Yoengam is his hometown. He passed the Mugwa, military service examination, and served as ruler of Geosando, Ungcheon and Jeju. However, he was dismissed from office due to the conflict with Moksa, the administrator of Mok. In 1592 (the 25th year of the reign of King Seonjo) Jeong Un was the Left Jeolla Naval Commander, Nokdomanho. On September 1, 1592 (by the lunar calendar) when Admiral Yi Sun-sin destroyed about 100 of 400 Japanese ships in the Busanpo Sea Battle, Jeong Un, then Nokdomanho, died while leading the army as the right naval leader under Admiral Yi Sun-sin.
His descendents and local residents perform the rite at the Lord Jeong Un Monument in memory of his death every year on September 1 of the lunar calendar.
Lord Jeong Un Monument, located at Molundae, San-114, Dadae-dong, is designated as Local Monument No. 20.