Digital halftoning is used to quantize a grayscale image to a binary image. Error diffusion halftoning generates a high-quality binary image, but also generates some defects such as the warm effect, sharpening, and so forth. To reduce these defects, Kite proposed a modified threshold modulation method that utilizes a multiplicative parameter for controlling sharpening. Nevertheless, some degradation was observed near the edges of objects with a large luminance change. In this paper, we propose a method of controlling the multiplicative parameter in proportion to the magnitude of the local edge slope. The results of computer simulation show a greater reduction of sharpening in the halftone image. In particular, there is a great improvement in the quality of the edges of objects with a large luminance change.

We study analysis of hybrid systems under incomplete knowledge. The class of hybrid systems to be considered is assumed to have the form of a rectangular hybrid automaton such that each constant in invariants and guards is given as a parameter. We develop a method based on symbolic computation that computes an approximation of the discrete behavior of the automaton. We also show an implementation on a constraint logic programming language.

The PN triangle method has a great significance in processing tessellation at the hardware level without software assistance. Despite its significance, however, the conventional PN triangle method has certain defects such as inefficient GE operation and degradation of visual quality. Because the method tessellates a curved surface according to the user-defined fixed LOD (Level Of Detail). In this paper, we propose adaptive tessellation of PN triangles using minimum-artifact edge linking. Through this method, higher efficiency of tessellation and better quality of scene are obtained by adaptivity and minimum-artifact edge linking, respectively. This paper also presents a hardware architecture of a PN triangle method using adaptive LOD, which is not a burden for overall 3D graphics hardware.

We propose a robust edge detection method based on independent component analysis (ICA). It is known that most of the basis functions extracted from natural images by ICA are sparse and similar to localized and oriented receptive fields, and in the proposed edge detection method, a target image is first transformed by ICA basis functions and then the edges are detected or reconstructed with sparse components only. Furthermore, by applying a shrinkage algorithm to filter out the components of noise in the ICA domain, we can readily obtain the sparse components of the original image, resulting in a kind of robust edge detection even for a noisy image with a very low SN ratio. The efficiency of the proposed method is demonstrated by experiments with some natural images.

This paper introduces a new type of microwave isolator. The operation is based on the two phenomena; the ferrite edge-mode and the photo-generated plasma on silicon substrate. Conventional ferrite edge-mode isolator has been made of the ferrite and the resistive material. The later is used to absorb the reverse-propagating wave of the isolator. An inadequate choice of the resistive body leads to the imperfect absorption; the isolation ratio decreases. In this paper, the isolation-variable isolator is introduced by using this change of isolation. The control is realized by the change of the surface resistance on the silicon. On this isolator, the frequency response is investigated both experimentally and numerically. The numerical analysis is conducted by FDTD method. The experiment is carried out on the prototype isolator. Both experimental and numerical results have shown that the isolation ratio can be controlled for 39 dB at 12 GHz by the irradiation.

TCP (Transmission Control Protocol) is the prevalent reliable transport protocol used for many kinds of the popular Internet services like web browsing and e-mail. Because these services are the dominant applications on the Internet, TCP can be said to control the large majority of today's Internet traffic and we can say the enhancement of TCP performance means the improvement of the most Internet performance. This paper compares various ACK generation TCP strategies that play very important roles in TCP operation and proposes advanced delayed ACK algorithms to mitigate the negative effect of delayed ACK algorithm. Even if delayed ACK has the bright side to save network resources and power consumption that are the very important factors especially for mobile and wireless environment, it has also dark side not to take full advantage of network bandwidth in Slow Start phase. It is reported that delayed ACK timeout of the first and last segment causes severe degradation problem in TCP throughput performance. We suggest new algorithms to solve delayed ACK penalty and to guarantee fairness with other traffics in Slow Start. In wired-cum-wireless network environments,'BADA (Base station Aided Delayed ACK)' with SNDA (Sender Notification Delayed ACK), the combination of our proposed algorithm shows the best performance in terms of throughput as well as in terms of network resource sharing. Our simulation shows significantly improved performance in TCP throughput.

