HyongSoon KIM PyungSoo KIM SangKeun LEE
In this letter, a new estimation filtering is proposed when a delay between signal generation and signal estimation exists. The estimation filter is developed under a maximum likelihood criterion using only the finite observations on the delay interval. The proposed estimation filter is represented in both matrix form and iterative form. It is shown that the filtered estimate has good inherent properties such as time-invariance, unbiasedness and deadbeat. Via numerical simulations, the performance of the proposed estimation filtering is evaluated by the comparison with that of the existing fixed-lag smoothing, which shows that the proposed approach could be appropriate for fast estimation of signals that vary relatively quickly. Moreover, the on-line computational complexity of the proposed estimation filter is shown to be maintained at a lower level than the existing one.
Thinning and line extraction of binary images not only reduces data storage amount, automatically creates the adjacency and relativity between line and points but also provides applications for automatic inspection systems, pattern recognition systems and vectorization. Based on the features of construction drawings, new thinning and line extraction algorithms were proposed in this study. The experimental results showed that the proposed method has a higher reliability and produces better quality than the various existing methods.
Erin-Ee-Lin LAU Wan-Young CHUNG
A novel RSSI (Received Signal Strength Indication) refinement algorithm is proposed to enhance the resolution for indoor and outdoor real-time location tracking system. The proposed refinement algorithm is implemented in two separate phases. During the first phase, called the pre-processing step, RSSI values at different static locations are collected and processed to build a calibrated model for each reference node. Different measurement campaigns pertinent to each parameter in the model are implemented to analyze the sensitivity of RSSI. The propagation models constructed for each reference nodes are needed by the second phase. During the next phase, called the runtime process, real-time tracking is performed. Smoothing algorithm is proposed to minimize the dynamic fluctuation of radio signal received from each reference node when the mobile target is moving. Filtered RSSI values are converted to distances using formula calibrated in the first phase. Finally, an iterative trilateration algorithm is used for position estimation. Experiments relevant to the optimization algorithm are carried out in both indoor and outdoor environments and the results validated the feasibility of proposed algorithm in reducing the dynamic fluctuation for more accurate position estimation.
Jong-Hwan OH Byoung-Ju YUN Se-Yun KIM Kil-Houm PARK
The TFT-LCD image has non-uniform brightness that is the major difficulty of finding the visible defect called Mura in the field. To facilitate Mura detection, background signal shading should level off and Mura signal must be amplified. In this paper, Mura signal amplification and background signal flattening method is proposed based on human visual system (HVS). The proposed DC normalized contrast sensitivity function (CSF) is used for the Mura signal amplification and polynomial regression (PR) is used to level off the background signal. In the enhanced image, tri-modal thresholding segmentation technique is used for finding Dark and White Mura at the same time. To select reliable defect, falsely detected invisible region is eliminated based on Weber's Law. By the experimental results of artificially generated 1-d signal and TFT-LCD image, proposed algorithm has novel enhancement results and can be applied to real automated inspection system.
Preeti SHARMA Shiban K. KOUL Sudhir CHANDRA
This letter reports a high-performance Ka-band equilateral triangular microstrip patch (ETMP) antenna suspended on a thin dielectric membrane. The membrane is released using a silicon bulk-micromachining technique. A set of closed-form expressions to calculate the resonant frequency of the proposed antenna on the micromachined substrate is also presented. The measured performance of the antenna structure is verified using the finite element method (FEM) based Agilent High Frequency Structure Simulator (version 5.5). The fabricated antenna exhibited a wide -10 dB return loss bandwidth of 1.2 GHz at 35.4 GHz. The measured antenna cross-polarization level is less than -15 dB in both the E- and H-planes.
