Showing papers by "Shojiro Nishio published in 2007"

Wikipedia mining for an association web thesaurus construction

Abstract: Wikipedia has become a huge phenomenon on the WWW. As a corpus for knowledge extraction, it has various impressive characteristics such as a huge amount of articles, live updates, a dense link structure, brief link texts and URL identification for concepts. In this paper, we propose an efficient link mining method pfibf (Path Frequency - Inversed Backward link Frequency) and the extension method "forward / backward link weighting (FB weighting)" in order to construct a huge scale association thesaurus. We proved the effectiveness of our proposed methods compared with other conventional methods such as cooccurrence analysis and TF-IDF.

H-Mine: Fast and space-preserving frequent pattern mining in large databases

Abstract: In this study, we propose a simple and novel data structure using hyper-links, H-struct, and a new mining algorithm, H-mine, which takes advantage of this data structure and dynamically adjusts links in the mining process. A distinct feature of this method is that it has a very limited and precisely predictable main memory cost and runs very quickly in memory-based settings. Moreover, it can be scaled up to very large databases using database partitioning. When the data set becomes dense, (conditional) FP-trees can be constructed dynamically as part of the mining process. Our study shows that H-mine has an excellent performance for various kinds of data, outperforms currently available algorithms in different settings, and is highly scalable to mining large databases. This study also proposes a new data mining methodology, space-preserving mining, which may have a major impact on the future development of efficient and scalable data mining methods. †Decreased

A Thesaurus Construction Method from Large ScaleWeb Dictionaries

Abstract: Web-based dictionaries, such as Wikipedia, have become dramatically popular among the Internet users in past several years. The important characteristic of Web-based dictionary is not only the huge amount of articles, but also hyperlinks. Hyperlinks have various information more than just providing transfer function between pages. In this paper, we propose an efficient method to analyze the link structure of Web-based dictionaries to construct an association thesaurus. We have already applied it to Wikipedia, a huge scale Web-based dictionary which has a dense link structure, as a corpus. We developed a search engine for evaluation, then conducted a number of experiments to compare our method with other traditional methods such as cooccurrence analysis.

Data Replication Considering Power Consumption in Ad Hoc Networks

Abstract: In mobile ad hoc networks, a mobile host holding data items frequently accessed by other hosts needs to transmit them many times and consumes more power than other hosts. In this paper, we propose replica allocation methods for not only improving data availability but also balancing the power consumption among mobile hosts. In these methods, each mobile host replicates data items taking into account their access frequencies, the numbers of their replicas, and the host's remaining battery power. We present simulation results to evaluate the performance of our proposed methods.

A Broadcasting Scheme Considering Units to Play Continuous Media Data

Abstract: Due to the recent proliferation of digital broadcasting systems, various schemes for broadcasting continuous media data such as music or movies have been studied. In general broadcasting systems, since clients have to wait until their desired data are broadcast, these schemes reduce the waiting time by dividing the data into several segments of equal size. However, continuous media data often have units for playing portions of the data. For example, data encoded by MPEG2 can be played every GOP (group of pictures). In this paper, we propose a scheme to reduce the waiting time considering the units. Our proposed scheme divides a continuous media data at every unit. By scheduling divided data so that clients finish receiving a unit before starting to play the unit, waiting time is effectively reduced.

OPA browser: a web browser for cellular phone users

Abstract: Cellular phones are widely used to access the WWW. However, most available Web pages are designed for desktop PCs. Cellular phones only have small screens and poor interfaces, and thus, it is inconvenient to browse such large sized pages. In addition, cellular phone users browse Web pages in various situations, so that appropriate presentation styles for Web pages depend on users' situations. In this paper, we propose a novel Web browsing system for cellular phones that allocates various functions for Web browsing on each numerical key of a cellular phone. Users can browse Web pages comfortably, selecting appropriate functions according to their situations by pushing a single button.

A Scheduling Protocol for Continuous Media Data Broadcasting With Large-Scale Data Segmentation

Abstract: Due to the recent popularization of mobile multimedia broadcasting, broadcasting continuous media data such as audio and video has attracted great deal of attention. In general continuous media data broadcasting, since clients have to wait to receive data before playing it, various schemes to reduce waiting time have been studied. Some reduce the waiting time by dividing the data into several segments and broadcasting preceding segments frequently with a single channel. However, by dividing the data into numerous segments and producing an effective broadcast schedule, the waiting time can be further reduced. In this paper, we propose a scheduling protocol to reduce waiting time with large-scale data segmentation.

