An SSD‐Based Storage System for an Interactive Media Server Using Video Frame Grouping

For real‐time interactive multimedia operations, such as video uploading, video play, fast‐forward, and fast‐rewind, solid state disk (SSD)‐based storage systems for video streaming servers are becoming more important. Random access rates in storage systems increase significantly with the number of users; it is thus difficult to simultaneously serve many users with HDD‐based storage systems, which have low random access performance. Because there is no mechanical operation in NAND flash‐based SSDs, they outperform HDDs in terms of flexible random access operation. In addition, due to the multichannel architecture of SSDs, they perform similarly to HDDs in terms of sequential access. In this paper, we propose a new SSD‐based storage system for interactive media servers. Based on the proposed method, it is possible to maximize the channel utilization of the SSD's multichannel architecture. Accordingly, we can improve the performance of SSD‐based storage systems for interactive media operations.     

Reverse‐Conducting IGBT Using MEMS Technology on the Wafer Back Side

In this paper, we present a 600‐V reverse conducting insulated gate bipolar transistor (RC‐IGBT) for soft and hard switching applications, such as general purpose inverters. The newly developed RC‐IGBT uses the deep reactive‐ion etching trench technology without the thin wafer process technology. Therefore, a freewheeling diode (FWD) is monolithically integrated in an IGBT chip. The proposed RC‐IGBT operates as an IGBT in forward conducting mode and as an FWD in reverse conducting mode. Also, to avoid the destructive failure of the gate oxide under the surge current and abnormal conditions, a protective Zener diode is successfully integrated in the gate electrode without compromising the operation performance of the IGBT.     

A New Digital Sense Multiple Access (DSMA) Protocol for High-Speed Wireless Networks

In this paper, we propose a new digital sensemultiple access with delayed transmission (DSMA/DT)protocol for reverse channel in high-speed wirelessnetworks. The new protocol is motivated by theobservation that the existing DSMA protocol does not yieldsatisfactory throughput for long round-trip propagationand processing delay, which occurs in outdoor high-speedenvironments or when the receiver hardware requires long signal processing time. The newDSMA/DT protocol is intended to reduce the performanceimpacts of the round-trip delay. Look-ahead busy/idleflag, seizure queueing, and reserved time slots are also devised for the new protocol. Whilerequiring at most two additional status bits on theforward channel and no additional hardware capability,these features further enhance the protocol performance and enable constant-bit-rate service withlittle added complexity in control. The channelthroughput of the DSMA/DT protocol and the optionalfeatures are analyzed. Closed-form expressions for thethroughput are obtained. For non-negligible round-tripdelay relative to packet transmission time, ournumerical results show that the new protocol improvesthe throughput by as much as 60% when compared to theexisting DSMA protocol. For superior performance andsimplicity, the DSMA/DT protocol will be appropriate foruse in high-speed wireless networks.     

The dynamic response analysis of a pyroelectric thin-film infraredsensor with thermal isolation improvement structure

Both theoretical and experimental studies of the substrate effect on the thermal behavior of a PbTiO₃ infrared (IR) sensor have been reported. With active cantilever dimensions of 200×100×5 μm³ formed by etching processes, the pyroelectric micro-electro-mechanical system (pyro/MEMS) structure exhibits a much superior performance to that of a traditional IR-sensing bulk structure under the 800-μW incident optical light with wavelength of 970 nm. Two-order improvement in current responsivity is obtained for the pyro/MEMS structure. This shows the substrate effect on the performance of a pyro/MEMS IR sensor is very significant. A simple model has also been proposed to illustrate the substrate effect more comprehensively     

High-nonlinearity fiber optical parametric amplifier with periodicdispersion compensation

Theory shows that the maximum gain and bandwidth of one-pump fiber optical parametric amplifiers made from high-nonlinearity fiber, operated with a pump wavelength λ_p far from the fiber zero-dispersion wavelength λ₀ can greatly be improved by periodic dispersion compensation. We have performed experiments and obtained good agreement with theory: for λ_p=1542 and λ₀=1591 nm, we have increased the bandwidth from 7 to 28 nm, and the maximum gain from 15 to 20 dB, by splicing three pieces of standard fiber at regular intervals in a 40-m long nonlinear fiber     

Noise limit in heterodyne Interferometer demodulator for FBG-based sensors

This paper reports the results of a recent investigation on the noise-limited performance in heterodyne interferometric demodulation systems for fiber Bragg grating strain sensors. Theoretical and simulation results are presented and compared with experimental results.     