Masakazu AOKI Shin-ichi OHKAWA Hiroo MASUDA
Random variations in Id-Vg characteristics of MOS transistors in an LSI chip are shown to be concisely characterized by using only 3 transistor parameters (Vth, β0, vSAT) in the MOS level 3 SPICE model. Statistical analyses of the transistor parameters show that not only the threshold voltage variation, ΔVth, but also the current factor variation, Δβ0, independently induces Id-variation, and that Δβ0 is negatively correlated with the saturation velocity variation, ΔvSAT. Using these results, we have proposed a simple method that effectively takes the correlation between parameters into consideration when creating statistical model parameters for designing a circuit. Furthermore, we have proposed a sensitivity analysis methodology for estimating the process window of SRAM cell operation taking transistor variability into account. By applying the concise statistical model parameters to the sensitivity analysis, we are able to obtain valid process windows without the large volume of data-processing and long turnaround time associated with the Monte Carlo simulation. The process window was limited not only by ΔVth, but also by Δβ0 which enhanced the failure region in the process window by 20%.
Orthogonal frequency-division multiplexing (OFDM) systems often use a cyclic prefix (CP) to simplify the equalization design at the cost of bandwidth efficiency. To increase the bandwidth efficiency, we study the blind equalization with linear smoothing [1] for single-input multiple-output (SIMO) OFDM systems without CP insertion in this paper. Due to the block Toeplitz structure of channel matrix, the block matrix scheme is applied to the linear smoothing channel estimation, which equivalently increases the number of sample vectors and thus reduces the perturbation of sample autocorrelation matrix. Compared with the linear smoothing and subspace methods, the proposed block linear smoothing requires the lowest computational complexity. Computer simulations show that the block linear smoothing yields a channel estimation error smaller than that from linear smoothing, and close to that of the subspace method. Evaluating by the minimum mean-square error (MMSE) equalizer, the block linear smoothing and subspace methods have nearly the same bit-error-rates (BERs).
Tae-Won OH Hak-Kyu LEE Chang-Hee LEE
We demonstrate a wavelength division multiplexing passive optical network (WDM-PON) based on wavelength-locked Fabry-Perot laser diodes and thin-film filters. Twelve Fast Ethernet signals are bi-directionally transmitted over the multi-branch optical distribution network (ODN). The ODN has distributed branch nodes and bus networks.
Chan-Sei YOO Ji-Min MAENG Sang-Sub SONG Kwang-Seok SEO Woo-Sung LEE
This paper presents the ultrawideband filters for UWB fullband (range of 3.1-10.6 GHz) applications. This filter consists of ring filter for wide-bandwidth and coupled line structure for suppressing unwanted passband in upper and lower stopbands. Especially, the filter structure was realized on silicon substrate using thin film technology, adequate for wafer level packaging, which can be integrated with CMOS UWB chipset that is currently on development. To minimize the dimension of the filter, the Hilbert structure was applied in ring filter and the meander shaped broadside coupled structure was also adopted in the coupled line structure. The size of the fully realized filter structure is 4.43.6 mm2. The insertion loss in passband is 1.5 dB and the return loss is larger than 15 dB, respectively. The group delay in center frequency is 0.2 ns and the group delay variation is less than 0.15 ns.
Manabu ITO Masato KON Chihiro MIYAZAKI Noriaki IKEDA Mamoru ISHIZAKI Yoshiko UGAJIN Norimasa SEKINE
We demonstrate a novel display structure for color electronic paper for the first time. Fully transparent amorphous oxide TFT array is directly deposited onto color filter array and combined with E Ink Imaging Film. Taking advantage of the transparent property of the oxide TFT, the color filter and TFT array are positioned at the viewing side of the display. This novel "Front Drive" display structure facilitates the alignment of the color filter and TFT dramatically.
