The effect of subarray size (equal to the order of the prediction model plus one) on the estimation performance of a previously proposed forward-backward linear prediction (FBLP) based cyclic method is investigated. This method incorporates an overdetermined FBLP model with a subarray scheme and is used to estimate the directions-of-arrival (DOAs) of coherent cyclostationary signals impinging on a uniform linear array (ULA) from the corresponding polynomial or spectrum formed by the prediction coefficients. However, the decorrelation is obtained at the expense of a reduced working array aperture, as it is with the spatial smoothing (SS) technique. In this paper, an analytical expression of the mean-squared-error (MSE) of the spectral peak position is derived using the linear approximation for higher signal-to-noise ratio (SNR). Then the subarray size that minimizes this approximate MSE is identified. The effect of subarray size on the DOA estimation is demonstrated and the theoretical analysis is substantiated through numerical examples.

We investigated the electrical properties of hole transport materials such as TPD, α-NPD and m-MTDATA using in-situ field effect measurement. TPD, α-NPD and m-MTDATA films showed p-type semiconducting properties, and their electrical parameters such as conductivity, carrier mobility and carrier concentration were obtained. We also examined the effect of the substrate temperature during vacuum deposition and the thermal treatment after deposition, on the electrical parameters of the films. Experimental results showed that conductivity and carrier mobility decreased as the substrate temperature increased over the glass transition temperature. These decreases in conductivity and carrier mobility as a result of thermal treatment appear to be strongly related to the degradation mechanism of organic electroluminescent devices.

An all-or-nothing transform (AONT), which has been proposed by Rivest, is one of encryption modes. The AONT is intended to increase the cost of brute-fore attacks on a block cipher. This paper provides the revised definition of an unconditionally secure AONT, and shows the instance of an optimal unconditionally secure AONT. In addition, we propose a computationally secure AONT such that any information on a message cannot be obtained regardless of the position of the lost block due to a linear code.

We report some leading research on superconducting devices in Taiwan. Research includes thin films, Josephson junctions, junction arrays and resonators etc. In device physics characteristics of Josephson junctions, junction array, and SQUIDs are reported. Applications of SQUIDs include: (1) studies of brain activities (magnetoencenphalogram) using multichannel low Tc SQUIDs system; (2) detection of weak magnetic fields (magnetocardiogragh, etc. ) using high-Tc SQUIDs; (3) nondestructive evaluation (NDE) of deep flaws using high-Tc SQUIDs. Research projects in the future in our group are briefly reported.

We report our studies on the spectral sensitivity of superconducting NbN thin-film single-photon detectors (SPD's) capable of GHz counting rates of visible and near-infrared photons. In particular, it has been shown that a NbN SPD is sensitive to 1.55-µm wavelength radiation and can be used for quantum communication. Our SPD's exhibit experimentally measured intrinsic quantum efficiencies from 20% at 800 nm up to 1% at 1.55-µm wavelength. The devices demonstrate picosecond response time (<100 ps, limited by our readout system) and negligibly low dark counts. Spectral dependencies of photon counting of continuous-wave, 0.4-µm to 3.5-µm radiation, and 0.63-µm, 1.33-µm, and 1.55-µm laser-pulsed radiations are presented for the single-stripe-type and meander-type devices.

We report our studies on electrical current pulse perturbation of superconducting YBa2Cu3O7-x (YBCO) epitaxial thin films. When a current pulse is applied to a YBCO microbridge, a voltage develops across it that depends on the amplitude of the input current pulse. For a total current (input current pulse plus the dc bias) that is lower than the critical current Ic, an inductive voltage response is observed. When the total current exceeds Ic, a resistive response is generated and is observed after a certain delay time td. The origin of the resistive response was analyzed using the Geier and Schon model, which is based on the time-dependent Ginzburg-Landau equation. Our experimental samples consisted of 200-nm-thick epitaxial YBCO films, patterned into coplanar-strip (CPS) transmission lines, containing either two-microbridge or single-microbridge test structures. For the two-microbridge samples, a train of 100-fs-duration optical pulses was used to excite the larger microbridge and generate 2-ps-duration electrical pulses, which were then applied to perturb the smaller microbridge, which was independently biased in the superconducting state. In this case, an electro-optic sampling system was used to measure the YBCO kinetic-inductive voltage responses with the picosecond time resolution. For the single-microbridge structures, an electronic pulse generator was employed to supply the input current pulse, and a 14-GHz sampling oscilloscope was used to monitor the microbridge responses. The latter signals were in very good agreement with the model of Geier and Schon, assuming that the quasiparticle dynamics process that resulted from the nanosecond-wide current excitation was bolometric and followed the phonon escape time τes.

