Double-sided YBa2Cu3O7 (YBCO) films were successfully prepared on 50-mm-diameter CeO2-buffered sapphire substrates by metalorganic deposition (MOD) process using an acetylacetonate coating solution. Mapping analysis of superconducting current densities (Jc) at 77.3 K revealed that Jc values of the double-sided films indicated in excess of 2 MA/cm2 in the center parts with a small decrease of Jc at the outer side of the specimens. The Jc values of one side (A) are higher than those of the other side (B). Microwave surface resistance (Rs) of sides A and B of the film exhibited 0.57 and 0.60 mΩ, respectively, at 70 K (12 GHz). The difference in the Rs values should be attributed to the slight difference in the Jc values, which arose from the surface morphology of the CeO2 buffer layer and heat treatment conditions during the firing process in MOD.

An algorithm is described for solving the node-to-set disjoint paths problem in bi-rotator graphs, which are obtained by making each edge of a rotator graph bi-directional. The algorithm is of polynomial order of n for an n-bi-rotator graph. It is based on recursion and divided into three cases according to the distribution of destination nodes in the classes into which the nodes in a bi-rotator graph are categorized. We estimated that it obtains 2n-3 disjoint paths with a time complexity of O(n5), that the sum of the path lengths is O(n3), and that the length of the maximum path is O(n2). Computer experiment showed that the average execution time was O(n3.9) and, the average sum of the path lengths was O(n3.0).

We propose a new practical input interface for the recognition of Non-Audible Murmur (NAM), which is defined as articulated respiratory sound without vocal-fold vibration transmitted through the soft tissues of the head. We developed a microphone attachment, which adheres to the skin, by applying the principle of a medical stethoscope, found the ideal position for sampling flesh-conducted NAM sound vibration and retrained an acoustic model with NAM samples. Then using the Julius Japanese Dictation Toolkit, we tested the feasibility of using this method in place of an external microphone for analyzing air-conducted voice sound.

In this paper, we propose a framework for virtual reality, I2-NEXT, which enables users to interact with virtual objects by tangible objects in immersive networked virtual environment. The primary goal of this framework is to support rapid development of immersive and interactive virtual reality systems as well as various types of user interfaces. The proposed framework consists of user interface for interactions, immersive virtual environment, and networking interface. In this framework, we adopt several design patterns to guarantee that either developers or users (artists) can easily implement their VR applications without strong knowledge of VR techniques such as programming, libraries etc. One of the key features of this framework is the presence of the device module which supports a natural user interaction in a virtual environment. For example, the proposed framework provides users with tangible objects so that the users are able to manipulate virtual objects by touching real objects. The proposed framework also supports large scale stereoscopic display through clustering technique. To realize the effectiveness of the proposed framework, we have been developing an application for digital heritage reconstruction. Having been through development of the system, we believe that virtual reality technology is one of the promising technologies which enable users to experience realities in a digital space. Detailed explanations of each component and system architecture are presented.

Our group is exploring interactive multi- and hypermedia, especially applied to virtual and mixed reality multimodal groupware systems. We are researching user interfaces to control source→sink transmissions in synchronous groupware (like teleconferences, chatspaces, virtual concerts, etc.). We have developed two interfaces for privacy visualization of narrowcasting (selection) functions in collaborative virtual environments (CVES): for a workstation WIMP (windows/icon/menu/pointer) GUI (graphical user interface), and for networked mobile devices, 2.5- and 3rd-generation mobile phones. The interfaces are integrated with other CVE clients, interoperating with a heterogeneous multimodal groupware suite, including stereographic panoramic browsers and spatial audio backends & speaker arrays. The narrowcasting operations comprise an idiom for selective attention, presence, and privacy-- an infrastructure for rich conferencing capability.

In this paper, we propose a novel virtual display system for a real object surface by using a video projector, so that the viewer can feel as if digital images are printed on the real surface with arbitrary shape. This system consists of an uncalibrated camera and video projector connected to a same PC and creates a virtual object by rendering 2D contents preserved beforehand onto a white object in a real world via a projector. For geometry registration between the rendered image and the object surface correctly, we regard the object surface as a set of a number of small rectangular regions and perform geometry registration by calculating homographies between the projector image plane and the each divided regions. By using such a homography-based method, we can avoid calibration of a camera and a projector that is necessary in a conventional method. In this system, we perform following two processes. First of all, we acquire the status of the object surface from images which capture the scene that color-coded checker patterns are projected on it and generate image rendered on it without distortion by calculating homographies. After once the projection image is generated, the rendered image can be updated if the object surface moves, or refined when it is stationary by observing the object surface. By this second process, the system always offers more accurate display. In implementation, we demonstrate our system in various conditions. This system enables it to project them as if it is printed on a real paper surface of a book. By using this system, we expect the realization of a virtual museum or other industrial application.

