1. Cummins Engine Company, Box 3005, Mailcode 41618, Columbus, IN 47202-3005
2. Department of Mechanical Engineering, Hanyang University, Kyungki-Do 425-791, Korea
3. School of Industrial Engineering, Purdue University, 1287 Grissom Hall, West Lafayette, IN 47907-1287
4. School of Aeronautics and Astronautics, Purdue University, 1282 Grissom Hall, West Lafayette, IN 47907-1282