1. Intelligent Devices and Systems Research Group, DGIST, 333, Techno Jungang-daero, Hyeonpung-eup, Dalseong-gun, Daegu 711-873, Republic of Korea
2. Department of Geoinformatics, University of Seoul, 163 Seoulsiripdaero, Dongdaemun-gu, Seoul 130-743, Republic of Korea