Från länk :

Visa-free Entry for tour and transit

Nationals of the countries below can enter Korea without a Korean visa for a stay of up to 30 days, if their purpose of visit is tour or transit

Asia

MACAO, BRUNEI, SAUDI ARABIA, U.A.E, YEMEN, OMAN, JAPAN, QATAR, TAIWAN, H.K(90days), KUWAIT
※ Only Diplomatic·Official passport : INDONESIA, LEBANON

North America

U.S.A, CANADA(6months)

South America

GUYANA, GUATEMALA, VENEZUELA, ARGENTINA, ECUADOR, HONDURAS, URUGUAY, PARAGUAY

Europe

MONACO, Vatican, BOSNIA HERCEGOVINA, Cyprus, SAN MARINO, Serbia & Montenegro, SLOVENIA(90days), ANDORRA, ALBANIA, CROATIA

Oceania

GUAM, NAURU, NEW CALEDONIA New Caledonia, MICRONESIA, SAMOA, SOLOMON IS, KIRIBATI, FIJI, AUSTRALIA(90days), MARSHALL IS, PALAU

Africa

SOUTH AFRICA, Mauritius, Seychelles, SWAZILAND, EGYPT

(Observera att Vietnam inte finns på listan.)

Visitors meeting the following requirements also can enter Korea without a Korean visa for a stay of up to 30 days, if their purpose of visit is transit

Note) Nationals of Cuba,Macedonia ,however, must apply for korean visa, even if they meet these requirements

• Holding a visa or a re-entry permit of the U.S. Japan, Canada, Australia, or New Zealand (5 countries)

• Travelling from either of the five countries to a third country via Korea, or travelling from a third country to either of the five countries via Korea

• Holding a confirmed onward flight ticket for departure within 30 days

• No Immigration offence records, while in the five countries

Those who have visited Korea more than 4 times in recent two years, or those who have visited Korea more than 10 times in total can enter Korea without a Korean visa, notwithstanding the requirements above

Note) However, this facility for frequent visitors is not applicable to nationals of "China (P.R.C)", "Cuba" , "Macedonia"

Det verkar som om du är berättigad till transitering utan visum om du inte har några tidigare immigrationsbrott i något av de fem länderna.

Flygbolagsagenter går Tidtabell , som anger:

Passengers with a visa issued by Australia, Canada, New Zealand or USA to nationals of any country except for China (People's Rep.), Cuba, Iran, Macedonia (FYROM), Sudan and Syria, only if in transit through Korea (Rep.): -holding confirmed onward tickets on flights departing within 30 days; when arriving from a third country, departing to the country that issued the visa (e.g. DEL-ICN-YVR); or arriving on a direct flight from the country that issued the visa (a visa that expired on departure from that country is accepted), departing to a third country (e.g. YVR-ICN-DEL).

Med andra ord: ja , du kan gå till Seoul och tillbringa en natt där. Skriv ut den här webbplatsen för att visa flygbolaget bara om det är

Enligt Timatic :

Visa required, except for Holders of onward tickets transiting Seoul Incheon (ICN), for a max. transit For details time of 24 hours.

Så länge din transitering är under 24 timmar och du reser genom Seoul behöver du inte visum oavsett din nationalitet eller destination.