu-Zn ferrites
    INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference 2005., 2005
    Co-Authors: E. Otsuki, Jeong-su Kim
    Abstract:

    The power loss analysis was carried out for Ni-Cu-Zn ferrite samples with different content of NiO and ZnO. The power loss, Pc/spl nu/ decreases monotonically with increasing temperature and attains to a certain value at around 100/spl sim/120 degrees Celsius. The frequency dependence of Pc/spl nu/ can be explained by Pc/spl nu//spl sim/f, and n is independent of the frequency, f up to 1 MHz. The Pc/spl nu/ decreases with an increase in ZnO/NiO. The Pc/spl nu/ was separated to hysteresis loss, Ph and residual loss, (Pc/spl nu/-Ph). The temperature characteristics and compositional dependence of Pc/spl nu/ can be attributed to the Ph, while (Pc/spl nu/-Ph) is not affected by both temperature and ZnO/NiO. By analyzing temperature and composition dependence of Ph and initial Permeability, u/sub i/ following equations could be formularized. u/sub i/u/sub 0/ = I/sub s//sup 2//(K/sub I/ + bs/sub 0/l/sub s/) (1), Wh = 13.5(I/sub s//sup 2//u/sub i/u/sub 0/) (2), where u/sub 0/ is Permeability of Vacuum, I/sub s/ saturation magnetization, K/sub I/ anisotropy constant, s/sub 0/ internal heterogeneous stress, l/sub s/ magnetostriction constant, b unknown constant. Wh hysteresis loss per one cycle of excitation (Ph = Wh*f). Steinmetz constant of Ni-Cu-Zn ferrites, m = 1.64/spl sim/2.2 is smaller than the one of Mn-Zn ferrites, which suggests the difference of loss mechanism between these materials.

  • Power Loss and Electro-Magnetic Characteristics of Ni-Cu-Zn Ferrites
    Journal of the Korean Institute of Resources Recycling, 2004
    Co-Authors: E. Otsuki, Jeong-su Kim
    Abstract:

    The power loss analysis was carried out for Ni-Cu-Zn ferrite sample with different content of NiO and ZnO. The power loss, Pcv decreases monotonically with increasing temperature and attains to a certain value at around 100~120 degrees Celsius. The frequency dependence of Pcv can be explained by Pcv~f, and n is independent of the frequency, f up to 1 MHz. The Pcv decreases with an increase in ZnO/NiO. The Pcv was separated to hysteresis loss(Ph) and residual loss(Pcv-Ph). The temperature characteristics and compositional dependence of Pcv can be attributed to the Ph, while Pcv-Ph is not affected by both temperature and ZnO/NiO. By analyzing temperature and composition dependence of Ph and initial Permeability, like following equations could be formularized. Wh=13.5(I Where is Permeability of Vacuum, I is saturation magnetization, K is anisotropy constant, is internal heterogeneous stress, is magnetostriction constant, b is unknown constant, and Wh is hysteresis loss per one cycle of excitation (Ph=Whf). Steinmetz constant of Ni-Cu-Zn ferrite, m=1.64~2.2 is smaller than that of Mn-Zn ferrites, which suggests the difference of loss mechanisms between these materials.

Sergii Mamilov - One of the best experts on this subject based on the ideXlab platform.

  • Some Aspects of Mathematical Modeling of the Electromagnetic Field Influence on the Human Brain
    Innovative Biosystems and Bioengineering, 2019
    Co-Authors: Alina Prigancova, Michal Hvoždara, Igor Tunyi, Yuriy Gorgo, Sergii Mamilov
    Abstract:

    Background. One of lacks of the use of high technologies is the megascopic level of unfavorable electromagnetic smog. Therefore, the study of influencing of the external electromagnetic field (EMF) is actual, within the limits of wide row of frequencies, on man's organs and brain. Objective. Modeling of influences on the brain of electric induction arising up at penetration of the EMF of a different frequency in the reserved sphere. Methods. A mathematical model of the EMF influence on human brain is considered. Namely, the model of a multi stratified sphere as an approximation of a human head is proposed. This sphere embedded into the unlimited nonconductive space (σ 0 = 0) of the dielectric constant e 0 . Skin and bones of head have a magnetic Permeability of Vacuum μ 0 . Influences on a brain are given as induction of the electric field, arising up at penetration of the variable electromagnetic field in the reserved sphere. Results. The results of numerical calculations for the three-layered model of head showed that induced of the electric field in the layer of brain has increased on the frequencies 10 7 –10 8 Hz of external EMF. Distributions on the sphere of electromagnetic fields with f ≤ 10 6 Hz leave their amplitudes by unchanged regardless of depth of penetration. Fading of amplitudes shows up only for frequencies 10 7 and 10 8 Hz. Conclusions. Exposed in a model changes of electromagnetic waves on the frequencies 10 7 –10 8 Hz can activate the parameters central nervous system and brain, that substantially will affect of man's activity. Will allow the further study of influencing of the electromagnetic field of a different frequency to identify to extent of brain activity, and also stress, positive and negative influencing of external EMF.

