The "5000 won"

The "5000 won (오천원)", the correct pronunciation is "o-chon won".
Obverse the bill is Lee I (이이), who was one of the most Korean Confucian of the Joseon Dynasty. Gangneun (강릉시) also appears on the bill with the black bamboo, native to China but Korea has many of these plants.
On the reverse: We can see a watermelons with plants and insect, this was painted by Lee I's mother, Shin Saimdang (신 사임당).