• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.1
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• pp.47-51
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• 2000

To make a practical application of a micro-strain sensors with ultrahigh sensitivity, a strain on electrical properties of micro-patterned amorphous (Fe\ulcornerco\ulcorner)\ulcornerSi\ulcornerB\ulcorner films had influenced on the impedance over frequency range from 1 MHz to 1 GHz. Reflecting excellent magnetomachanical couping properties of films, high frequency impedance was subject to change sensitively by a strain : a change in impe-dance of 39% was observed at 200 MHz applied a strain of 224$\times$10\ulcorner. To determine a optimum shape of micro-patterned films, film impedance was analyzed by virtue of its constitutive components of resis-tance and reactance. Result was shown that reduction of the resistance term(hence increase of resultant reactance term) of impedance is more effective for enhancing the strain sensitivity of films at relatively low frequency range.

• Journal of Power System Engineering
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• v.14 no.3
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• pp.46-51
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• 2010

A torsional guided wave was applied to detect a defect in petrochemical pipes. Phase and group velocity dispersion curves for the longitudinal and torsional modes of the inspected pipe were presented for the theoretical analysis. It was found through mode shape analysis that there was mode conversion when torsional wave is incident at an asymmetric defect. An artificial notch was fabricated in the pipe and the detectability was examined from the distance 2m of the end of the pipe by using magnetostrictive sensors. The relativities between the amplitude of the reflected signal and the size of the defect was examined. It was shown that the T(0,1) mode could be used for the long range inspection for the petrochemical pipes.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.9
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• pp.841-848
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• 2010

Previous experimental results show that the magnetostrictive transducer has the peculiar characteristic with relation to their reversible magnetization and its practical usage will be hindered by this phenomena. In this paper, the idea of anhysteretization is adopted in order to solve this problem. The experimental results reveal that the anhysteretization can get rid of the extraordinary phenomena which are occurred by the change of biasing magnetic field. The effects of two important parameters, which are the amplitude and the decaying time of this process, on the anhysteretization are investigated experimentally. Finally the best operating condition is proposed in order to maximize the sensitivity under the anhysteretization.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.3
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• pp.75-81
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• 1998

In the machining process, variation in cutting forces results in relative displacements between the tool and the workpiece leading to tool vibration. Also there is a demand to change the depth of cut very frequently. One solution for the both cases is to develop a system which has the ability to reposition a cutting tool to a very small level, i.e., micron. This paper presents the development of a micropositioner using a magnetostrictive material. The developed micropositioner is implemented to a lathe and subjected to various tests. The results show that the micropositioner with a magnetostrictive actuator has good potential for machining application.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.4
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• pp.383-390
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• 2001

Long-range guided wave inspection is a new emerging technology for rapidly and globally inspecting a large area of a structure from a single test location. This paper describes a general overview of the guided wave properties and its application for long-range inspection of structures the principle and instrument system for a guided wave inspection technology called "magnetostrictive sensor (MsS)" that generates and detects guided waves electromagnetically in the material under testing, and examples of long-range guided wave inspection of structures that can be accomplished using the MsS.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.12
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• pp.520-526
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• 2005

Demands for the noise reduction of a transformer has been becoming an common issue because it has been used mainly at the residence area such as an apartment complex. This paper shows 2 trouble shooting examples that high noise sources were found out structural resonance of a transformer by 120Hz exciting frequency caused from magnetostrictive vibration of core. This paper presents that vibration data are very important to find noise source and how to avoid natural frequency of core and tank wall

• Proceedings of the KIEE Conference
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• 2001.11b
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• pp.109-112
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• 2001

The specific goal of this research is to develop a non-contact measurement technique of stress waves propagating in a rotating shaft. This technique will enable on-line damage detection in shafts in power-generating systems. To minimize measurement errors due to shaft rotation, we have employed magnetostrictive sensors. The sensors are not only cost-effective but also insensitive to liftoff or fill factors. Several experimental results showed the effectiveness of the present technique. The damage location in a rotating shaft was accurately predicted by the wave signal measured by the present approach.

• Journal of the Optical Society of Korea
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• v.19 no.6
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• pp.575-585
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• 2015

Magnetic field in magnetic bearings is the physical medium to realize magnetic levitation, the distribution of the magnetic field determines the operating performance of magnetic bearings. In this paper, a thin-slice Fiber Bragg Grating-Giant Magnetostrictive Material magnetic sensor used for the air gap of magnetic bearings was proposed and tested in the condition of dynamic magnetic field. The static property of the sensor was calibrated and a polynomial curve was fitted to describe the performance of the sensor. Measurement of dynamic magnetic field with different frequencies in magnetic bearings was implemented. Comparing with the finite element simulations, the results showed the DC component of the magnetic field was detected by the sensor and error was less than 5.87%.

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.140-141
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• 2002

In proto-type microactuators driven by magnetostrictive Tb-Fe thin films, the deflection was observed to be much smaller than that expected from large-sized "standard" Tb-Fe thin films. A striking difference was observed when the results from a thin substrate of 28 $\mu\textrm{m}$ for microactuator applications were compared with those from a standard substrate. At a standard substrate thickness (several hundred $\mu\textrm{m}$), an amorphous phase was formed and the coercivity was low being 80 Oe. (omitted)

• Journal of Magnetics
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• v.3 no.3
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• pp.78-81
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• 1998

Large magneto crystalline anisotropy energy and demagnetization energy of rare earth-transition metal (RF-TM) alloys play roles of bottlenecks towards their commercial applications for giant magnetostrictive and blue wavelength magneto optical recording materials, respectively. To solve the above problems, boron is added into amorphous RE-TM alloys to produce its electron transferring. The boron added amorphous RE-TM alloys show novel magnetic and magneto-optical properties as follows; 1) an amorphous $(Sm_{33}Fe_{76})$97B3 alloy obtains the magnetostriction of$ -550{times}10^{-6}$ at 400 Oe compared with saturation magnetostriction of$ -60{\times}10^{-6}$ in conventional Ni based alloys, 2) an amorphous$ (Nd_{33}Fe_{67})_{95}B_5$ alloy increases effective magnetic anisotropy to$ -0.5{\times}10^{-6} ergs/cm^3 from -3.5{\times}10^6 ergs/cm^3$ without boron, which correspond to the polar Kerr rotation angles of 0.52$^{\circ}$and 0.33$^{\circ}$, respectively. These results attribute to selective 2p-3d electron orbits exchange coupling (SEC).