Surname Sung-Joo (성주 
, Sung-Joo 
) , globally, is an extremely rare last name. The cognomen Sung-Joo is habitual in Northern Europe, particularly the United Kingdom, where it is an extremely rare surname. Much more frequently, Sung-Joo is the forename as well as the last name. Parts of the name also exists independently as a last name Sung, and a first name Joo.