Previous posts consider that if the size is Ok the weight does not matter. The weight aspect is supposedly for safety reasons. On a Finnair flight in J to Helsinki a cabin attendant, contrary to airline advice to be careful, opened the bin above my head carelessly and my large Toshiba laptop fell out 2+ meters onto my right knee. I was on my way to a trade show in Europe and had to walk around with a massive bruise around my kneecap. Needless to say the laptop gave up the ghost. (She just walked away without saying anything !) If pax cannot lift up their own bags they should not be taking them on board and flights should carry a small digital scale so they can offload overly heavy ones to the hold.
In OP's message he is leaving Incheon and then transiting HKG to SFO so he has 2 chances of being caught out. It would be interesting to know how he gets on. Here is a useful link for OP.
http://www.seatguru.com/airlines/Cat...ys/baggage.php