Family name Yunseok (윤석 
, Yunseok 
) , in all the world, is a rare cognomen. The cognomen Yunseok is habitual in South Korea, where it is a rare surname, Cambodia, where it is a very rare surname, and Thailand, where it is an extremely rare surname. Measured by absolute frequency, it is the most numerous in South Korea, China, and Thailand. Much more frequently, Yunseok is the forename as well as the last name.