1. a Department of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Korea
2. b Department of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Korea
3. c Agency for Defense Development, Yuseong P. O. Box 35-3, Daejeon 305-600, Korea
4. d Agency for Defense Development, Yuseong P. O. Box 35-3, Daejeon 305-600, Korea
5. e Agency for Defense Development, Yuseong P. O. Box 35-3, Daejeon 305-600, Korea
6. f Department of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Korea