I. Introduction
Currently, the metallurgical industry, especially steel production, as one of the primary parts of this industry, occupies an important place in the Slovak economy. The steel industry annually produces millions of tons of steel for domestic and foreign markets. However, the quality and quantity of steel produced still needs to be increased to be able to compare ourselves on the global scale of this industry. In order to increase the quality of products in technological and production processes, it is necessary to know these processes, to correctly measure the process parameters, and, last but not least, to control these processes.