The database lists most IP address ranges assigned to Korea by APNIC, plus any older ARIN ranges with a history of sending spam. The list includes networks, not individual computers.
As networks clean up their act, get rid of their spammers, fix their abusable relays and proxies, and set up a reasonable procedure to receive and act on complaints, they have started removing well run networks from the list. Their goal is to stop the flow of spam, not to cut anyone (other than spammers) off from the Net.
Note: The database includes networks, not individual computers. Do not write to ask to have your computer removed, unless your entire network has its spam problem under control.