This paper deals with graph colouring games, an example of pseudo-telepathy, in which two players can convince a verifier that a graph G is c-colourable where c is less than the chromatic number of the graph. They win the game if they convince the verifier. It is known that the players cannot win if they share only classical information, but they can win in some cases by sharing entanglement. The smallest known graph where the players win in the quantum setting, but not in the classical setting, was found by Galliard, Tapp and Wolf and has 32,768 vertices. It is a connected component of the Hadamard graph GN with N=c=16. Their protocol applies only to Hadamard graphs where N is a power of 2. We propose a protocol that applies to all Hadamard graphs. Combined with a result of Frankl, this shows that the players can win on any induced subgraph of G12 having 1609 vertices, with c=12. Moreover combined with a result of Godsil and Newman, our result shows that all Hadamard graphs GN (N ≥ 12) and c=N yield pseudo-telepathy games.

In provisioning packet data service on wireless cellular networks, a scheme of altering connection status between mobile and base stations appeared intending to efficiently utilize resource during idle periods. In such a scheme, connection components are sequentially released as an idle period persists, while the transmitting station converts to an transmission activity mode as the station is loaded with packets. However, actual resume of transmission activity is postponed by connection retrieval time to restore lost connection components. In general, an idle period affects the following connection retrieval time, which in turn produces an impact on the forthcoming idle period. Such chain reaction also makes a significant influence on overall packet delay performance. In this paper, as a way of improving packet delay performance, we propose two schemes identified as conservative extension and load threshold schemes. In the conservative extension scheme, we intentionally extend connection retrieval times so that each connection retrieval time is guaranteed not to be lower than a certain value. On the other hand, according to the load threshold scheme, a retrieval of lost connection components is postponed until packets are accumulated at the transmitting station up to a prescribed threshold. An increase in the value and threshold incurs an additional stand-by before resuming transmission activity in both proposed schemes. In turn, such intentional stand-by may contribute to regulating the length of idle period and connection retrieval time, and subsequently improving packet delay performance. To inspect the impact of conservative extension and load threshold schemes on packet delay performance, we first investigate the properties of idle periods. Secondly, for Poisson packet arrivals, we present an analytical method to exactly calculate the moments of packet delay time (at steady state) in each scheme. From numerical examples, we confirm the existence of non-trivial optimal value and threshold minimizing average packet delay or packet delay variation and conclude that conservative extension and load threshold schemes are able to enhance packet delay performance in various environments.

Mechanical prosthetic cardiac valves generate not only the widely recognized audible closing clicks but also ultrasonic closing clicks, as previously reported by us. A personal-computer-based measurement and analysis system with the bandwidth of 625 kHz has been developed to clarify the characteristics of these ultrasonic closing clicks. Fifty cases in total were assessed clinically, including cases with tilting disk valves, bileaflet valves, and flat disk valves. The ultrasonic closing clicks are damped vibrations continuing for about two milliseconds, and their frequency range was confirmed to be from 8 kHz to 625 kHz, while that of the audible click was up to 8 kHz. Although the sensitivity of the sensor decreased by approximately 30 dB at 625 kHz, effective power of the ultrasonic closing click was confirmed at this frequency. Moreover, it was shown that, surprisingly, the signal power at 625 kHz was still at the same level as that at around 100 kHz. Those wide bandwidth signal components exist independent of the type of mechanical valve, but the spectral pattern shows some dependence on the valve type.

A new in vitro experimental tool was developed to study the mechanism of the ultrasonic closing clicks' genesis of mechanical heart valves. Since the newly developed tester adopted compressed air flow directly instead of the blood analog fluid to drive the mechanical heart valve, it is not possibe to generate any cavitation. Closing clicks were measured with a small accelerometer at the surface of the valve holder made of silicone rubber. Ultrasonic closing clicks as well as audible closing clicks, similar to those measured clinically, could be observed using this setup. Thus, it was confirmed that the ultrasonic closing clicks can be generated without the existence of cavitation. Simultaneous measurements of the valve motion were made with a high-speed video camera, and the analysis of the video frames and clicks showed that higher frequency signal components of more than 50 kHz could be generated only at the instant of the closure, which means the collision of the occluder with the housing. Eighteen miniature accelerometers with an area of one square millimeter were developed and stuck on the housing to monitor the distribution of the housing vibrations in detail, and it was found that the vibrations correspond to the ultrasonic closing clicks propagated from the valve stop: the collision point of the occluder with the housing. This fact indicated that the generation of ultrasonic closing clicks are limited to the small area of the collision. From those results, it was concluded that the major origin of the ultrasonic closing clicks' genesis should be the collision of the occluder with the housing.

