The studies on the biological effects of ELF electric fields conducted in Japan are reviewed. Among international studies, they are characterized as the studies from the viewpoint of bioengineering. In early studies, the safety standard of high voltage transmission lines was determined by a distinct biological effect, i.e., the sensation of the spark discharge caused by electrostatic induction. In numerical analysis, the field coupling to both animal and human bodies became well understood. Some new measurement techniques were developed which enabled us to evaluate the field exposure on a human body. A system was developed to realize the chronic exposure of an electric field on mice and cats. An optical telemetry technique was developed to measure the physiological response of an animal when it was exposed to an electric field. An ion-current shuttle box was developed to investigate the behavioral change of a rat when it was exposed to an ion-current as well as an electric field. In animal experiments, a mechanism of sensing the field was investigated. The cause of the seasonal change of field sensitivity was found. In cases of chronic exposure, suppression of growth was suspected. In shuttle box studies, an avoidance behavior from an ion-current was quantified. To find whether there are any adverse or beneficial effects of the field exposure on human beings, further study is required to clarify the mechanisms of the biological effects.

A simple method for separating the dissipation factors associated with both conductor losses and dielectric losses of printed circuit boards in microwave frequencies is presented. This method utilizes the difference in dependence of two dissipation factors on the dimensions of bounded stripline resonators using a single printed circuit board specimen as a center strip conductor. In this method, the separation is made through a procedure involving the comparison of the measured values of the total dissipation factor with those numerically calculated for the resonators. A method, which is based on a TEM wave approximation and uses Green's function and a variational principle, is used for the numerical calculation. Both effective conductivity for three kinds of industrial copper conductor supported with a substrate of polymide film and dielectric loss tangent of the substrates are determined using this method from the values of the unloaded Q measured at the 10 GHz region. Radiation losses from the resonator affecting the accuracy of the separation are discussed, as well as the values of the effective conductivity of metals on the polyimide substrate which is calculated using the above method. The resulting values of the effective conductivity agree with those using the triplateline method within 10%.

Binary decision diagrams (BDD's) are graph representations of Boolean functions, and at the same time they can be regarded as a computational model. In this paper, we discuss relations between BDD's and other computational models and clarify the computational power of BDD's. BDD's have the property that each variable is examined only once according to a total order of the variables. We characterize families of BDD's by on-line deterministic Turing machines and families of permutations. To clarify the computational power of BDD's, we discuss the difference of the computational power with respect to the way of reading inputs. We also show that the language TADGAP (Topologically Arranged Deterministic Graph Accessibility Problem) is simultaneously complete for both of the class U-PolyBDD of languages accepted by uniform families of polynomial-size BDD's and the clas DL of languages accepted by log-space bounded deterministic Turing machines. From the results, we can see that the problem whether U-PolyBDD U-NC1 is equivalent to a famous open problem whether DL U-NC1, where U-NC1 is the class of languages accepted by uniform families of log-depth constant fan-in logic circuits.

There have been several interesting investigations on the space functions constructed by one-dimensional or two-dimensional Turing machines. On the other hand, as far as we know, there is no investigation about the space functions constructed by three-dimensional Turing machines. In this paper, we investigate about space constructibility by three-dimensional deterministic Turing machines with cubic inputs, and show that the functions log*n and log(k)n, k1, are fully space constructible by these machines.

This paper presents an efficient algorithm for constructing at-most-k levels of an arrangement of n lines in the plane in time O(nk+n log n), which is optimal since Ω(nk) line segments are included there. The algorithm can sweep the at-most-k levels of the arrangement using O(n) space. Although Everett et al. recently gave an algorithm for constructing the at-most-k levels with the same time complexity independently, our algorithm is superior with respect to the space complexity as a sweep algorithm. Then, we apply the algorithm to a bipartitioning problem of a bichromatic point set： For r red points and b blue points in the plane and a directed line L, the figure of demerit fd(L) associated with L is defined to be the sum of the number of blue points below L and that of red ones above L. The problem we are going to consider is to find an optimal partitioning line to minimize the figure of demerit. Given a number k, our algorithm first determines whether there is a line whose figure of demerit is at most k, and further finds an optimal bipartitioning line if there is one. It runs in O(kn+n log n) time (n=r+b), which is subquadratic if k is sublinear.

