Faculty Profiles - YAMAZAKI Tatsuya

Papers - YAMAZAKI Tatsuya

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A multimedia service composition scheme for ubiquitous networks Reviewed

M Kosuga, N Kirimoto, T Yamazaki, T Nakanishi, M Masuzaki, K Hasuike

JOURNAL OF NETWORK AND COMPUTER APPLICATIONS 25 ( 4 ) 279 - 293 2002.10

Language：English Publishing type：Research paper (scientific journal) Publisher：ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD

It is a challenging task to develop a high quality and secure multimedia service for mobile terminals used in the ubiquitous computing environment. One of the issues is the resource limitation of mobile terminals. In this paper, we presented a multimedia service composition scheme for sharing computer and communication resources by using plural terminals to compensate for this resource limitation. The proposed scheme is based on user authentication, service access control, and the multi-agent-based adaptive Quality-of-Service (QoS) control framework that we developed. We also proposed a novel access mode control based on the trustworthiness of users and extension of the multi-agent-based adaptive QoS control framework to plural users. Focusing on the home network as a typical ubiquitous network, we implemented a prototype testbed system and showed experimental results for the multimedia service composition. (C) 2002 Elsevier Science Ltd. All rights reserved.

DOI： 10.1006/jnca.2002.0140

A Study of Multimedia Communication Coordination with Content Processing

YAMAZAKI Tatsuya, HASUIKE Kazuo, MASE Kenichi, SENGOKU Masakazu

ITE Technical Report 26 ( 13 ) 25 - 30 2002.2

Language：Japanese Publisher：The Institute of Image Information and Television Engineers

Distributing multimedia data to edge servers prevents concentration of access, so that end-users are provided high-quality multimedia services. The CCS (Communication Coordination Server) that we propose is a kind of edge server and provides QoS (Quality of Service) transform by a transcoding technique. We propose a new communication service coordination scheme for the CCS by content processing according to user's requirement or purpose.

DOI： 10.11485/itetr.26.13.0_25

Proactive information supply for activating conversational interaction in virtual communities Reviewed

N. Kurabayashi, T. Yamazaki, T. Yuasa, K. Hasuike

Proceedings - IEEE Workshop on Knowledge Media Networking, KMN 2002 167 - 170 2002

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Institute of Electrical and Electronics Engineers Inc.

This paper describes a method for activating conversational interaction in virtual communities. Our method supplies information proactively to promote utterances of participants. The notion of subjective usefulness of information is introduced to guide conversation effectively so that the participants can obtain or exchange useful information. We implemented an agent that employs our method and conducted the experiments to verify validity of our method. As a result, we found that our method was able to activate conversational interaction and assist participants in obtaining or exchanging useful information.

DOI： 10.1109/KMN.2002.1115180

A multiagent-based adaptive QoS management scheme Reviewed

M Kosuga, T Yamazaki, N Ogino, J Matsuda

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART I-COMMUNICATIONS 85 ( 10 ) 96 - 105 2002

Language：English Publishing type：Research paper (scientific journal) Publisher：SCRIPTA TECHNICA-JOHN WILEY & SONS

With the improvement of speed in personal computers and workstations for communication networks and communication terminals, various applications have been emerging in recent years based on multimedia communications, including stream-type media. In these communication applications, there must be a framework by which the QoS of its stream is determined and adjusted to meet its own purposes according to the user's request and the situation of the terminal and the network. When such an adaptive QoS control mechanism is built in an individual communi cation application, however, the communication application will become complicated. It is thus desirable that the adaptive QoS control mechanism should be realized as a common basis for various communication applications. This paper proposes a framework to realize an adaptive QoS control mechanism that can serve as the common basis for various communication applications, based on direct or indirect collaboration by multiple agents. The proposed framework is implemented and its operation is verified. (C) 2002 Wiley Periodicals, Inc.

DOI： 10.1002/ecja.1135

Composing a multimedia service by plural terminals in ubiquitous networks Reviewed

N Kirimoto, M Kosuga, T Yamazaki, T Nakanishi, M Masuzaki, K Hasuike

IEEE WORKSHOP ON KNOWLEDGE MEDIA NETWORKING, PROCEEDINGS 57 - 62 2002

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE COMPUTER SOC

It is a challenging task to develop a high quality and secure multimedia service for mobile terminals used in the ubiquitous computing environment. One of the issues is the resource limitation of mobile terminals. In this paper, we presented a multimedia service composition scheme for sharing computer and communication resources by using plural terminals to compensate for this resource limitation. The proposed scheme is based on user authentication, service access control, and the multiagent-based adaptive QoS control framework that we developed We also proposed a novel access mode control based on the trustworthiness of users and extension of the multi-agent-based adaptive QoS control framework to plural users. Focusing on the home network as a typical ubiquitous network, we implemented a prototype testbed system and showed experimental results for the multimedia service composition.

