The board shall by rule and regulation define the qualifications for wardens, superintendents, and other personnel employed in the state and county correctional institutions. The board shall by rule and regulation specify appropriate titles of personnel so employed, but no such personnel shall be known as or designated by the board as "guards" or "prison guards." The wardens and deputy wardens of the various county correctional institutions shall be appointed by the governing authority of the county, subject to approval of the board, and shall serve at the pleasure of the county or the board.