• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
• /
• 2001.02a
• /
• pp.172-175
• /
• 2001

AC loss which is generated in an HTS wire varies with the direction of the external magnetic field. This paper calculates the AC loss in an HTS tape, where effects of the perpendicular direction of the magnetic field are considered. Brandt equation is used to calculate the loss by perpendicular magnetic field. In the calculation, current densities are varied along the variation of the magnitude of the external magnetic field. Results of calculation are compared with those of the conventional method.

• Proceedings of the Korean Magnestics Society Conference
• /
• 2002.12a
• /
• pp.17-17
• /
• 2002

The magnetic effects connected to finite-size of the particles become dominant at transition of particles in region several nanometers and less [1]. At reduction of atom numbers in magnetic cluster (tens or hundreds atoms), along the classical features, essential appear the quantum phenomena resulting in spin transformation of magnetic structure, both with reduction of the size and at applying of an external magnetic field. (omitted)

• Progress in Superconductivity
• /
• v.1 no.1
• /
• pp.68-72
• /
• 1999

Since the discovery of high Tc superconductors, great efforts have been focused to develop high performance HTS magnets for the ultimate applications to power system devices. Magnet designers, however, have had difficulties in the estimation of the maximum operating current of the designed magnet from the tested short sample data, due to the degradation of the critical current density in the magnet. Similar story applies to the HTS electrical bus bar. It has been found that the critical current of Bi-2223 stacked tapes is much less than the total summation of critical currents of each tape, which is mainly attributed to the self magnetic fields. Furthermore, since the critical current degradation of Bi-2223 tape is greater in the normal magnetic field (to the tape surface) than in the parallel one, detailed magnetic field configurations are required to reduce the self field effects. In this paper, we calculate the self field effects of a stacked conductor, defining self field factors of normal and parallel magnetic fields to the tape surface. Finally, the critical current degradations in the HTS magnet are explained by the introduced self field factors of the stacked conductor.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.49 no.5
• /
• pp.291-296
• /
• 2000

Recently large size color TV and computer monitor are very popular and a lot techniques are being developed to get a high quality picture on the screen through reducing the convergence error among the red, green and blue beams and achieving a high focusing. One of the techniques is considering the mutual effects of the components of the Brown tube. The magnetic deflection yoke, especially, stands immediately next to the electron gun and generates the leakage magnetic fields at the electron gun which affects the trajectories of the electron beams inside the gun. Hence a shield cup made of thin conducting plate is located at the end of electron gun in order to shield the leakage flux from the deflection yoke. Since the red, green and blue beams are placed unsymmetrically the shielding effects of the shield cup on the beams are not same and eddy current controller, made of thin conducting plate, is auxiliary placed inside the shield cup. In this paper a transient magnetic field analysis algorithm is developed using boundary element method, and applied to the analysis of the shielding effects of the eddy current controller of shield cup in an electron gun.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.51 no.11
• /
• pp.616-621
• /
• 2002

With biological effects by ELF (Extremely Low Frequency) magnetic field generated from power system, the transient magnetic field from electric appliances is a major issue presently. Because the transient magnetic field induces higher current than the power frequency field inside living bodies, transient magnetic field exposure has been much focused. In this paper, it is shown that transient magnetic field from electric home appliances can be characterized as magnetic dipole moment. In this method, the dipole moment vector is assumed by allowing an uncertainty of 6dB in the estimated field. A parameter M that represents biological interaction was applied also. The proposed method was applied to 7 types of appliances (hair drier, heater, VDT, etc.) and their equivalent magnetic dipole moment and harmonic components were estimated. As the results, the useful data for quantifying magnetic field distribution around electric appliances were obtained.

• Journal of Acupuncture Research
• /
• v.19 no.3
• /
• pp.77-87
• /
• 2002

Like acupuncture, magnetic therapy has been known to yield effectiveness when it is applied to relieve from fatigue, musculoskelectal diseases, sore sites, rheumatic arthritis and chronic pain syndromes. However, combined application of acupuncture and magnet has not yet been studied. This study is designed to investigate effectiveness of acupuncture therapy when in the magnetic field for the pain relief. Magnetic field was made by magnetic ring ($7{\psi}{\times}2.3{\psi}{\times}1.5mm$). Twenty-one male swimmers with latent muscular pain at the GB21 area in the university course of physical education in Daegu were chosen and divided into three groups; 1) acupuncture treatment group (n=7), 2) acupuncture treatment with iron ring group (n=7), 3) acupuncture treatment with magnetic ring group (n=7). Manual Acupuncture was given to the GB21 point for 20 minutes. The degree of pressure pain threshold (PPT, $kg/cm^2$) in GB21 was measured with algometer. Before acupuncture treatment, the PPT values were $6.08{\pm}1.69$, $6.39{\pm}1.72$ and $5.59{\pm}1.11$ in acupuncture treatment group, acupuncture treatment with iron ring group, acupuncture treatment with magnetic ring group, respectively. After acupuncture treatment, the PPT values were $6.48{\pm}2.33$, $6.31{\pm}1.31$ and $6.59{\pm}1.80$, respectively. Pressure threshold was significantly increased in the acupuncture treatment with magnetic ring group compared to the other groups. Based on these results, acupuncture treatment with magnetic ring produced better effects on pain threshold, and these effects can be considered to be associated with the currents or voltages induced by the acupuncture needle and magnetic ring at present.

