Nuntuschaporn Senawong Department of Mathematies, Faculty of Science, Mahasarakham University, Maha Sarakham Thailand
Supawadee Wichitchan Department of Mathematies, Faculty of Science, Mahasarakham University, Maha Sarakham Thailand
Orawich Kumphon Department of Mathematies, Faculty of Science, Mahasarakham University, Maha Sarakham Thailand