Please answer the following question: Information:  - Chung Dong-young (born July 27, 1953 in Sunchang County, North Jeolla) is a politician and was the United New Democratic Party candidate for President of South Korea in 2007.  - The 17th South Korean presidential election took place on 19 December 2007 . The election was won by Lee Myung - bak of the Grand National Party , returning conservatives to the Blue House for the first time in ten years . Lee defeated United New Democratic Party candidate Chung Dong - young and independent candidate Lee Hoi - chang by the largest margin since direct elections were reintroduced in 1987 . It also marked the first time a president - elect in Korea was under investigation by a prosecutor . Voter turnout was 63.0 % , an all - time low according to the National Election Commission .  - The United New Democratic Party (Hangul: , Hanja: , Abbreviation: UNDP) was a political party of South Korea. It was formed out of the Uri Party and its resulting splinter groups. Chung Dong-young was the UNDP candidate in the South Korean presidential election, 2007; he lost to Lee Myung-bak. On February 17, 2008, the party merged with the Democratic Party to form the United Democratic Party.  - Lee Myung-bak (; born 19 December 1941) is a South Korean politician and businessman who served as the 10th President of South Korea from 25 February 2008 to 25 February 2013. Before his election as president, he was the CEO of Hyundai Engineering and Construction, as well as the mayor of Seoul from 1 July 2002, to 30 June 2006. He is married to Kim Yoon-ok and has three daughters and one son. His older brother, Lee Sang-deuk, is a South Korean politician. He attends the Somang Presbyterian Church. Lee is a graduate of Korea University and received an honorary degree from Paris Diderot University on 13 May 2011.  - Lee Hoi-chang (born June 2, 1935) is a South Korean politician and lawyer who served as the 26th Prime Minister of South Korea from 1993 to 1994. He was a presidential candidate in the 15th, 16th and 17th presidential elections of South Korea. Prior to his presidential campaigns, Lee served as Chief Justice of the Supreme Court of South Korea.  - The President of the Republic of Korea () is, according to the South Korean constitution, the chairman of the cabinet, the chief executive of the government, commander-in-chief of the armed forces, and the head of state of South Korea. The Constitution and the amended Presidential Election Act of 1987 provide for election of the president by direct, secret ballot, ending sixteen years of indirect presidential elections under the preceding two governments. The president is directly elected to a five-year term with no possibility of re-election. If a presidential vacancy should occur, a successor must be elected within sixty days, during which time presidential duties are to be performed by the prime minister or other senior cabinet members in the order of priority as determined by law. While in office, the chief executive lives in Cheong Wa Dae (the "Blue House"), and is exempt from criminal liability (except for insurrection or treason).  - The Prime Minister of the Republic of Korea ( / , "Gungmuchongni") is appointed by the President of South Korea, with the National Assembly's approval. The officeholder is not required to be a member of the National Assembly. The Prime Minister is not the head of government but rather serves in a role similar to that of a vice-president.    Given the paragraphs above, decide what entity has the relation 'office contested' with 'president of south korea'.
Answer:
south korean presidential election