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.

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%.

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.

In this paper, we discuss design of quadrature mirror filter (QMF) banks using digital allpass networks in the frequency domain. In the QMF banks composed of a parallel connection of two allpass networks, both aliasing error and amplitude distortion are always completely canceled. Therefore, we only need to design the analysis filters and eliminate phase distortion of the overall transfer function. We consider design of the QMF banks in two cases where phase responses of the filters are repuired or not required. In the case where the phase responses are not required, the design problem can be reduced to design of phase difference of two allpass networks. In the case where the phase responses are required, we present a procedure for designing the QMF banks with both equiripple magnitude and phase responses.

A subharmonic injection-locked oscillator (ILO) MMIC chain is proposed for the local oscillators and synthesizers used at millimeter-wave frequencies. A fabricated, primary 11-GHz-band injection-locked oscillator MMIC for the first stage ILO in the ILO-chain MMIC, achieves a wide subharmonic-injection-locking range at the subharmonic factors, 1/n (n=1, 2, 3, ), of 1/1, 1/2 and 1/3. The ILO MMIC abilities for synthesizer applications were confirmed with an injection-locking time of only 100-200 nsec, which is less than 1/100 that of PLL oscillators, and also with free-running oscillation performance and a wide injection locking range within a temperature range of -30 and 80.

Standard Site Method (SSM) is theoretically analyzed using matrix representations to examine its validity and develop an improved method. The analysis reveals that the SSM yields an antenna factor specifically related to the effective load impedance presented by the cable and associated devices which are disconnected from the antenna during the SSM site attenuation measurements. Therefore, an additional conversion is required to determine the desired antenna factor under actual load conditions. It is also concluded that the SSM is not applicable to antennas having height-dependent antenna factors. In addition, the SSM correction factors are found to be theoretically inappropriate. Uncertainty of the antenna factor obtained using the SSM is discussed and the required antenna separation distance is investigated. To improve the existing SSM, it is proposed that both transmitting and receiving antennas are placed at the same height during the site attenuation measurements. Experiments exhibit the superiority of the improved method.

In this paper, we propose two parallel processing methods for multidimensional (MD) sampling lattice alteration. The use of our proposed methods enables us to alter the sampling lattice of a given MD signal sequence in parallel without any redundancy caused by up- and down-sampling, even if the alteration is rational and non-separable. Our proposed methods are provided by extending two conventional block processing techniques for FIR filtering: the overlap-add method and the overlap-save method. In these proposed methods, firstly a given signal sequence is segmented into some blocks, secondly sampling lattice alteration is implemented for each block data individually, and finally the results are fitted together to obtain the output sequence which is identical to the sequence obtained from the direct sampling lattice alteration. Besides, we provide their efficient implementation: the DFT-domain approach, and give some comments on the computational complexity in order to show the effectiveness of our proposed methods.

This paper presents an improved neural network for channel assignment problems in cellular mobile communication systems in the new co-channel interference model. Sengoku et al. first proposed the neural network for the same problem, which can find solutions only in small size cellular systems with up to 40 cells in our simulations. For the practical use in the next generation's cellular systems, the performance of our improved neural network is verified by large size cellular systems with up to 500 cells. The newly defined energy function and the motion equation with two heuristics in our neural network achieve the goal of finding optimum or near-optimum solutions in a nearly constant time.

To support high bit rate and high quality indoor radio communication systems, we have to solve intersymbol interference (ISI) problem caused by frequency-selective fading. Recently multi-carrier modulation technique is considered to be one of the effective methods for this problem. In this paper we propose Partial Frequency ARQ (Automatic Repeat reQuest) system which can achieve effective ARQ scheme for multi-carrier packet communication. This system operates partial retransmission of erroneous power faded packets, and it is superior to the traditional ARQ systems. Furthermore two different protocols are examined for this system: Static Carrier Assignment (SCA) and Dynamic Carrier Assignment (DCA). By computer simulation we found that DCA method can achieve better performance than SCA in terms of both throughput and packet transmission delay.

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.

Closed-form solutions of the characteristic initial value problem for electric and magnetic fields propagating as nonsinusoidal plane TEM-waves in lossy unbounded media are calculated with Riemann's method and discussed in detail. As an application, the reflection and transmission of waves on a planar boundary is examined, when one semi-infinite medium is lossy.

