In this study, a substrate-bias assisted 2-step pulse programming method is proposed for realizing 4-bit/1-cell operation of the SONOS memory. The programming voltage and time are considerably reduced by this programming method than a gate-bias assisted 2-step pulse programming method and CHEI method. It is confirmed that the difference of 4-states in the threshold voltage is maintained to more than 0.5 V at least for 10-year for the multi-level characteristics.

In this paper, the properties of SnZnO films obtained from solution process with different component fractions were compared. The thermal behavior of the SnZnO solutions showed only a slight change according to the component fraction change. However, the definite changes were revealed at the structural properties of the SnZnO films. With diverse analyses, the origin of the changes was proved to the influence of phase change from SnO2 to ZnO in SnZnO lattice. With the SnO2-phase-dominant SnZnO, the highest field effect mobility and on/off ratio of about 8.6 cm2/Vs and 2 × 108 were achieved, respectively.

Lead-free piezoelectric ceramic/epoxy composites with ``0-3`` connectivity were prepared by cold-pressing with a temperature controlled curing method. A ceramic powder with a composition of (Na0.51K0.47Li0.02)(Nb0.8Ta0.2)O3 was synthesized by a conventional solid state reaction route. The dielectric and piezoelectric properties of ceramic/epoxy composites were characterized as a function of the volume fraction (φ) of piezoelectric ceramics, which was varied from 70 to 95vol%. The results indicated that the piezoelectric properties of composites were significantly affected by the volume fraction of ceramics. In terms of the piezoelectric properties, specimens showed the best performance at φ= 85vol%, resulting in the piezoelectric constant d33 of 39pC/N and the figure of merit as a piezoelectric energy harvester (d33·g33) of 1.24 pm2/N.

The properties of green sheet were investigated in order to understanding an effects of organic solvent mixture ratio for solid oxide fuel cells fabrication, The purpose of this work is to optimize the slurry condition using the design of experiment to improve green sheet properties. The elongation increased with increasing amount of binder and solvent. With increasing amount of solvent, the air permeability increased but the tensile strength decreased. The best properties of the green sheet appeared amount of the binder 17 wt%, solvent 35 wt% and powder 48 wt%. The optimum condition of green and sintered density for solid oxide fuel cells fabrication was obtained in the sample pressured at 800kgf/㎠.

In this paper, heat-releasing sheets made of AlN powder and acryl binder as thermoset were prepared using tape casting method. The crystal structure and morphology, the thermal properties as nonvolatile solid content and thermal conductivity, and the surface resistance of heat- releasing sheet were measured by using X-ray diffractometer, field emission-scanning electron microscopy, thermo gravimetric analyzer and laser flash instrument, and surface resistance meter. It was proved that thermal conductivity is greatly affected by the content of binder in heat-releasing sheet. Superior thermal conductivity above 3.5W/mK and suface resistance were obtained at heat-releasing sheet with above 90% of AlN powder.

As lead-free piezoelectric materials, Ag2O doped 0.95(K0.5Na0.5) NbO3-0.05LiNbO3+ x mol% (where x = 0, 0.5, 1, 1.5, 2, 2.5 and 3, respectively) ceramics were fabricated by a conventional sintering process. The doping effects on the microstructure and electrical properties of the 0.95(K0.5Na0.5) NbO3-0.05LiNbO3 ceramics were systematically investigated. When the 3 mol % Ag2O doped 0.95(K0.5Na0.5)NbO3-0.05LiNbO3 samples were sintered at 1,080℃ for 5 hrs in air, these ceramics showed excellent values of density=4.20 g/cm3, piezoelectric constant (d33)=174pC/N and phase transition temperature(Tc)=421.6℃, respectively.

For the application of photo-detector as active layer, we have studied how to deposit SiGe thin film using an independent Si target and Ge target, respectively. Both targets were synthesized by purity of 99.999%. Plasma generators were generated by radio frequency (rf, 13.56 MHz) and direct current (dc) power. When Ge and Si targets were sputtered by dc and rf power, respectively, we could observe the growth of highly crystalline Ge thin film at the temperature of 400℃ from the result of raman spectroscopy and X-ray diffraction method. However, SiGe thin film did not deposit above method. Inversely, we changed target position like that Ge and Si targets were sputtered by rf and dc power, respectively. Although Ge crystalline growth without Si target sputtering deteriorated considerably, the growth of SiGe thin film was observed with increase of Si dc power. SiGe thin film was evaluated as microcrystalline phase which included (111) and (220) plane by X-ray diffraction method.

We have developed an implantable wireless sensor for real time pressure monitoring of blood circulation system. MEMS (micro-electro-mechanical system) technology was adopted as a sensor development method. The sensor is composed of photolithographically patterned inductors and a distributed capacitor in gap between the inductors. A resulting LC resonant system produces its resonant frequency in range of 269 to 284 MHz at 740 mmHg. To read the resonant frequency changed by blood pressure variation, we developed a custom readout system based on a network analyzer functionality, The bench-top testing of the pressure sensors showed good mechanical and electrical functionality. A sensor was implanted into tibial artery of farm pig, and interrogated wirelessly with accurate readings of blood pressure. After 45 days, the sensor`s electrical response and histopathology were studied with good frequency reading and biocompatibility.

