1. Department of Mathematics, Sungkyunkwan University, Suwon 440-746, Republic of Korea
2. Department of Mathematics-Computer Sciences, Necmettin Erbakan University, Faculty of Science, Meram Yeniyol, 42100, Konya , Turkey
3. Department of Mathematics, Uludag University, Faculty of Science and Art, Gorukle Campus, 16059, Bursa , Turkey
4. Department of Mathematics, Selcuk University, Faculty of Science, Campus, 42075, Konya , Turkey