The Journal of King Mongkut's University of Technology North Bangkok
วารสารวิชาการพระจอมเกล้าพระนครเหนือ

Salinthip Daengkongkho
Department of Mathematics, Faculty of Science and Technology, Pibulsongkram Rajabhat University, Phitsanuloke 65000
Thailand

Pairote Yiarayong
Department of Mathematics, Faculty of Science and Technology, Pibulsongkram Rajabhat University, Phitsanuloke 65000
Thailand