Jeong Mong-ju (1338 ¡V 1392), known by his pen name Poeun. Korean scholar-official and diplomat during the late Goryeo period. Jeong Mong-ju was assassinated in 1392 on the Sonjuk Bridge in Gaeseong. Politically motivated, the murder was ordered by Yi Bang-won (later Taejong of Joseon), the fifth son of Yi Seong-gye, who overthrew the Goryeo Dynasty in order to establish the Joseon Dynasty. Jeong Mong-ju was murdered because he refused to betray his loyalty to the Goryeo Dynasty.