Three custom LSIs for EB60, a direct wafer exposure electron beam system, have been developed using 0.8 µm BiCMOS and SST bipolar technologies. The three LSIs are i) a shot cycle control LSI for controlling each exposure cycle time, ii) a linear matrix computation LSI for coordinate modification of the exposure pattern data, and iii) a position calculation LSI for determining the precise position of the wafer. These LSIs allow the deflection corrector block of the revised EB60 to be realized on a single board. A new adaptive pipeline control technique which optimizes each shot period according to the exposure data is implemented in the shot-cycle control LSI. The position calculation LSI implements a new, highly effective 2-level pipeline exposure technique, the levels refer to major-field-deflection and minor-field-deflection. The linear-matrix computation LSI is designed not only for the EB60 but also for a wide variety of parallel digital processing applications.

This paper describes the linguistic procedure of our speech dialogue system. The procedure is composed of two processes, syntactic analysis using a finite state network, and discourse analysis using a plan recognition model. The finite state network is compiled from regular grammar. The regular grammar is described in order to accept sentences with various styles, for example ellipsis and inversion. The regular grammar is automatically generated from the skeleton of the grammar. The discourse analysis module understands the utterance, generates the next question for users and also predicts words which will be in the next utterance. For an extension number guidance task, we obtained correct recognition results for 93% of input sentences without word prediction and for 98% if prediction results include proper words.

In 1990, Menezes, Okamoto and Vanstone proposed a method that reduces EDLP to DLP, which gave an impact on the security of cryptosystems based on EDLP. But this reducing is valid only when Weil pairing can be defined over the m-torsion group which includes the base point of EDLP. If an elliptic curve is ordinary, there exists EDLP to which we cannot apply the reducing. In this paper, we investigate the condition for which this reducing is invalid.

The security problems of object-oriented database system are investigated and security level assignment constraints and an access control mechanism based on the multilevel access control security policy are proposed. The proposed mechanism uses the Trusted Computing Base. A unique feature of the mechanism is that security levels are assigned not only to data items (objects), but also to methods and methods are not shown to the users whose security level is lower than that of the methods. And we distinguish between the security level of a variable in a class and that in an instance and distinguish between the level of an object when it is taken by itself and it is taken as a variable or an element of another complex object. All of this realizes the policy of multilevel access control.

Given an integer N, it is easy to determine whether or not N is prime, because a set of primes is in LPP. Then given a composite number N, is it easy to determine whether or not N is of a specified form? In this paper, we consider a subset of odd composite numbers +1MOD4 (resp. +3MOD4), which is a subset of odd composite numbers consisting of prime factors congruent to 1 (resp. 3) modulo 4, and show that (1) there exists a four move (blackbox simulation) perfect ZKIP for the complement of +1MOD4 without any unproven assumption; (2) there exists a five move (blackbox simulation) perfect ZKIP for +1MOD4 without any unproven assumption; (3) there exists a four move (blackbox simulation) perfect ZKIP for +3MOD4 without any unproven assumption; and (4) there exists a five move (blackbox simulation) statistical ZKIP for the complement of +3MOD4 without any unproven assumption. To the best of our knowledge, these are the first results for a language L that seems to be not random self-reducible but has a constant move blackbox simulation perfect or statistical ZKIP for L and without any unproven assumption.

The performance of an enciphered B+-tree can be improved by the selective encryption of the components of the nodes in the tree. This paper suggests an approach to the selective encryption of nodes in a B+-tree and a method to substitute the plaintext search keys in order to increase the security of the tree. The method is based on structures in combinatorial block designs, and it allows for faster traversal of the tree, hence improving the overall speed of query responses. It also represents a trade-off between security and performance in that the substitution method affords less security compared to encryption. However, assuming the use of a secure cryptosystem with parameters which are kept secret, the encrypted state of the data pointers and data blocks still prevents an intruder from accessing the stored data. The method based on block designs has the advantage of requiring only a small amount of information being kept secret. This presents a considerable savings in terms of space used to hold security-related information.

A high resolution iterative algorithm for estimating the direction-of-arrival of multiple wide band sources is proposed in this paper. For equally spaced array structure, two Unitary Transform based approaches are proposed in frequency domain for signal subspace processing in both coherent multipath and incoherent environment. Given a priori knowledge of the initial estimates of DOA, with proper spatial prefiltering to separate multiple groups of closely spaced sources, our proposed algorithm is shown to have high resolution capability even in coherent multipath environment without reducing the angular resolution, compared with the use of subarray. Compared with the conventional algorithm, the performance by the proposed algorithm is shown by the simulations to be improved under low Signal to Noise Ratio (SNR) while the performance is not degraded under high SNR. Moreover the computation burden involved in the eigencomputation is largely reduced by introducing the Pesudo-Hermitian matrix approximation.

Formation of thin insulating SiO2 films by anodic oxidation of silicon was studied as a part of investigating an alternative method of fabricating low-cost silicon MIS solar cells. Anodization in the constant-voltage mode was carried out in nonaqueous ethylene glycol solution. The film thickness was carefully measured using an ellipsometer of wavelength 6238 . MIS cell performance was evaluated by comparing the open circuit voltage VOC and the short circuit current density ISC with those of the bare Schottky cell (without anodization) under illumination by a tungsten lamp. It was found that anodization in the constant-voltage mode can increase VOC without reducing ISC, and that anodization in the constant-voltage mode is more controllable and reproducible. The optimun formation voltage which gives the maximum VOC of the MIS cell depends on the forming voltage of oxide. A brief discussion on the mechanism for VOC increase is given.

