Therefore, we focus on developing new Internet services and making the medium more user-friendly. Our current research interests span the following areas:
Internet Quality of Experience
In the study of network data transfer optimization, defining "good network quality"' is one of the most important steps. From the user's perspective, we try to define objective "network quality indexes'' based on the subjective perceptions of application users, and then apply the defined indexes to optimize the quality of applications. Our research topics and results include: 1) user satisfaction indexes for Skype and a massively multiplayer online role playing game (MMORPG); 2) a number of schemes that improve the efficiency of VoIP data transfer by adjusting packet rates and packet redundancy factors; and 3) an efficient and application-independent framework for user satisfaction measurement that can quantify users' satisfaction with audio and video content, as well as games over the Internet at a relatively low cost.
In this field, we study how to prevent and solve privacy and security issues on the Internet. Specifically, our research covers the following topics. 1) We analyze and quantify the degree of involuntary information leakage in social network services. 2) Phishing is an increasingly serious problem on the Internet. To date, we have proposed an effective and efficient scheme for phishing page detection, and developed a browser plugin tool for public use. 3) Social moderation systems are designed for reporting inappropriate content; however, malicious users may collude and abuse such systems by accusing innocent users of misbehavior. As part of our ongoing research, we have proposed a graph-theoretic algorithm to detect such collusion.
Our progress is summarized as follows. 1) To improve the real-timeliness and interactivity of games, we have already proposed an efficient data transmission mechanism and overlay path selection algorithm. 2) With regard to game security, we focus on two of the most serious issues, namely, using game bots to acquire unreasonable profits in a short time, and stealing other players' virtual goods by hijacking their accounts. We are developing various techniques to detect such cheating behavior. 3) In terms of scalability, we study how to help millions of players freely interact with each other simultaneously in a virtual world. 4) To enhance playability, we analyze players' perceptions of a game based on their behavior, such as their game play time and interaction with other gamers. Then, from the analysis results, we try to determine the causes of changes in players' perceptions, e.g., other players' behavior or a certain game design, in order to improve the game's playability.