Two-electrode resistance of magnetic bead solution in deionized distilled water(ddH₂O) depending on the magnetic field was analyzed. The average diameter of magnetic bead composed of Silanol(Si-OH) group is about 1 µm. The distribution of the magnetic beads in solution is drawn according to the magnitude of the external magnetic field between the two-terminal Cu electrodes. As the magnitude of the external magnetic field increases and decreases, magnetic beads are split on both sides and evenly mixed, respectively. The maximum magnetoresistance ratio from magnetoresistance curve sweeping at 0.7 mHz was about −40 % at around ±10 Oe. Magnetoresistance ratios caused by hysteresis characteristics for the motion of magnetic beads were changed to −36 % and −21 % as increasing of the sweeping frequency 3.7 mHz and 10.7 mHz, respectively. These results show the possibility of using magnetic beads as the material of sensitive magnetoresistance sensor.

In this study, the displacement sensor using the phenomenon that the mutual inductance of two LC resonators is dependent on the proximity distance is investigated. The inductance of the air core inductor was measured in the frequency range of 1~100 kHz and the capacitance was calculated from the measured resonant frequency. When two LC resonant elements fabricated with the air-core inductor and an external capacitor were close to each other, the signal obtained from the primary resonant element depended on the proximity distance of two resonant elements. It was confirmed that the measured frequency characteristics of the output signal were also depended on the proximity distance. The reason why the output signal changes were depending on the proximity distances could be explained by the fact that the mutual inductance between the two resonator elements depends on the proximity distance.

A vibrating sample magnetometer with a unimorph piezoelectric actuator as vibrating mechanism is proposed in this paper. By adopting a piezoelectric vibrating mechanism, we could achieve both high sensitivity and small-sizing of VSM. To enhance the sensitivity, the optimal vibrating frequency was investigated by a set of FEM structural analysis. When an alternating voltage was applied to the unimorph piezoelectric actuator, the acryl cantilever is vibrated transversely. At the end of the cantilever, on which a magnetic specimen was attached, the maximum vibration amplitude was ~1.6 mm at 160 Hz. The proposed VSM showed high resolution ~2 × 10⁻⁵ emu due to an extremely large vibrating amplitude, even if it has an extremely small size (30 × 25 × 25 cm³) compare with conventional VSMs.

This paper deals with the heat transfer analysis through the electromagnetic- thermal coupling analysis of large scale synchronous generator. The synchronous generator is a wound field synchronous generator, and the operation characteristic curve is derived through electromagnetic analysis. Through this, the synchronous generator is classified into the heating limitation region by the armature winding, the field winding, and the stator end region. Next, for the analysis of the main heat source of generator, the losses incurred at the rated output within the heat limit region were calculated. Core loss was derived by using finite element method and copper loss was calculated by using the copper loss equation. Finally, the characteristics of the generator based on the air-cooled system were analyzed by the convection heat coefficients through the electromagnetic-thermal coupling analysis. Convection heat coefficients were considered both natural convection and forced convection, and confirmed the thermal analysis according to the convection coefficient, generator saturation temperature, and thermal strain alalysis.

Since Nd₂Fe₁₄B permanent magnet was developed in 1982, a new permanent magnet with higher performance than Nd₂Fe₁₄B has not been reported yet. On the other hand, new permanent magnet materials, which do not include rare-earth elements but are competible to ferrites in price, also are needed to be searched urgently. In this paper, we will review required material properties for good permanent magnets and discuss ways to search new permanent magnets, using first principles calculations. The goal to search the new permanent magnets should be set to find materials to have higher performance than Nd₂Fe₁₄B or to be consisted of 3d transition metal as magnetic elements with compatible performance to Nd₂Fe₁₄B to replace high performance rare-earth magnets or cheap ferrites.

Magnetic micro/nano robots have the potential to revolutionize technological change in biotechnology and medicine. As a main feature, it is driven by an external magnetic field and controlled wirelessly to achieve miniaturization. Thus, minimally invasive diagnosis and treatment are possible. There is a growing interest in research to replace the traditional robot technology with the micro robot technology for the minimally invasive and targeted treatment. Therefore, this paper examines the control method, mechanism and research trend of micro robot.