Author(s):
1. Mladen Tomić, The School of Higher Technical Professional Education, Niš, Serbia
2. Biljana Milutinović, College of Applied Technical Sciences Niš, Serbia
3. Predrag Živković, Faculty of Mechanical Engineering in Niš, Serbia
4. Petar Djekic, The School of Higher Technical Professional Education, Niš, Serbia
5. Mirjana Laković, Faculty of Mechanical Engineering in Niš, Serbia