• The korean journal of orthodontics
• /
• v.25 no.2 s.49
• /
• pp.201-208
• /
• 1995

Recently, magnetic forces are considered as a method for more efficient tooth movement. The purpose of this study was to evaluate the effects of the changes of the magnetic volume on the magnetic forces. The universal testing machine and the electronic balance were used for the exact measurement of the force with constant air gap. While the magnet was kept same on one side, the magnetic volume of the other side was increased gradually in four manners. In the first group, the thickness was increased by adding same size of the magnets one after another while the thickness was increased by changing with a thicker magnet gradually in the second group. In the third group. the width was increased by adding same size of the magnets while the width was increased by changing with a wider magnet gradually in the last group. The results were as follows : 1. With the increase of the thickness, the magnetic force increased, while the magnetic force decreased with the increase of the width. 2. The magnetic force according to the change of the magnetic volume showed the distribution of the logarithmic function. 3. An originally thick magnet showed larger force than the added magnets although both of them had same volume.

• Journal of Magnetics
• /
• v.7 no.2
• /
• pp.45-50
• /
• 2002

A magnetic field annealing is firstly used for nanostructured Sm-Co/Co films, prepared by magnetron sputtering method. The effects of magnetic field annealing on single-layered Sm-Co films are different from those on multi-layered Sm-Co/Co films. A detailed analysis of microstructures and magnetic properties is made by means of HRTEM, Auger electron spectroscopy, XRD and Physical Property Measurement System (PPMS). From magnetic properties and microstructure analysis, it was confirmed that these differences originate from the effects of magnetic field annealing on crystallization behavior of the films. The relationship between magnetic properties and microstructures explains a different demagnetization process of single-layered and multilayered films. For the single-layered Sm-Co films, magnetic-field-annealing makes the main phases change from $CaCu_5/ to Zn_2Th_{17}$ structure, resulting in a decrease of coercivity. The results show that the magnetic-field-annealing is useful to improve the properties of nanostructured Sm-Co(30 nm)/Co(10 nm) films, which ascribe to improving the pinning effectiveness in coercivity mechanism and decreasing the magnetostatic interaction of films. A very high coercivity about 0.7 T was obtained from nanoscaled multi-layered Sm-Co(30 nm)-/Co(10 nm) films.

• Coupled systems mechanics
• /
• v.2 no.1
• /
• pp.1-22
• /
• 2013

Under thermal environment, Magneto-Electro-Elastic (MEE) material exhibits pyroelectric and pyromagnetic effects which can be used for enhancing the performance of MEE sensors. Recently studies have been published on material constants such as pyroelectric constant and pyromagnetic constant for magneto-electro-thermo-elastic smart composite. Hence, the main aim of this paper is to study the pyroelectric and pyromagnetic effects on behavior of MEE plate under different boundary conditions subjected to uniform temperature. A numerical study is carried out using eight noded brick finite element under uniform temperature rise of 100 K. The study focused on the pyroelectric and pyromagnetic effects on system parameters like displacements, thermal stresses, electric potential, magnetic potential, electric displacements and magnetic flux densities. It is found that, there is a significant increase in electric potential due to the pyroelectric and pyromagnetic effects. These effects are visible on electric and magnetic potentials when CFFC and FCFC boundary conditions are applied. Additionally, the pyroelectric and pyromagnetic effects at free edge is dominant (nearly thrice the value in CFFC in comparison with FCFC) than at middle of the plate. This study is a significant contribution to sensor applications.

• Journal of Powder Materials
• /
• v.13 no.3 s.56
• /
• pp.217-222
• /
• 2006

The relationship between electrical properties of superconductor and externally applied magnetic field was studied to develop a magnetic field sensor. The electrical resistance of the superconductor was increased by applying external magnetic field and even after removal of the magnetic field. This behavior was related to the magnetic flux trapped in the superconductor, which penetrated through the material by the external magnetic field. Some portion of the superconductor was changed to a normal state by the trapped magnetic flux. The appearance of the normal state yielded to enhance the electrical resistance.