Muhammad Hamka Ibrahim, Chiba University, Indonesia; Subuh Pramono, Universitas Sebelas Maret, Indonesia; Jing-Yuan Wang, Hisato Kashihara, Chiba University, Japan; Gregorius Haryuatmanto, PT Waindo SpecTerra, Indonesia; Yuta Izumi, Muroran Institute of Technology, Japan; Josaphat Tetuko Sri Sumantyo, Chiba University, Japan