Not because of Korea... but because of this:
※ After an applicant receives their alien registration card, the applicant must submit the Korean Health Medical Report within 3 months/ 90 days.
Contents of Korean Medical Report: A drug test, (for narcotics), a TBPE (Tuberculosis) test, and an HIV/ AIDS test. (K4E note: The government also include a cannabinoid test (cannabis) test,in its requirement, but this was removed sometime in late 2008 or early 2009. However, in Spring 2009 it began talking about adding it again).
(korea4expats.com)
I have a GIANT fear of needles/injections/etc...