1. Digital Appliance Research Laboratory, LG Electronics Inc., Korea. E-mail: jwsung@lge.com
2. Department of Electrical Engineering, The University of Seoul, Korea. E-mail: gskim318@uos.ac.kr
3. Department of ECE, University of Wisconsin, USA. E-mail: lipo@engr.wisc.edu
4. School of Information & Communation Engineering, SungKyunKwan University, Korea. E-mail: won@yurim.skku.ac.kr
5. Department of Contr. and Instru. Engineering, Seoul National University of Techlogy, Korea. E-mail: schoi@snut.ac.kr