• Elastomers and Composites
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• v.45 no.2
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• pp.106-111
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• 2010

Magneto-rheological elastomers (MREs) were manufactured by incorporation of magnetic responsible powder (MRP) into natural rubber and silicone rubber. The optimum loading amounts of MRP was 30 vol.% and the natural rubber based MRE (NR-MRE) showed better mechanical property than that of silicone rubber based MRE (S-MRE). However, the modulus shift ratio caused by S-MRE, measured by Self-modified Electromagnet Applied Fast Fourier Transform Analyser (SEFFTA), was higher than that of NR-MRE. The modulus shift ratio caused by NR-MRE was 10%, while the modulus shift ratio caused by S-MRE was 35.7%. The modulus shift ratio could be improved by orienting the magnetic direction of MRP before crosslinking the MRE. The degree of orientation of MRP was analyzed using SEM.

• Journal of Navigation and Port Research
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• v.27 no.4
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• pp.413-424
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• 2003

Up to now it has been widely conceived that mariner's compass was introduced to Europe from China via the Arabic people. But the proofs to support the above orthodox dissertation have not been found yet. In general it has been approved that the Chinese used the compass for navigation in the 11th century and European did in the 12th century. During the above period the communication between the Europe and the China was made only by the mediation of the Arabic people. But it is known that the beginning of Arabic people's compass usage was one century later than that of the European. It may raise a historical question about ‘was mariner's compass introduced to Europe from China via the Arabic people\ulcorner’ In this paper the authors tried to prove the simultaneity of the mariner's compass usage by the European with the Chinese by reviewing historical materials and modern researches. The results are as following; The first, there is a strong similarity in the evolving steps of compass appliance of both civilizations, such as from using magnetized and pivoted needle to fixing card thereto. Second, the Chinese and the European started to use the mariner's compass almost at the same time, and they developed it independently.

• Resources Recycling
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• v.14 no.2
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• pp.43-55
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• 2005

As world population increases and the world economy expalds, so does the demand for natural resources especially strategic metals such as cobalt. An accurate assesment of the nation's minerals must include not only the resources available in the ground but also those that become available through recycling. In this paper, data on domestic and international supply of cobalt and its applications by end-user were analyzed for stable security of cobalt resources and effective recycling of cobalt scraps. Also, an initial evaluation of the flow of cobalt-containing materials in the United States was prepared. In 2003, 8,000 metric tons of cobalt were consumed in the United States and an estimated 28% of U.S. cobalt supply was derived from scrap. The superalloy industry and catalyst industries have well-established recycling or cobalt recovery practices. Recycling rates of cobalt scraps from magnet alloy and cemented carbide were relatively low.

• Journal of the Korean Institute of Gas
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• v.6 no.1 s.17
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• pp.10-16
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• 2002

This paper introduces developed prototype intelligent pig which detects corrosion on pipeline by using Magnetic Flux Leakage technology. The 8 inch developed MFL(Magnetic Flux Leakage) pig is composed of 5 yokes which magnetize pipeline wall and 45 Hall sensors which detect MFL signal. The designed MFL modules are analyzed by using magnetic circuit method in order to confirm whether pipeline wall is fully saturated. A variety of artificial defects are manufactured on 8 inch diameter steel pipeline in order to acquire MFL signals. So leakage flux of the axial, radial and circumferential component was acquired as defects. The results of this paper show that design technique for 8 inch MFL pig can be applied to large diameter MFL pig and 0.5mm defect depth can be detected.