Catálogo de publicaciones - libros

With a tremendous increase of Internet users, the Internet computing environments are getting more complicated along with the network management structure in order to support diverse traffic characteristics. A successful end-to-end realization of Grid services presumes well-defined QoS measuring framework in the service provider’s and customer’s networks. Most traditional network performance management systems utilize a passive measuring method based on SNMP, allowing an administrator to understand only network conditions. However, it is difficult for network managing systems that are based on a passive measuring method to accurately understand the situations surrounding time-varying networks. Our objective in this paper is to describes a Grid monitoring architecture based practical measuring framework for network performance measurement. It includes concepts as well as step-by-step procedures of an active measuring method for measuring performance of any section at any time.

This paper presents an adaptive synchronization scheme for compensating for the variable transmission delay and synchronizing media data through the use of terminal buffering in mobile multimedia network. The proposed scheme can meet the requirement for synchronization of media data by adjusting synchronization intervals using the maximum time delay jitter and by flexibly handling the variable queue time according to variations in delay time, and reduce media data loss time due to increase in traffic as well as data loss due to variations in delay time by using delay jitters in adjusting synchronization intervals.

This paper proposes an educational information system based on u-learning that supports two phase feature extract. A key frame selected by user in annotation-based retrieval takes query image of feature-based retrieval and by agent searches and displays the most similar key frame image after comparing query image with key frames in the DB through full image and center image, binary image histogram techniques which we proposed. Therefore, user can get more correct retrieval result by agent’s learning through repeated retrievals about video data for the environment education of infants. From experiment, the designed and implemented system shows increase of recall rate of about 1.5% and 2.0% as precision rate 94.2% for video data scene retrieval in performance assessment.

In this study, the surveyed Trip Length Frequency Distribution (TLFD)is determined as a criterion for the reliability of evaluating the true O/D matrix. The surveyed TLFD can be used to check the similarity between the surveyed (true) Trip Length Distribution and the Trip Length Distribution of the estimated O/D matrix by the traffic counted models. When the surveyed TLFD is similar to the estimated TLFD, the reliability and correctness of the estimated O/D are high. Therefore, the objective of this paper is the development of the travel demand (O/D matrix) estimation using traffic counts on the large-scaled network. The Gradient Method is used for the model and the multi-class assignment technique is used for the equilibrium loading procedure in the model. This leads to the good guideline to the usage of the traffic count based O/D estimation in practice and gives a confidence to the transport planner. It is because the traffic counted O/D estimation models gives multiple solutions by its characteristics. In this paper we analyze the merits and demerits in each of a single-class based model and a multi-class based model in a large scale network. As a result, we have concluded that the multi-class based model has a closer value to the surveyed (true) TLFD than the TLFD of the estimated O/D matrix by the single-class based gradient method.

There are about 800,000 map sheets for 36,500,000 parcels of land of Korea. They have been used for almost 100 years with the known problems of the shrinkage-expansion of the paper cadastral maps. The area of a parcel is recorded in a cadastre, and the maps are used just as a reference drawing for the location and the shape of the land. However, digitization of the maps began to reveal the problem of distortion of the map as the conflict between the areas on the cadastre and the digital maps was shown in numerical form. The distortion problem is tried to be resolved in this paper. Using the fact that original maps drawn on the plane tables in the years of 1910 to 1918 have grid lines and have been preserved well, a strategic flow was developed, which applies the refinement techniques to the digital maps with the original maps as controls. Several types of distortions and corrections were simulated, and errors between an error-free map and the distortion corrected map were evaluated. The RMS errors in the corrected digital maps were allowable, thus, the method developed in this study was applicable for the digital cadastral maps.

Various traffic simulation programs have been developed, and the role of micro simulation increases recently, and the car following theory provides the theoretical background. However, current car following models apply the uniform driver factors regardless the characteristics of driver, vehicle and highway, then there exists a gap between the simulation result and real situation. This study is performed to derive the driver’s sensitivity parameters which are even closer to the real. The fuzzy approximate reasoning can find the driver’s sensitivity which varies by the traffic situation. Result shows better performance than the GM model. It means that the proposed driver’s sensitivity parameters can represent the real situation better.

This paper is to develop a model for evaluation of highway alignment design considering the drivers’ behavior in order to enhance the highway safety. The vehicle spacing is suggested as a new evaluation index. The suggested model is based on the artificial neural network, which can explain the non-linear relationship on the highway geometric elements. The model shows better fitting comparing with the current regression models explaining only the linear relationship. It may be helpful to evaluate the safety of newly designed highway and safety improvement program for highways in-service.

This paper is on the design and development of a conversion mechanism for MPEG-4 contents services on Web environment. The service was provided on Web environment first by parsing the MPEG-4 contents, then converting them to SMIL. After the two-dimensional profile of the MPEG-4 XMT and SMIL schemes was analyzed, the correlation among the nodes with the same or similar meanings was set as a rule. With the defined rule, an XSL document was created, and XMT was converted to SMIL using the converted XSL document and XSLT, which was derived from MSXML. Moreover, the two-dimensional geometric object that cannot be expressed in SMIL was authored in SVG to add SMIL media characters. Its advantage is that it services current MPEG-4 contents in various environments such as the Web or mobile environments, and it can be converted to service more playable environments if one knows the syntax definition of other scene description languages.

With the rapid development of Mobile Ad-hoc Networks (MANET) and Peer-to-Peer (P2P) computing, it is envisioned that building P2P multimedia sharing system over MANETs is promising. In this paper, we propose a geographic-information based distributed index structure, Geographically Hierarchical Index (GHI), based on which, we could design improved p2p algorithms especially for the multimedia sharing over MANET.

The proposed hybrid MAC (H-MAC) protocol characterizes distributed and asynchronous operation. It uses an implicit token for a real-time traffic and the CSMA/CA for a non-real time traffic, guaranteeing QoS. The proposed hybrid MAC protocol allocates the assured bandwidth to real time traffic and dynamically reallocates the remaining bandwidth to a non-real time data traffic.