Author(s):
1. Dragana Grujić, Faculty of Technology Banja Luka, Republic of Srpska, Bosnia and Herzegovina
2. Dragana Cerović, University of Belgrade, Faculty of Physics, Serbia
3. Blanka Škipina, Faculty of Technology Banja Luka, Republic of Srpska, Bosnia and Herzegovina
4. Ljiljana Topalić-Trivunović, Faculty of Technology Banja Luka, Republic of Srpska, Bosnia and Herzegovina
5. Aleksandar Savić, Faculty of Technology Banja Luka, Republic of Srpska, Bosnia and Herzegovina

Abstract