Search results

Asian languages such as Japanese, Korean and in particular Chinese, are beginning to gain popularity in the information retrieval (IR) domain. The quality of IR systems has traditionally been judged by the system’s retrieval effectiveness which, in turn, is commonly measured by data recall and data precision. This paper proposes and describes a process for generating an automatic Chinese thesaurus that can be used to provide related terms to a user’s queries to enhance retrieval effectiveness. In the absence of existing automatic Chinese thesauri, techniques used in English thesaurus generation have been evaluated and adapted to generate a Chinese equivalent. The automatic thesaurus is generated by computing the co‐occurrence values between domain‐specific terms found in a document collection. These co‐occurrence values are in turn derived from the term and document frequencies of the terms. A set of experiments was subsequently carried out on a document test set to evaluate the applicability of the thesaurus. Results obtained from these experiments confirmed that such an automatic generated thesaurus is able to improve the retrieval effectiveness of a Chinese IR system.

The dynamic nature of information content on the Web has posed a serious problem to users who need constantly to keep track of the latest updates on specific information. Traditional search engines enable users to retrieve potentially relevant Web information, but they do not track and monitor Web pages based on users’ interests. On the other hand, Web information monitoring systems are designed specifically to help users track and monitor Web information. However, to make Web monitoring effective, it is necessary to identify and understand typical Web page update characteristics so that useful monitoring features and functions can be designed and built into these systems. In this study, a total of 105 Web pages from the Internet were collected and monitored over a one‐month period. These pages are selected from seven domains under Yahoo!’s directories. The analysis results are presented according to Web site domains, Web page types, Web page attributes and change frequency. Based on this study, different functions and features for a Web monitoring system are identified. These features have been incorporated into a Web monitoring system, WebMon, that has been developed at the School of Computer Engineering, Nanyang Technological University, Singapore.

The Internet environment, with its packet‐switched network and lack of resource reservation mechanisms, has made the delivery of low bit‐rate real‐time communication services particularly difficult and challenging. The high potential transmission delay and data packet loss under varying network conditions will lead to unpleasant and unintelligible audio and jerky video play‐out. The Internet TCP/IP protocol suite can be extended with new mechanisms in an attempt to tackle such problems. In this research, an integrated transmission mechanism that incorporates a number of existing techniques to enhance the quality and deliver “acceptable” real‐time services is proposed. These techniques include the use of data compression, data buffering, dynamic rate control, packet lost replacement, silence deletion and virtual video play‐out mechanism. The proposed transmission mechanism is designed as a generic communication system so that it can be used in different systems and conditions. This approach has been successfully implemented and demonstrated using three separate systems that include the Internet Phone, WebVideo and video‐conferencing tool.

Knowledge of the Internet Protocol (IP) address is essential for connection establishment in certain classes of synchronous distributed applications, such as Internet telephony and video‐conferencing systems. A problem of dynamic IP addressing arises when the connection to the Internet is through an Internet service provider, since the IP address is dynamically allocated only at connection time. Proposes and draws a contrast between a number of generic methods that can be classified as online and offline methods for the resolution of dynamic IP addressing. Online methods, which include the World Wide Web, exchange server and the dynamic Domain Name System, are only effective when both the caller and recipient are logged on to the Internet. On the other hand, offline methods, which include electronic mailing and directory service look‐up, provide an additional means to allow the caller to leave messages when the recipient is not logged on to the Internet. Of these methods, the dynamic Domain Name System and directory service look‐up appear to be the best for resolving dynamic IP addressing.

An Internet telephony system functions like a conventional telephone to support real‐time voice communication over the Internet. Numerous proprietary systems have surfaced since its introduction as a result of its main attraction of allowing transcontinental telephone calls to be made at the price of local telephone calls. Currently, these systems are at their infancy stage with no support for standards to allow interoperability among systems. A proper framework to allow evaluation or comparison between systems is also lacking. This paper proposes such a framework that utilises a feature and functionality appraisal together with both quantitative and qualitative assessment techniques to allow a systematic evaluation of Internet telephony systems to take place. These techniques include voice process evaluation through signal reproduction, Diagnostic Rhyme Test, Diagnostic Acceptability Measure, Degradation Category Rating, and Free Conversation Test. This framework has been successfully demonstrated and utilised for the evaluation of five Internet telephony systems.

The study outlines a number of security requirements that are typical of a host of Web‐based applications using a case study of a real life online Web‐based customer support system. It subsequently proposes a security solution that employs a combination of Web server security measures and cryptographic techniques. The Web server security measures include the formulation and implementation of a policy for server physical security, configuration control, users’ access control and regular Web server log checks. Login passwords, in conjunction with public key cryptographic techniques and random nonces, are used to achieve user authentication, provide a safeguard against replay attacks, and prevent non‐repudiatory usage of system by users. These techniques, together with the use of session keys, will allow data integrity and confidentiality of the customer support system to be enforced. Furthermore, a number of security guidelines have been observed in the implementation of the relevant software to ensure further safety of the system.