Next generation wired/wireless networks will be based on IP technology. In the IP based networks, it is crucially required to support seamless mobility especially for proving real-time services in the mobile environment. The conventional Mobile IP protocols cannot satisfy such seamless mobility requirements for real-time services. Therefore various extensions of Mobile IP are being proposed. In this paper, we propose a new handover scheme to enhance the existing tunnel-based fast handover method, which is a typical Mobile IP extension to support seamless mobility. It is shown that the proposed method reduces the traffic overhead in the networks. It is expected that the proposed method will be particularly useful in the IP-based networks in which there are a number of users simultaneously using the long-lived real-time services, or in the condition that the traffic overhead is considered as a critical performance measure.

We compared two edge-blending methods for multi-projection displays, elliptic and rectangular blending, by simulating three common situations: (1) an inaccurately estimated calibration parameter, (2) a worn projector lamp, and (3) a shifted viewpoint. We used a two-level-of-detail display including a high-gain rear-projection screen in the simulation to demonstrate an extreme case. The comparisons showed how strongly inaccurate elements affect a composite besides affecting the appearance itself. A subjective assessment was also carried out to obtain the evaluations of actual users. The simulation results showed that in many cases elliptic blending is more effective than rectangular blending.

We have been developing new cycling environments by using knowledge sharing and speech communication. We have offered multimodal knowledge contents to share knowledge on safe and exciting cycling. We accumulated 140 contents, focused on issues such as riding techniques, trouble shootings, and preparations on cycling. We have also offered a new way of speech communication using an ad-hoc wireless LAN technology for safe cycling. Group cycling requires frequent communication to lead the group safely. Speech communication achieves spontaneous communication between group members without looking around or speaking loudly. Experimental result through actual cycling has shown the effectiveness of sharing multimodal knowledge contents and speech communication. Our new developed environment has an advantage of increasing multimodal knowledge through the accumulation of personal experiences of actual cycling.

A nearly equitable edge-coloring of a multigraph is a coloring such that edges incident to each vertex are colored equitably in number. This problem was solved in O(kn2) time, where n and k are the numbers of the edges and the colors, respectively. The running time was improved to be O(n2/k + n|V|) later. We present a more efficient algorithm for this problem that runs in O(n2/k) time.

Recently, the mulitihop wireless network system attracts the interest of many people as a communication network system of the next generation. The multihop wireless network has unique features in which neither base stations nor wired backbone networks are required and a terminal can communicate with the other terminal beyond the transmission range by multihopping. In this network, a communication link between two terminals which can communicate directly is required a channel. Since cochannel interference may occur, we need to assign channels to communication links carefully. In this paper, we describe a channel assignment strategy which takes the degree of cochannel interference into consideration, and we evaluate an effectiveness of this strategy by computer simulations. We show that this strategy is more effective than a strategy which does not take the degree of cochannel interference into consideration. And we also consider a few channel assignment algorithms briefly.

The modeling of an application domain and its specific knowledge description language are important for developing knowledge-based systems. A rapid-prototyping approach is suitable for such developments since in this approach the modeling and language development are processed simultaneously. However, programming languages and their supporting environments which are usually used for prototyping are not necessarily adequate for developing practical applications. We have been developing an integrated development environment for knowledge-based systems, which supports all the development phases from the early prototyping phase to final commercial development phase. The environment called INSIDE is based on a Prolog abstract machine, and provides all of the functions required for the development of practical applications in addition to the standard Prolog features. This enables the development of both prototypes and practical applications in the same environment. Moreover, their efficient development and maintenance can be achieved. In addition, the effectiveness of INSIDE is described by examples of its practical application.

This paper describes the design concept and implementation of a software platform for realization of symbiotic robots that interact intelligently with human in symbiosis manner. Such robots require proper combination of various technologies on a common platform that allows them to work co-operatively. "SPAK" has been developed to serve this purpose. It is a Java-based software platform to support knowledge processing and co-ordination of tasks among several software modules and agents representing the robotic hardware connected on a network. SPAK features frame-based knowledge system, a GUI knowledge building tool, forward and backward chaining engines, networking support, and class libraries for building software agent components. Beside the robotic applications, SPAK can be used as a general-purpose frame system as well. An experimental application of SPAK in human-robot interaction is also given.

A new low power edge-triggered and logic embedded flip-flop based on complementary pass transistor circuit is proposed. This flip-flop provides small clock load, short propagation delay, single-phase clock scheme and small layout area. The flip-flop can reduce 35.2% power consumption while improving 24.7% propagation delay in comparison to conventional transmission-gate master-slave flip-flop in a standard 0.35 µm CMOS technology at 1.5 V power supply. In addition, logic functions can be embedded in the flip-flop. In 2-inputs multiplexer and flip-flop circuit, the proposed circuit can reduce 28.0% power consumption and improve 20.3% propagation delay compared to conventional circuit.

