Citizens of visa-free countries are allowed to tour or visit Korea without a visa and to stay in the country for up to 30 days (or 90 days).
You can find out if you need a VISA or not from “Korea VISA Portal” website.
The electricity supply commonly used in Korea is 220-volt 60Hz system. Because most newly built hotels and houses have the 220-volt wiring installed, you are advised to check your electronic equipment beforehand.
The average annual temperature of INCHEON is reported to be 12.5℃ and April’s average temperature is reported 13℃ - 19℃.
The Korean local currency is the Won. Major foreign currencies can be exchanged at banks, hotels, and the airport. Most hotels, restaurants, and shops accept major international credit cards including Visa, American Express, Diners Club, Master Card, and JBC. Foreign-issued ATM cards may have limited use.