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
From 1978 to 2001, the North Korean government maintained an iconic rate of 2.16 won to the US dollar; since then banks in the country exchange at rates closer to the black market rate. However, rampant inflation has been eroding the North Korean wŏn's value to such an extent that currently it is believed to be worth about the same as the South Korean wŏn (needs sourcing). In any case, the U.S. dollar and other currencies are still worth more in North Korean wŏn on the black market than officially.