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

Wachirapong Jirakitpuwapat
Department of Mathematics, Faculty of Science, King Mongkut’s University of Technology Thonburi, Bangkok
Thailand

Poom Kumam
Department of Mathematics, Faculty of Science, King Mongkut’s University of Technology Thonburi, Bangkok
Thailand