ZrO₂/PSS thin film with a high refractive index was fabricated on a glass substrate by a layer-by-layer self-assembly method. The surface morphology and thickness of the fabricated ZrO₂/PSS thin films were measured as a function of the number of (ZrO₂/PSS)n. As the number of (ZrO₂/PSS)n increased from n = 5 to n = 20, RMS roughness decreased from 29.01 nm to 8.368 nm. The ZrO₂ thin films exhibited high transmittance of 85% or more; and the 15-bilayer thin film exhibited the highest transmittance among the samples. The transmittance of the fabricated (ZrO₂/PSS)₁₅ thin film was ca. 90.8% in the visible range. The refractive index of the glass substrate coated by a (ZrO₂/PSS)₁₅ thin film with a thickness of 160 nm increased from ca. 1.52 to 1.74 at the 632 nm wavelength.

Thermal and structural stability in the glass transition region of chalcogenide glasses has been investigated in terms of thermodynamics for application to various optoelectronic devices. In this study, the compositions of Ge_xSb₂₀Se_80-x (x = 10, 15, 20, 25, and 30) were selected to investigate the glass stability according to germanium ratios. The chalcogenide bulks were fabricated by using a traditional melt-quenching method. Thin films were deposited by a thermal evaporation system, maintaining the deposition ratio of 3~5 A in order to have uniformity. The thermal and structural properties were measured by a differential scanning calorimeter (DSC) and X-ray diffraction (XRD). The DSC analysis provided thermal parameters and theoretical glass region stabilities. The XRD analysis supported the theoretical stabilities because of where the crystallization peak data occurred.

In this paper, we analyzed the structural design and electrical characteristics of a 3.3 kV super junction FS IGBT as a next generation power device. The device parameters were extracted by design and process simulation. To obtain optimal breakdown voltage, we researched the breakdown characteristics. Initially, we confirmed that the breakdown voltage decreased as trench depth increased. We analyzed the breakdown voltage according to p pillar dose. As a result of the experiment, we confirmed that the breakdown voltage increased as p pillar dose increased. To obtain more than 3.3 kV, the p pillar dose was 5×10¹³ cm^-2, and the epi layer resistance was 140 Ω. We extracted design and process parameters considering the on state voltage drop.

An IGBT (insulated gate bipolar transistor) device has an excellent current-conducting capability. It has been widely employed as a switching device to use in power supplies, converters, solar inverters, and household appliances or the like, designed to handle high power. The aim with IGBT is to meet the requirements for use in ideal power semiconductor devices with a high breakdown voltage, an on-state voltage drop, a high switching speed, and high reliability for power-device applications. In general, the concentration of the drift region decreases when the breakdown voltage increases, but the on-resistance and other characteristics should be reduced to improve the breakdown voltage and on-state voltage drop characteristics by optimizing the design and structure changes. In this paper, using the T-CAD, we designed the NPT-IGBT (non punch-through IGBT) and FS-IGBT (field stop IGBT) and analyzed the electrical characteristics of those devices. Our analysis of the electrical characteristics showed that the FS-IGBT was superior to the NPT-IGBT in terms of the on-state voltage drop.

In this paper, in order to develop excellent composition ceramics for a piezoelectric energy- harvesting device, we synthesized 0.99(Na_0.52 K_0.443 Li_0.037)(Nb_0.883 Sb_0.08 Ta_0.037)O₃ + 0.01(Sr_0.95 Ca_0.05)TiO₃ + 0.3 wt% Bi₂O₃ + 0.3 wt% Fe₂O₃ + 0.3 wt% CuO (abbreviated as NKN-SCT) ceramics with different sintering times, using the ordinary solid-state reaction method. The effect of sintering time on the microstructure and piezoelectric properties was investigated. The ceramics with the sintering time of 7 h have the optimum values of the piezoelectric constant (d₃₃), piezoelectric voltage constant (g₃₃), planar piezoelectric coupling coefficient (kp), mechanical quality factor (Qm), and dielectric constant (εr): d₃₃= 314 [pC/N], g₃₃= 20.07 [10^-3 mV/N], kp = 0.442, Qm = 93, εr = 1,768, all being suitable for a piezoelectric energy-harvesting device.

In this study, in order to develop composition ceramics for refrigeration device application at a temperature of less than 90°C, a Ba(Ti_1-xZr_x)O₃ composition was fabricated using a conventional solid-state method. Electrocaloric properties of these ceramics were investigated using the characteristics of P-E hysteresis loops in a wide temperature range from room temperature to 150°C. The Curie temperature of Ba(Ti_1-xZr_x)O₃ ceramics decreased with the increase of x. The maximum value of □T = 0.07°C in an ambient temperature of 85°C under 30 kV/cm appeared when x = 0.125. It was concluded that the composition (x = 0.125) ceramics can be used for refrigeration device applications.

