1. LG PRI,222 LG-ro Jinwin-myeon,Pyeongtaek-si, Gyeonggi-do 451-713, Koreae-mail: k.noh@lge.com
2. Department of Aerospace and Mechanical Engineering,University of Southern California,3650 McClintock Avenue, Room 430,Los Angeles, CA 90089-1453e-mail: bingen@usc.edu