  • Some Aspects of Mathematical Modeling of the Electromagnetic Field Influence on the Human Brain
    National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute", 2019
    Co-Authors: Alina Prigancova, Michal Hvoždara, Igor Tunyi, Yuriy Gorgo, Sergii Mamilov
    Abstract:

    Background. One of lacks of the use of high technologies is the megascopic level of unfavorable electromagnetic smog. Therefore, the study of influencing of the external electromagnetic field (EMF) is actual, within the limits of wide row of frequencies, on man's organs and brain. Objective. Modeling of influences on the brain of electric induction arising up at penetration of the EMF of a different frequency in the reserved sphere. Methods. A mathematical model of the EMF influence on human brain is considered. Namely, the model of a multi stratified sphere as an approximation of a human head is proposed. This sphere embedded into the unlimited nonconductive space (σ0 = 0) of the dielectric constant ε0. Skin and bones of head have a magnetic Permeability of Vacuum μ0. Influences on a brain are given as induction of the electric field, arising up at penetration of the variable electromagnetic field in the reserved sphere. Results. The results of numerical calculations for the three-layered model of head showed that induced of the electric field in the layer of brain has increased on the frequencies 107–108 Hz of external EMF. Distributions on the sphere of electromagnetic fields with f ≤ 106 Hz leave their amplitudes by unchanged regardless of depth of penetration. Fading of amplitudes shows up only for frequencies 107 and 108 Hz. Conclusions. Exposed in a model changes of electromagnetic waves on the frequencies 107–108 Hz can activate the parameters central nervous system and brain, that substantially will affect of man's activity. Will allow the further study of influencing of the electromagnetic field of a different frequency to identify to extent of brain activity, and also stress, positive and negative influencing of external EMF

Ronald B. Goldfarb - One of the best experts on this subject based on the ideXlab platform.

  • Electromagnetic Units, the Giorgi System, and the Revised International System of Units
    IEEE Magnetics Letters, 2018
    Co-Authors: Ronald B. Goldfarb
    Abstract:

    The centimeter-gram-second system of electromagnetic units (EMU) has been used in magnetism since the latter part of the 19th century. The International System of Units (SI), a successor to Giorgi's 1901 rationalized four-dimensional meter-kilogram-second system, was adopted by the General Conference on Weights and Measures in 1960 with the ampere as the fourth base unit. However, EMU remains in common use for the expression of magnetic data. The forthcoming revision of the SI will accentuate its differences with EMU. The Permeability of Vacuum will no longer be a fixed constant, which recalls the Giorgi system and prompts a review of historical arguments on the concepts of magnetic flux density and magnetic field strength in Vacuum. The redefinition of the ampere in terms of the fixed numerical values of two defining constants could allow for independent experimental measurements of the Permeability of Vacuum, i.e., determination of the magnetic constant.

  • The Permeability of Vacuum and the Revised International System of Units
    IEEE Magnetics Letters, 2017
    Co-Authors: Ronald B. Goldfarb
    Abstract:

    The International System of Units (SI) is expected to be revised such that all seven base units, including the kilogram, will be defined in terms of fixed numerical values of seven defining constants. The revised SI will include a redefinition of the ampere. One consequence is that the Permeability of Vacuum will not have a fixed numerical value but will become, in principle, a measurable quantity. The constitutive relation among magnetic flux density, magnetic field strength, and magnetization will not change. However, its expression in the centimeter-gram-second system of electromagnetic units (EMU), where the Permeability of Vacuum is unity, will no longer be ontologically equivalent, and quantities will not be exactly convertible to the SI. Already contrary to international convention, the still common EMU system will become obsolete.