Olympic gold medal swimmer and rival to American douchebag swim champion Ryan Lochte, Park Tae-hwan, has been banned 18 months by the International Swimming Federation for testing positive for testosterone. You can read the story here.
The important note here is that Park's eligibility for the Olympics relies completely on Korea. His ban will be over by the time the 2016 Games begin, but Korea would have to give him a special exemption after he misses the World Championships. Park is Korea's best, and possibly only hope at Olympic gold in the men's 200 and 400 meters.