Panarat CHERNTANOMWONG Jun-ichi TAKADA Hiroyuki TSUJI
Although subspace-based methods for estimating the Angle of Arrival (AOA) require a precise array response to achieve highly accurate results, it is difficult to obtain this response in practice even though the antennas are calibrated. Therefore, a method of compensating for errors in calibration is required. This paper proposes a procedure to enable precise AOA estimates to be obtained in a real system by applying array calibration and spatial smoothing preprocessing (SSP). Measured data were collected from experiments using two scenarios, i.e., in an anechoic chamber and at an open site, where a single source signal arrived at the array antenna. All measured data were then calibrated by using data obtained at 0 deg in an anechoic chamber before the AOAs were estimated. Nevertheless, errors in the array response remained after calibration because errors in the AOA estimates could still be observed. SSP was then applied to the calibrated data to obtain more accurate AOA estimates. We found that SSP can reduce the random error in an array response obtained in a real system, leading to reduced errors in AOA estimates in the observed data. To generalize the problem that SSP can reduce random perturbation in the array response, simple expressions are illustrated and verified by Monte-Carlo simulation. Random gain and phase errors in the array response are only considered in this paper and ESPRIT was used to estimate the AOAs.
Ujjwal NEUPANE Motoki MIURA Tessai HAYAMA Susumu KUNIFUJI
The problem with traditional Brain Writing (BW) is that the users are restricted from viewing all sets of ideas at one time; and they are also restricted from writing down more than three ideas at a time. In this research we describe distributed experimental environment for BW which was designed to obtain better results and can thus eliminate the problems of traditional BW technique. The actual experimental system is an integration of three BW modes with mutually different features and characters. We conducted three different tests implementing this environment, and confirmed quality and quantity of ideas generated by three different groups. It was confirmed that unrestricted inputs are effective in generating a large quantity of ideas, whereas limiting the number of sharable/viewable ideas shows better tendency in some aspects. However, qualitative evaluation results were not confirmed as different functions show variant results. The evaluation of the functions that support viewing and sharing of ideas show that synergy is not always an advantage in generating ideas. The results of number of ideas in correlation with time show that 20 minutes time was appropriate to conduct BW in distributed environment.
Natsumi ENDO Hiroyoshi YAMADA Yoshio YAMAGUCHI
Direction of arrival estimation of coherent multipath waves by using superresolution technique often requires decorrelation preprocessings. Spatial smoothing preprocessings are the most popular schemes as the techniques. In mobile environment, position change of the target/transmitter often brings us decorrelation effect. In addition, multiple signals transmitted by an antenna array, such as a MIMO transmitter, can also cause the same effect. These effects can be categorized as the spatial smoothing preprocessing at the transmitter. In this paper, we analyze the spatial smoothing effect at the transmitter in the presence of multipath coherent waves. Theoretical and simulation results show that the spatial smoothing at the transmitter has a good feature in comparison with the conventional SSP at the receiving array. We also show that better decorrelation performance can be obtained when the SSPs at the transmitter and receiving array are applied simultaneously.
Takahiro HANDA Mitsuru OHTAKE Masaaki FUTAMOTO
Fe thin films were deposited directly and via Ag underlayer on glass and MgO(100) substrates by MBE. Polycrystal Fe films grew on the glass substrate while single crystal films grew on the MgO(100) substrate. Fe film growth followed the Volmer-Weber mode for both cases. The Fe film structure was influenced by the surface roughness of Ag underlayer at the early stage of film growth. The relationships between the Fe thin film morphology and the magnetic properties are discussed.
Fashen LI Jianrong SUN Xuewen WANG Jianbo WANG
Mn1-xZnxFe2O4 thin films with various Zn contents, 300 nm in thickness, were synthesized on glass substrates directly by electroless plating in aqueous solution at 90 without a heat treatment. With XRD, SEM, VSM, the crystallographic structure, morphology of the films and the macroscopic magnetic properties were characterized. The Mn-Zn ferrite films have a single phase spinel structure and well-crystallized columnar grains grow perpendicularly to the substrate. The change of the coercivity is not consistent with that of the bulk materials. As the Zn content in the films increases, the value of Hc decreases firstly, and then increases. At x=0.5, the minimum value of Hc is 3.7 kA/m and the value of Ms is 419.6 kA/m. The hyperfine magnetic fields, cation occupations and the distribution of the magnetic moments in film plane were studied by the conversion electron Mossbauer spectroscopy (CEMS).
