lol -- you must be quite handsome!
Me personally -- I'm not sure about formal rules of contact.
In Korea it is quite common to be in close quarters, on a bus, on the subway, in a crowd, so Koreans do not freak out as much as westerners when personal space is violated.
When I was in Korea the first time, while riding the city bus with standing room only, I kept my hands off other people as the bus swayed to a stop and some standing near me lost balance and nearly fell. After all, in the west it's 'every man for himself.' Needless to say I got some harsh glances along the lines of 'if looks could kill.' I soon got in the habit of catching other people in such situations. Upon my return trip to the US I took a shuttle bus from LAX to the valley where I live, and as we got off the bus a 70=yr old white woman lost balance and was falling down in the isle in front of me -- I instinctively reached out and grabbed her shoulders --preventing a fall that might have broken her hips... thankful?... she screamed and turned and yelled 'Don't touch me!" --I thought 'Oh yeah, right, this is America, we don't touch each other here.'
I have never had a guy friend take me by the hand in the US... I have never had a guy friend in the US put his arm on my shoulder as we walked (except when I was like 7 years old), but I have had these experiences in Korea, and with some Koreans in the US. A gay visitor to Korea might think he had hit the jackpot until he finds out that this is just the culture and not looking for an intimate encounter..
On my 09 visit to Korea I did notice that they seem to be more aware of personal space than in days past. Maybe it's the western influence, or just that I am older and uglier than in my youth ha! However, I still had the experience of having one fellow I had known for an hour take me by the hand and lead me around, and another fellow I was sharing a few drinks with putting his arm around me and patting my knee.
Girls -- well, before I was married it was not uncommon for them take me arm-in-arm as we walked and talked. However, open displays of affection (i.e. petting and kissing in public) is not as common as here in the US. And of course with married people it goes without saying that male-female contact other than between spouses is typically 'no touch', other than the hug at church or to have them put a couple of hands on your arm and say "부탁이에요 -네?."
Oh well... Koreans have 정 - that's what got me hooked.