We propose an improved reference speaker weighting (RSW) and speaker cluster weighting (SCW) approach that uses an aspect model. The concept of the approach is that the adapted model is a linear combination of a few latent reference models obtained from a set of reference speakers. The aspect model has specific latent-space characteristics that differ from orthogonal basis vectors of eigenvoice. The aspect model is a "mixture-of-mixture" model. We first calculate a small number of latent reference models as mixtures of distributions of the reference speaker's models, and then the latent reference models are mixed to obtain the adapted distribution. The mixture weights are calculated based on the expectation maximization (EM) algorithm. We use the obtained mixture weights for interpolating mean parameters of the distributions. Both training and adaptation are performed based on likelihood maximization with respect to the training and adaptation data, respectively. We conduct a continuous speech recognition experiment using a Korean database (KAIST-TRADE). The results are compared to those of a conventional MAP, MLLR, RSW, eigenvoice and SCW. Absolute word accuracy improvement of 2.06 point was achieved using the proposed method, even though we use only 0.3 s of adaptation data.

In this paper, we proposed two models, the full multiple MCS (Multicast Server) model and the hybrid multiple MCS model to support multiple MCS over a single large cluster in ATM (Asynchronous Transfer Mode) networks. Also, we presented two methods for MCS assignment which are known as 2PSPMT (2 Phase Shortest Path based on Multicast tree) and hybrid-2PSPMT, and evaluated its performance by simulation. When an ATM host requests joining a specific multicast group, the MARS (Multicast Address Resolution Server) designates a proper MCS among the multiple MCSs for the group member to minimize the average path delay between the sender and the group members. Each method for MCS assignment construct a 2-phase partial multicast tree based on the shortest path algorithm. We reduced the average path delay in the multicast tree using these methods with various cluster topologies and MCS distribution scenarios in addition to distributing the load among multiple MCSs.

Power consumption is one of the most important factors in successfully designing of wireless sensor networks since it directly affects network lifetime. We propose a topology control scheme that reduces power consumption by minimizing, as much as possible, the number of active nodes, in a highly dense region as well as to decrease packet transmission delay. Simulation results show that our scheme can effectively solve the energy inefficiency problem caused by unbalanced power consumption, and can significantly reduce packet transmission delay.

IPv6 is designed to solve the exhaustion of the address space, which are one of the biggest problems in the current Internet. The WIDE project has been involved in IPv6 since its early stage, and organized the KAME project in 1998 in order to accelerate its deployment. The KAME project has provided a free, specification-compliant implementation of IPv6 on BSD variants. With its quality and the continuous efforts on it, the implementation has established the position of a reference to IPv6, and has been adopted in BSD variants and in several commercial products. This paper first gives an overview of the IPv6 specifications, including its plug-and-play function, API, DNS, security and transition tools. It then describes the implementation by the KAME project. It is based on the BSD's original network stack, but explores some original enhancements for Neighbor Discovery or IPv6 addressing. Finally, it explains what is missing for the next steps of IPv6, concentrating on plug-and-play and security. The KAME project has joined, and will continue, the standardization and implementation efforts on the new issues.

We have developed a 17-inch WXGA full-color polymer OLED display by using newly developed ink-jet printing method. On the ink-jet technology, both droplet volume and landing position were precisely controlled pixel by pixel in order to get luminance uniformity. A pixel circuit having Vth variation-cancellation was adopted and the circuit was modified to realize high uniformity and high gray scale reproduction under the short horizontal period operation. Correction on gamma profile difference among RGB OLEDs was achieved by optimizing on configuration between integrated source driver circuit and outer reference voltage circuit in spite of using a common source driver IC having only one gamma profile. Peak control system, that is important for the large size and high luminance display, was utilized and improved image quality on human feeling and actual power consumption. With these efforts a uniform picture with 260,000 colors and wide viewing angle was achieved. It was proved that the ink-jet method was the optimal manufacturing technology for large-size and high-resolution OLED displays. And we found there is no singular problem on the large size OLED display utilized the ink-jet technology.

A conventional waveguide filter is usually composed of a waveguide which is set with irises and posts inside. When dielectric material is not loaded inside the filter, the filter is too large to mount it on a planar circuit even if the frequency band is as high as the millimeter-wave band. In this paper, we propose a dielectric waveguide filter using LTCC (Low-Temperature Co-fired Ceramics) which can be mounted on a planar circuit. The dielectric waveguide filter using LTCC is composed of a dielectric-loaded waveguide including posts (via holes) and TEM-TE10 converters. The design method of the filter is shown and comparison of the simulated and the experimental results in the 6 GHz band is demonstrated. The simulated results agreed well with the experimental ones. To improve the attenuation characteristics, particularly at the above pass-band frequencies, an attenuation pole is added using a cross patch set inside the LTCC filter in the 25 GHz band. The effect of the cross patch is confirmed using the same simulation method as used for the 6 GHz band. As a result, it is confirmed that the cross patch is very useful for improving the attenuation characteristics at the above pass-band frequencies.