Kwang-Jin Paek1, Ui-Sung Song2, Hye-Yong Kim3,+ and Jongwan Kim4
1Convergence SW Research Division
Electronics and Telecommunications Research Institute
Daejeon 305-700, Korea
2Department of Computer Education
Busan National University of Education
Busan 611-736, Korea
3College of Game
Hongik University
Chungnam 339-701, Korea
4Department of Computer Science and Engineering
Korea University
Seoul 136-701, Korea