Magnetite nanoparticles were synthesized from Fe(OH)₂ using a high pressure homogenizer without any dispersing agents and oxidant. The observed X-ray diffraction (XRD) patterns revealed that all the samples had the inverse spinel structure of magnetite nanoparticles. The average size of the synthesized magnetite particles was found to be controlled by the number of passes in the high pressure homogenizer nozzle. The average particle size estimated by the XRD and transmission electron microscopy (TEM) analysis ranged from 17 to 22 nm. Magnetic hysteresis measurements were performed using a vibrating sample magnetometer (VSM) to investigate the magnetic properties of the magnetite nanoparticles at room temperature, revealing the appearance of superparamagnetism in the magnetite nanoparticles synthesized through 1 to 3 passes at 1500 bar.

The paper presents the characteristic analysis on the high speed synchronous generator of guided weapon considering load conditions and loss. The generator consists of the rotor with the short-circuited field coil connected to armature coils of an exciter and a stator with three-phase winding. To analyze the generator characteristics considering load conditions and loss, First, the equivalent circuit method considering the effect of saliency and Finite Element Method (FEM) are applied. Second, an accurate loss calculation, magnetic field analyses in stator core considering, magnetic field analyses in stator core considering the time harmonics are performed. And using the nonlinear finite element analysis (FEM), we applied separated rotating and alternating magnetic filed to core loss calculation. Finally, using electrical parameter such as resistance, we are applied to calculate the copper loss of synchronous generator.

In this paper, a finite element simulation using time domain reflectometry for detection of water trees in power cables is verified through an experimental test. For the purpose of doing this, a diagnostic pulse generator which can be internally charged up to a maximin voltage of 5 kV is first produced, and then the experimental setup equivalent to simulation conditions is realized. In order to examine simulation results, two-type artificial defects are created for a 6.6 kV distribution power cable, and reflected pulse signals are measured on each individual case. Finally, the validity of computer simulation for detection of water trees in power cables based on the pulse propagation characteristics is proved through a comparative analysis between simulated and experimental data of the concerned cable with and without the defect.

Recently, the demand of high efficient/miniaturized parts is increasing with the development of industry. Especially, the hybrid/electric vehicle market is rapidly growing because of the energy saving and environmental problems. The Nd-Fe-B magnet is one of the most important material in the automobile industry, which determines the efficiency and performance of traction motors. However, the issues on the resource and the price of heavy rare-earth (HRE) metals which are used to improve thermal stability of the magnet are constantly emerging. In addition, as the demand for Nd-Fe-B magnets is rapidly increasing with the growth of the electric vehicle market, Nd is also expected to be in short supply to meet the demand. Thus, there is a growing interest in research to replace Nd/Pr with Ce/La which is more abundant and cheaper than Nd along with the development of HRE lean/free magnets. The present article introduces the trend in research and development of a Nd-reduced rare-earth magnet to solve the problem of rare-earth resources.

Spin-orbit torque (SOT) is a spin torque based on spin-orbit coupling in a nonmagnet/ferromagnet heterostructure. In this structure, transverse spin current that is generated by an in-plane charge current and exerts torque on the adjacent ferromagnetic layer. This is intensively investigated because it can be used to switch the ferromagnet effectively in various spintronic devices. Here, we discuss various experimental methods to evaluate the SOT in nonmagnet/ferromagnet bilayer structures.