Development and validation of operator's cognitive model are made to be implemented into an integrated dynamic simulation system SEAMAID for real-time simulation of complex human-machine interaction in various emergency situations of nuclear power plant. The effectiveness of human model usage is confirmed by applying the SEAMAID for the three areas: (i)estimation of time reliability curve of human cognitives, (ii)virtual reality based visualization system, and (iii)comparative evaluation of control board designing. Future subjects are also discussed for realizing virtual collaborator capable of interactive communication to human in virtual world. Copyright((C)) 2001 IFAC.