DOI： 10.1109/KMN.2002.1115163

QoS adjustment scheme for video transmission to a heterogeneous receivers group Reviewed

T Yamazaki

PROCEEDINGS OF THE 6TH JOINT CONFERENCE ON INFORMATION SCIENCES 6 996 - 1000 2002

Language：English Publishing type：Research paper (international conference proceedings) Publisher：ASSOC INTELLIGENT MACHINERY

In this paper, a QoS adjustment scheme is proposed for real-time video transmission applications which deal with heterogeneous receivers. The heterogeneity of the receivers includes the performance difference of user terminals and networks as well as the difference of the user requirements for multimedia services. The proposed scheme considers the user's respective communication environments and calculates a feasible QoS for each user to utilize the system resources like CPU powers or network bandwidths efficiently. The proposed scheme is implemented in a proxy server, which intermediates between a video server and a group of receivers.

Spline-based QoS Mapping Mechanisms for Hierarchical Multilevel QoS Models.

Tatsuya Yamazaki

IEICE Trans. Fundam. Electron. Commun. Comput. Sci. 85-A ( 6 ) 1349 - 1351 2002

Publishing type：Research paper (scientific journal)

A generic multilevel quality-of-service (QoS) model for distributed multimedia applications is presented. QoS mapping mechanisms are required to translate the QoS parameters among the hierarchical levels. One QoS mapping mechanism based on the spline functions is proposed, hence two splines are compared. One is natural splines and the other is B-splines. QoS measurement experiments were conducted, and it is found that the B-splines give more accurate mapping results than the natural splines once the knots for the splines are selected appropriately.

Other Link： https://dblp.uni-trier.de/db/journals/ieiceta/ieiceta85.html#Yamazaki02

A scalable resource allocation scheme over DiffServ towards end-to-end QoS assurance Reviewed

A Alexelis, T Yamazaki, K Hasuike

IEICE TRANSACTIONS ON COMMUNICATIONS E84B ( 12 ) 3113 - 3123 2001.12

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

In recent years, the concept of Quality of Service (QoS) has gained attention in thc network research community and its extension towards delivering QoS level assurance to sensitive applications has generally been agreed to be crucial for the longevity and usability of the Internet On the Internet, the Differentiated Services (DiffServ) architecture is a general framework for the differentiated treatment of traffic aggregates in the core network. However, DiffServ does not extend to end-to-end QoS assurance, In this paper, we propose a simple. resource-brokering scheme, operating over a hierarchically connected internetwork of administratively-independent DiffServ-capable domains that is a simplified model of the Internet. The proposed asynchronous, multi-agent resource-brokering scheme operates locally but avoids conflicts globally. In this way, the traffic control reflects the underlying structure of the internetwork, introduces only a localized complexity thus scaling up well, and permits independent policies between the interconnected domains.

Subjective video Quality Measurement Experiments for Adaptive QoS Control

YAMAZAKI Tatsuya, SATO Noriyuki, FUKUNAGA Shigeru

ITE Technical Report 25 ( 17 ) 23 - 29 2001.2

Language：Japanese Publisher：The Institute of Image Information and Television Engineers

A real-time MPEG-4 video transmission system is used to conduct subjective video quality measurements. In the measurements, three video QoS(Quality of Service)parameters, that is, the frame size, frame rate, and quantization scale change, then the double stimulus continuous quality scale method is used to obtain the subjective test scores from the testees. This report provides the experimental results and discusses on the correlation between the QoS parameters and the user assessment, which might be useful for user-adaptive QoS control in video streaming service.

DOI： 10.11485/itetr.25.17.0_23

Subjective video quality assessment for adaptive quality-of-service control Reviewed

Tatsuya Yamazaki

Proceedings - IEEE International Conference on Multimedia and Expo 397 - 398 2001

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE Computer Society

A real-time MPEG-4 video transmission system is used to conduct subjective video quality measurements. In the measurements, three video QoS (Quality of Service) parameters, that is, the frame size, frame rate, and quantization scale change, then the double stimulus continuous quality scale method is used to obtain the subjective test scores from the subjects. This report provides the experimental results and discusses on the correlation between the QoS parameters and the user assessment, which might be useful for user-adaptive QoS control in video streaming service.

