Korean currency
In 1902, won was introduced as the official currency unit replacing yang at 1 won = 5 yang. The bank of Korea was established 1909 but soon after in 1910, Imperial Japan annexed Korean Empire. Under Colonial rule, the country was made to use the currency unit "yen" in the name of Korean yen, which took over the Korean won at par. After the division of Korea, the state of South Korea was established and recognized in 1948, and won was again made the official currency of the new state. "jeon" was made the subunit of the currency that divided it into 100 equal parts. Bank of Joseon issued the currency for independent South Korea for the first time that too in banknotes only.
Korean currency
The country then had to switch over to a new currency unit named "hwan" replacing won at 1 hwan = 100 won. Like South Korean won, this currency unit was also issued in banknotes initially but in 1959, coins denominated in hwan were also issued and were the first circulating coins in South Korea. Hwan had a peg with US dollar but with time it also got devaluated. This was the reason for the reintroduction of won in 1962 as the official currency unit. South Korean currency was still pegged to the US dollar until in 1997 when it was floated into the world market.