We hope that network systems will become smarter and more responsive to people's needs. For example, if people find the network quality is unacceptable when attending a video conference or playing an online game, the systems will "perceive" this situation and know how to adjust the parameters and re-balance the network resources to mitigate the problem. Designing such smart systems is challenging. Thus, we are investigating how to estimate and quantify human perceptions and reactions, and then use these measures in the design of computer systems.

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.

We hope that, in the not too distant future, Internet surfing will be safe and users' privacy be secured, where users need not constantly upgrade antivirus tools to block computer viruses and Trojan horses, or worry about computer frauds. This is why we chose to do research on detecting and preventing malicious/fraudulent activities. We envisage a time when users' network experiences will not be disturbed by privacy threats and acts of piracy, such as the deletion of documents by malicious software, the theft of credit card details and online game accounts, and the unauthorized publication of sensitive information, e.g., the records of visiting dating websites. Thus, how to detect and prevent malicious/fraudulent activities on the Internet is also one of our research areas.

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.

Although online gaming has become one of the major Internet activities, when playing online games, users are often bugged by serious network lags; or they must tolerate seeing the characters of cheaters wearing sparkling magical armor fighting mighty dragons while their own characters can only wear secondhand scale armor and defeat wild dogs; or they may experience in being shot by bot-controlled characters with an all-the-time perfect accuracy while playing first-person shooting games. Moreover, some players may find that their characters' valuable virtual goods have been ripped off by crackers when they log into a game. We have teamed up with online game companies in order to solve these problems related to performance, fairness, and security from the aspect of game design mechanisms and human behavior.

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.