Youn-Young Jung, Korea Basic Science Institute, Cheongju, South Korea, Dong-Chan Koh, Korea Institute of Geoscience and Mineral Resources, Daejeon, South Korea, Seong-Taek Yun, Korea University, Department of Earth and Environmental Sciences & K-COSEM Research Center, Seoul, South Korea and Kwang-Sik Lee, Korea Basic Science Inst, Cheongwon, Korea, Republic of (South)