An extension of the notion of cryptographically strong pseudo-random generator to a distributed setting is proposed in this paper. Instead of a deterministic function to generate a pseudo-random bit string from a truly random shorter string, we have a deterministic secure protocol for a group of separate entities to compute a secretly shared pseudo-random string from a secretly shared and truly random shorter string. We propose a precise definition of this notion in terms of Yao's computational entropy and describe a concrete construction using Shamir's pseudo-random number generator. Several practical applications are also discussed.

This paper uses both network analysis and experiments to confirm that the neural network learning algorithm that minimizes output variation (BPV) provides much more robustness than back-propagation (BP) or BP with noise-modified training samples (BPN). Network analysis clarifies the relationship between sample displacement and what and how the network learns. Sample displacement generates variation in the output of the output units in the output layer. The output variation model introduces two types of deformation error, both of which modify the mean square error. We propose a new error which combines the two types of deformation error. The network analysis using this new error considers that BPV learns two types of training samples where the modification is either towards or away from the category mean, which is defined as the center of sample distribution. The magnitude of modification depends on the position of the training sample in the sample distribution and the degree of leaning completion. The conclusions is that BPV learns samples modified towards to the category mean more stronger than those modified away from the category mean, namely it achieves nonuniform learning. Another conclusion is that BPN learns from uniformly modified samples. The conjecture that BPV is much more robust than the other two algorithms is made. Experiments that evaluate robustness are performed from two kinds of viewpoints: overall robustness and specific robustness. Benchmark studies using distorted handprinted Kanji character patterns examine overall robustness and two specifically modified samples (noise-modified samples and directionally-modified samples) examine specific robustness. Both sets of studies confirm the superiority of BPV and the accuracy of the conjecture.

This paper presents a linear time algorithm for testing whether or not there is a path ,vm> of an undiercted tree T (|V(T)|n) that coincides with a string ss1sm (i.e., label(v1)label(vm)s1sm). Since any path of the tree is allowed, linear time substring matching algorithms can not be directly applied and a new method is developed. In the algorithm, O(n/m) vertices are selected from V(T) such that any path pf length more than m 2 must contain at least one of the selected vertices. A search is performed using the selected vertices as 'bases' and two tables of size O(m) are constructed for each of the selected vertices. A suffix tree, which is a well-known-data structure in string matching, is used effectively in the algorithm. From each of the selected vertices, a search is performed with traversing the suffix tree associated with s. Although the size of the alphabet is assumed to be bounded by a constant in this paper, the algorithm can be applied to the case of unbounded alphabets by increasing the time complexity to O(n log m).

The Minimum Covering Run (MCR) expression used for representing binary images has been proposed [1]-[3]. The MCR expression is an adaptation from horizontal and vertical run expression. In the expression, some horizontal and vertical runs are used together for representing binary images in which total number of them is minimized. It was shown that, sets of horizontal and vertical runs representing any binary image could be viewed as partite sets of a bipartite graph, then the MCR expression of binary images was found analogously by constructing a maximum matching as well as a minimum covering in the corresponding graph. In the original algorithm, the most efficient algorithm, proposed by Hopcroft, solving the graph-theoretical problems mentioned above, associated with the Rectangular Segment Analysis (RSA) was used for finding the MCR expression. However, the original algorithm still suffers from a long processing time. In this paper, we propose two new efficient MCR algorithms that are beneficial to a practical implementation. The new algorithms are composed of two main procedures; i.e., Partial Segment Analysis (PSA) and construction of a maximum matching. It is shown in this paper that the first procedure which is directly an improvement to the RSA, appoints well a lot of representative runs of the MCR expression in regions of text and line drawing. Due to the PSA, the new algorithms reduce the number of runs used in the technique of solving the matching problem in corresponding graphs so that satisfactory processing time can be obtained. To clarify the validity of new algorithms proposed in this paper, the experimental results show the comparative performance of the original and new algorithms in terms of processing time.

