Most restaurant open 24 hours.

I am not sure how many store is in Korea, however you can find easily McDonald restaurant around main street.

04:00 ~ 11:00 : Morning menu, morning set is 3,000 KRW

11:00 ~ 14:00 : Lunch set

14:00 ~ 04:00 : Regular menu

The lunch set is below :
BigMc set(3,500KRW), Shanghai Chicken set(3,900KRW), Bacon Tomato Deluxe set(3,900KRW), Chicken Sandwich set(3,000 KRW), Bulgogi Burger Set(3,000KRW), Shrimp Burger Set(3,000KRW)

Unfortunately since June 2009, no more re-fill soda drink.