The Korean local time is 9 hours ahead of GMT with no daylight savings time.
Korean Standard Time
The coming of autumn brings continental winds and clear, dry weather, making these months perhaps the most pleasant time of year. November's vivid gold and vibrant red create a colorful panorama.
Major foreign currencies that can be exchanged at banks, hotels, and the airport include the US Dollar, Japanese Yen, Euro, and UK Sterling. Most hotels, restaurants, and shops accept major international credit cards including Visa, American Express, Diners Club, Master Card, and JCB. Foreign-issued ATM cards may have limited use.
Tipping is not a regular practice in Korea. Service charges are included in your bill for rooms, meals and other services at hotels and upscale restaurants.
Visitors can receive a refund on a receipt for a minimum purchase of KRW 50,000 (around US$52). To receive this refund, present refund receipts with the purchased goods at the customs desk at the Incheon International Airport when departing. These receipts can be cashed in at the Cash Refund Office in front of the Airport Duty Free Shop.
Incheon Int'l Airport: https://www.airport.kr
Travelers who carry internationally recognized credit cards can get a cash advance in Korea Won from Automated Teller Machines (ATMs) installed at airports, major hotels, department stores, subway stations and tourist attractions. ATMs are in operation 24 hours a day. Most stores, hotels and restaurants in Korea accept major international credit cards. However, it is advisable to carry some cash as some occasions will require them. For example, to add on or load money to fare cards, only cash is accepted.
Cellphones can be rented at Incheon International Airport. Users can rent a handset and pay rental and call charges upon returning the phone. Applicants require identification, credit card, and a service contract (available at the booth).
Prepaid SIM Card
Prepaid SIM cards can be bought online in advance or offline. Incheon Airport, outlets run by Korean mobile service providers (KT, SKT, LG U+), and major convenience stores, such as GS25, CU, Seven Eleven, also provide SIM cards.
More on prepaid SIM cards: https://blog.trazy.com/survival-tip-all-about-sim-card-prepaid-sim-card-for-foreigners/
Prepaid SIM Card
International dialing code in Seoul, Korea is +82-2 (Area code).
Please omit (0) when dialing from overseas.
The standard voltage in Korea is 220 volts. The socket has two round holes and is the same type used in France, Germany, Austria, Greece, Turkey, and many other countries. The multi-voltage travel adapters are available at hotel's front desk. They can also be purchased at a duty-free shop, convenience shop at Incheon Int'l Airport, or Yongsan Electronics Shopping Town.
Government office hours are usually from 9:00 am to 06:00 pm on weekdays and closed on weekends. Banks are open from 9:00 am to 4:00 pm on weekdays and closed on Saturday and Sunday. Major stores are open every day from morning hours until 08:00 to 10:00 pm including Sundays.