Sunheum Lee KwanSun Choi Dongsik Kim Changwan Jeon Young Doo Ahn A Novel Method for Performance Evaluation of Focused Ultrasonic Transducers. 448-452 2007 FGCN (2) http://dx.doi.org/10.1109/FGCN.2007.28 conf/fgcn/2007 db/conf/fgcn/fgcn2007.html#LeeCKJA07