DOI： 10.1109/ICME.2001.1237740

Zinger: Conversation support based on interest similarity Reviewed

Noriyuki Kurabayashi, Tatsuya Yamazaki, Kazuo Hasuke, Taiichi Yuasa

Proceedings - IEEE International Conference on Multimedia and Expo 435 - 438 2001

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE Computer Society

In this paper, we introduce a conversation support agent called Zinger. Zinger acquires the current interest of a participant, identifies a partner who has a similar interest, and recommends several topics related to the interest. This recommendation is expected to help the participant establish common ground in conversing with the partner. The participant can get valuable information with a successful conversation. Experimental results show that Zinger could promote utterances of 35% subjects. In addition, factors affecting the participant's utterances are examined by multiple regression analysis. The results suggest that providing helpful information and appropriate presentations can contribute to better utterances.

DOI： 10.1109/ICME.2001.1237750

A multi-agent reinforcement learning method for a partially-observable competitive game. Reviewed

Yoichiro Matsuno, Tatsuya Yamazaki, Shin Ishii

Proceedings of the Fifth International Conference on Autonomous Agents, AGENTS 2001, Montreal, Canada, May 28 - June 1, 2001 39 - 40 2001

Publishing type：Research paper (international conference proceedings) Publisher：ACM

This article proposes a reinforcement learning (RL) method based on an actor-critic architecture, which can be applied to partially-observable multi-agent competitive games. As an example, we deal with a card game "Hearts". In our method, the actor plays so as to enlarge the expected temporal-difference error, which is obtained based on the estimation of the state transition. The state transition is estimated by taking the inferred card distribution and the other player's action models into account.

DOI： 10.1145/375735.375856

Other Link： http://dblp.uni-trier.de/db/conf/agents/agents2001.html#conf/agents/MatsunoYIM01

A Study of Color Image Segmentation Based on a Multi-dimensional Histogram

YAMAZAKI Tatsuya

ITE Technical Report 24 ( 50 ) 9 - 14 2000.9

Language：Japanese Publisher：The Institute of Image Information and Television Engineers

A deta-driven segmentation algorithm based on a multi-dimensional histogram is proposed for color images. An image is observed as a mixture of multi-variate data, but the number of clusters in the mixture is generally unknown. The proposed algorithm determines the width of a histogram to use and then obtains the number of clusters according to the observed multivariate data. Next, the statistics for each cluster are computed, since this is a requisite for clustering all of the other elements. The proposed clustering method can be applied to various kinds of images, because it is not restricted by an image model used in model-based approaches. The effectiveness of the algorithm is evaluated by computer simulation, and the algorithm is applied to real color image clustering.

DOI： 10.11485/itetr.24.50.0_9

Adaptive QoS management for multimedia applications in heterogeneous environments Reviewed

T Yamazaki, M Kosuga, N Ogino, J Matsuda

PROCEEDINGS OF THE FIFTH JOINT CONFERENCE ON INFORMATION SCIENCES, VOLS 1 AND 2 5 ( 2 ) A564 - A567 2000

Language：English Publishing type：Research paper (international conference proceedings) Publisher：ASSOC INTELLIGENT MACHINERY

In heterogeneous communication environments of wired and wireless networks, gaps in network and terminal performance bring about QoS (Quality of Service) differences. In addition, individual user's QoS requirement changes according to his/her communication situation. We have developed an agent-based adaptive QoS management framework called MARM (Multi-Agent Resource Management) to satisfy the user's requirement in consideration of usable network and terminal resources. In this paper we present a proxy server called CCS (Communication Coordination Server) to intermediate among sender/receiver terminals and to compensate the QoS differences. The CCS is equipped with QoS transformation and error resilience control functions. The CCS is useful to mitigate the complex QoS negotiation in the MARM framework, and facilitates multicasting of media streams in heterogeneous environments.

Adaptive QoS Management Using Layered Multi-Agent System for Distributed Multimedia Applications. Reviewed

Masakatsu Kosuga, Tatsuya Yamazaki, Nagao Ogino, Jun Matsuda

Proceedings of the International Conference on Parallel Processing 1999, ICPP 1999, Wakamatsu, Japan, September 21-24, 1999 388 - 394 1999

A model of adaptive QoS management platform based on cooperation of layered multi-agents Reviewed

N Ogino, M Kosuga, T Yamazaki, J Matsuda

GLOBECOM'99: SEAMLESS INTERCONNECTION FOR UNIVERSAL SERVICES, VOL 1-5 1 406 - 413 1999

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

It is important for distributed multimedia applications to assure end-to-end QoS of media streams. Moreover, the end-to-end QoS needs to be managed adaptively according to fluctuation of system states and variation of user requests. In this paper, a model of adaptive QoS management platform for distributed multimedia applications is proposed. In this model, the adaptive QoS management is achieved by direct and indirect cooperation of layered multi-agents. By using the layered multi-agents system, the proposed QoS management platform can flexibly adapt to user's QoS requirements and large variation of system states, and can quickly adapt to small fluctuation of system states, simultaneously.

