A new fabrication method employing two-step trench etching and twice self-alignment technique was developed to obtain high cell density trench power MOSFETs by using only three mask steps. This method was implemented to increase cell density, to decrease on-resistance and to improve leakage current characteristics. The trench DMOSFETs with 1.6 μm cell pitch and 140 Mcell/in2 cell density were fabricated. The specific on-resistance of the device is about 0.48 mΩ˖cm2 with the breakdown voltage of 43 V.

Wireless power transfer (WPT) is the technology that forces the power to transmit electromagnetic field to an electrical load through an air gap without interconnecting wires. This technology is widely used for the applications from low power smartphone to high power electric railroad. In this paper, the model of wireless power transfer circuit for the low power system is designed for a resonant frequency of 13.45 MHz. Also, a feedback WPT circuit is proposed, and the methodology for power efficiency improvement is studied as the coupling coefficient increases above 0.01, at which the split frequency is made.

This paper demonstrates the performance of a metal-substrate power module with multiple fabricated chips for a high current electrical application, and evaluates the proposed module using a 1.5-kW sinusoidal brushless direct current (BLDC) motor. Specifically, the power module has a hybrid structure employing a single-layer heat-sink extensible metal board (Al board). A fabricated motor driver IC and trench gate DMOSFET (TDMOSFET) are implemented on the Al board, and the proper heat-sink size was designed under the operating conditions. The fabricated motor driver IC mainly operates as a speed controller under various load conditions, and as a multi-phase gate driver using an N-ch silicon MOSFET high-side drive scheme. A fabricated power TDMOSFET is also included in the fabricated power module for three-phase inverter operation. Using this proposed module, a BLDC motor is operated and evaluated under various pulse load tests, and our module is compared with a commercial MOSFET module in terms of the system efficiency and input current.

This work proposes high performance of permanent-magnet synchronous motor (PMSM) driver IC integrated with position sensorless scheme and current sensing circuits. The position sensorless scheme is adapted with digital sliding mode observer (SMO) method that has high robust characteristics of motor parameter variations. For current sensing circuits, 10-bit successive approximation (SAR) analog-to-digital converters (ADC) and various (1~16) gain amplifiers are implemented in the fabricated IC. The proposed PMSM driver IC is fabricated with 0.18um BCD process. Compared with the commercial module, with the accurate SMO scheme, a speed error is reduced to 0.7% at 3000rpm and a system efficiency is increased to 1.9 % at 3000rpm, 5N·m. The high precision position estimating driver IC is achieved without any position/current sensors.

The sensing materials of potentiometric CO2 sensors utilize alkali/alkali-earth metal carbonates or their combinations. However, lithium carbonate easily responds to humidity resulting in incorrect information regarding CO2 concentration. Herein, the authors report a new sensing material combination (Li2CO3/BaCO3/LiOH/Ba(OH)(2) (1:2:0.05:0.1 molar ratio)) for a potentiometric CO2 sensor that is not affected by humidity. The electromotive force (EMF) of the sensor using a combination of Li2CO3, BaCO3, LiOH, and Ba(OH)(2) drifted by 1.5% when the relative humidity was changed from 25% to 70%, which is superior to a drift of 6% of a sensor using Li2CO3 and BaCO3, as this sensing material is known to be robust to changes in humidity.

Zirconia matrix ZrO2/CNT composite materials reinforced with multiwall carbon nanotubes were fabricated using a spark plasma sintering technique. The effects of the amount of CNTs addition, sintering temperature and sintering pressure on the properties of the resulting ZrO2/CNT composites were examined. 0 to 9 vol. % CNTs were dispersed in zirconia powder, and the resulting mixture was sintered. The electrical conductivity, hardness, flexural strength, and density were measured to characterize the composites. The friction and wear properties of the composites were also tested. The flexural strength and friction coefficient of the composites were improved with up to 6 vol.% of CNT addition and the flexural strength showed a close relationship with the relative density of the composite. The electrical conductivity increased with increasing proportion of the CNTs, but the efficiency was reduced at more than 6 vol.% CNTs.

In this study, we report the synthesis and characterization of novel hybrid nanocoating based on carbon nanotubes (CNTs) on anodized aluminum surfaces (AAO). The hybrid nanocoating was deposited by number of methods which include spray coating, spin coating and dip coating. The bonding of nanocoating with metal surface is an important parameter for successful modification of the metal surfaces. The improved adhesion of nanocoating on metal surfaces could be attributed to chemical bonding of sol-gel nanocoating with anodized surfaces. The nanocoated anodized aluminum surfaces showed superior adhesion and excellent anticorrosive properties. The nanocoated panels showed enhanced galvanic protection comparable to 80% of titanium metal as determined by galvanic corrosion measurements. It also showed higher thermal conductivities than stainless steel and bare anodized surfaces.

Boron-doped diamond (BDD) has been attracting special attentions as a suitable electrode material for water disinfection due to its high chemical and electrochemical stability. In this paper, we had succeeded to generate ozone by using the BDD electrode with high efficiency and more safely compared to traditional lead oxide (PbO2) electrode. The BDD film was deposited on the Ti substrate by microwave plasma chemical vapor deposition to use as an anode for ozone kit. The morphology of samples were observed by Scanning Electron Microscopy (SEM) and the structural-chemical properties of synthesized diamond layer was investigated by Raman Spectroscopy. Conductivity, carrier concentration and Hall mobility was determined by a Hall-effect measurement unit, based on the van der Pauw method. The Ozone concentration in water, which was measured by Ozone Colorimeter.