The use of computers with private networks has accelerated the electronic storage of business information in office systems. With the rapid progress in processing capability and small sizing of the computer world, private networks are going to be more intelligent. The utilization of shared information is a key issue in modern organizations, in order to increase the productivity of white-collar workers. In the CSCW research field, it is said that informal and unstructured information is important in group work contexts but difficult to locate in a large organization. Many researchers are paying particular attention to the importance of support systems for such information. These kinds of information are called Organizational memory or Group Memory. Our research focuses on knowledge propagation with private networks in the organization. This means emphasis on the process; with which organized information or the ability to use information is circulated throughout the organization. Knowledge propagation has three issues: knowledge transmission, destination locating and source locating. To cope with these issues we developed FISH, which stands for Flexible Information Sharing and Handling system. FISH was designed to provide cooperative information sharing in a group work context and to explore knowledge propagation. FISH stores fragmental information as cards with multiple keywords and content. This paper discusses a three-layered model that describes computer supported knowledge transmission. Based on this model, three issues are discussed regarding knowledge propagation. FISH and its two-year experiment are described and knowledge propagation is explored based on the results of this experiment.

New critical-dimension controlling technique of off-axis illumination for aperiodic patterns has been developed. By means of arranging not-imaging additional pattern near 0.25 micron isolated patterns, the depth of focus of an isolated pattern was improved as well as the periodic patterns. Simulation and experimental results were verified on a 0.48 numerical-aperture, KrF excimer laser stepper. Using new deep-ultra-violet hardening technique for chemically amplified positive resist, the critical dimension loss of resist pattern was prevented. 0.25 micron design rule pattern was obtained with excellent mask linearity without critical-dimension-loss. The combination techniques are achieved quarter micron design rule complex circuit pattern layouts.

Thin (Ba0.75Sr0.25)TiO3 (BST) films to be used as dielectric materials in 256 Mbit DRAM capacitors were investigated. These films were deposited by an rf-sputtering method at substrate temperatures of 480 to 750. As substrate temperature increases, the dielectric constant to the films also increases, from 230 to 550. BST films prepared at temperatures higher than 700 show larger current leaks than films prepared at lower temperatures. A dielectric constant of 250, corresponding to a silicon oxide equivalent thickness (teq) of 0.47 nm, and a leak current density about 110-8 A/cm2 were obtained in 30-nm-thick film deposited at 660. Both of these values are sufficient for use in a 256 Mbit DRAM capacitor.

A polyomino is a configuration composed of squares connected by sharing edges. A k-coloring of a polyomino is an assignment of k colors to the squares of the polyomino in such a way no two adjacent squares receive the same color. A k-coloring is called balanced if the difference of the number of squares in color i and that of squares in color j is at most one for any two colors i and j. In this paper, we show that any polyomino has balanced k-coloring for k3.

It has become more important to shorten development periods of high performance computer systems and their LSIs. During debugging of computer prototypes, logic designers request very frequent LSI refabrication to change logic circuits and to add some functions in spite of their extensive logic simulation by several GFLOPS supercomputers. To meet these demands, an automated on-chip direct wiring modification system has been developed, which enables wire-cut and via-digging by a precise focused ion beam machine, and via-filling and jumper-writing by a laser CVD machine, directly on pre-redesign (original) chips. This modification system was applied to LSI reworks during the development of Hitachi large scale computers M-880 and S-3800, and contributed to shorten system debugging period by four to six months.

