A new junction termination method employing shallow trenches filled with oxide

A new junction termination method employing shallow trenches filled with oxide, which successfully decreased the junction termination area, is proposed and fabricated without any complicated process such as Si-deep etching. Shallow trenches between the floating field limiting rings successfully redistributed the single electric field peak into two peaks so that the breakdown voltage could be increased with the same junction termination area. The experimental results show that the proposed method decreased the junction termination area by more than 25% compared to a conventional field limiting ring structure when breakdown voltages are equal.     

Itraconazole–Laponite: Kinetics and mechanism of drug release

A clay-drug nanohybrid was prepared by interfacial boundary ion exchange reaction, from which the release mechanism of a poorly water soluble drug, itraconazole, was studied systematically. The effect of cation types on drug release was investigated on the basis of a UPS 25 guide line and the effect of Laponite dissolution was also studied at pH = 1.2. To describe the release patterns, mathematical modeling was preformed using first-order, Elovich, parabolic diffusion, and power function equations.     

Complexity‐Reduced Algorithms for LDPC Decoder for DVB‐S2 Systems

This paper proposes two kinds of complexity‐reduced algorithms for a low density parity check(LDPC) decoder. First, sequential decoding using a partial group is proposed. It has the same hardware complexity and requires a fewer number of iterations with little performance loss. The amount of performance loss can be determined by the designer, based on a tradeoff with the desired reduction in complexity. Second, an early detection method for reducing the computational complexity is proposed. Using a confidence criterion, some bit nodes and check node edges are detected early on during decoding. Once the edges are detected, no further iteration is required; thus early detection reduces the computational complexity.     

Controlled release of bovine serum albumin using MPEG–PCL diblock copolymers as implantable protein carriers

MPEG–PCL diblock copolymers consisting of methoxy polyethylene glycol (MPEG) and poly(?‐caprolactone) (PCL) as drug carriers were synthesized by ring‐opening polymerization. It is possible to control the balance between hydrophilic and hydrophobic by changing the MPEG and the ratio of ?‐CL to MPEG. Implantable wafers were easily fabricated by the direct compression method after physical mixing of diblock copolymers and bovine serum albumin–fluorescein isothiocyanate (BSA‐FITC) as a model protein drug. The BSA release from wafers prepared by MPEG–PCL diblock copolymers were higher than that from PCL with the physical blending of MPEG. The wafers prepared by a variety of MPEG–PCL diblock copolymers exhibited the controlled BSA release profiles with a dependence on MPEG–PCL diblock copolymer compositions. In addition, the changing of MPEG and PCL molecular weights within MPEG–PCL diblock copolymer controlled the initial burst of BSA. We confirmed that the diblock copolymers could be served as protein delivery carrier in implantable wafer form. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:1561–1567, 2006     

Fluoride ion cleaning of gas turbine components using PTFE grease

An improved method for fluoride ion cleaning (FIC) utilizing the thermal decomposition of polytetrafluoroethylene (PTFE) powder was developed and applied to oxide scales on narrow deep cracks formed on the surface of gas turbine blades during service exposure. This method is characterized by directly filling-up the cracks with PTFE grease. The results of this improved method were compared with the conventional method. When processed in an FIC reactor using PTFE powder, the surface oxides in the cracks filled with PTFE grease were much better reduced and cleaned than those of unfilled. The difference was more evident at the deep and narrow crack tips, and was well attributed to the wetting and the subsequent capillary action of melted PTFE on the oxide surface in the cracks during the process.     

Motion Error Compensation Method for Hydrostatic Tables Using Actively Controlled Capillaries

To compensate for the motion errors in hydrostatic tables, a method to actively control the clearance of a bearing corresponding to the amount of error using actively controlled capillaries is introduced in this paper. The design method for an actively controlled capillary that considers the output rate of a piezo actuator and the amount of error that must be corrected is described. The basic characteristics of such a system were tested, such as the maximum controllable range of the error, micro-step response, and available dynamic bandwidth when the capillary was installed in a hydrostatic table. The tests demonstrated that the maximum controllable range was 2.4 /im, the resolution was 27 nm, and the frequency bandwidth was 5.5 Hz. Simultaneous compensation of the linear and angular motion errors using two actively controlled capillaries was also performed for a hydrostatic table driven by a ballscrew and a DC servomotor. An iterative compensation method was applied to improve the compensation characteristics. Experimental results showed that the linear and angular motion errors were improved to 0.12 μm and 0.20 arcsec, which were about 1/15^th and l/6^th of the initial motion errors, respectively. These results confirmed that the proposed compensation method improves the motion accuracy of hydrostatic tables very effectively.     

Fabrication of tin oxide film by sol–gel method for photovoltaic solar cell system

Transparent conducting tin(IV) oxide thin films have been developed with a sol–gel method, which is a low-cost process for the electrode materials of solar cell substrate. The precursor solution was made of tin isopropoxide dissolved in isopropyl alcohol. The hydrolysis rate was controlled by the addition of triethanolamine. Dipping and spin-coating technique were applied to coat tin oxide on borosilicate glass. The resistivity of the thin film was lower than 0.01 Ω-cm and the transmittance was higher than 90% in a visible range.     

Fabrication of wavelength-tunable butt-coupled sampled grating DBR lasers using planar buried heterostructure

Planar buried heterostructure (PBH) was adopted to fabricate a sampled grating distributed Bragg reflector laser diode (SGDBR-LD) having a low threshold current and a stable fundamental transverse mode. The etching process for butt-coupling was optimized to improve the reproducibility and the uniformity of the butt-coupled waveguide. The maximum output power of the fabricated SGDBR-LD was 20 mW at 200-mA continuous-wave operation at 25/spl deg/C. The output power was measured 10 and 9 mW higher than those of ridged waveguide (RWG) structure and buried ridge stripe (BRS), and the threshold current was slightly higher than those of RWG and BRS. The spectra of 25 channels spaced 50 GHz within the tuning range of 44.4 nm was obtained by a precise control of SG and phase control currents. The side-mode suppression ratio of more than 35 dB was obtained in the whole tuning range. The output power variation was less than 5 dB, which is 4 dB smaller than that of RWG structure.