This paper describes a spatial and temporal multipath channel model which is useful in array antenna environments for mobile radio communications. From this model, a no distortion criterion, that is an extension of the Nyquist criterion, is derived for equalization in both spatial and temporal domains. An adaptive tapped-delay-line (TDL) array antenna is used as a tool for equalization in both spatial and temporal domains. Several criterion for such spatial and temporal equalization such as ZF (Zero Forcing) and MSE (Mean Square Error), are available to update the weights and tap coefficients. In this paper, we discuss the optimum weights based on the ZF criterion in both spatial and temporal domains. Since the ZF criterion satisfies the Nyquist criterion in case of noise free, this paper applies the ZF criterion for the spatial and temporal equalization as a simple case. The Z transform is applied to represent the spatial and temporal model of the multipath channel and to derive the optimal weights of the TDL array antenna. However, in some cases the optimal antenna weights cannot be decided uniquely. Therefore, the effect on the equalization errors due to a finite number of antenna elements and tap coefficients can be shown numerically by computer simulations.

This paper condiders a problem of logecal configuration in reconfigurable VCDN (Virtual Circuit Data Networks) which is analyzed through a mimimax approach, and its objective is to minimize the largest delay on any logical link, measured in both queueing delay and propagation delay. The problem is formulated as a 0/1 mixed integer programming and analyzed by decomposing it into two subproblems, called routing and dimensioning problems, for which an efficient hauristic algorithm is proposed in an iterating process made beween the two subproblems for solution improvement. The algorithm is tested for its performance eveluation.

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 proposes a novel architecture and MMICs for an integrated 2-32 GHz front-end of a spectrum analyzer. The architecture achieves miniaturization by eliminating the large YIG tracking filter and also achieves multi-octave measurement with less than one octave sweep of the first local oscillator. The MMIC's demonstrate ultra-wideband performances with reduced chip sizes by utilizing newly developed FET cells for power combination, multi-order frequency conversion, low leakage variable resistance, and active impedance translation. The MMIC's are a fundamental/harmonic frequency converter, a variable attenuator, a single-pole triple-throw switch, a single-pole double-throw switch, a distributed pre-amplifier, and an active LC lowpass filter. All the MMIC's are smaller than 1 mm2, except the pre-amplifier and the filter.

A down sampling technique was applied to signal processing of fiber optic gyroscopes with optical phase modulation. The technique shifts the frequency spectrum of the gyroscopic signal down to low frequencies, and lowers the speed requirements for analog-to-digital (A/D) conversion and numerical operations. A single-chip digital signal processor (DSP) with a built-in A/D converter and timers was used to demonstrate the proposed technique. The DSP internally generated a phase modulation signal and sampling trigger timing. The reference signals for digital lock-in discrimination of gyroscopic spectrum are generated by using an external binary counter, and their phases were adjusted optimally by DSP software. The DSP compensated for fluctuations in laser source intensity and phase modulation index, using the signal spectrum extracted, and linearized the gyroscopic response. The measured resolution of rotation detection was 0.9 deg/s (with a full scale of 100 deg/s) and it agreed with the resolution in A/D conversion.

This paper described discrete time Cellular Neural Networks (DT-CNN) with two types of neuron circuits for image coding from an analog format to a digital format and their VLSI implementations. The image coding methods proposed in this paper have been investigated for a purpose of transmission of a coded image and restoration again without a large loss of an original image information. Each neuron circuti of a network receives one pixel of an input image, and processes it with binary outputs data fed from neighboring neuron circuits. Parallel dynamics quantization methods have been adopted for image coding methods. They are performed in networks to decide an output binary value of each neuron circuit according to output values of neighboring neuron circuits. Delayed binary outputs of neuron circuits in a neighborhood are directly connected to inputs of a current active neuron circuit. Next state of a network is computed form a current state at some neuron circuits in any time interval. Models of two types of neuron circuits and networks are presented and simulated to confirm an ability of proposed methods. Also, physical layout designs of coding chips have been done to show their possibility of VLSI realizations.

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.

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.

A 1.5 GHz band Si power MOS amplifier module with 50% total efficiency, 1 W output power and 30 dB power gain has been developed for front-end transmitter of digital cellular telephones. A combination of a highly efficient power MOSFET for the output stage and an integrated two stage MOS amplifier for the driver with an impedance matching circuit minimizing the length of striplines made it possible to achieve high total efficiency, high power gain, and smaller size of the amplifier module.