• The Magazine of the IEIE
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• v.13 no.1
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• pp.86-95
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• 1986

The basic physical principles involved in the operation of monolithic magnetic sensors are reviewed and technological aspects outlined. More or less conventional devices based on Hall effect, magnetoresistance or current path deflection are described. It is shown that such sensors with 2, 3, 4 or 5 terminal contacts are achievable with standard silicon integrated circuit process. Several kinds of magnetodiodes (p+nn+,p+n, Schottky, MOS, memory, CMOS) have been fabricated on Si and on SOS films and present attractive properties. Finally, the magneto-transistor family is discussed with emphasis to split-terminals, CMOS, unijunction and fila-mentary devices.

• Journal of Sensor Science and Technology
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• v.29 no.5
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• pp.283-292
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• 2020

Current sensors that use a Hall element and Hall IC to measure the magnetic fields generated in steel silicon core gaps do not distinguish between direct and alternating currents. Thus, they are primarily used to measure direct current (DC) in industrial equipment. Although such sensors can measure the DC when installed in expensive equipment, ascertaining problems becomes difficult if the equipment is set up in an unexposed space. The control box is only opened during scheduled maintenance or when anomalies occur. Therefore, in this paper, a method is proposed for facilitating the safety management and maintenance of equipment when necessary, instead of waiting for anomalies or scheduled maintenance. A Bluetooth 4.0 low-energy current-sensor system based on near-field communication is used, which compensates for the nonlinearity of the current-sensor output signal using a piecewise linear model. The sensor is controlled using its generic attribute profile. Sensor nodes and cell phones used to check the signals obtained from the sensor at 50-A input currents showed an accuracy of ±1%, exhibiting linearity in all communications within the range of 0 to 50 A, with a stable output voltage for each communication segment.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.11
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• pp.9-16
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• 2010

This paper examines the temperature characteristics of an Optical CT (optical current transformer) using the Faraday effect for measuring high current in a super high voltage-power apparatus. It is performed as follows by the sensor for embodying Faraday effect. $\cdot$ A single-mode optical fiber capable of maintaining a polarization state is used. $\cdot$ A light source is applied at 1310[nm] to a Laser Diode. $\cdot$ The Linear of Faraday effect to a large current is evaluated and $\cdot$ A possible application using an Optical CT was shown. An Influence of Faraday effect to the surrounding temperature measured -40~50[$^{\circ}C$], and the characteristic of the current sensitivity was reported. An application using the results of the temperature compensation system was used in order to compensate for surrounding temperatures. A possibility of applying Optical CT for electric power apparatus was advanced further. We were able to confirm that this temperature calibration method can minimize the fluctuation of the output signal depending on the temperature conditions.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.27 no.2
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• pp.175-181
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• 2017

In the present work, to achieve high braking performance with restricted size, characteristics of magneto-rheological (MR) fluid brake is numerically investigated considering different magnetic core shapes. As a first step, structural configuration of the MR brakes are proposed with four different magnetic core shapes, such as single flat, single inclined, dual flat and dual inclined. To estimate braking performance of the proposed MR brakes, electromagnetic analysis is carried out and the results of magnetic field intensity distribution are observed. Based on the electromagnetic analysis results, braking torque of the MR brake is estimated according to magnitude of current input and results are discussed. It is observed that enhanced braking torque can be achieved by adopting the modified magnetic core shape under limited small size of the MR brake.

• Journal of Mechanical Science and Technology
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• v.19 no.10
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• pp.1835-1845
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• 2005

In this paper a safe arm with passive compliant joints and visco-elastic covering is designed for human-friendly service robots. The passive compliant joint (PCJ) is composed of a magneto-rheological (MR) damper and a rotary spring. In addition to a spring component, a damper is introduced for damping effect and works as a rotary viscous damper by controlling the electric current according to the angular velocity of spring displacement. When a manipulator interacts with human or environment, the joints and cover passively operate and attenuate the applied collision force. The force attenuation property is verified through collision experiments showing that the proposed passive arm is safe in view of some evaluation measures.

