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High engineering critical current density ( J e) is demanded in high-performance large-scale applications such as power cables, high-magnetic-field magnets, accelerators, and fusion reactors. In developing high current capacity and low vulnerability under a high magnetic field, high-temperature superconducting (HTS) rare-earth barium copper oxide coated conductors (CCs) have undergone various trials, and CC tape characteristics have ultimately been greatly improved. The Korea Electrotechnology Research Institute recently developed a “multiple HTS layers on one substrate” (MHOS) conductor that can carry high critical current, I c, based on the number of superconducting layers deposited on one substrate. The superconducting layers in a MHOS conductor are much thicker than in a single-layered CC tape, possibly affecting the degradation behaviors of I c under a mechanical load. To ensure the performance and reliability of MHOS conductors, it is necessary to evaluate the strain/stress response of I c. In this study, the electromechanical properties of MHOS conductors were investigated using the uniaxial tension test method as well as the single-sided bending test at 77 K and self-field and at 0.5 T using a pair of neodymium permanent magnets.

The charge trapping characteristics of silicon (Si) substrates covered with a self-assembled monolayer (SAM) were studied using on a local biasing method with Kelvin-probe force microscopy. A hexadecyl SAM (HD-SAM) on a Si substrate, in which the molecules were covalently bonded to the Si substrate, was found to have no charge trapping sites at its monolayer/Si interface while an ocatadecylsilyl SAM (ODS-SAM) on a Si substrate, in which a thin oxide layer was inserted between the molecules and the Si substrate, showed a distinct charge trapping behavior. The alkyl monolayer directly fixed on Si is promising as a very thin insulating layer in Si microelectronics.

Cross-linking polyethylene (XLPE) power cables are widely used as an excellent insulation material for high-voltage direct current (HVDC) transmission. For the design and operation of HVDC-based power cables, the conduction properties of XLPE insulation must be obtained. This study aimed to establish a highly reliable conductivity-measurement system that can diagnose the XLPE insulation of cables before and after aging by evaluating the repeatability of their conductivity. In this study, a conductivity-measurement circuit was constructed using the polarization-and-depolarization-current technique. Conductivity was measured according to the conductor temperature by using an applied electric field, and then the repeatability of the measured conductivity was evaluated using a statistical method. The experimental results show that the minimum repeatability was 6%, thereby demonstrating the establishment of a reliable conductivity-measurement system.

XLPE (Cross Linking-Polyethylene) is widely used as an insulating material for HVDC (High Voltage Direct Current) transmission cables, and it is important to evaluate the aged state of XLPE due to long-term operation. The purpose of this paper is to evaluate the conduction characteristics of XLPE model cables before and after aging using PDC (Polarization and Depolarization Current) technique. The test sample is a model cable for research with an insulation thickness of 2.5 mm in which the inner semiconductor, XLPE insulation and outer semiconductor are incorporated. The model cable was aged at 35 kV / mm for the applied average electric field and the conductor temperature of $90^{\circ}C$ for 30 days. In order to evaluate the conduction characteristics of the test samples before and after aging, the conductivity of XLPE was measured under the conductor temperatures of $30 ^{\circ}C$, $60^{\circ}C$ and $90^{\circ}C$ and applied average electric fields of 10 kV / mm, 15 kV / mm, 20 kV / mm and 25 kV / mm respectively. After 30 days of aging, the increasing tendency of XLPE conductivity with respect to electric field turned out to be decreased compared with that of unaged model cable sample.

In order to increase the current capacity of a high-temperature superconducting REBCO-coated conductor, in this paper, a lighter aluminum alloy was employed for mechanical reinforcement. Two GdBCO tapes fabricated using the reactive coevaporation by deposition and reaction (RCE-DR) process were laminated with three Al alloy (AA-3104) tapes using a two-step process involving pretinning and bonding. It was confirmed that ultrasonic soldering using Sn-3 wt% Ag-0.5 wt% Cu was efficient at laminating the GdBCO and aluminum alloy tapes. The bonding strengths and critical currents of the laminated conductors were evaluated.

We report the fabrication of Gd films with dimples on the surface by vacuum evaporation method on Hastelloy substrate. The Gd films are structurally and morphologically studied by x-ray diffraction and field emission scanning electron microscope respectively and found to be hexagonal crystal structure. The magnetocaloric properties are studied and found to be well comparable with commercial Gd sheet. The calculated magnetic entropy change in Gd films is 9.57 J/kg K at Curie temperature (TC) of 294 K with second order magnetic phase transition under applied magnetic field 5 T.

Nanocrystalline ZnO powders have been synthesized by co-precipitation method and investigated planetary ball milling effects on structural and optical properties. These powders were characterized using X-ray diffraction, field emission scanning electronic microscope, Infrared spectrophotometer, UV–vis spectrophotometer and Photoluminescence. It was found that prepared ZnO powders have hexagonal close packed structure which was annealed at 500 °C for 30 min. The bandgap energy of ZnO powders varied from 3.13 to 2.85 eV. The room temperature PL spectra exhibits low intensity UV emission peak at 383 nm and green emission band around 520 nm shows shifting towards higher wavelength with decrease in intensity of peak with time of planetary ball milling. Hence, it was observed that planetary ball milling can be used to tailor the optoelectronic properties of ZnO nanostructures.

Ni doped ZnO nanopowders have been synthesized by the co-precipitation route followed by planetary ball milling. The synthesized powder was characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), High Resolution Transmission Electron Microscopy (HR-TEM), UV–vis spectrophotometry, fluorescence spectrophotometry and Quantum Design PPMS for structural, morphological, microstructural, optical and magnetic properties measurements. All the samples show wurtzite hexagonal crystal structure. The optical absorption spectra show a shift in the position of band edge towards lower energy. The estimated band gap is found to decrease with higher nickel doping. The room temperature PL measurements illustrate UV emission centered at 390 nm (3.17 eV), which is ascribed to the near-band-edge (NBE) emissions of ZnO and broad green emission around 540 nm. Room temperature ferromagnetism in the Ni doped ZnO nanopowders has been confirmed by magnetic property measurements.