This was recently posted on the State Department website.
Adoption Notice: The Republic of Korea Signs the Hague Adoption Convention
On May 24, 2013, the Republic of Korea (South Korea) signed the Convention on Protection of Children and Co-operation in Respect of Intercountry Adoption (the Convention). This is the first step for South Koreain becoming a Convention partner.
Adoptions between the United States and South Korea, however, are not yet subject to the requirements of the Convention and relevant implementing laws and regulations.
According to the Ministry of Health and Welfare, which will be designated as South Korea's Central Authority, there is no set date when South Korea will deliver its instrument of ratification or when the Convention will enter into force with respect to South Korea.