Author(s):
1. Mladen Tomić, The School of Higher Technical Professional Education, Niš, Serbia
2. Predrag Živković, Faculty of Mechanical Engineering in Niš, Serbia
3. Mića Vukić , Faculty of Mechanical Engineering in Niš, Serbia
4. Mirko Dobranjac, University of Banja Luka, Faculty of mechanical engineering,
Republic of Srpska, Bosnia and Herzegovina
5. Gradimir Ilić, Faculty of Mechanical Engineering in Niš, Serbia