An efficient TDMA slot assignment protocol in mobile ad hoc networks

Abstract: Because of its ability to provide the collision-free packet transmission regardless of the traffic load, TDMA has been applied effectively in ad hoc networks. Until now, assuming a stationary ad hoc network, a TDMA slot assignment protocol which achieves the high channel utilization has been proposed. In this paper, we extend the protocol to accomodate the dynamic topology change due to the movement of nodes. In our protocol, since each node autonomously detects a change in network topology and assigns a slot to itself, the high channel utilization in the previous protocol can be kept even when nodes in a network move. Furthermore, we verify the effectiveness of the protocol by simulation experiments. The results show that our protocol improves channel utilization in comparison to conventional protocols.

A web browsing system for cellular-phone users based on adaptive presentation

Abstract: Cellular phones are widely used to access the Web. However, most available Web pages are designed for desktop PCs, and it is inconvenient to browse these large Web pages on a cellular phone with a small screen and poor interfaces. Users who browse a Web page on a cellular phone have to scroll through the whole page to find the desired content, and must then search and scroll within that content in detail to get useful information. This paper describes the design and implementation of a novel Web browsing system for cellular phones. This system includes a Web page overview to reduce scrolling operations when finding objective content within the page. Furthermore, it adaptively presents content according to its characteristics to reduce burdensome operations when searching within content.

An Information Layout Method for an Optical See-through HMD Considering the Background

Abstract: In wearable computing environments, an optical see-through head mounted display (HMD) is one of the most suitable wearable devices for displaying information. Although the HMD can display information without interfering with the user's view, the displayed information is difficult to see when the HMD background is too complex or too bright. We have created an information layout method for the optical see-through HMD that takes the background into account. It determines the ideal area for displaying objects by evaluating the HMD background captured by a camera.

A Route Planning Method Using Cost Map for Mobile Sensor Nodes

Abstract: In this paper, we propose a route planning method for mobile sensor nodes using cost map. The proposed method achieves novel route planning that can solve several practical problems from previous works: the limitations of sensing ranges, obstacles on the node's routes, and restriction of their movements. This method can determine the route that has the lowest power consumption. We also propose a sensing area defining method for dealing with many kinds of sensors. Furthermore, we compared the proposed method to A*algorithm, a well-known route planning algorithm. We implemented a prototype of the sensor node to verify our algorithm in a real environment.

Quorum-based consistency management among replicas in ad hoc networks with data update

Abstract: In this paper, we propose a consistency management method that constructs quorums with a small number of mobile hosts in ad hoc networks. In this method, when a mobile host discovers paths to other mobile hosts that construct quorums, it restricts the propagation area of query packets. As a result, this method can reduce the communication overhead while keeping the strict consistency among replicas.

A Data Dissemination Method for Information Sharing Based on Inter-Vehicle Communication

Abstract: In an Intelligent Transport System (ITS), information sharing based on inter-vehicle communication is effective for improving data availability. In this paper, we propose a data dissemination method for sharing data items among vehicles, which increases the opportunity for vehicles to acquire more fresh data items that users request. In our proposed method, vehicles are grouped according to their locations, and movement directions are estimated from their route information. Then, data items that are more likely to be accessed in the near future are disseminated between two groups. We also present simulation results to evaluate the performance of our proposed method.

An Adaptive Control Method in the Hybrid Wireless Broadcast Environment

Abstract: In this paper, we investigate adaptive control for broadcast scheduling and base station caching in the hybrid wireless broadcast (HWB) environment. The proposed adaptive method can adapt well to different access conditions and bandwidth capabilities and adequately exploit the three data delivery modes: push-based broadcast, pull- based broadcast, and pull-based point-to-point communication. Simulation studies demonstrated that our proposed method achieves significant performance improvement in average waiting time and success rate.

CLAD: a Sensor Management Device forWearable Computing

Abstract: There has been increasing interest in wearable computing. In wearable computing environments, a wearable computer runs various applications with various sensors (wearable sensors). Since conventional wearable systems do not manage the power supply flexibly, they consume excess power resources for unused sensors. Additionally, sensors frequently become unstable for several reasons such as a breakdown. This instability is hard to detect simply from the sensed data. To solve these problems, we propose a new sensor management device CLAD (cross-linkage for assembled devices) that has various functions for power management and sensed-data management. CLAD improves power saving, data accuracy, and operational reliability.

An Update Propagation Strategy for Delay Reduction and Node Failure Tolerance in Peer-to-Peer Networks

Abstract: Recently, there has been increasing interest in research on data sharing in peer-to-peer networks. In our previous work, we proposed a novel update propagation strategy that creates an n-ary tree, whose root is the owner of the original data while the other nodes are peers holding its replicas, and propagates the update information according to the tree. In this paper, we extend our previous strategy to further reduce the delay for update propagation and to tolerate peers' failure. To achieve this, in the extended strategy, peers participating in the tree record the information of their ancestors and children in the tree and reconstruct the tree using that information when some peers in the tree fail.

