Korea Pass

Korea Pass is a prepaid tourism card designed by Korea's Ministry of Culture, Sports and Tourism (MCST) and
the Korea Tourism Organization (KTO).

KOREA PASS cards are available in denominations of 50,000, 100,000, 300,000 and 500,000won.
KOREA PASS cards are also available with an optional transportation function,
the balance of which is separate from that of the main, prepaid service of the card.
The transportation credit on these cards must be recharged separately from the main credit.
In the case of KOREA PASS BUSAN, the design of cards differs according to where they are bought
and the amount of prepaid balance on the card. Cards with a prepaid balance of 50,000won are red,
while those with a prepaid balance of more than 50,000 won are blue.

Link: http://www.koreapass.or.kr/en/