Yong Sul Choi (1904-1986): is recognized as one of the most influential people in Korean martial arts. Born in 1904 at Choong Buk province, he lost both his parents at an early age. As a child, Choi was kidnap and taken to Japan where he studied Daito Ryu Aiki Jujutsu under the the instruction of Sokaku Takeda (1859-1943) the head of the Daito Ryu Aiki-jujutsu school. Choi began his studies at the age of nine. By the time Choi returned to the mainstream world, Korea had already been liberated from colonial Japanese rule. He returned to Korea in 1945 and took a train to the city of Tae Gu where one of his bags was lost. Unfortunately for Choi, he had his money and his certificates for his martial arts training he had received in Japan in that bag. Choi had originally planned to return to hishome at Choong Buk province but decided to stay in Tae Gu since he had no money. After saving enough money in one year as a bread salesman, he began raising pigs.

Choi would get up early every morning to to go to the Suh Brewery and receive free grain chaff leftover from brewing so that he could feed his pigs. There were always many people lined up to receive the free grain chaff and on one particular morning the President of the brewery, Suh Bok-sub, looked out of his second story window to see a conflict between those who were waiting. He saw one man defend himself against several attackers with a minimum of effort. Suh was very interested in what he witnessed and had one of his clerks bring the man to his office. When Choi arrived, Suh inquired about the techniques he had used to defend himself and Choi asked why he was interested. Suh replied that he wanted to learn the techniques to use in a martial arts tournament.

Choi demonstrated a few simple techniques on Suh and immediately Suh begged for Choi to teach him. He promised to continue to give him free chaff along with money for his lessons and Choi agreed. Suh then built a dojang at the brewery and Choi was given the opportunity to teach Yu Sool to students. Later, "Yu Sool" was changed to Yu Kwon Sool" at the suggestion of Suh Bok-sub. While Yu Sool emphasizes joint locks and throws, Yu Kwon Sool includes punches and kicks. Suh began demonstrating Yu Kwon Sool and it soon became very popular among the public. Suh subsequently sold his brewery and opened a Yu Kwon Sool school In Tae Qu and in 1965, Suh opened a school in Seoul. Choi proceeded to impart the techniques he had learned to a select group of disciples. It was not until the 1957 that Hapkido was first taught to the common person when Choi students began to spread and popularize Hapkido during the Korean conflict.