To compare an electrical and optical characteristics of indium tin oxide (ITO) and carbon nanotube (CNT) electrode on flexible and reflective display, we fabricate two charged particle-type display panels under the same panel condition of which the width of ribs is 10 ㎛, the cell size is 300 ㎛ × 300 ㎛, the q/m value of the white particles is -4.3 μC/g and that for the black is +1.3 μC/g, and the cell gap is 75 ㎛, 125 ㎛, and 175 ㎛. We use plastic substrates coated with ITO and CNT electrode. To evaluate optical property, we measure a response time of particles using a laser and a photodiode. Threshold and driving voltages of CNT electrode according to the sheet resistance of 300, 600, 1,000 (ohm/sq) are compared with ITO electrode of 10 (ohm/sq). A response time of the CNT panel is similar to that of ITO panel, but the threshold and driving voltages of CNT panel are higher than that of ITO panel, inducing a large bombardment of the particles and shortening the lifetime of the panel. High difference of a threshold and a driving voltage of CNT panel will induce an particle clumping, resulting degradation of the panel. A bending radius of the fabricated CNT panel is 18 ㎛.

We studied the emission characteristics of white phosphorescent organic light-emitting diodes (PHOLEDs), which were fabricated using a two-wavelength method. To optimize emission characteristics of white PHOLEDs, white PHOLEDs with red/blue, blue/red and red/blue/red emitting layer (EML) structures were fabricated using a host-dopant system. In case of white PHOLEDs with red/blue structure, the best efficiency was obtained at a structure of red (15 nm)/blue (15 nm). But the emission color was blue-shifted white. In case of white PHOLEDs with blue/red structure, the better color purity and efficiency were observed at a blue (29 nm)/red (1 nm) structure. For additional improvement of color purity in white PHOLEDs with blue (29 nm)/red (1 nm) EMLs, we fabricated white PHOLEDs with red (1 nm)/blue (28 nm)/red (1 nm) structure. The current efficiency, external quantum efficiency, and CIE (x, y) coordinate were 27.2cd/A, 15.1%, and (0.382, 0.369) at 1,000cd/㎡, respectively.

In this paper, heat-releasing composite sheets made of AlN, graphite, Al powder and acryl binder as thermoset were prepared using tape casting method, The crystal structure, morphology, thermal conductivity of heat-releasing composite sheet were measured by using X-ray diffractometer, field emission-scanning electron microscopy and laser flash instrument. It was found thermal conductivity of sheet was decided by solid content, composition including AlN, graphite, Al in heat-releasing composite sheets. As a result, 4.56W/mK of thermal conductivity could be obtained by using LFA 447.

A functionally graded material (FGM) spacer, which the distribution of dielectric permittivity inside an insulator changes spatially, can considerably reduce the electric field concentration around a high-voltage electrode and along the gas-insulator interface when compared to a conventional spacer with a uniform permittivity distribution, In this research, we propose the FGM spacer with an elliptical permittivity distribution instead of that with a distribution of dielectric permittivity varying along a radial direction only in order to improve efficiently the insulation capability. The optimal design of the elliptical FGM spacer configuration is performed by using the response surface methodology (RSM) combined with the steepest descent method (SDM).

Diagnostic tests were performed on two high voltage (HV) motor stator windings. These tests included the measurement of insulation resistance, polarization index, AC current, dissipation factor (tanδ) and partial discharge (PD) magnitude. Surface contamination of HV motor stator windings has an effect on the AC current and tanδ. When the stator windings were finished cleaning and insulation reinforcement, the increase rate of AC current (ΔI) and dissipation factor (Δtanδ) were very small compared to those before cleaning. However, the PD magnitude remained the same. These tests show that cleaning and insulation reinforcement of HV motor stator windings can reduce the insulation failure.

ZnO nanowires were synthesized by hydrothermal technique. Prepared synthesis aqueous solutions were preserved by preheating in autoclave type synthesis equipment with various preheating time of 1 h difference. ITO-coated corning glass substrates deposited with AZO seed layers were then inserted in the preheated synthesis aqueous solutions and ZnO nanowires were grown for 180 min at 90℃. Density, length and aspect ratio of the grown ZnO nanowires were investigated. Composition, structural and optical properties of the grown ZnO nanowires were analyzed, Characteristics of the ZnO nanowires were comparatively studied in relation with Zn2+ ion concentration measured directly after the preheating of synthesis aqueous solution.

La7.33Bi2 (SiO4)6O2 specimens were fabricated by standard solid-state synthesis route for solid oxide electrolytes. The calcined powders exhibited uniform particles with a mean particle size of about 28μm. The room-temperature structure of La7.33Bi2 (SiO4)6O2 specimens was analyzed as hexagonal, space group P63 or P63/m, and the unit cell volume increased with increase a sintering temperature. The specimens sintered at 1,175℃ showed X-ray patterns of homogeneous apatite single phase without the second phase such as La2Si2O7 and La2SiO5. The specimen sintered at 1,175℃ showed the maximum sintered density of 5.49 g/cm3. Increasing the sintering temperature, total conductivities increased, activation energy decreased and the values were 1.98 × 10-5 Scm-1 and 1.23eV, respectively.