Shigeru UMEMURA Shinsuke MISU-MATSUHASHI Shigeru HIRONO
To realize highly conductive and wear-durable thin films, we deposited metal doped carbon films onto silicon substrates by RF sputtering method. The dopant metals were various precious metals and transition metals. The electrical conductivity and wear durability of the deposited films were evaluated. We have found that Ir doping especially increased the electrical conductivity for the given amount of dopant metal. The wear durability of Ir-doped carbon films did not deteriorate even below a 7 at.% Ir concentration, and the conductivity of 7 at.% Ir-doped carbon was twenty times that of a non-doped carbon thin film.
Burst assembly at edge nodes is an important issue for the Optical Burst Switching (OBS) networks because it has a great impact on the traffic characteristics. We analyze the assembled traffic of the Science Information Network (SINET) by using the Fractional Brownian Motion (FBM) model. The analytical and simulation results show that existing assembly schemes cannot avoid increasing the burstiness, which will deteriorate the network performance. Here, burstiness is defined as the variance of the bitrate in small timescales. Therefore, we address the issue of how to reduce the burstiness of the assembled network traffic. Firstly, a sliding window-based assembly algorithm is introduced to reduce the burstiness of assembled traffic by transmitting bursts at an average rate in a small timescale. Next, an advanced timer-based assembly algorithm is introduced, by which the traffic rate is smoothed out by restricting the burst length to a threshold. The simulation results show that both the sliding window-based and advanced timer-based assembly algorithms perform better than existing assembly algorithms do in terms of the burst loss ratio. The simulation also indicates that the advanced timer-based assembly algorithm performs better in terms of the edge buffering delay than the sliding window-based assembly algorithm does.
This paper describes a novel parameter generation algorithm for an HMM-based speech synthesis technique. The conventional algorithm generates a parameter trajectory of static features that maximizes the likelihood of a given HMM for the parameter sequence consisting of the static and dynamic features under an explicit constraint between those two features. The generated trajectory is often excessively smoothed due to the statistical processing. Using the over-smoothed speech parameters usually causes muffled sounds. In order to alleviate the over-smoothing effect, we propose a generation algorithm considering not only the HMM likelihood maximized in the conventional algorithm but also a likelihood for a global variance (GV) of the generated trajectory. The latter likelihood works as a penalty for the over-smoothing, i.e., a reduction of the GV of the generated trajectory. The result of a perceptual evaluation demonstrates that the proposed algorithm causes considerably large improvements in the naturalness of synthetic speech.
Tetsuo ENDOH Kazuyuki HIROSE Kenji SHIRAISHI
The physical origin of stress-induced leakage currents (SILC) in ultra-thin SiO2 films is described. Assuming a two-step trap-assisted tunneling process accompanied with an energy relaxation process of trapped electrons, conditions of trap sites which are origin of SICL are quantitatively found. It is proposed that the trap site location and the trap state energy can be explained by a mean-free-path of hole in SiO2 films and an atomic structure of the trap site by the O vacancy model.
Kazuya KATSUKI Manabu KOTANI Kazutoshi KOBAYASHI Hidetoshi ONODERA
In this paper, we show that speed and yield of reconfigurable devices can be enhanced by utilizing within-die (WID) delay variations. An LUT Array LSI is fabricated to confirm whether FPGAs have clear WID variations to be utilized. We can measure delay variations by counting the number of LUTs a signal propagates within a certain time. Clear die-to-die (D2D) and WID variations are observed. We propose a variation model from the measurement results. Adequacy of the model is discussed from randomness of the random component. Effect of the speed and yield enhancement is confirmed using the proposed model. Yield increases from 80.0% to 100.0% by optimizing configurations.