This may sound like a strange thing to talk about, but I thought it important enough that it deserved its own post.
Crossing the road can be dangerous in Korea. Even if you wait for the green man at the cross walk, you should look left and right CONTINUALLY as you cross the road. It is very common for people to run red lights. There is also a rule in Korea where you can turn right at an intersection EVEN IF THE LIGHT IS RED provided there is no traffic (though I have seen people rip into the intersection even when there is oncoming traffic).
I would say taxi's and scooters are the biggest offenders. Taxi's will drive out into the intersection as far as they can (which normally means stopping on the pedestrian crossing) so they can get a good view up and down the street so they can see when it is "safe" to run the red light. Scooters sometimes will decide to join you on the pedestrian crossing as you cross the road as a "safe" means for them to run the red light. Scooters really are a law onto themselves here. They ride on the footpath, run red lights and drive the wrong way up streets all while they are talking on their phone without the use of a hands free kit.