A novel nonlinear analysis method of high power amplifier instability has been developed. This analysis method deals with a loop oscillation in a closed loop circuit and presents the conditions for oscillation under large-signal operation by taking account of mixing effect of FETs. Applying this analysis to the high power amplifier instability that an output power for the fundamental wave (f0-wave) decreases at some compression point where a half of the fundamental wave (f0/2-wave) is observed, it has been found that this instability is caused by an f0/2 loop oscillation. In addition, it has been verified by analysis and experiment that the oscillation can be removed by employing an isolation resistor in a closed loop circuit.

A new three-dimensional MMIC structure and an ultra-wideband miniature MMIC balun are proposed. The MMIC is a combined structure of multilayer MMICs and U-shaped micro-wires. This technology effectively reduces chip size and enhances MMIC performance. The proposed balun is constructed with three narrow conductors located side by side. The U-shaped micro-wire technology is employed to reduce the insertion loss and chip size. 1.51 dB insertion loss over 10 to 30 GHz, and 2 dB and 5 degrees of amplitude and phase balances over 5 to 35 GHz have been obtained. The intrinsic area of the balun is only 450800 µm, about 1/5 to 1/3 the area of recently reported miniaturized MMIC baluns.

A computer-based system for the automatic determination of the physical parameters of rainfall was developed. The measuring device consists of a light source and two TV cameras. Images of raindrops that fell through the slit were observed on a frosted glass plate as shadow images which were photographed simultaneously by two TV cameras with different shutter speeds and analyzed. The data indicated that the shape of raindrops were spheroid in case of small diameter but were slightly deformed into an oblate spheroid in case of larger diameter, and the fall velocity tends to increase with increasing size of raindrops. Rainfall rates calculated from the shape and velocity were compared with those measured directly and found to agree.

The electroretinogram (ERG) is used to diagnose many kinds of eye diseases. Our final purpose in this paper is a detection of diabetic retinopathy by using only ERG. In this paper, we describe a method to examine whether presented ERG data belong to a group of diabetic retinopathy. The ERG mainly consists of the a-wave, the b-wave and the oscillatory potential (op-wave). It was known that the op-wave varies as progress of retinopathy. Thus, we use the latency, the amplitude and the peak frequency of the op-wave. First, we study these features of sample ERG data, statistically. It was clarified that some of these characteristics are significantly different between a normal group and a group of diabetic retinopathy. By using some of these characteristics, we classify unknown ERG data on the basis of the Mahalanobis' generalized distance or the linear discriminant function. The highest accuracy of this method for the unknown data is about 92.73%.

This paper presents a system for recognition of on-line cursive Hangul (Korean characters) by means of DP matching of structural information. The penalty function has the following special features. In order to prevent short spurious strokes from causing large penalties, an input stroke is weighted by its length relative to other input strokes. In order to make use of pen-up and pen-down information, a penalty is incurred when 2 strokes of differing type (i.e. pen-up with pen-down) are matched. Finally, to reduce the chance of obtaining a suboptimal solution which can result from using the greedy algorithm in DP matching, we look-ahead an extra match. In a computer simulation we obtained a recognition rate of 92% for partially cursive characters and 89% for fully cursive characters. Furthermore, for both cases combined the correct character appears 98% of the time in the top 10 candidates. Thus we confirmed that the proposed algorithm is effective in recognizing cursive Hangul.

This paper presents a theoretically best algorithm within the framework of our image noise model for reconstructing 3-D from two views when all the feature points are on a planar surface. Pointing out that statistical bias is introduced if the least-squares scheme is used in the presence of image noise, we propose a scheme called renormalization, which automatically removes statistical bias. We also present an optimal correction scheme for canceling the effect of image noise in individual feature points. Finally, we show numerical simulation and confirm the effectiveness of our method.

A bottleneck identification methodology is proposed for the performance-oriented design of shared-bus multiprocessors, which are composed of several major subsystems (e.g. off-chip cache, bus, memory, I/O). A subsystem with the longest access time per instruction is the one that limits processor performance and creates a bottleneck to the system. The methodology also facilitates further refined analysis on the access time of the bottleneck subsystem to help identify the causes of the bottleneck. Example performance model of a particular shared-bus multiprocessor architecture with separate address bus and data bus is developed to illustrate the key idea of the bottleneck identification methodology. Accessing conflicts in subsystems and DMA transfers are also considered in the model.

