See also:
http://www.mofat.go.kr/en/visa/e_visa.mof
... for a more comprehensive list of countries under visa exemption etc.
Some of us are blessed with non-US passports, Ken :-)
Heh, I guess the termology in my first note was imprecise; I should have
said "US passport holders" instead of "US residents". My apologies.
But my reading of that web page implies that the USA is _not_ one of the
countries you can enter Korea from without a visa when travelling on
business (but it looks like a lot of countries in Europe are on the
list).
--Ken