1. Department of Mathematics, Ajou University, Suwon, Korea
2. Department of Mathematics, Ajou University, 206 World cup-ro, Yeongtong-gu, Suwon, 16499, Korea
3. Department of Mathematics Education, Jeonju University, Jeonju, Korea
4. Department of Mathematics Education, Jeonju University, 303 Cheonjam-ro, Wansan-gu, Jeonju, 55069, Korea