In this study, we fabricated a TFT gas sensor with ZnO nanorods grown by hydrothermal synthesis. The suggested devices were compared with the conventional ZnO film-type TFTs in terms of the gas-response properties and the electrical transfer characteristics. The ZnO seed layer is formed by atomic-layer deposition (ALD), and the precursors for the nanorods are zinc nitrate hexahydrate (Zn(NO₃)₂·6H₂O) and hexamethylenetetramine ((CH₂)6N₄). When 15 ppm of NO gas was supplied in a gas chamber at 150°C to analyze the sensing capability of the suggested devices, the sensitivity (S) was 4.5, showing that the nanorod-type devices respond sensitively to the external environment. These results can be explained by X-ray photoelectron spectroscopy (XPS) analysis, which showed that the oxygen deficiency of ZnO nanorods is higher than that of ZnO film, and confirms that the ZnO nanorod-type TFTs are advantageous for the fabrication of high-performance gas sensors.

The effect of particle sizes on the aerosol deposition (AD) of Cu films is investigated in order to understand the deposition behaviors of metal powder during the AD process. The Cu coatings fabricated by using 2 μm Cu powders had a dense microstructure, a high deposition rate (1.6 ± 0.2 μm/min), and low resistance (9.42 ± 0.4 μΩ·cm) compared to that from using Cu powder with a particle size greater than 5 μm. Also, from estimating the internal micro-strain of Cu films, the Cu coatings fabricated by using 2 μm Cu particles exhibited a high micro-strain value of 3.307×10^-3. On the other hand, the strain of Cu coatings fabricated with 5 μm particles was decreased to 2.76×10^-3. These results seem to show that the impacted Cu particles are compressed and flattened by shock waves, and that their bonding is associated with the high internal micro-strain caused by plastic deformation.

This paper proposes a private display that can adjust viewing angles by using an electric-field-driven (EFD) LC Lens. The EFD LC Lens design and simulation were analyzed by using the Extended Jones Matrix Method. The conventional method for attaching a private film to the display was difficult. In order to solve this problem, in this study, by using the EFD LC Lens, we devised a method that can view images more conveniently. We analyzed the luminance and illumination of the optical viewing distance by using the Extended Jones Matrix Method. We also measured the intensity of the viewing angles. The simulation attached the EFD LC Lens to the 14" Full HD RGB stripe wide panel. We calculated the relative luminance distribution and the luminance distribution on the viewing angle of the image at the optimum viewing distance of 60 cm, using the EFD LC Lens and the lenticular lens. The proposed method could be used to design private displays that can adjust the viewing angle of the EFD LC Lens.

Pulverized FeS₂ (pyrite) gives different discharge test results with as-received FeS₂ electrodes. The as-received FeS₂ electrode shows three voltage plateaus during the discharge test. However, the ball-milled FeS₂ electrode shows two voltage plateaus. To interpret this result, the effect of FeS₂ particle size on electrochemical reactions is investigated by unit cell discharge tests, SEM and XRD. As a result, it is found that the transition reaction product (Li₂ + xFe + xS₂) of FeS₂ explains the difference. The as-received FeS₂ reacts according to three reaction steps (FeS₂ → Li₃Fe₂S₄ → Li₂ + xFe₁ + xS₂ → LiFe₂S₄). However, ball-milled FeS₂ reacts without the Li₂ + xFe₁ + xS₂ stage. In this study, this result is explained by the difference in electrochemical reaction mechanism. The as-received FeS₂ has a larger radius than the ball-milled FeS₂. Therefore, the lithium ion has to diffuse into the FeS2 unreacted core, and Li₂ + xFe₁ + xS₂, the transition reaction product of as-received FeS₂, is formed during this stage.

Nowadays, it is increasingly important to detect whether cables are live for the operator`s safety if there is a sudden power failure. It is especially hard to detect the electrical field of an underground line because of shielding. This paper on detection of live-line states in cables studied the detection characteristics of the change in the magnetic field and axis as the frequency, voltage, and distance at the same load are changed using 3 axes. A search coil type was used as a magnetic field sensor with non-contact. We found that magnetic fields decrease proportionally to the square of the distance and the decrease of rated voltage with load effected to magnetic field. The magnetic field was detected by 3-axis sensors given correct proximity, but appeared as noise components beyond a distance of 2 cm.

Recently energy consumption has been increasing because of advances in the industry, and electrical fires have accounted for 31.9% of all fire accidents. An electrical fire is caused by a short circuit, power surge, or poor contact. Safety devices for short circuits or power surges are currently mandatory and can actually detect problems, but arcing caused by contact failure is difficult to detect in advance. This study used an IR sensor to detect the heat concentration caused by the arc. The data from the low-resolution sensor was amplified as much as four times by interpolation to find the exact location of the heat source and were then investigated.