Author(s):
1. Sara Srebrenkoska, Faculty of Mechanical Engineering, Goce Delcev University, Krste Misirkov, No. 10-A Stip, Republic o, Macedonia
2. Vineta Srebrenkoska, University “Goce Delčev”, Štip, Faculty of Technology, Macedonia
3. Svetlana Risteska, University of St.Kliment Ohridski Bitola, Faculty of Economics - Prilep, Macedonia