Catálogo de publicaciones - libros

This paper proposes new method for object reference which enables a person to find surrounding objects and develops a navigation system named CoCo. CoCo employs an ultrasonic directional speaker with a rotating base. Ultrasonic wave transmitted by an ultrasonic directional speaker is converted to audible sound when it reflects on floor, wall, or object. Based on this property, CoCo can emit audible sound from arbitrary place using a rotating base. When CoCo navigates a person to an object, CoCo transmits ultrasonic wave so as to hear audible sound continuously from the line between the ultrasonic directional speaker and the object. We designed and implemented an object management system as an application using 3D position sensors and a navigation system CoCo. This paper shows how CoCo navigates a person to an object using position data from an object management system.

For online social networking service in the ubiquitous computing and networking environment, a ubiquitous Web service accessible with a mobile user interface was studied using single-character domain names among multi-lingual domain names, especially for mobile social networking. As convenient user interface for accessing a Web service for a social community, instead of long URL strings, the multi-lingual single-character domain names as indexing keys to social information in a ubiquitous Web service are convenient mobile interfaces to search social information as well as to register information and knowledge for mobile social networking service. We studied the convenience and performance of accessibility to ubiquitous Web and studied resource utilization for a mobile social networking service.

In this paper, we describe the development of gloves that can be used in a ubiquitous computing environment. The ubiHand gloves were developed to access information devices in various wireless environments, including mobile computing, games, and in-vehicle telematic systems. The gloves are equipped with chording keyboard mechanism for flexible input and control of the wireless devices, an embedded RFID reader and a set of accelerator sensors for gathering information from the users’ various hand gestures. The system configuration and keymaps for ubiquitous information access as well as the interface for input and control for the gloves are presented.

To construct constraint-free human-computer interaction (HCI) environments, the wireless communication is one of the most essential research issues. Among the numerous wireless communication technologies, IEEE 802.15.4 low-rate wireless personal area networks (LR-WPANs) is the most suitable for ubiquitous and pervasive HCI environments, such as home networking applications, monitoring systems, and so on. In LR-WPANs, the power-efficiency is one of the most attractive issues. Therefore, this paper proposes a power saving medium access scheme for star topology beacon-enabled LR-WPANs. To achieve power efficiency, we turn off communication modules when the time slots are not used for data communications. On the other hand, we turn on the modules. The proposed scheme predict the time for data communications in a given superframe structure. Our simulation result shows that our algorithm achieves desired properties.

A MA(Mobile Agent) is a computer program which autonomously migrates within the network and works on behalf of a user. With the progress of ubiquitous computing environments, MA paradigm becomes more useful paradigm because MA paradigm makes it possible for various user-centric services, such as follow-me service, private secretary service, and etc. Also, in ubiquitous environments, the cell phone has very important role, but the cell phone cannot support the MA technology because J2ME(Java2 Micro Edition) CLDC(Connected Limited Device Configuration), which is the java platform for cell phone, does not support the essential facilities for the mobility of the mobile agents such as reflection, dynamic class loading, and object serialization due to security problem of the cell phone. So, in this paper, we propose the scheme that the MAP(Mobile Agent Platform) dynamically generates the UI(User Interface) according to the user’s device. Also, we show the experimental results of our proposed scheme. By using our proposed scheme, the user gets the service of MA by the cell phone.

TCP application in wireless HCI environments communicates to each other frequently through wireless networks. Therefore, it is important that significant TCP performance is guaranteed in wireless network. TCP New Jersey, known as the best existing scheme in terms of goodput in wireless networks, improves wireless TCP performance using the available bandwidth estimation at the sender and the congestion warning at intermediate routers. Although TCP New Jersey achieves 17% and 85% improvements in goodput over TCP Westwood and TCP Reno, respectively, we further improve TCP New Jersey by exploring enhanced available bandwidth estimation and suitable error recovery mechanism. Hence, we propose TCP NJ+. It outperforms other TCP variants by 19% to 104% in terms of goodput even when the network is in bi-directional congestion. Hence TCP NJ+ can provide the best services to user in wireless HCI environments.

Short text message (SMS) as a key communication means in China received a lot of attention in research community. 114 subjects attended the study, sharing totally 10843 SMS they sent and received daily. We divided the SMS into two categories (instrumental and expressive), analyzed vocabularies, functions and effects of demographic factors and SMS categories on SMS lengths and found: 1) Top 400 Chinese characters occupied 85% and top 388 words occupied 73% in SMS. Punctuations appeared frequently (18%), while Smiley appeared very little (less than 0.1%). 2) People sent both instrumental and expressive messages regardless of their age. Female users tended to send longer SMS. Retired people sent longest SMS, followed by working people and students. People exchanged SMS with close friends and families. Expressive SMS have more words than instrumental SMS. 3) People over 40s exchange more SMS with children than with friends.

A multilingual disaster information system (MLDI) has been developed to overcome the language barrier during times of natural disaster. MLDI is a web-based system that includes templates in nine languages so that translated texts can be made available immediately. Mobile phone e-mail with graphic text is a useful tool for delivering multilingual disaster information. We assessed the performance of the translation system and the multilingual graphical characters, and found that they are sufficiently useable. We discussed the usage of mobile phones for multilingual disaster information delivery system including Early Earthquake Warning system. Multilingual mobile information and measures is useful for a safe and barrier-free society.

Multi-view video is a new multimedia service which provides immersion and realism using the multiple view channels. However, as the number of cameras increases, the enormous data volume generated by them inevitably calls for better video compression and processing algorithms. However, the multiple images taken at any certain time instants always have inconsistency among the views in their intensity, color, sharpness, and so on. It not only degrades the compression efficiency greatly but also causes subjective quality loss such as dizziness and unnaturalness in random view access. To solve this problem, in this paper, we propose a new multi-view compensation method which uses the Kalman filter. It estimates the illumination discrepancy parameters autonomously both in encoder and decoder. Therefore, our method needs not transmit any additional data for illumination discrepancy information.

This study focuses on an analysis of the naturalistic driving behavior before making a right turn at an intersection. We conducted experiments on a public road and measured driver behavior, vehicle state, and headway and rear distances. The results suggest that the positions of the front and rear vehicles and the vehicle velocity have an influence on the onset location of covering the brake pedal. Structural equation modeling (SEM) was applied to estimate these relationships quantitatively. The results imply that the SEM with latent variables can represent the hypotheses obtained from the analysis of the measured data. We propose a detection method of unusual driver behavior by predicting the driver’s preparatory behavior using the SEM, and possible new application of in-vehicle navigation systems is discussed.