With the advent of digital video and digital broadcasting, copyright protection of video data has been one of the most important issues. We present in this paper a novel method of digital watermark for video data based on the discrete wavelet transform. In this method, we embed the watermark in the lowest frequency components of each frame in the uncoded video by using a controlled quantization process. The watermark can be extracted directly from the decoded video without access to the original video. Experimental results show that the proposed method gives the watermarked image of better quality and is robust against MPEG coding and re-encoding. Furthermore, we discuss multiple watermarking with regard to the generational copy control for video contents.

It is the purpose of this paper to review the generation of quantized voltage steps in Josephson-junctions, and also the recent practical application of these precise measurements. A 10-V Josephson-junction-array-voltage standard system has been established with a Josephson-junction-array, a phase-locked millimeter wave, and a precise null-detection system. Based on these technologies, the AC Josephson effect has been applied to other precise measurements such as DC error voltage of a multi-integrating analog-to-digital converter and for a pulse-width-modulation type precise voltage calibrator.

Recent progress of high-temperature superconductor Josephson junction technology is reviewed in the light of the future application to digital circuits. Among various types of Josephson junctions so far developed, ramp-edge-type junctions with a barrier layer composed of oxide materials in the vicinity of metal-insulator transition seem to offer a unique opportunity to fulfill all the requirements for digital circuit applications by virtue of their small junction dimensions, overdamped properties and relatively high IcRn product values at the temperature of around 30-40 K. Recently developed interface engineered junctions can be classified as junctions of this type. These junctions also raise an interesting problem in physics concerning the possibility of resonant tunneling of Cooper pairs via localized states in the barrier. From the viewpoint of practical applications, the improvement of the spread of the junction parameters is still a serious challenge to the present fabrication technology. Although interface engineered junctions seem to be most promising in this regard at present, 1σ spread of around 8% in the present fabrication technology is far from satisfactory for the fabrication of large-scale integrated circuits. The detailed understanding of the barrier formation mechanism in the interface engineered junction is indispensable not only for advancing this particular fabrication technology but also for improving other junction technology utilizing ramp-edge structures.

A portable cryo-system using a high-Tc SQUID for the measurement of the remanant magnetic field of a rock specimen was designed and fabricated. The sensing surface of the SQUID faces upward in our system, although the system for bio-magnetics faces down. The SQUID is cooled by liquid nitrogen via a sapphire heat transfer rod. The total heat transfer of the system was measured by means of a boiling-off method and was found to be 1.65 W. It was demonstrated that the system can be operated for more than 17 hours without any maintenance such as filling with liquid nitrogen. The system was applied to the measurement of the remanent magnetic field distributions of rock samples cored from deep underground. We have successfully measured the distributions.

We report on progress in the development of high current density NbN/AlN/NbN tunnel junctions for application as submillimeter wave SIS mixers. A ultra-high current density up to 120 kA/cm2, roughly two orders of magnitude larger than any reported results for all-NbN tunnel junctions, was achieved in the junctions. The magnetic field dependence and temperature dependence of critical supercurrents were measured to investigate the Josephson tunneling behaviour of critical supercurrents in the high-Jc junctions. We have developed a low-noise quasi-optical SIS mixer with the high-current density NbN/AlN/NbN junctions and two-junction tuning circuits which employ Al/SiO/NbN microstriplines. The tuning characteristics of the mixer were investigated by measuring the response in the direct detection mode by using the Fourier Transform Spectrometer (FTS) and measuring the response in the heterodyne detection mode with the standard Y-factor method at frequencies from 670 to 1082 GHz. An uncorrected double sideband receiver noise temperature of 457 K (12hν/kB) was obtained at 783 GHz.

Power exponentiation is an important operation in modern cryptography. This operation can be efficiently calculated using the concept of the addition chain. In this paper, two new systematic methods, a Run-length method and a Hybrid method, are proposed to generate a short addition chain. The performance of these two methods are theoretically analyzed and it is shown that the Hybrid method is more efficient and practical than known methods. The proposed methods can reduce the addition chain length by 8%, in the best case, compared to the Window method.