A mobile sensor control method for sparse sensor networks

Abstract: Due to the ability to construct a large-scale sensing system by the cooperative behaviors of multiple sensor nodes, sensor networks are expected to be applied to many applications such as environmental monitoring. On the other hand, with the development of robotics technology in recent years, there has been many studies on sensors with a moving function (mobile sensors).In this paper, we propose an effective mobile sensor control method for sparse sensor networks. Our method uses two types of sensor nodes, fixed node and mobile node. The data acquired by nodes are accumulated on a fixed node before transferred to the sink node. In addition, our method transfers the accumulated data efficiently by constructing the communication route of multiple mobile nodes between fixed nodes. We also conducted simulation experiments to evaluate the performance of our method.

A system for controlling LED blink in wearable fashion

Abstract: Recently, gadgets and clothes using luminous equipments, which consist of wearable fashion, have attracted attention in many events such as fashion shows and exhibitions. Flicker patterns of these electronic equipments are sometimes controlled by microcomputers. By using a microcomputer, it is possible to use a complex pattern controlled by a program. However, it is difficult for a user to program his/her desired flicker pattern with a microcomputer. In this paper, we present a control system of flicker patterns focusing on LEDs. Our proposing system introduces the notion of the incremental programming for designing flicker patterns. Then, a long time pattern can be stored in a microcomputer by compressing a flicker pattern data. Moreover, we discuss the validity of this system through experiences in several events.

Mobile Clavier: new music keyboard for flexible key transpose

Abstract: Musical performers need to show off their virtuosity for selfexpression and communicate with other people. Therefore, they are prepared to perform at any time and anywhere. However, a musical keyboard of 88 keys is too large and too heavy to carry around. When a portable keyboard that is suitable for carrying around is played over a wide range, the notes being played frequently cause the diapason of the keyboard to protrude. It is common to use Key Transpose in conventional portable keyboards, which shifts the diapason of the keyboard. However, this function creates several problems such as the feeling of discomfort from the misalignment between the keying positions and their output sounds. Therefore, the goal of our study is to construct Mobile Clavier, which enables the diapason to be changed smoothly. Mobile Clavier resolves the problems with Key Transpose by having black keys inserted between any two side-by-side white keys. This paper also discusses how effective Mobile Clavier was in an experiment conducted using professional pianists. We can play music at any time and anywhere with Mobile Clavier.

Cooperation Strategy for Broadcast Scheduling and Base Station Caching in Hybrid Wireless Broadcast Environment

Abstract: Recent advances in computer and wireless communication technologies have increased interest in combinations of various techniques such as pull-based data dissemination, data broadcasting, and data caching, as well as investigations into data management in hybrid data delivery systems. This paper proposes cooperative data management based on the Hybrid Wireless Broadcast (HWB) model to provide more efficient data delivery to mobile clients. Our cooperative strategy integrates broadcast scheduling with cache management of the base station, taking heterogeneous and homogeneous access of clients into consideration, by making effective use of HWB data dissemination, i.e., push-based broadcast, pull-based broadcast, and pull-based point-to-point wireless communication. Our simulation results confirmed that the strategy we propose can improve the performance of the system even further.

Topology Re-formation Algorithms for Ubiquitous P2P Networks Based on Response Statistics

Abstract: Recently, peer-to-peer (P2P) networks are becoming popular as communication forms for ubiquitous environments. Flooding-based P2P networks such as Gnutella have a problem that they generate a huge amount of network traffic. Moreover, their recall ratio is generally low because their topologies are constructed regardless of preference of each peer. In this paper, we propose a topology re-formation algorithm for flooding-based P2P networks. In the proposed algorithm, each peer observes responses that passed through itself and re-forms the topology so that peers with a content matching the query can be located near the query issuer. By simulation experiments, we show that peers with similar preferences get collected in the P2P network, and the recall ratio improves greatly

Query processing methods considering the deadline of queries for database broadcasting systems

Abstract: In recent years, there has been an increasing interest in the database broadcasting system where the server periodically broadcasts contents of a database to mobile clients such as portable computers and PDAs. There are three query processing methods in the database broadcasting system: (i) the server processes a query and then broadcasts the query result to the client, (ii) the client stores all data that are necessary to process the query and then processes it locally, and (iii) the server and the client collaborate in processing the query. Since the performance of each method changes according to the situation such as the interval of query generation and the size of query results, it is difficult to choose the optimal method among them statically. In this paper, we propose new query processing methods which dynamically change the order of queries submitted in the queue at the server and also change processing methods for the queries according to the deadline of queries and the system situation. These methods improve the success rate as well as reduce the response time in most cases. © 2007 Wiley Periodicals, Inc. Syst Comp Jpn, 38(2): 21– 31, 2007; Published online in Wiley InterScience (). DOI 10.1002sscj.20689

Effective data dissemination for information sharing based on inter-vehicle communication

Abstract: In an Intelligent Transport System (ITS), information sharing based on inter-vehicle communication is effective for improving data availability. In this paper, we propose a data dissemination method for sharing data items among vehicles, which increases the opportunity for vehicles to acquire more fresh data items that users request. In our proposed method, vehicles are grouped according to their locations, and movement directions that are estimated from their route information. Then, data items that are more likely to be accessed in the near future are disseminated between two groups. We also present simulation results to evaluate the performance of our proposed method.

