• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1154-1158
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• 2006

This investigation suggests a new non-contact type sensor that can measure flexural vibrations of a non-ferromagnetic pipe. The sensor works on the reversed Lorentz force mechanism; however, anti-symmetric bias magnetic field suggested in this work should be applied to measure bending vibration of a non-ferromagnetic pipe. The importance of the suggested magnetic field is verified by a series of experiments. The sensor is applied to the bending vibration measurement and modal testing of an aluminum pipe and shows satisfactory working performance compared to others.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.6
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• pp.74-80
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• 2004

An internal finishing process by the application of magnetic abrasive machining has been developed as a new technology to obtain a fine inner surface of pipe. In this paper, the finishing process of a non-ferromagnetic pipe by a static magnetic field method is introduced and its finishing characteristics is discussed with effective factors by various experiments. From these experimental results, it is found that the magnetic abrasives inserted in the pipe are arranged according to the magnetic force line. Through the experimental, it is possible to estimate the proper supply volume of the abrasive, which in proportional to the diameter of pipe.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.779-782
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• 2000

An internal finishing process by the application of magnetic abrasive machining has been developed as a new technology to obtain a fine inner surface of pipe. In this paper, the finishing process of a non-ferromagnetic pipe by a static magnetic field method is introduced and its finishing characteristics is discussed with effective factors by various experiments. From these experimental results, it is found that the proper suppling quantity of magnetic abrasives per diameter of pipe is important, and the inner surface roughness of pipe is not changed much after certain critical finishing time. As a result of this investigation the 3.2$\mu$m Rmax in inner surface roughness of stainless steel pipe is improved to 0.7$\mu$m Rmax after 6 minutes finishing.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.960-963
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• 2001

An internal finishing process by the application of magnetic abrasive machining has been developed as a new technology to obtain a fine inner surface of pipe. In this paper, another method of magnetic abrasive machining in which the N and S magnetic poles are vibrated and a workpiece is rotated only is tried in a non-ferromagnetic pipe(SUS304), and its finishing characteristics is experimental results, it is found that the vibration effects of magnetic poles on the finishing characteristics are large in internal finishing.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.6
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• pp.483-489
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• 2016

The typical methods used for inspecting ferromagnetic pipes include the ultrasonic testing (UT) contact method and the following non-contact methods: magnetic flux leakage (MFL), electromagnetic acoustic transducers (EMAT), and remote field eddy current testing (RFECT). Among these methods, the RFECT method has the advantage of being able to establish a system smaller than the diameter of a pipe. However, the method has several disadvantages as well, including different sensitivities and difficult-to-repair coil sensors which comprise its array system. Therefore, a giant magneto-resistance (GMR) sensor was applied to address these issues. The GMR sensor is small, easy to replace, and has uniform sensitivity. In this experiment, the GMR sensor was used to measure remote field and defect signal characteristics (in the axial and radial directions) in a ferromagnetic pipe. These characteristics were measured in an effort to investigate standard defects at changing depths within a pipe. The results show that the experiment successfully demonstrated the applicability of the GMR sensor to RFECT signal detection in ferromagnetic pipe.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.4 no.1
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• pp.7-12
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• 2005

An internal finishing process by the application of magnetic abrasive finishing has been developed as a new technology to obtain a fine inner surface of pipe. In this paper, another method of magnetic abrasive machining in which the N and S magnetic poles are vibrated and a workpiece is rotated only is tried in a non-ferromagnetic pipe(SUS304), and its finishing characteristics is experimently investigated by various effective factors such as vibrating frequency and amplitude. From the experimental results, it is found that the vibration effects of magnetic poles on the finishing characteristics are large in internal finishing.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.915-918
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• 1997

An internal finishing process by the application of magnetic abrasive machining has been developed as a new technology to obtain a fine inner surface of pipe. In this paper, an abrasive circulation system was designed and manufactured. As a result, it was found that a fine inner surface abrasive of pipe was available by the use of this machining methods. The basic machining characteristics of pin-type magnetic tools were analyzed experimentally. In addition, the experimental results show that we can realize that pin-type magnetic tools have more machining efficiency than iron particles as magnetic tools.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.3
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• pp.293-298
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• 2008

Non-contact modal testing for longitudinal modes of a pipe is discussed in this work. The suggested method can generate and measure longitudinal vibrations without mechanical contact by using the coupling phenomenon between deformation and magnetic field, known as the magnetostrictive effect. This effect has been used to generate and measure ultrasonic waves, but seldom used to deal with audible vibrations. In this investigation, the validity of the developed method in a typical vibration frequency range is checked with an Inconel pipe being used in nuclear power plants.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1343-1347
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• 2006

Non-contact modal testing for longitudinal modes of a pipe is discussed in this work. The suggested method can generate and measure longitudinal vibrations without mechanical contact by using the coupling phenomenon between deformation and magnetic field, known as the magnetostrictive effect. This effect has been used to generate and measure ultrasonic waves, but seldom used to deal with audible vibrations. In this investigation, the validity of the developed method in a typical vibration frequency range is checked with an inconel pipe being used in nuclear power plants.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.2
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• pp.144-149
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• 2004

The objective of this investigation is to develop an efficient method to generate and measure torsional waves in non-ferromagnetic waveguides by using magnetostrictive transducers. In existing methods using a nickel strip that is attached circumferentially to the test specimen, large current input to the magnetostrictive transducer often generates undesired wave modes in addition to the desired torsional wave. However, we propose a new method to generate the torsional waves without being accompanied with other undesirable wane modes regardless of the input current magnitude. The specific transducer configuration is suggested and its performance is also checked through a series of experiments.