1. Henry Samueli School of Engineering, Univ. of California, Irvine, Irvine, CA 92697; also, Dept. of Control and Instrumentation Engineering, Chungbuk National Univ., Cheong-Ju, Chungbuk 361-763, Korea.
2. Henry Samueli School of Engineering, Univ. of California, Irvine, Irvine, CA 92697.