Question: The confucian academy, Dosan Seowan, located in the East Asian country bordered by China to the northwest and Russia to the northeast, was founded by two prominant Confucian scholars, one being known as Yi Yulgok. What was the "pen" name of the other founding scholar?
Sentence (from "Korea"): Korea is a historic country in East Asia, since 1945 divided into two distinct sovereign states: North Korea (officially the "Democratic People's Republic of Korea") and South Korea (officially the "Republic of Korea").
Relevant evidence: No