1. Department of Environmental Engineering, Kongju National University, Chungnam 331-717, Korea, Department of Earth System Sciences, Yonsei University, Seoul 120749, Korea, Research Institute of Instrumentation Frontier, National Institute for Advanced Industrial Science and Technology (AIST), Ibaraki 305-8565, Japan, Methane Hydrate Research Center, National Institute for Advanced Industrial Science and Technology (AIST), Ibaraki 305-8569, Japan, Department of Energy and Resources Engineering, Korea...