A Data Collecting Scheme using Broadcast Delivery in Sensor Networks

Abstract: To make a weather observation or see the picture of a disaster, sensor networks, in which sensors such as temperature or humidity communicate, have recently attracted attention. Several schemes are proposed to collect data generated by sensors effectively. However, when there are many sensors, it takes long time to collect sensor data since information traffic is large. In this paper, we proopse a data collecting scheme that conjectures sensor data and broadcasts them. In our proposed scheme, sensors that have data vastly differ from conjectured data only transmit their sensor data. Accordingly, information traffic is reduced and the necessary time for collecting data becomes short. Our evaluations show that our proposed scheme can collect data faster than a conventional collecting scheme when there are many sensors.

A Position Detection Mechanism enabling Location-aware Pin&Play

Abstract: We propose a position detection mechanism enabling location-aware Pin&Play. Though the positions of inserted pins are important for most applications, it could not be detected in previous systems. The proposed method detects the positions of pins by processing images taken with a camera placed in front of the board. The proposed method has an error estimation mechanism to avoid the accumulation of position error. We also clarify the effectiveness of our proposed method through performance evaluations.

A Text Input Interface using a Portable Clavier for Pianists

Abstract: Due to the miniaturization of computers, wearable computing has attracted great attention. Several text input interfaces for wearable computing devices have already been proposed. However, those devices are not customized for specific users, so the devices do not facilitate sufficiently easy and quick text input. Therefore, the goal of our study is to construct a text input method specialized to pianists by exploiting characteristics of pianists and claviers. The proposed method achieves simple and quick text input by restricting users to pianists. The results of the evaluation suggest that the input speed achieved using proposed interface is twice as fast as that of the Twiddler.

An automatic matching algorithm between devices and application functions for tangible user interfaces

Abstract: To enable easy and intuitive control of applications there is increasing demand for Tangible User Interfaces (TUIs). To allow use of TUI devices to control applications, a system needs to associate functions with the TUI devices. Several TUI applications and toolkits have been proposed, but it is difficult to use these for various applications since conventional toolkits require the user to perform several inconvenient operations. In this paper, we propose an automatic matching algorithm that can be used between TUI devices and application functions. A user can freely place TUI devices on a board and our system will associate the TUI devices with application functions by considering three types of user preferences: the favorite type of device for each function, an intuitive position for functions, and the relationships between functions. The proposed method achieved 87% accuracy in automatic function assignments.

TEMPEST: A Text Input System with Musical Expression

Abstract: 近年，計算機の普及に伴い，電子メール，ブログ，チャットなどテキストベースのコミュニケーションが活発に行われている．また，感情や込めたい思いをより良く表現し他者に伝えるために，写真，ムービー，効果音，音楽，香りなどさまざまなコミュニケーションメディアやインタフェース，システムが提案されてきた．一方，ピアニストは鍵盤楽器を使って感情や思いを巧みに表現している．したがって，文字入力に演奏者の音楽的な表現力を付加できれば，感情や思いをより豊かに表現・伝達できると考えられる．そこで本研究では，鍵盤を使って文字入力に音楽表現を付加できる文字入力システムTEMPEST (TExt input and Musical PErforming SysTem) を提案する．TEMPEST の文字入力方式は，楽器演奏による感情伝達を考慮した設計になっており，ユーザはあたかも演奏しているかのように文字入力できる．さらに，実装したプロトタイプを用いた，文字入力演奏の視聴評価実験の結果から，提案システムは感情伝達手段として有効であることが証明された．

Cooperation of LED control chips in ubiquitous environment

Abstract: In this paper, we propose a programming method for controlling multiple LEDs to create art works or wearable fashion. In conventional systems, a programmer must repeat try and error to check the total appearance, and he/she must rewrite the source code and the binary code stored in each device in each trial, which forces him/her a lot of burden. Our proposing method introduces the notion of incremental programming, which enables a programmer to describe just the difference from the previous trial. In this paper, incremental programming is applied in two stages; on a PC and on a device. The former enables the programmer to express his/her intension in an intuitive manner, and the latter makes the update fast. We show our experimental results of using the implemented system.