The simulation of a specific absorption rate (SAR) with a temperature distribution becomes more important in the treatment planning for microwave hyperthermia. The simulation technique can also be used to estimate SAR distribution inside human body under hazardous electromagnetic (EM) field circumstances. In the simulation, to use exact permittivity of biological tissues becomes very important to obtain accurate SAR distribution. The permittivity of the medium is very sensitive to the temperature. Therefore, it is considered that the SAR distribution is also very sensitive to the tissue temperature. In this paper, SAR distribution is calculated using FDTD method considering tissue temperature under the electromagnetic (EM) field irradiation. Simulations of temperature distribution are also performed using heat transfer equation. In addition, temperature depending blood flow is taking into account to obtain temperature depending SAR distribution. The results can be used to estimate temperature depending heat generation which can be applied such as microwave hyperthermia treatment.

This paper proposes a human interface where a novel input method is used to substitute conventional input devices. It overcomes the deficiencies of physical devices, as it is based on image processing techniques. The proposed interface is composed of three parts: extraction of a person's handshape from a digitized image, detection of its fingertip, and interpretation by a software application. First, images of a pointing hand are digitized to obtain a sequence of monochrome frames. In each frame the hand is isolated from the background by means of gray-level slicing; with threshold values calculated dynamically by the combination of movement detection and histogram analysis. The advantage of this approach is that the system adapts itself to any user and compensates any changes in the illumination, while in conventional methods the threshold values are previously defined or markers have to be attached to the hand in order to give reference points. Second, once the hand is isolated, fingertip coordinates are extracted by scanning the image. Third, the coordinates are inputted to an application interface. Overall, as the algorithms are simple and only monochrome images are used, the amount of processing is kept low, making this system suitable to real-time processing without needing expensive hardware.

We have developed a planar devic technology consisting of 0.15-µm Au/WSiN-gate GaAs-heterostructure MESFETs (HMESFETs) fabricated by self-aligned ion-implantation. The gate-drain breakdown voltage has been improved to 10 V by using an asymmetric LDD structure, and the maximum oscillation frequency is 190 GHz. Because asymmetric and symmetric FETs can be fabricated simultaneously, this technology is suitable for use in making multi-functional millimeter-wave MMICs.

A new variable step size Least Mean Square (LMS) FIR adaptive filter algorithm (VSS-CC) is proposed. In the VSS-CC algorithm the step size adjustment (α) is controlled by using the correlation between the output error (e(n)) and the adaptive filter output ((n)). At small times, e(n) and (n) are correlated which will cause a large α providing faster tracking. When the algorithm converges, the correlation will result in a small size α to yield smaller misadjustments. Computer simulations show that the proposed VSS-CC algori thm achieves a better Echo Return Loss Enhancemen (ERLE) than a conventional NLMS Algorithm. The VSS-CC algorithm was also compared with another variable step algorithm, achieving the VSS-CC a better ERLE when the additive noise is incremented.

A novel method is presented for designing discrete coeffcient FIR linear phase filters using Hopfield neural networks. The proposed method is based on the minimization of the energy function of Hopfield neural networks. In the proposed method, the optimal solution for each filter gain factor is first searched for, then the optimal filter gain factor is selected. Therefore, a good solution in the specified criterion can be obtained. The feature of the proposed method is that it can be used to design FIR linear phase filters with different criterions simultaneously. A design example is presented to demonstrate The effectiveness of the proposed method.

A full confocal Gaussian beam open resonator system that determines the dielectric properties of low-loss materials in the 60-GHz band is developed. To achieve high Q values a quasi-optical coupling method is used to feed the resonator. It is connected to a computer-controlled HP 8510C vector network analyzer for automatic measurement. The frequency variation method is used and the data are processed using the open resonator scalar theory. Results from 96% and 99.5% alumina samples with thicknesses ranging from 0.38 mm to 1 mm, are presented in the V band, with loss tangent values of the order of 100 µ radians. This system should be able to measure substrates as thin as less than 0.1 mm to 0.3 mm, which are the thicknesses of substrates in practical use.

This paper presents a simple and efficient method for estimation of parameters useful for textured image analysis. On the basia of a 2-D Wold-like decomposition of homogenenous random fields, the texture field can be decomposed into a sum of two mutually orthogonal components: a deterministic component and an indeterministic component. The spectral density function (SDF) of the former is a sum of 1-D or 2-D delta functions. The 2-D autocorrelation function (ACF) of the latter is fitted to the assumed anisotropic ACF that has an elliptical contour. The parameters representing the ellipse and those representing the delta functions can be used to detect rotation angles and scaling factors of test textures. Specially, rotation and scaling invariant parameters, which are applicable to the classification of rotated and scaled textured images, can be estimated by combining these parameters. That is, a test texture can be correctly classified even if it is rotated and scaled. Several computer experiments on natural textures show the effectiveness of this method.

