Reasons for simulation being underutilized • Simulation modeling is a time-consuming and knowledge/information intense process • Most models developed are customized “rigid” models that cannot be reused or easily adapted to other even similar problems (Arons 1999, 2000; Zhou 2004) • Conceptual modeling is a critical step that directly affects the quality and efficiency of simulation projects, but hardly supported with current technology, and still a very difficult and ad-hoc process that depends on the skill and experience of individual modelers (Mclean, 2001; Robinson, 2004)