In iron and steel industry, the crude steel products, such as billets, slabs, blooms and ingots, are the semi-finished products which are the basis of manufacturing in shipbuilding, automobiles, construction, machinery, tools, and other industrial and domestic equipment. These products are obtained from continuous molten liquid metal by using a continuous-casting machine. One of the significant role of the machine is to produce these products in the desired sizes. Due to the extremely high temperature of molten liquid metal and being massive structures, it is difficult to obtain accurate measurements. In the current technology, there have been no appropriate sensors working under such level of temperature. I would like to thank my dear wife, my children and my family, my teacher, and all the teachers in the university for helping me to write this book. When writing this book, the university and industry had to be kept together as much as possible, so that the actual results could emerge. I believe that I continued to work as an engineer both in graduate and in industry. I think it will appeal to all readers and technology enthusiasts.