The deblocking filter in H.264 is an efficient tool to reduce blocking artifact, but it also blurs the details or retains blocking artifact perceptible in some high-activity areas. In this paper, we improve the filtered pixel classification and filtering schemes used by the deblocking filter in H.264 to keep the sharpeness of real edges and minimize over-smoothing.

This paper studies the state-of-the-art software optimization methodology for symmetric cryptographic primitives on Pentium III and 4 processors. We aim at maximizing speed by considering the internal pipeline architecture of these processors. This is the first paper studying an optimization of ciphers on Prescott, a new core of Pentium 4. Our AES program with 128-bit key achieves 251 cycles/block on Pentium 4, which is, to our best knowledge, the fastest implementation of AES on Pentium 4. We also optimize SNOW2.0 keystream generator. Our program of SNOW2.0 runs at the rate of 2.75 µops/cycle on Pentium III, which seems the most efficient code ever made for a real-world cipher primitive. Our another interest is to optimize cryptographic primitives that essentially utilize 64-bit operations on Pentium processors. For the first example, the FOX128 block cipher, we propose a technique for speeding-up by interleaving two independent blocks using a register group separation. For another examples, we consider fast implementation of SHA512 and Whirlpool. It will be shown that the new SIMD instruction sets introduced in Pentium 4 excellently contribute to fast hashing of SHA512.

Contract signing is a practical application of the fair exchange of digital signatures. This application used to be realized by directly adopting the results of the fair exchange of signatures, which do not completely meet the requirements of the signing of a secret contract. The assistance of a trusted third party (TTP) and some cryptographic technology are required to allow two parties to exchange their signatures through the network in a fair manner because these two parties potentially may be dishonest or mistrust each other. This paper presents a subtle method of preventing the off-line TTP from gaining the exchanged signature and the corresponding message when a dispute occurs between the two parties wherein the TTP is required to take part in the exchange procedure. An advanced concept, the non-disclosure property, is proposed in order to prevent a party from misusing evidence left during the exchange process. Two approaches, namely the secret divide method and the convertible signature are demonstrated. To satisfy the properties of the traditional paper-based contract signing, the technique of multi-signature scheme is used in the proposed protocols.

A free-space method is in wide spread use for the reflectivity measurement of electromagnetic wave absorbers (EMA) in VHF and UHF range. In the free-space method, the reflection levels from EMA and from the metal plate with same size as the EMA are measured, and the reflectivity is calculated from their ratio. The incident angle such as normal or oblique must be defined, and the polarization of electromagnetic (EM) wave must be specified to be TE, TM, or circularly-polarized mode. In this paper, a parallel EM wave beam method using dielectric lenses in front of horn antennas was studied experimentally. Electromagnetic wave absorption was measured with the vertical and the oblique incidence by using this parallel EM wave beam. This measurement system has following features:• It is compact because equiphase parallel EM wave beam was obtained in a short distance from the dielectric lens.• It requires no anechoic chamber because of little multi-reflection due to high directivity of parallel EM wave beam.• It allows a large oblique incident measurement by using high directive parallel EM wave beam.

This paper investigates a modifying orthogonality factor for synchronous DS-CDMA uplink in dispersive Rician multipath fading channels, which reflects upon the effects of specular path power as well as decaying channel characteristics. Using this investigation, the orthogonal factors in indoor environments are evaluated and compared with the various parameters such as decaying factor, line-of-sight component, and the number of multipaths.

Mobile devices have acceleratedly penetrated into our daily lives. Though they were originally designed as a communication tool or for personal use, and due to the rapid availability of wireless network technologies, people have begun to use mobile devices for supporting collaborative work and learning. There is, however, a serious problem in mobile devices related to their user interfaces. In this paper, we try to alleviate the problem and propose intuitive techniques for information transfer, which is one of the typical usages of mutually-connected computers. Our system, Toss-It, enables a user to send information from the user's PDA to other electronic devices with a "toss" or "swing" action, like a user would toss a ball or deal cards to others. The implementation of Toss-It consists of three principle parts - gesture recognition, location recognition, and file transfer. We especially describe the details of gesture recognition and location recognition. We then evaluate the practicability and usability of Toss-It through the experiments. We also discuss user scenarios describing how Toss-It can support users' collaborative activities.

This paper investigates some modular powering functions suitable for cryptography. It is well known that the Rabin encryption function is a 4-to-1 mapping and breaking its one-wayness is secure under the factoring assumption. The previously reported encryption schemes using a powering function are variants of either the 4-to-1 mapping or higher n-to-1 mapping, where n > 4. In this paper, we propose an optimized powering function that is a 3-to-1 mapping using a p2q-type modulus. The one-wayness of the proposed powering function is as hard as the infeasibility of the factoring problem. We present an efficient algorithm for computing the decryption for a p2q-type modulus, which requires neither modular inversion nor division. Moreover, we construct new provably secure digital signatures as an application of the optimized functions. In order to achieve provable security in the random oracle model, we usually randomize a message using random hashing or padding. However, we have to compute the randomization again if the randomized message is a non-cubic residue element--it is inefficient for long messages. We propose an algorithm that can deterministically find the unique cubic residue element for a randomly chosen element.