Noise properties in cascaded erbium-doped fiber amplifiers used in subcarrier multiplexed analog video distribution systems are experimentally examined. The noise dependency on signal wavelength is measured for a 4 stage EDFA cascade, and it is shown that an optical narrow bandpass filter is not necessary after each fiber amplifier for signal wavelength of 1.5511.560µm and that optical bandpass filters are necessary for shorter wavelength than 1.551µm to avoid the noise degradation by spontaneous-spontaneous beat noise. Finally, the attainable distribution loss is estimated for AM and FM video distribution systems.

This letter proposes a non-metallic optical fiber cable which contains fiber ribbons inserted into slots, with a high impact resistant sheath which affords protection against shotgun pellets. The protective performance of the materials is investigated experimentally. Based on the results, non-metallic 100-fiber cable with a high impact resistant sheath was manufactured and its performance was evaluated. It is confirmed that this cable has excellent transmission, mechanical and antiballistic characteristics.

This paper presents an efficient multi-precision modular-multiplication algorithm which minimizes the calculation RAM space required when implementing public-key schemes with software on general-purpose computers including smart cards and personal computers. Many modular-multiplication algorithms cannot be efficiently realized on small systems due to their high RAM consumption. The Montgomery algorithm, which can rapidly perform modular multiplication, has received a lot of attention. Unfortunately, the Montgomery algorithm is difficult to implement, especially in smart cards which have extremely limited RAM space. Furthermore, when the modulus of modular multiplication is frequently changed, or when the number of permissible repeated modular multiplications is small, pre- and post-processing operations such as conversion from/to the Montgomery space become wasteful. The proposed algorithm avoids these problems because it requires only half the RAM space and no pre- and post-processing operations. The algorithm is a radical extension to the approximation methods that use the most significant bits and our newly proposed lookahead determination method. This paper gives a proof of the completeness of this method, describes implementation results using a smart card, introduces a theory supported by the results, and considers the optimal technique to enhance the speed of this method.

We indicate the existence of optimum expanded mode field diameters in thermally-diffused expanded core (TEC) fiber. The optimum ranges under our experimental conditions were from 14µm to 18µm for both 1.3µm-single-mode fiber and 1.55µm-dispersion-shifted fiber. By applying the TEC fiber fabricated in our experimental conditions to a multifiber connector, the connection loss can be reduced to less than 0.2dB without improving fiber and connector ferrule fabrication accuracy.

In this paper, we propose an extended LR parsing algorithm, called LR parsing with a category reachability test (the LR-CRT algorithm). The LR-CRT algorithm enables a parser to efficiently recognize those sentences that belong to a specified grammatical category. The key point of the algorithm is to use an augmented LR parsing table in which each action entry contains a set of reachable categories. When executing a shift or reduce action, the parser checks whether the action can reach a given category using the augmented table. We apply the LR-CRT algorithm to improve a speech recognition system based on two-level LR parsing. This system uses two kinds of grammars, inter- and intra-phrase grammars, to recognize Japanese sentential speech. Two-level LR parsing guides the search of speech recognition through two-level symbol prediction, phrase category prediction and phone prediction, based on these grammars. The LR-CRT algorithm makes possible the efficient phone prediction based on the phrase category prediction. The system was evaluated using sentential speech data uttered phrase by phrase, and attained a word accuracy of 97.5% and a sentence accuracy of 91.2%

A new optical interconnection system suitable for high-speed ICs using a novel complementary optical interconnection technique has been developed. This system uses paired light sources and photodetectors for optical complementary operation, and greatly lowers the power consumption compared with conventional systems. Analyses and experimental results indicate that this system can operate in the gigabit range, and reduces power consumption to less than 20% of that in conventional systems at 1 Gb/s.

This paper describes design issues of a speech dialogue system, the evaluation of the system, and the data collection of spontaneous speech in a transportation guidance domain. As it is difficult to collect spontaneous speech and to use a real system for the collection and evaluation, the phenomena related with dialogues have not been quantitatively clarified yet. The authors constructed a speech dialogue system which operates in almost real time, with acceptable recognition accuracy and flexible dialogue control. The system was used for spontaneous speech collection in a transportation guidance domain. The system performance evaluated in the domain is the understanding rate of 84.2% for the utterances within the predefined grammar and the lexicon. Also some statistics of the spontaneous speech collected are given.

It is difficult to decide whether or not a given cryptographic protocol is secure even though the cryptographic algorithm used for the protocol is assumed to be secure. We have proposed an algorithm to decide the security of cryptographic protocols under several conditions. In this paper, we review our algorithm and report a system to verify the security. The system has be implemented on a computer. By using this system, we have verified the security of several protocols efficiently.

In this paper, a new scheme for ohrase recognition in conversational speech is proposed, in which prosodic and phonemic information processing are usefully combined. This approach is employed both to produce candidates of phrase boundaries and to discriminate phonemes. The fundamental frequency patterns of continuous utterances are statistically analyzed and the likelihood of the occurrence of a phrase boundary is calculated for every frame. At the same time, the likelihood of phonemic characteristics of each frame can be obtained using a hierarchical clustering method. These two scores, along with lexical and grammatical constraints, can be effectively utilized to develop a possible word sequences or a word lattices which correspond to the continuous speech utterances. Our preliminary experjment shows the feasibility of applying prosody for continuous speech recognition especially for conversational style utterances.

We propose two types of key management systems that use complementary exponential calculation, in which users in the system divide into groups, and the different modulus numbers are assigned to each group and edges between groups. Key generation information over the modulus numbers is issued to a user by a trusted center. The user who receives the information can generate shared encryption keys between users in the system without using key exchange protocol. In our proposed system, the number of primes is one of the parameters for generating key generation information. The number decreases in inverse proportion to the square of the number of groups compared to the original method. Our proposed technique enabled us to extend the number of users in the system to more than one million, which is not possible with the original method.