• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.8
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• pp.1039-1045
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• 2014

Acoustic noise from a transformer, recently, has drawing more and more attentions. One of the main source of the noise is thought to be magnetostriction of the electrical steel sheets which compose transformer core. This paper deals with the magnetostriction of a highly grain-oriented electrical steel sheet measured by using a vector single sheet tester and a three-axial strain gauge. The results show that direction and axis ratio as well as the magnitude of the applied magnetic flux density contribute much to magnetostriction.

• Transactions of Materials Processing
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• v.3 no.3
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• pp.335-346
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• 1994

The effect of sheet steel properties and lubrication on the optimal range of blank holding force (BHF) was investigated by means of the model die stamping of various sheet steels. The optimal range of blank holding force was expressed as the range between the lower BHF at flange wrinkling and the upper BHF at local necking. It showed that mechanical properties, thickness of sheet steel and lubrication condition were important factors affecting the optimal range of BHF in sheet steels. Especially, lubrication played an important role in the case of coasted sheet steels.

• 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.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.5
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• pp.42-49
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• 2005

In general, multi-lap spot weld joints are frequently present in automobile. Most research, however, has been focused on the single-lap spot weld joints until now. In this paper, tensile-shear strength tests are performed to examine the weldability of 3-lap spot joint welded by using the high strength steel sheet and the zinc coated steel sheet. The indentation depth and nugget diameter are used to propose the optimum welding conditions. The weldability is affected by the welding current and welding time for 3-lap spot joint. Meanwhile the expulsions is round to decrease with the increase of electrode force. The optimum welding conditions are presented for 3-lap spot joints of high strength steel sheet and zinc coated steel sheet.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.97-100
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• 2007

This study deals with the sound insulation performance of the damping sheet, which is widely used in a train. The wall of train is assumed to be a plate made of steel and two damping sheets. In case of damping sheet only, the sound transmission loss follows the mass law. If a steel plate is attached to damping sheet, the transmission loss is found to be higher than single of only steel plate, as we can anticipated, about $3{\sim}5$ dB. This is very well known consequence that is because the density of area increases. However, the increase of the transmission loss is not higher than what we can expect by the mass law. That's because the steel is perfectly blocked from the transmission of the air ; There is no defect in that material.

• Journal of the Korean institute of surface engineering
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• v.26 no.6
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• pp.307-315
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• 1993

A study on a new anti-finger printed EGI steel sheet with high corrosion resistance has been carried out to meet the recent requirement of high quality and performance of the pure zinc electrogalvanized steel sheet. The substrate was the pure zinc electrogalvanized sheet with the metallic coating of 20g/$\m^2$. The two differ-ent processes for inorganic(chromating) and organic(resin) coating were applied. One was a two coat/two bake type to separately treat chromating and resin coating which is now widely used. The other was a one coat/one bake type to simultaneously treat them which is newly developed in this study. The solution for the one coat/one bake type was an aqua-base coating agents which was composed of inorganic and organic components. The new anti-finger printed EGI steel sheet with the Cr and resin coating weight of 13mg/$\m^2$ and 800mg/$\m^2$, respectively shows the superior corrosion resistance besides the good paintability, formability fingerprint resistance and earth characteristics properties.

• Design & Manufacturing
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• v.15 no.1
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• pp.21-25
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• 2021

When the product is removed from the mold after molding during the sheet metal molding process, elastic recovery causes a springback phenomenon. Much research has been done to minimize this phenomenon. In this study, V-bending experiments were conducted using galvanized steel sheets, stainless steel, and aluminum sheet materials, using a total of nine types of thin sheet materials of 1.0t, 1.5t, and 2.0t, respectively. Molding analysis and experimental data were compared and analyzed. In the case of galvanized steel sheets, it was considered that the springback phenomenon occurs more frequently in molding analysis than in experiments. It was considered that the springback phenomenon occurs greatly in the experiment, not the interpretation of the molding of the stainless steel plate and the aluminum plate. It was considered that the springback occurrence tendency of the molding analysis and the experiment was the same, and the springback occurrence error rate of the molding analysis and the experimental result was about 4.0%.

• Journal of Power System Engineering
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• v.11 no.3
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• pp.47-52
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• 2007

Punching, blanking, trimming and slitting are widely used in shearing processes in sheet metal forming of automotive parts. In this paper the effects of clearance, cutting angle and tool sharpness on the formation of burr were investigated by experimental method in shearing processes of steel sheets, SPCEN and SPRC35E. The amount of burr and the shapes of burr were different between two kinds of steel sheets. It has been shown that the cutting angle of the shearing blade had no effects on the height of burr when the clearance was below the 10% of the steel sheet thickness, and also that the height and shape of burr were not affected by the cutting angle when the wear of shearing blade was below the 10% of the steel sheet thickness. It was known that there had been existing the critical clearance of 10 to 15% for the tested steel sheet, SPCEN and SPRC35E.

• Journal of Magnetics
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• v.20 no.2
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• pp.148-154
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• 2015

48-V ISG (Integrated Starter Generator) system has attracted attention to improve the fuel efficiency of ICE (Internal Combustion Engine) vehicle. One of the key components that significantly affects the cost and performance of the 48-V ISG system is the motor. In an ISG motor, the core and copper loss make the motor efficiency change because the motor has a broad driving operated range and more diverse driving modes compared with other motors. When designing an ISG motor, the selection of an electrical steel sheet is important, because the electrical steel sheet directly influences the efficiency of the motor. In this paper, the efficiency of the ISG motor, considering core loss and copper loss, is analyzed by testing different types of electrical steel sheets with respect to the driving speed range and mode. Using the results of a finite element method (FEM) analysis, a method to select the electrical steel sheet is proposed. This method considers the cost of the steel sheet and the efficiency according to driving mode frequency during the design process of the motor. A wound rotor synchronous machine (WRSM) was applied to the ISG motor in this study.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.642-945
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• 1995

The problem of autobody corrosion has been addressed over the past decade by the increasing use of zinc and zinc alloy costed steels in automotive application. this paper describes the evaluation of formability, weldability and painted corrosion performance of galvalume steel sheet. This paper presents an overview of the program and some initial test results on the weldability, lifetime of the electrode tip shpae of the spot welding and corrosion protection. Galvalume steel sheet improved corrosion performance and spot weldability of galvalume steel has no problem for the variation of welding current. And tip lifetime was changed according to the influence of shape.