In this paper, we present the Tangible Media Control System (TMCS), which allows users to manipulate media contents through physical objects in an intuitive way. Currently, most people access digital media contents by exploiting GUI. However, it only provides limited manipulation of the contents. The proposed system, instead of a mouse and a keyboard, adopts two types of tangible objects, i.e. a RFID-enabled object and a tracker-embedded object. The TMCS enables users to easily access and control digital media contents through tangible objects. In addition, it supports an interactive media controller which can be used to synthesize media contents according to users' taste. It also offers personalized contents, which suits users' preferences, by exploiting context such as the users' profile and situational information. Accordingly, the TMCS demonstrates that tangible interfaces with context can provide more effective interfaces to satisfy users' demands. Therefore, the proposed system can be applied to various interactive applications such as multimedia education, entertainment, multimedia editor, etc.

Digital watermarking used for fingerprinting may receive a collusion attack; two or more users collude, compare their data, find a part of embedded watermarks, and make an unauthorized copy by masking their identities. In this paper, assuming that at most c users collude, we give a characterization of the fingerprinting codes that have the best security index in a sense of "(c,p/q)-secureness" proposed by Orihara et al. The characterization is expressed in terms of intersecting families of sets. Using a block design, we also show that a distributor of data can only find asymptotically a set of c users including at least one culprit, no matter how good fingerprinting code is used.

This letter investigates a distinct set of complex unitary matrices for differential space time coding by using QPSK modulation. The numerical results show that the properly selection of the initial transmission matrix and the set of unitary matrices can efficiently improve the bit error rate (BER) performance, especially for the antennas correlated fading channel. The computer simulations are evaluated over slow and fast Rayleigh fading channels.

The adaptive Volterra filter (AVF) is attractive in adaptive filtering applications because its expansion is a linear combination of the input and output signals. However, the formidable computational work of AVF is prohibitive for practical applications. In this letter, we present a parallel fast recursive least squares (RLS) second-order adaptive Volterra filter (PAVF) to reduce computational load. Our discussion is based on the approach of the fast RLS AVF [3], by which the computational complexity has been reduced to O(N3) multiplications per time instant, where O(·) denotes "order of," and N is the filter length. Proposed PAVF consists of several subfilters partitioned from the conventional AVF, with parallel implementation, the computational work can be reduced effectively. Several simulation results are presented to validate the proposed method.

Face motion is composed of rigid motion and non-rigid motion. The rigid motion occurs from movements of the human head and the non-rigid motion derives from human's facial expression. In this paper, we present a technique for estimating these rigid/non-rigid motions of the human face simultaneously. First, we test whether the face motion is rigid. If it is rigid motion, we estimate the translation and rotation parameters over image sequences. Otherwise, the non-rigid motion parameters based on the spring-mass-damper (SMD) model are estimated using optical flow. We separate the rigid motion parameters explicitly from the non-rigid parameters for parameters de-coupling, so that we can achieve the face motion estimation more accurately and more efficiently. We will describe the details of our methods and show their efficacy with experiments.

It has been a very important issue to evaluate the performance of transmission control protocol (TCP), and the importance is still growing up because TCP will be deployed more widely in future wireless as well as wireline networks. It is also the reason why there have been a lot of efforts to analyze TCP performance more accurately. Most of these works are focusing on overall TCP end-to-end throughput that is defined as the number of bytes transmitted for a given time period. Even though each TCP's fast recovery strategy should be considered in computation of the exact time period, it has not been considered sufficiently in the existing models. That is, for more detailed performance analysis of a TCP implementation, the fast recovery latency during which lost packets are retransmitted should be considered with its relevant strategy. In this paper, we extend the existing models in order to capture TCP's loss recovery behaviors in detail. On the basis of the model, the loss recovery latency of three TCP implementations can be derived with considering the number of retransmitted packets. In particular, the proposed model differentiates the loss recovery performance of TCP using selective acknowledgement (SACK) option from TCP NewReno. We also verify that the proposed model reflects the precise latency of each TCP's loss recovery by simulations.

This paper presents new algorithms for the Tate pairing on a prime field. Recently, many pairing-based cryptographic schemes have been proposed. However, computing pairings incurs a high computational cost and represents the bottleneck to using pairings in actual protocols. This paper shows that the proposed algorithms reduce the cost of multiplication and inversion on an extension field, and reduce the number of calculations of the extended finite field. This paper also discusses the optimal algorithm to be used for each pairing parameter and shows that the total computational cost is reduced by 50% if k = 6 and 57% if k = 8.