This paper describes a system that can enchance the speech quality degradation due to severe band limitation during speech transmission. We have already proposed a spectrum widening method that utilizes aliasing in sampling rate conversion and digital filtering for spectrum shaping. This paper proposes a new method that offers improved performance in terms of the spectrum distortion characteristics. Implementation procedures are clarified, and its performance is discussed. The proposed method can effectively enhance speech quality.

This paper deals with the method of integration of voice and data in wireless communication systems. By applying the DSV (Data Steal into Voice) technique to D-TDMA (Dynamic Time Division Multiple Access) systems, this paper presents an MAC (Media Access Control) method of integration of voice and data for the systems such as cellular radios and cordless phones. After a brief review of the D-TDMA scheme and the DSV technique, the protocol called D-TDMA/DSV is described. Then, a static analysis to derive the channel capacity and a dynamic analysis to evaluate the throughput and delay performance are presented. An extension of TFA (Transient Fluid Approximation) analysis is employed in the dynamic analysis. With the same system parameters, the capacity of D-TDMA/DSV is compared with that of the traditional D-TDMA. Under the limitation of the blocking probability required for cellular radios, some numerical examples of dynamic analysis are given to show the throughput and delay performance of the system.

This paper describes modifications to a previously proposed 8-kb/s 4-ms-delay CELP speech coding algorithm with a view to improving the speech quality while maintaining low delay and only moderately increasing complexity. The modifications are intended to improve the effectiveness of interframe pitch lag prediction and the sub-optimality level of the excitation coding to the backward adapted synthesis filter by using delayed decision and joint optimization techniques. Results of subjective listening tests using Japanese speech indicate that the coded speech quality is significantly superior to that of the 8-kb/s VSELP coder which has a 20-ms delay. A method that reduces the computational complexity of closed-loop 3-tap pitch prediction with no perceptible degradation in speech quality is proposed, based on representing the pitch-tap vector as the product of a scalar pitch gain and a normalized shape codevector.

This paper proposes a modified normalized LMS algorithm based on a long-term average of the reference input signal power. The reference input signal power for normalization is estimated by using two leaky integrators with a short and a long time constants. Computer simulation results compare the performance of the proposed algorithm with some previosuly proposed adaptive-step algorithms. The proposed algorithm converges faster than the conventional adaptive-step algorithms. Almost 30dB of the ERLE (Echo Return Loss Enhancement), which is comparable to the conventional algorithms, is achieved in noisy environments.

This paper presents a newly developed architecture for a highly parallel DSP suited for realtime image reaognition. The programmable DSP was designed for a variety of image recognition systems, such as computer vision systems, character recognition systems and others. The DSP consists of functional units suited for image recognition: a SIMD processing core, a hierarchical bus, an Address Generation Unit, Data Memories, a DMA controller, a Link Unit, and a Control Unit. The high performance of 3.2GOPS is realized by the eight-parallel SIMD core with a optimized pipeline structure for image recognition algorithms. The DSP supports flexible data transfers including an extraction of lacal images from raster scanned image data, a table-loop-up, a data-broadcasting, and a data-shifting among processing units in the SIMD core, for effective execution of various image processing algorithms. Hence, the DSP can process a 55 spatial filtering for 512512 images within 13.1 msec. Adopting the DSP to a Japanese character recognition system, the speed of 924 characters/sec can be achieved for feature extractions and feature vectors matchings. The DSP can be integrated in a 14.514.5 mm2 single-chip, using 0.5 µm CMOS technology. In this paper, the key features of the architecture and the new techniques enabling efficient operation of the eight parallel processing units are described. Estimation of the performance of the DSP is also presented.

Multifrequency microwave radiometry has been investigated for non-invasive measurement of temperatures in a human body. In this paper, we propose a new temperature profile model function, which is based on thermo-physiological considerations, for use in model fitting method of retrieving a temperature profile from a set of multifrequency radiometric data. The microwave radiometric technique using the new model function was tested by numerical simulations against animal experiment and clinical data reported elsewhere. The results show that the microwave radiometric technique can be used effectively to measure temperature profiles in tissues over a depth range from 0 to about 4.5 cm.