They are the real thing and therefore infinitely better quality than the fakes sold in Bangkok. One immediate use for them is buying concessionary subway tickets. With a student card you can buy a 20,000 won ticket at the reduced price of 16.000 won. Every little helps. With a little observation, you need never pay for the subway again.
All stations have at least one free moving turnstile for officials and policemen to use.
By memorising their positions at your regular stops, and making it look as though you are using your ticket, you can come and go as you please. Phonecards are available everywhere, but with a little patience you can always find a coin operated payphone close by, with enough credit for an extra call. When ringing abroad and you do not have a Kallback account or something similar, use the Dacom 002 prefix for cheaper international rates. Alternatively, find out if your Hakwan has fax machine. The USO is a great place and you should not be afraid to use it just because you are not an American.