On 19 April 1950, he won the Boston Marathon with a record time of 2:32:39, under coach Sohn Kee-chung, the marathon winner at the 1936 Berlin Olympics.
On 19 April 1950, he emerged victorious at the Boston Marathon with a record time of 2:32:39, under the guidance of coach Sohn Kee-chung, who had won the marathon at the 1936 Berlin Olympics.