A compact wide-band antennas design for the 2.4 GHz/5.8 GHz dual ISM-band application is introduced by combing a single-feed and single-layer microstrip antenna in the form of a T-type strip with an edge perturbation. Good impedance bandwidth performance for the dual-band is observed. The advantage of the design suggested in this paper is its simplicity of manufacturing and low cost.

Mining generalized frequent patterns of generalized association rules is an important process in knowledge discovery system. In this paper, we propose a new approach for efficiently mining all frequent patterns using a novel set enumeration algorithm with two types of constraints on two generalized itemset relationships, called subset-superset and ancestor-descendant constraints. We also show a method to mine a smaller set of generalized closed frequent itemsets instead of mining a large set of conventional generalized frequent itemsets. To this end, we develop two algorithms called SET and cSET for mining generalized frequent itemsets and generalized closed frequent itemsets, respectively. By a number of experiments, the proposed algorithms outperform the previous well-known algorithms in both computational time and memory utilization. Furthermore, the experiments with real datasets indicate that mining generalized closed frequent itemsets gains more merit on computational costs since the number of generalized closed frequent itemsets is much more smaller than the number of generalized frequent itemsets.

Free-standing 2D slab photonic band-edge lasers based on square lattice and triangular lattice are realized by optical pumping at room-temperature. Both in-plane-emission and surface-emission photonic band-edge lasers are observed and compared. Analyses on optical loss mechanisms for finite-size photonic band-edge lasers are also discussed.

There are two main types of digital watermark systems. In the first, users are given their own detection programs by which to verify the presence of watermark in data they have in their possession. In the second, users must request such verification from a detection center. The disadvantage of the first type is the possibility that a user might be able to analyze the detection program sufficiently to be able to obtain the secret data (secret key) used to embed the watermark. The disadvantage of the second is the possibility that a center might give dishonest results. In this paper, we propose a watermark detection scheme that can be used to overcome the disadvantages of both: it prevents users from obtaining secret key, and it prevents a center from reporting dishonest results. Our scheme is based on a previously proposed scheme which nearly achieved the same goals but, unfortunately, allowed users to receive watermark detection results for data specially created by them so as to reveal, through the results, secret information about how a center created its watermarks. To overcome this drawback, we have developed new scheme by which a center can prove its detection results to a user without revealing any other information. This scheme was developed by extending the work found in. Moreover we provide an option that prevents the center from encroaching on a user's privacy. The resulting watermark detection scheme is the first that, in addition to protecting secret keys of watermarks from user-tampering, is also able to prevent a center from reporting dishonest results. Although the proposed scheme is introduced first using the patch-work watermarking system, it is straightforward to extend it to a scheme that uses the correlation-based watermarking system, which yields a more robust watermark detection scheme.

This letter proposes a millimeter-wave band transformer to connect a standard waveguide to a very thin post-wall waveguide. The post-wall waveguide height is the same as a microstrip or coplanar line. A dielectric substrate with slits etched on both edges is inserted in the standard waveguide for matching. A 22 GHz transformer gives 3.6% bandwidth for a 0.5 mm-height post-wall waveguide. The effects of various mechanical misalignments upon the frequency characteristics of the reflection are also estimated by analysis and measurements.

Goldwasser and Sipser proved that every interactive proof system can be transformed into a public-coin one (a.k.a. an Arthur-Merlin game). Unfortunately, the applicability of their transformation to cryptography is limited because it does not preserve the computational complexity of the prover's strategy. Vadhan showed that this deficiency is inherent by constructing a promise problem Π with a private-coin interactive proof that cannot be transformed into an Arthur-Merlin game such that the new prover can be implemented in polynomial-time with oracle access to the original prover. However, the transformation formulated by Vadhan has a restriction, i.e., it does not allow the new prover and verifier to look at common input. This restriction is essential for the proof of Vadhan's negative result. This paper considers an unrestricted transformation where both the new prover and verifier are allowed to access and analyze common input. We show that an analogous negative result holds even in this unrestricted case under a non-standard computational assumption.