Yun entered politics in 1945 following
Gwangbokjeol (Liberation Day) by October of the same year Yun became Advisor to the Department of Agriculture and Commerce of the US Military Government, Administrative Advisory Committee, Advisor to the Financial and Economic Committee, and lastly the advisor to the governor of Kyungki province. The first
Doctor of Philosophy from Princeton University in Korea, as well as first President of South Korea, Dr.
Syngman Rhee, was his
mentor. By 1947, Yun was serving as Secretary to the Korean Chief of Staff. In 1948, Rhee appointed Yun to the position of mayor of
Seoul. A year later, he was made Minister of Commerce and Industry. However, Yun soon began to disagree with Rhee's authoritarian policies. While serving as president of the
Red Cross Society, he was elected to the
National Assembly in 1954. A year later, he co-founded the opposition South Korean Democratic Party. In 1959, he became a representative to the Supreme Council of the Democratic Party. == Presidency (1960–62) ==