Existing byte error control codes require too many check bits if applied to a memory system that uses recent semiconductor memory chips with wide I/O data such as 16 or 32 bits, i.e., b=16 or 32. On the other hand, semiconductor memory chips are highly vulnerable to random double bit within a memory chip errors when they are used in some applications, such as satellite memory systems. Under this situation, it becomes necessary to design suitable new codes with double bit within a chip error correcting capability for computer memory systems. This correspondence proposes a class of codes called Double bit within a block Error Correcting - Single b-bit byte Error Correcting ((DEC)B-SbEC) codes where block and byte correspond to memory chip and memory sub-array data outputs, respectively. The proposed codes provide protection from both random double bit errors and single sub-array data faults. For most of the practical cases, the (DEC)B-SbEC codes presented in this correspondence have the capability of accommodating the check bits in a single dedicated memory chip.

The authors have developed V-band high electron mobility transistor (HEMT) MMICs adopting benzo-cyclo-butene (BCB) thin-film layers on GaAs substrates. Since the BCB thin-film layers, which can change the thickness of arbitrary parts on a circuit, are used for these MMICs, both a thin-film microstrip (TFMS) line, offering the advantages of great flexibility in layout and small size, and a coplanar waveguide (CPW), offering the advantage of low loss, can be used according to the purpose of the MMIC. Here we introduce the four types of V-band MMICs that we fabricated: low noise amplifier (LNA), mixer, voltage controlled oscillator (VCO), and power amplifier (PA). The optimum transmission lines were chosen from the TFMS line and the CPW for these MMICs. Miniaturization of the LNA MMIC and the mixer MMIC were attained by adopting the TFMS line, whereas adoption of the CPW enabled the VCO MMIC to achieve high performance. These results indicate that it is important to choose the optimum transmission line according to the purpose of the circuit function for each MMIC. It was confirmed that these newly developed MMICs using the BCB thin-film dielectric layers are attractive for millimeter-wave applications.

Employing reactive sputtering using an electron-cyclotron-resonance microwave plasma without oxidation process, high coercivity ferrite thin-films with perpendicular magnetic anisotropy were successfully prepared without NiO underlayer at low substrate temperature. The ferrite thin-film deposited on glass substrate had smooth surface and were composed of small grains. Perpendicular recording was performed on the ferrite thin-film hard disk. The ferrite thin-films with high coercivity could be prepared on flexible film substrates (Polyimide and PET).

This paper describes the implementation of a proposed image filter into a Discrete-Time Cellular Neural Network (DT-CNN). The three stages that compose the filter are described, showing that the resultant filter is capable of (1) erasing or detecting several concentric shapes simultaneously, (2) thresholding and (3) thinning of gray-scale images. Because the DT-CNN has to fill certain conditions for this filter to be implemented, it becomes a modified version of a DT-CNN. Those conditions are described and also experimental results are clearly shown.

Microstructures of CoCr-alloy thin film media were investigated by cross-sectional transmission electron microscopy focussing on the initial growth region of the magnetic layer grown on nonmagnetic underlayers. An introduction of nonmagnetic hcp-CoCrRu layer between an hcp-CoCrPt recording layer and an hcp- or a bcc-underlayer improved the crystallographic quality of the initial growth region. Sharp compositional distributions of alloying elements at the interfaces of a CoCrPt/CoCrRu/CrTi perpendicular medium and a CoCrPt/CoCrRu/CrTi longitudinal medium were respectively confirmed by electron energy loss spectroscopy employing a finely focussed electron beam. Coercivity and squareness of the thin film media increased by realizing good hetero-epitaxy between the nonmagnetic and the magnetic hcp-layers.

Magnetoplumbite type Ba ferrite (BaM) disks were prepared on Pt and Pt-Ta underlayers using facing targets sputtering apparatus. Pt underlayers are more effective than ZnO underlayers to promote c-axis orientation of BaM layers, especially for extremely thin BaM films. Pt-Ta underlayer was used to decrease the grain size of BaM layers. BaM/Pt-Ta disks revealed larger S/N ratio than BaM/Pt disks because of their larger signal output and lower media noise level. BaM disks with 50 nm thick BaM layers revealed lower noise level and larger S/N ratio than that with 100 nm thick BaM layers due to smaller grain size.

This paper examines similarities between the Decision Diffie-Hellman (DDH) assumption and the Quadratic Residuosity (QR) assumption. In addition, we show that many cryptographic protocols based on the QR assumption can be reconstructed using the DDH assumption.

Triple-layer CoCrPt magnetic thin films with different bias configurations were fabricated by DC magnetron sputtering on CrV and glass substrate. In-plane coercivity (Hc) showed an increase for those films with bias sputtered CoCrPt layer. The in-plane coercivity (Hc) was optimized in NB-B-NB type film prepared with substrate heating at 300C (NB: no bias and B: rf bias applied in sputtering). Better in-plane crystal texture was observed in NB-B-NB type film by XRD and this is believed to be the main reason for the coercivity improvement. The other resource for the coercivity improvement was due to the decoupling of intergrain magnetic interactions. This was discussed accordingly to the results obtained from TEM, MFM and SIMS depth profiling.

