Korean skiers and snowboarders do not give alot of room to people around them. Thus, there are alot of accidents. In my opinion this is due to their culture. Alot of people living very close to one another. They are just used to being close together. The dangerous part is that it leads too way to many impacts. Also beware of the people that just stop in the middle of the slope. Groups will also stop in the middle. They rarely go to the side to stop.
When skiing or snowboarding in korean. Beaware of those around you. Don't be surprised if someone hits you.
It can get very crowded during the weekends at Yongin Everland as a lot of locals visit the theme park, so it is better to avoid this time. Also peak season such as summer and autumn brings in a lot of people.
Some of the rides involving water might cause you to be wet even though plastic covers are provided, so be careful especially electronic equipments such as cameras and videos.