The applications of reactance-loaded beam tilting dipole antennas have been reported by many researchers. The reactance elements loaded on the applications reported up to date have been used only for the purpose of beam tilting. This paper presents the basic characteristics of the beam tilting dipole antenna element in which one reactance element is used for the impedance matching at the feed point. The radiation pattern is tilted by the properly determined driving point position, and the loading reactance is used to obtain forced resonance without great changes in tilt angle. The numerical results demonstrate that the reactance element should be loaded in the region where the driving point is placed to obtain forced resonance of the antenna with little changes in beam tilt angle. In case the proposed forced resonant beam tilting antenna with 0.8λ length is driven at 0.2λ from the center, the main beam tilt angle of 57.7 degrees, the highest power gain of 8.6 dB, and VSWR=2.2 are obtained.

A method for locating underground pipes from a pulse radar image is presented. The method employs the Laplacian of Gaussian filter to extract edges and employs the Hough transform to determine the depth of the pipes. A preliminary experiment showed its ability to detect deeply buried pipes with weak signal echoes.

In this study, we propose a branch-point scheme for multicast ABR service in ATM networks. The performance of the proposed scheme is obtained to show that the consolidation noise and delay can be reduced more effectively than those of the existing schemes.

We propose an untraceable electronic money system. Our system uses the partially blind signature based on the discrete logarithm problem, and applies secret key certificates to the payment protocol.

In this paper, system capacity of the reverse link of a wireless multimedia CDMA system with transmission power control is analysed for receivers with and without CCI cancellers. For N classes of users, system capacity is represented by a point in an N-dimensional space. It is shown that system capacity is improved considerably with CCI cancellers, that system capacity region is non-convex in general, and that its boundary is well approximated with a unique hyper plane when CCI cancellers are fully employed.

In this paper, we propose the introduction of space diversity techniques to the code acquisition of a direct-sequence spread-spectrum signal. In this scheme, both a transmitter and a receiver have multiple antennas and the signals corresponding to all the combinations of the transmitter and receiver antennas are combined at the acquisition circuit of the receiver. The performance is evaluated for an indoor packet radio communication system from the viewpoints of the average time for acquisition, the probability of success of acquisition, and the necessary preamble length. As the result, we show great performance improvements by the proposed scheme under slow and flat Rayleigh fading environment.

I would like to draw the attention of the editorial board of IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences and its readers to a recent paper, Tianruo Yang, "The integrated scheduling and allocation of high-level test synthesis," vol. E82-A, no. 1, January 1999, pp. 145-158. (Here we call this paper the Yang's paper. ) Yang did not give the correct information about the originality of the paper. I will point out that the writings (and the idea accordingly) of section 6 of Yang's paper came from papers [1] and [2].

This paper introduces an acoustic echo canceller system materialized with a 16-bit fixed point processing type DSP (Analog Devices, ADSP-2181). This experimental system uses the tri-quantized-x individually normalized least mean square (INLMS) algorithm little degrading the convergence property under the fixed point processing. The experimental system also applies a small step gain to the algorithm to prevent the double-talk from increasing the estimation error. Such a small step gain naturally reduces the convergence speed. The experimental system compensates the reduction by applying the block length adjustment technique to the algorithm. This technique enables to ceaselessly update the coefficients of the adaptive filter even when the reference signal power is low. The experimental system thus keeps the echo return loss enhancement (ERLE) high against the double-talk.

This paper examines fairness of service in the up-link of CDMA cellular slotted-ALOHA packet communication systems with site diversity reception. Site diversity rescues the packets originating mainly from near the edge of the cells, whereas packets originating near the base stations can not obtain the benefits of diversity reception. This situation causes an unfairness in packet reception that depends on location of the mobile station. Two transmission control schemes for reducing this unfairness are proposed. In the first scheme, mobile stations control the target received power for the open-loop power control based on the reception level of the pilot signals of the surrounding base stations. In the second, mobile stations control transmit permission probability. Successful packet reception rate, fairness coefficient and throughput performance are evaluated in fading environments with imperfect power control. Computer simulation shows that both schemes improve service fairness for all mobile stations and throughput performances. A performance comparison between the two schemes concludes that transmission power control outperforms transmit permission probability control as a simple technique for maintaining fairness of services.