Optimization of the Ni(P) Thickness for an Ultrathin Ni(P)-Based Surface Finish in Soldering Applications

The effects of the Ni(P) thickness δ _Ni(P) on the interfacial reaction between an Sn-3Ag-0.5Cu solder and an Au/Pd(P)/Ni(P)/Cu pad (thickness: 0.05/0.05/0.1–0.3/20 μm) and the resulting mechanical properties were investigated using scanning electron microscopy equipped with an electron backscatter diffraction system, a focused ion beam system, electron probe microanalysis, and high-speed ball shear (HSBS) testing. Regardless of δ _Ni(P), all of the Au/Pd(P)/Ni(P) surface finishes examined were completely exhausted in one reflow, exposing the Cu pad underneath the solder. Cu₆Sn₅ dissolved with various Ni contents, termed (Cu,Ni)₆Sn₅, was the dominant intermetallic compound (IMC) species at the solder/Cu interface. Additionally, Ni₂SnP and Ni₃P IMCs might form with the (Cu,Ni)₆Sn₅ in the thick Ni(P) case, i.e., δ _Ni(P) = 0.3 μm, and the two IMCs (Ni₂SnP and Ni₃P) were gradually eliminated from the interface after multiple reflows. A mass balance analysis indicated that the growth of the Ni-containing IMCs, rather than the dissolution of the metallization pad, played a key role in the Ni(P) exhaustion. The HSBS test results indicated that the mechanical strength of the solder joints was also δ _Ni(P) dependent. The combined results of the interfacial reaction and the mechanical evaluation provided the optimal δ _Ni(P) value for soldering applications.     

Development of a microelectromechanical system pressure sensor for rehabilitation engineering applications

Based on computer finite-element analysis ANSYS 5.3 and microelectromechanical systems (MEMS) technologies, a micropressure sensor was designed and fabricated. The sensor can be used to measure the distribution of normal stress between soft tissues on an above-knee amputee's skin and the contacting surface of a rehabilitation device. A square membrane with dimensions 2400 µm × 2400 µm × 80 µm is formed by backside photolithography and wet etching of an n-type ?100? monolithic silicon wafer. On the middle of the membrane edge, an X-shaped silicon wafer was implanted with boron ions and then enhanced by diffusion to form a piezoresistive strain gauge. In the design process, a finite-element method is used to analyse the effects of pressure sensitivity and its temperature coefficients. The developed micropressure sensors, which have smaller weight and volume than a conventional machine type, perform well and fit our design specifications.     

A low-power 2/5.8-GHz dual-wide-band CMOS LC-VCO with switched-inductor technique

A fully integrated dual-band LC voltage control oscillator, designed in a 0.18-µm CMOS technology for 5.8-GHz/2.0-GHz wireless communication applications, is described. The frequency band switching is accomplished with switched-inductor technique. The dual-band oscillator can be operated in 5.38–6.23?GHz and 1.78–2.07?GHz with 15% frequency tuning range. Two different inductors are used for the frequency band switching. Frequency tuning is implemented by varying the capacitance of a MOS varactor. The measured phase noise is ?109?dBc/Hz @ 1?MHz and ?112?dBc/Hz @ 1?MHz for frequency at 5.8?GHz and 2?GHz, respectively. This oscillator is fabricated in UMC's 0.18-µm one-poly-six-metal 1.8?V process. The power dissipation of this dual-band VCO is 11.7 and 9.3?mW for oscillation frequency of 2?GHz and 5.8?GHz, respectively.     

Optimization of polymer light emitting devices using TiOx electron transport layers and prism sheets

The internal and external efficiency of polymer light emitting devices were found can be simultaneously improved by insertion a high refractive index material, titanium oxide (TiO_x), to the emission layer and a prism sheet attached to the substrate. The TiO_x layer increased the internal efficiency due to a better electron injection and hole confinement. However, it led a wider angular emission profile with more photons trapped in the substrate. By using the prism sheet, those trapped light was efficiently coupled to the air. The extraction efficiency enhancement was increased from 33.1% to 54.4% and the overall current efficiency was improved up to 86%.