1. Korea Institute of Geoscience and Mineral Resources (KIGAM), Mineral Resources Research Division, Exploration Geophysics and Mining Engineering Department, 92 Gwahang-no, Yuseong-gu, Daejeon 305-350, South Korea.
2. Laboratory of Geophysical-Satellite Remote Sensing & Archaeo-environment, Institute for Mediterranean Studies, Foundation of Research and Technology-Hellas, P.O. Box 119, Rethymnon, 74100 Crete, Greece.
3. Corresponding author.