We have developed a diagnostic Case-Based Reasoning (CBR) system, Doctor, which infers possible defects in a home electrical appliance and lists up necessary service parts. The CBR is suitable to build a diagnostic system for the field service because the CBR imitates how experienced service technicians infer and is able to learn defect trends and novel repair cases from a service report database. In order to apply a CBR system to this real-world problem, Our system has the following new features: (1) Its CBR mechanism utilizes not only repair cases, but also diagnostic rules that are elicited from human experts so that accurate diagnosis can be achieved. (2) Its casebase maintenance mechanism updates the casebase and adapts it to the changing real world.

A new class of nonlinear filters called Vector Median Rational Hybrid Filters (VMRHF) for multispectral image processing is introduced and applied to color image filtering problems. These filters are based on Rational Functions (RF). The VMRHF filter is a two-stage filter, which exploits the features of the vector median filter and those of the rational operator. The filter output is a result of vector rational function operating on the output of three sub-functions. Two vector median (VMF) sub-filters and one center weighted vector median filter (CWVMF) are proposed to be used here due to their desirable properties, such as, edge and details preservation and accurate chromaticity estimation. Experimental results show that the new VMRHF outperforms a number of widely known nonlinear filters for multispectral image processing such as the Vector Median ilter (VMF) and Distance Directional Filters (DDf) with respect to all criteria used.

We have two goals in this paper. One is the comparison of Spread Spectrum (SS) CDMA and Spread Time (ST) CDMA. The other is to propose a new SS-ST CDMA system, which is an adaptive CDMA with both merits of SS and ST CDMA. SS and ST CDMA are compared from the view point of two dimensional space "frequency (B Hz)-time (T Sec)" together with their communication capacity. A primary modulation is assumed to be PPM in ST CDMA, and FSK in SS CDMA which is regarded as PPM in frequency axis. Both SS and ST CDMA are combined to give the proposed SS-ST CDMA, where transmitted signals are spread both in time and frequency domain. In order to realize the proposed system, a transmitter model is presented, and two receiver structures are discussed. The discrete Fourier transform (DFT) is employed for the system flexibility. Although SS, ST and SS-ST CDMA are shown to have the same capacity of 0.7213, the combined SS-ST CDMA has a merit of adaptability to adjust spreading gain of ST and SS according to property of channels, an impulsive noise dominated or a CW interference dominated channel. Numerical results of DFT are also shown to illustrate the waveform and spectrum of the proposed SS-ST CDMA system. Finally the symbol error probability performance of ST PPM, SS FSK and combined SS-ST systems in CW and impulsive environment is presented.

In our previous paper we presented a path-tracing method of multiple gate delay fault diagnosis in combinational circuits. In this paper, we propose an improved method that uses the ambiguous delay model. This delay model makes provision for parameter variations in the manufacturing process of ICs. For the effectiveness of the current method, we propose a timed 8-valued simulation and some new diagnostic rules. Furthermore, we introduce a preparatory process that speeds up diagnosis. Also, at the end of diagnosis, additional information from the results of the preparatory process makes it possible to distinguish between non-existent faults and undiagnosed faults.

As VLSI technology has developed, the interest in implementing an entire or significant part of a parallel computer system using wafer scale integration is growing. The major problem for the case is the possibility of drastically low yield and/or reliability of the system if there is no strategy for coping with such situations. Various strategies to restructure the faulty physical system into the fault-free target logical system are described in the literature [1]-[5]. In this paper, we propose an efficient approximate method which can reconstruct the 1 1/2 track-switch mesh arrays with faulty PEs using hardware as well as software. A logical circuit added to each PE and a network connecting the circuits are used to decide spare PEs which compensate for faulty PEs. The hardware compexity of each circuit is much less than that of a PE where the size of each additional circuit is independent of array sizes and constant. By using the exclusive hardware scheme, a built-in self-reconfigurable system without using a host computer is realizable and the time for reconfiguring arrays becomes very short. The simulation result of the performance of the method shows that the reconstructing efficiency of our algorithm is a little less than those of the exaustive and Shigei's ones [6] and [7], but much better than that of the neural one [3]. We also compare the time complexities of reconstructions by hardware as well as software, and the hardware complexity in terms of the number of gates in the logical circuit added to each PE among the other methods.