Co-ferrite thin films have been fabricated on Corning glass substrates by a chelating sol-gel process. Structural and magnetic properties of the films have been studied as a function of annealing temperature using an X-ray diffraction (XRD) and a vibrating sample magnetometer. XRD results revealed that most of the Co-ferrite grains were randomly oriented. Rapid annealing (RA) and standard annealing (SA) processes were used for the variation of heat treatment and the characteristic comparison. Coercivity was changed with the thermal condition and the magnetization increased with the soaking time. With prolonged soaking time, however, the coercivity decreased due to the diffusion of cations from the glass substrate. RA in the preparation of Co-ferrite thin films was effective for preventing interdiffusion at interfaces and for forming a single phase in the case of reduced soaking time. A yttria stabilized zirconia (YSZ) buffer layer between the Co-ferrite layer and the substrate was effective for improving the magnetic properties of the films at higher temperatures. It was observed that Co-ferrite thin films were composed of grains typically 35 nm in size and their rms roughness was approximately 1.3 nm. The saturation magnetization of the thin films by subjected to rapid annealing at 900C for 150 seconds was 400 emu/cm3 and the coercivity of the films was approximately 3000 Oe.

An optimization of the smoothing preprocessing for the correlated signal parameter estimation was considered. Although the smoothing factor (the number of subarrays) is a free parameter in the smoothing preprocessing, a useful strategy to determine it has not yet been established. In this paper, we investigated thoroughly about the smoothing factor and also proposed a new scheme to optimize it. The proposed method, using the smoothed equivalent diversity profile (SED profile), is able to evaluate the effect of smoothing preprocessing without any a priori information. Therefore, this method is applicable in the real multipath parameter estimation.

Medium noise is the dominant noise in ultrahigh density disk recording systems. The peak, width and jitter noise are analyzed by micromagnetic simulations. Four different media, with a fixed grain size of 135 and a coercivity of 2900 Oe, are chosen for medium noise analysis. The linear recording density is increased from 340 KFCI (Kilo flux-changes per inch) to 750 KFCI, while the area density goes up from 14.3 Gb/in2 to 31.5 Gb/in2. The peak-amplitude noise is studied by the distribution of the peak magnetization Mp in each bit. The distribution of Mp develops from a delta-function around the remanence Mr at low densities to a flat distribution at extremely high densities. It is found that the transition a-parameter is no longer proportional to the square root of Mrδ, as given in the William-Comstock approximation. The peak-jitter noise in the read back voltage is analyzed by the percentage of the transition jitter in a bit length.

In this paper we report on the modeling and simulation of tunneling current in MOS devices including quantum mechanical effects. The simulation model features an original scheme for the self-consistent solution of Poisson and Schrodinger equations and it is used for the extraction of the oxide thickness, by fitting CV curves, and the calculation of the tunneling current. Simulations and experiments are compared for different device types and oxide thicknesses (1.5-6.5 nm) showing good agreement and pointing out the importance of quantum mechanical modeling and the presence of many tunneling mechanisms in ultra-thin oxide MOS devices.

Layered Multicomposites by Sequential Adsorption (LAMSA) is layer by layer approach for ultrathin film fabrication that has been applied to a variety of organic and inorganic materials. In this paper, we present our objectives and work on the fabrication and modification of display devices and sensors primarily using LAMSA techniques. The term supramolecular layer assembly denotes the selective incorporation of processing techniques, layer configuration and molecular ordering that is achieved within planar devices. The first application involves modifying a polymer light emitting diode (PLED) device fabricated using the ITO/MEH-PPV/Ca protocol with ultrathin polyaniline derivatives. The second example involves photoinduced alignment in a hybrid LC cell configuration using polarized light with azo dye/polyelectrolyte ultrathin films. A supramolecular concept on substrates for opto- bioelectronic sensor configurations is described.

Layer-by-layer sequential adsorption process of polyelectrolytes had conventionally been used for the fabrication of the ultra-thin organic film formed by various polymers with different polarity of charge. In this study, hydrophobic Ruthenium complex monomer (tris (bilyridyl) ruthenium (II) hexafluorophosphate) was micelle-wrapped with an anionic surfactant, sodium dodecylbenzenesulfonate, and was assembled with PAH (poly (allylamine hydrochloride)) which has the opposite charge on ITO substrates. With this method, we succeed in fabricating ultra-thin organic films even when the adsorption material is not polymer but monomer. Moreover it was found that the bilayer thickness of the self-assembled (Ru micelle/PAH) was systematically changed by adjusting the solution pH of each bath. By using this process, EL device was fabricated by depositing the thin film of micelle-wrapping ruthenium complex monomer on ITO and formed Bi electrode on top of the film. Light emission was observed by applying voltage to this device.