Pannarat Guayjarernpanishk Faculty of Applied Science and Engineering, Khon Kaen University, Nong Khai Campus, Nong Khai Thailand
Tossapol Phoophifa Department of Mathematics, Faculty of Science, Mahasarakham University, Maha Sarakham Thailand
Piyapatr Busababodhin Department of Mathematics, Faculty of Science, Mahasarakham University, Maha Sarakham Thailand