1. Faculty of Mathematics, Otto Von Guericke University Magdeburg, Universitatsplatz 2, Magdeburg 39106, Germany
2. Department of IT Convergence Engineering, Daegu University, Gyeongsan-si, Gyeongsangbuk-do 38453, Republic of Korea
3. Department of Mathematics and Big Data, Daegu University, Gyeongsan-si, Gyeongsangbuk-do 38453, Republic of Korea