Holy sheep shit batman. This story freaks me out. I did not know this was a wide spread thing in Korea.
I had an argument with my wife about this subject years ago. She is from S. Korea and I am from the US. She had yelled at me because I left a fan on and fell asleep. When she got home from work and realized what happened she freaked out and told me I could die that way. At the time I remember thinking that she was absolutely crazy to believe this was possible. We argued for a long time about it and at the time I remember questioning her sanity, repeatedly. Eventually she dropped it and admitted it probably was wrong of her.
Every once in a while this strange superstitious stuff pops up with her. I love her deeply but it is not easy being married to a South Korean. :-)