[1] Kyungnam Univ, Dept Comp Sci & Engn, Kyungnam, South Korea
[2] Hosei Univ, Fac Comp & Informat Sci, Tokyo, Japan
[3] St Francis Xavier Univ, Dept Comp Sci, Antigonish, NS B2G 1C0, Canada
[4] Carnegie Mellon Univ, Human Comp Interact Inst, Pittsburgh, PA 15213 USA