1. Department of Geophysics, Kangwon National University, Chuncheon 200-701, Korea.
2. Corresponding author.
3. Office of Technology, Daewoo Shipbuilding Marine Engineering E&R, Seoul 100-180, Korea.
4. E&P Technology Team, LG International Corp., Seoul 150-721, Korea.
5. Office of Environmental Geology, Korea Rural Community Corporation, Euwang-si 437-703, Korea.