• Journal of the Society of Naval Architects of Korea
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• v.61 no.1
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• pp.61-67
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• 2024

A naval mine is an effective weapon system implemented for defending defends ports and seas. A mine is an underwater weapon that poses a great threat to ships sailing over the sea from shallow areas. Most of the influence-type naval mines detect magnetic field signals from ships and determine the final time of fire. Therefore, the level of underwater electro-magnetic signatures of ships is a key requirement for determining the survival of ships in wartime situations where mines are emplaced. The main reason why the high manganese steel is attracting attention for naval ship hulls is its nature as a non-magnetic steel. The non-magnetic hull does not generate electro-magnetic signatures; thus, it has the advantage improving the stealth of the ship. In this paper, I examine whether this material can be applied in the hulls material of naval ships that must be ableto reduce underwater electro-magnetic signatures by considering the non-magnetic characteristics of the first developed high manganese steel in the world.

• Journal of the Korean GEO-environmental Society
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• v.12 no.11
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• pp.71-77
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• 2011

Recently, non-destructive stress measurement method using magnetic anisotropy sensor has been applied to the construction site such as steel bridges and steel pipes. In addition, steel rib used in the tunnel construction site was found to be possible to measure the stress by non-destructive method. In this study, steel loading experiments using magnetic anisotropy sensor developed in Japan and strain gauges were conducted to derive stress sensitivity curve for domestic steel SS400. Also, additional steel loading experiments and numerical analysis were performed for evaluation of applicability for non-destructive stress measurement method using magnetic anisotropy sensor. As a result of this study, stress sensitivity curves for domestic steel SS400 were derived using output voltage measured by magnetic anisotropy sensor and average of stress measured by strain gauges depending on the measurement location. And as a result of comparing additional steel loading experiments with the numerical analysis, error level of magnetic anisotropy sensor is around 20MPa. When considering the level of the yield stress(245MPa) of steel, in case of using magnetic anisotropy sensor in order to determine the stress status of steel, it has sufficient accuracy in engineering. Especially, magnetic anisotropy sensor can easily identify the current state of stress which considers residual stress at steel structure that stress measurement sensor is not installed, so we found that magnetic anisotropy sensor can be applied at maintenance of steel structure conveniently.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.9
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• pp.1684-1692
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• 2011

Recently, several vector hysteresis models such as vector Preisach, vector Jiles-Atherton and dynamic E&S model have been proposed to describe vector magnetic properties of electrical steel sheets. However, it is still difficult to find an adequate vector hysteresis model in finite element application for both the Non-oriented and Grain-oriented electrical steel sheets under alternating and rotating field conditions. In this paper, an improved E&S vector hysteresis model is suggested to describe the vector magnetic properties of both Non-oriented and Grain-oriented electrical steel sheets under various magnetic field conditions including alternating and rotating magnetic field conditions. The validity of the proposed model is tested through comparisons with the experimental results under various magnetic field conditions.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.5
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• pp.250-257
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• 2006

It is well known that Grain-oriented electrical steel sheets have two dimensional magnetic properties according to the direction of exciting field such as non-linear phase difference between magnetic flux density and magnetic field intensity vectors, different iron loss and permeability even when an alternating magnetic field is applied. The measurement and application of the two dimensional magnetic properties of the Grain-oriented electrical steel sheets, therefore, are very important for the design and precise performance analysis of electric machines made of them. As the direction of exciting field changes, in this paper, the two dimensional magnetic properties of a Grain-oriented electrical steel sheet, i.e., non-linear B-H curves, phase difference between B and H, and iron loss characteristics, are measured using SST(Single Sheet Tester) which has two axes excitation. The measured results are presented in two ways: using $(B,\theta_B)$ method and using hysteresis loops along rolling and transverse directions, respectively.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.12
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• pp.617-622
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• 2006

It is necessary to measure precisely the magnetic characteristics of electrical steel sheets under rotating magnetic fields, to obtain an accurate numerical performance analysis of electric machines made of electrical steel sheets. In this paper, the two dimensional magnetic characteristics of an electrical steel sheet are measured and explained under rotating magnetic fields using a two-axes-excitation type single sheet tester (SST). Through experiments, the magnetic properties, under rotating magnetic fields, of a non-oriented and grain oriented electrical steel sheet were measured respectively. In addition, the iron losses due to not only the alternating magnetic fields, but also rotating magnetic fields were measured. These experimentally measured results can evidently be applied to the analysis of iron losses in electrical machines.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2535-2537
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• 2000

In order to detect and monitor the broken cords of steel-cord belt from being damaged by impact of large lump of materials and the corrosion of steel cord, we developed a non-contact magnetic coil detection system. This measures the deterioration of reinforcing cables in steel cord conveyor belt which transport the ores in raw material plant. In this research, magnetic coil sensor of broken-cord detection system has exciting part and sensing part. The broken-cord detection system is operated by supplying a transmitter coil with electric power to generate magnetic field, and then the change of induced voltage is detected in each receiver coils due to resultant magnetic flux effected by the broken steel cords at the inside of the conveyor belt. By the informations such as the position and size of the broken steel cords obtained by SCBMS(Steel Cord Belt Monitoring System), it is expected that not only the span of belt life will be lengthened, but also this system can enable operators to plan scheduled maintenance and prevent the enlargement of damaged parts in steel cord belt at an early stage

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.256.1-256.1
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• 2008

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.10
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• pp.461-469
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• 2005

In this paper, a double-excitation type single sheet tester is developed to measure the magnetic characteristics of the electrical steel sheets. The developed system has the uniform magnetic field area of 20$\times$20mm$^{2}$, and can be applied to the measurement of the magnetic characteristics of the Non-oriented and Grain oriented electrical steel sheets. In the developed system, the magnetic flux density and magnetic field intensity are measured by using B-coil and H-coil, respectively. The B-coil has 1 turn search coil for each direction, and H-coil has 640 and 640 turns for rolling direction and transverse direction on the Im thickness Glass-Epoxy basement, respectively. Through experiments, it Is shown that the system can measure the magnetic characteristics up to 1.87 of magnetic flux density in the rolling direction in case of the Grain oriented electrical steel sheet. The measured results are compared with those measured in Okayama university, .Japan.

• Journal of the Korean Society for Precision Engineering
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• v.6 no.4
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• pp.103-107
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• 1989

The effects of annealing temperature on the magnetic properties (maximum permeability, coercive force and remanence) and mechanical properties (hardness, tensile strength and elongation at rupture) were analyzed using the nondestructive impulsive magnetic analyzer in a medium carbon cold rolled steel sheet. This nondestructive method was very useful for the analysis of magnetic and mechanical properties of materials. As it was known in the literature, the three distinct processes that indicate the recovery, recrystallization, and grain growth of a metal were measured with the non-destructive analyzer.

• Proceedings of the KIEE Conference
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• 2008.07a
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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.