Graduate School of Engineering and Resources Science, Akita University, Akita, Japan
Department of Mining Engineering, Institut Teknologi Bandung, Bandung, Indonesia
Faculty of International Resources Science, Akita University, Akita, Japan
Copyright © 2016 Fadhila Achmadi Rosyid, Tsuyoshi Adachi et al. This is
an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any
medium, provided the original work is properly cited.