An agent-based adaptive QoS management framework and its applications Reviewed

M Kosuga, T Yamazaki, N Ogino, J Matsuda

INTERACTIVE DISTRIBUTED MULTIMEDIA SYSTEMS AND TELECOMMUNICATION SERVICES 1718 371 - 376 1999

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER-VERLAG BERLIN

For distributed multimedia applications, adaptive QoS management mechanisms need to be developed to guarantee various end-to-end QoS requirements. In this paper, we propose an adaptive QoS management framework based on multi-agent systems. Adaptation to system resource changes and various user requirements is achieved by the direct or indirect collaboration of agents in the respective phases. In the flow establishment and re-negotiation phase, application agents determine the optimal resource allocation through QoS negotiations to maximize the total users' utility. In the media-transfer phase, stream agents collaborate to adjust each stream QoS reactively. In addition, personal agents help novice users specify stream QoS without any a priori knowledge on QoS. Some multimedia applications have been designed based on the proposed framework.

DOI： 10.1007/3-540-48109-5_30

Remote sensing image classification for forestry using MRF models and VQ method

Tatsuya Yamazaki, Denis Gingras

IEEE International Symposium on Industrial Electronics 3 753 - 756 1997

Publishing type：Research paper (international conference proceedings)

Conventional pixelwise classification techniques have two drawbacks. The first is that they tend to occur isolated misclassifications because they classify each site independently using spectral information only. The second is that sample data which represent each class are indispensable to estimate model parameters or to train classification Neural Networks. In this manuscript a new unsupervised contextual method is proposed for multispectral remote sensing image classification. Markov Random Field (MRF) models are used for modeling the observed and classified images in the proposed method. Both spectral and spatial information can be exploited by the MRF models so as to dissolve contextual inconsistency caused by the first drawback. In addition the Vector Quantization (VQ) method is introduced to dissolve the second drawback. The VQ method classifies the observed data into several clusters without using any sample data. The image classified by the VQ method is so coarse that it includes misclassification and unknown-class sites, however it can be used as an initial classified image for the following MRF-based classification algorithm. The proposed method was applied to LANDSAT Thematic Mapper data to discriminate deciduous trees from ever-green trees. The accuracy of classification was 64.4% by the VQ method and it was improved up to 88.8% by the MRF-based method.

Contextual classification system for remote sensing using a multivariate Gaussian MRF model

Tatsuya Yamazaki, Denis Gingras

Proceedings - IEEE International Symposium on Circuits and Systems 2 648 - 651 1996

Publishing type：Research paper (international conference proceedings)

We propose a spatial contextual classification system for remote sensing images. In the system the observed multi-spectral images are modeled with a multivariate Gaussian Markov Random Field (GMRF) model and the hidden classified image is modeled with another type of MRF model. The classification is carried out from the viewpoint of Maximum a Posteriori (MAP) estimation. One of the well-known problems of MAP estimation is its high computational complexity involved. One way to avoid this problem is a pixelwise classification that is successfully implemented on a computer with a clique-type block matrix notation of a multivariate GMRF local conditional density function (LCDF). The proposed system is applied to real remote sensing data.

Data-driven segmentation of degraded images based on Markov random field models

Tatsuya Yamazaki, Mehdi N. Shirazi, Hideki Noda

Journal of the Communications Research Laboratory 41 ( 1 ) 19 - 36 1994.3

Publishing type：Research paper (scientific journal)

A data-driven segmentation algorithm is developed for images consisting of a known number of distinct regions corrupted by region-dependent white-Gaussian noises with unknown parameters. A recursive algorithm based on the Expectation and Maximization (EM) method is developed to estimate the parameters of the regional noises. Using these estimates, the initially segmented image is estimated by the conventional Maximum Likelihood (ML) method. The region process (true image) is modeled by a Markov Random Field (MRF); then the estimation of the parameters of the model and the segmentation of the true image are alternated using the Maximum Pseudo-Likelihood (MPL) and Iterated Conditional Modes (ICM) methods, respectively. The performance of the algorithm is shown through typical simulation results.

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