This blog defines semi-presidentialism in terms of the collective responsibility of the PM and cabinet to the legislature. As noted in a post a couple of weeks ago, according to the current South Korean constitution there is only individual PM responsibility. This has been demonstrated very neatly in the last few days.
PM Chung Un Chan resigned some weeks ago. President Lee Myung-bak nominated Kim Tae-ho as the new PM. However, Korea Herald reports that Kim withdrew his nomination on Sunday in the face of corruption accusations. However, even though two other ministerial appointments also resigned for the same reason, other ministerial appointments have been made.
In other words, the withdrawal of the PM’s nomination did not result in the withdrawal/resignation of the government as a whole. This is a clear sign that responsibility at appointment is individual. Therefore, for the purposes of this blog, South Korea under the 1987 constitution is not classed as semi-presidential.