• Journal of Drive and Control
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• v.15 no.1
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• pp.38-49
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• 2018

This research describes the development model and testing of a hybrid damper which can be applicable to a vehicle suspension. The hybrid damper is devised to improve the performance of a conventional passive oil damper using a magneto-rheological (MR) accumulator which consists of a gas accumulator and a MR device. The level of damping is continuously variable by the means of control in the applied current in a MR device fitted to a floating piston which separates the gas and the oil chamber. A simple MR device is used to resist the movement of floating piston. At first a mathematical model which describes all flows within the conventional oil damper is formulated, and then a small MR device is also devised and adopted to a mathematical model to characterize the performance of the device.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.3
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• pp.22-28
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• 2009

Recently, there has been an active study about smart fluid to control the vibration, in which MR fluid is evaluated as most efficient because it can generate different bonding forces based on the intensity of the external magnetic fields. This paper attempts to find a mechanism that, under limited conditions during a clutch production that uses such dynamic characteristic, defects the maximum intensity of electromagnetism. Using the finite element analysis program, we predicted a change within the bonding force of the MR fluid occurring inside the clutch when it is subjected to an increased electric current. In addition, we analyzed the change in the magnetic intensity when the coil comprising the coil control center is switched to multiple lines from the standard single line, to find a mechanism that can maximize the effect. Based on this analysis, we developed the clutch and tested its function, hoping to widen future MR fluid's range of application.

• Proceedings of the Korea Crystallographic Association Conference
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• 2003.05a
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• pp.7-7
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• 2003

Heteromagnetic nanostructures, which consist of two or more different layers such as nonmagnet, insulator, ferromagnet, antiferromagnet, and superconductor, have been widely used in current and likely future spintronics devices. Their many intriguing magnetic properties are originated from a variety of magnetic interactions at relevant length scales at or near interfaces and between different constituent layers as well as laterally different regions in chemical and magnetic heterogeneity. The fundamental properties can thus differ along depth and laterally in the film plane, depending on their relevant coupling length scales. The entire properties may be characterized by interface properties and/or the depth-varying properties of the individual constituent layers, and lateral inhomogeneity as well. It is a challenge to investigate both depth-varying properties and lateral heterogeneity in such heteromagnetic nanostructures. In this talk, soft x-ray magneto-optical effect as a nanometer scale probe of a variety of heteromagnetic structures is presented and its related noble techniques are introduced. For instances, magnetization vector imaging to investigate vector spin configurations in the film plane is presented, as well as the Kerr rotation, ellipticity, and intensity measurements as a depth sensitive probe on the atomic scales.

• Journal of the Korean Magnetics Society
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• v.8 no.2
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• pp.74-78
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• 1998

High quality single cystal Bi, Gd : YIG films have been grown on GCMZGG wafers by LPE techniques. The magnetic, magneto-optic and sensor properties of the films have been investigated. The films showed high linearity with almost no hystersis, saturaton Faraday rotation angle of 45$^{\circ}$, saturation field of about 1.1 kOe, Verdet constant of 5.6$^{\circ}$ /(Oe, cm) at room temperature, and temperture coefficient of Verset constant of 0.0056$^{\circ}$ /(Oe, cm, $^{\circ}C$) in the range of 0 $^{\circ}C$~100 $^{\circ}C$. The sensor made out of the film exhibited highly linear signal in the range of 3 A-300 A.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.6_spc
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• pp.660-666
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• 2016

This paper presents performance comparison results of magneto-rheological (MR) brake in the sense of wear characteristics. To create wear circumstance, the brake is operated in 100 000 cycles by DC motor. To make wear test in same design parameters such as the radius of the housing, ferromagnetic disc and gap size, small sample of stainless are inserted in housing of MR brake. The performances of brake are compared between the initial stage (no wear) and 100 000 revolution cycles operated stage (wear). At each circumstance, torque of the brake is measured and compared by applying step current and sinusoidal control input. The controller used in this work is a simple, but effective PID controller. It is demonstrated that the wear behavior is more obvious as the operating cycle is increased in the torque control process.