Major Yi was born on 1931 in Kyung–Buk, first son to Yi, Yong–Dal. He was part of the eleventh graduating class of the Naval Academy, and played for the rugby team.
He graduated from the Naval Academy on April 5th, 1953 with the rank of marine ensign. After commissioning, Yi attended the LFTU, and later participated in the Vietnam War as a member of the Chung–Ryong (Blue Dragon) unit of the ROK Marine Corps. He performed his duty as a captain of the first marine division, an operation aide, and as intelligence staff of the second marine brigade.
On August 1st, 1966, Major Yi sacrificed himself by throwing his body on a live grenade, saving his men while conducting Operation Sea–breeze around the Tuihoa area in South Vietnam. He was awarded the Order of the Military Merit of Taeguk, and the U.S. Silver Star.