Source: World Bank
For most government and private offices, business hours are from 9am to 6pm Monday to Friday. From November to February government offices may close an hour earlier. Tourist information centres are usually open from 9am to 6pm daily while national parks are open daily from sunrise to sunset. Keep in mind that many (but not all) government-run museums and tourist sites close on Mondays.
Banking hours are from 9.30am to 4pm Monday to Friday. The hours that ATMs are available vary and are written on the machine, but they are not generally open 24 hours. Post offices are generally open from 9am to 6pm Monday to Friday, but some are open longer hours.
Department stores traditionally open from 10.30am to 7.30pm six days a week. Nowadays some open every day and a few open until late evening. New youth-oriented shopping malls tend to stay open until 10pm. Small general stores often stay open until midnight even in suburban areas, and many convenience stores are open 24 hours. Shops are generally open from 10am to around 9pm every day, but the trend towards more days off means that some do now close on Sunday. Travel agents may take Saturday afternoon off as well as Sunday.
Restaurants usually open from 11am to 10pm every day. Cinemas traditionally open at 11am, with the last show ending just before midnight, but a few run later. In big cities, midnight showings and even all-night movies are becoming a more popular option.
Pubs and bars open daily from 6pm to midnight but they close later on Friday and Saturday. Some open at noon for the thirsty early birds.
There is plenty for night owls to do in Korean cities as some saunas, restaurants, PC bang (internet rooms), DVD bang (room for watching DVDs), noraebang (karaoke rooms), convenience stores, bars and nightclubs stay open all night.