• Proceedings of the Korean Magnestics Society Conference
• /
• 2000.09a
• /
• pp.574-575
• /
• 2000

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.7
• /
• pp.1265-1271
• /
• 2010

Power cable of an AC arc welder can surround a body of worker at the moment of welding. Applying the boundary element method, we calculated current densities induced in organs inside a worker to study the magnetic field reduction characteristics of shielding wear materials. We knew shielding wear with high permeability materials lowers current density more than high conductivity materials. We also found current density was lowest when high permeability materials were inside high conductivity materials in double layer shielding wear.

• Journal of Magnetics
• /
• v.16 no.1
• /
• pp.42-45
• /
• 2011

The present work studies a nondestructive evaluation of the degradation of modified 9Cr-1Mo steel using a magnetic method based on the existence of the peaks of reversible permeability (RP) in the differential magnetization around the coercive force. The apparatus is based on detection of the voltage induced in a coil using a lock-in amplifier tuned to the frequency of the AC perturbing field. Results obtained for the reversible permeability and Vickers hardness on the aged samples showed the peak interval of reversible permeability (PIRP) and Vickers hardness decrease as aging time increased. The correlation between Vickes hardness and the PIRP could be used to evaluate degradation of modified 9Cr-1Mo steel.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.1078-1079
• /
• 2006

The paper presents the possibilities of obtaining new composite materials based on sintered porous ceramics with particles and fibre of $Al_2O_3$ infiltrated by aluminum alloy. The EN AC - AlSi12 alloy features the matrix material, whereas the RF50AX-301 preform, of Saffil Automotive, was used as the reinforcement. Examinations of ceramics preforms permeability were made. Metallographic examination of composite materials made on light microscope and in scanning electron microscope show that aluminum alloys fill micropores in the matrix. New composite materials show twice higher value of hardness in comparison with matrix. Results indicate that it is possible to infiltrate porous ceramic with liquid aluminum alloy to obtain new composite materials were advantageous properties of each component are connected.

• Journal of Magnetics
• /
• v.3 no.2
• /
• pp.41-43
• /
• 1998

The frequency spectra of complex permeability have been measured as a function of ac field amplitude in the annealed amorphous $Fe_{83}Zr_7B_8Cu_2 $ ribbons. The longitudinal permeability results from the rotational magnetization at small fields, $h_o$<5 mOe in as-quenched samples. However, at the further increase of ho, the wall motion begins to be involved in the low frequency region. The permeability from the wall motion drastically decreases in the annealed sample, while that from the rotational magnetization increases up to annealing temperature of 50$0^{\circ}C$ and then drops there after.

• Journal of Magnetics
• /
• v.16 no.4
• /
• pp.398-402
• /
• 2011

A novel laminate composite of FeCuNbSiB/FeNi /PZT is proposed, where FeCuNbSiB has a permeability of around 100000, which is much larger than that of FeNi. The high-permeability FeCuNbSiB was laminated with piezomagnetic FeNi rather than attached to its ends. It is expected that the effect produced by the high permeability will act on the whole of the piezomagnetic layer. While a FeNi layer was laminated with a FeCuNbSiB layer, the strong demagnetization produced by the latter was expected to be imposed on the FeNi layer as well as the applied fields. The distribution of applied fields was altered by the high-permeability material (both bias and ac field) and the field variation positively contributed to the ME effect in piezomagnetic/piezoelectric composites. Thus the ME voltage coefficient along with the field sensitivity were improved.

• Journal of the Korean Magnetics Society
• /
• v.8 no.3
• /
• pp.125-130
• /
• 1998

13Cr-1.5Nb-Fe alloy powder was fabricated by water atomization method, and ring-shape specimen of this composition was fabricated by oil press, and then sintered in the vacuum furnace. Powder shape, size distribution, composition (C, N, O, S) analysis and saturation magnetization of as-prepared 13Cr-1.5Nb-Fe alloy powder were investigated. Ac permeability and power loss was measured after forming and sintering process. Saturation magnetization and contents of oxygen of the alloy powder is160 emu/g and about 6000 ppm, respectively. 50 % volume fraction indicate particle size of 70$\mu$m. The ac permeability of sintered specimen increases with increasing sintering temperature and forming pressure. The power loss is 107 W/cc at sintering temperature of 1200 $^{\circ}C$, 12 ton/$\textrm{cm}^2$ forming pressure, and 20 KHz. It is the lowest among the prepared specimen.

• Proceedings of the KIEE Conference
• /
• 2008.10a
• /
• pp.73-74
• /
• 2008

This paper analyses current densities induced inside a worker using AC arc welder when he wear a protective with double shielding cloth. Applying the boundary element method, we calculate current densities induced in organs inside a worker in case he was located at 1[cm] far from a power cable of AC arc welder. As results of study, we fined aa protective cloth, which has high permeability in inner layer and high conductivity in outer layer, can give a higher shielding efficiency.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.1343-1344
• /
• 2008

This paper analyses current densities induced inside a worker using AC arc welder when he wears a protective cloth. Applying the boundary element method, we calculate current densities induced in organs inside a worker in case he was located at 1[cm], 15[cm], 20[cm] far from a power cable of AC arc welder. As results of study, we find a maximum current density induced in all organs may be lower than 10[$mA/cm^2$] if he wears a protective cloth. We also know high permeability materials can lower current density more than high conductivity materials.

• Journal of Magnetics
• /
• v.1 no.1
• /
• pp.24-30
• /
• 1996

The relationship between effective permeability and the remanence ratio of an Fe-based amorphous alloy (Metglas 2605S3A) is investigated over a wide frequency range, in an effort to understand magnetization behavior of the alloy. In the frequency range from 1 to 200 kHz, the permeability is maximum at the remanence ratio of 0.4-0.5 and, at frequencies over 500 kHz, the correlation with negative coefficients emerges indicating that the permeability decreases with the remanent ratio, except for the ribbon coated with an insulating layer of MgO which exhibits both high values of the effective permeability and remanence ratio. It is considered from the correlation results that the boundary at which the dominant magnetization mechanism changes from domain wall motion to spin rotation is near 500 kHz. The core loss is also investigated as a function of annealing time when the samples are annealed at a fixed temperature of $435^{\circ}C$. The core loss in most cases decreases with the annealing time, the degree of the loss may consist of the hysteresis loss and anomalous eddy current loss. The two loss components are considered to be of similar magnitudes at low frequencies while, at high frequencies, the dominant contribution to the total loss is the anomalous loss.