The Synchronous Optical Network (SONET) technology offers technical possibilities to build high speed transport networks and enables the operator to react quickly to the customers' capacity requirements. Furthermore the advanced SONET equipment, with standardized control and operation features, provides opportunities for new services, such as broadband services, and cost-effective ways to enhance existing services, such as network survivability improvement. But SONET technology can also create a certain degree of complexity in building cost-efficient network, especially in case of SONET Self-Healing Ring (SHR). It is a challenge for network planner to find an effective way to select the most economical SONET ring, or combination of rings, for given demands between a set of nodes that are supposed to be connected in a certain type of ring configuration. Three types of ring are standard today: path unidirectional, 2-fiber line protection bidirectional and 4-fiber line protection bidirectional. For a given network, the choosing of ring architecture based on economical considerations involves two major factors. They are capacity requirement and equipment cost. Capacity requirements of different SONET ring architectures depend upon different conditions. While facility line rate, which is a key factor in deciding what kind self-healing ring can be deployed economically on these requirements. Routing decisions play a key role in deciding the ring capacities required, especially for bidirectional rings. In the paper, we will make the economic study on how SONET SHR architecture works out with a variety of demand patterns, to find criteria for ring selection. We first present two efficient demand loading algorithms for BSHR capacity calculation, and then analyze the results from their application on a variety of demand patterns. The economic study for SONET SHR networks based on different architectures are also discussed.

The modular and growable photonic ATM switch architecture described in this paper uses both time-division and wavelength-division multiplexing technologies, so the switch capacity can be expanded in both the time and frequency domains. It uses a new implementation of output buffering scheme that overcomes the bottleneck in receiving and storing concurrent ultra fast optical cells. The capacity in one stage of a switch with this architecture can be increased from 32 gigabits per second to several terabits per second in a modular fashion. The proposed switch structure with output channel grouping can greatly reduce the amount of hardware and still guarantee the cell sequence.

A new mobility model dependent upon electron concentration is presented for studying the screening effect on ionized impurity scattering. By coupling this model with the drift-diffusion and Hartree models, the effects of self-consistent and quasi-equilibrium screening on carrier transport in heavily doped systems are revealed for first time. The transport mechanism is found to be dominated by the electron-concentration-dependent mobility, and transconductance is shown to be determined by effective mobility and changes from degraded to enhanced characteristics with electron concentration modulation.

Beam-steering devices are attractive for spatial optical interconnections. Those devices are essential not only for fixed connecting routed optical interconnections, but for flexible connecting routed optical interconnections. The flexible connecting routed optical interconections are more powerful than the conventional fixed connecting routed ones. Structures and characteristics of beam-steering devices, a beam-scanning laser diode and a fringe-shifting laser diode, are reported for those interconnections. Using these lasers, the configurations of several optical interconnections, such as optical buses and optical data switching links as examples of fixed and flexible connecting routed optical interconnections are discussed.

This paper proposes an optimal free-sensors allocation problem (OFSAP) in safety monitoring systems. OFSAP is the problem of deciding the optimal allocation of several sensors, which we call free sensors, to plural objects. The solution of OFSAP gives the optimal allocation which minimizes expected losses caused by failed dangerous (FD)-failures and failed safe (FS)-failures; a FD-failure is to fail to generate an alarm for unsafe object and a FS-failure is to generate an alarm for safe object. We show an unexpected result that a safer object should be monitored by more sensors under certain conditions.

In this paper an identity-based non-interactive key sharing scheme (IDNIKS) is proposed in order to realize the original concept of identity-based cryptosystem, of which secure realization scheme has not been proposed. First the necessary conditions for secure realization of IDNIKS are considered from two different poinrts of view: (i) the possibility to share a common-key non-interactively and (ii) the security for entity's conspiracy. Then a new non-interactive key sharing scheme is proposed, of which security depends on the difficulty of factoring. The most important contribution is to have succeeded in obtaining any entity's secret information as an exponent of the obtainer's identity information. The security of IDNIKS for entity's conspiracy is also considered in details.