In 1968, as the intrinsic value of the brass 1 won coin far surpassed its face value, new aluminium 1 won coins were issued to replace them. As an attempt to further reduce currency production costs, new 5 and 10 won coins were issued in 1970, struck in brass. Cupronickel 100 won coins were also introduced that year, followed by cupronickel 50 won coins in 1972.
