in an altercation with several men in a dispute over grain at the Seo Brewing Company, the son of the chairman of the brewery, Seo Bok-seob, was so impressed by his self-defense skills that Seo invited Choi to teach the brewery's employees at a makeshift dojang that Seo had created on the premises for that purpose. In this way, Seo Bok-seob became Choi Yong-sool's first student. Later Choi became a bodyguard to Seo's father, who was an important congressman in Daegu. Spreading the art In 1951, Choi and Seo opened up the Daehan Hapki Yu Kwon Sool Dojang (), the first formal school to teach the art. In 1958 Choi Yong-sool opened up his own school using the shortened name Hapkido for the first time. Both schools were located in Daegu. Some of the more important students from this period of time were Kim Moo-Hong () and Moon Jong-Won (). Apparently Choi also taught people on his farm during the early years of the art and it was in this way that Ji Han-Jae (), one of the great exploiters of the art, came to learn from Choi. The founders of two arts, Lee Joo-Bang () of modern Hwa Rang Do and Seo In-Hyuk (; Suh In-Hyuk) of Kuk Sool Won, are thought by some to have trained with Choi Yong-Sool, although this is controversial. Others assert that their training came from Kim Moo-Hong's hapkido school in Seoul, with which they were known to have been associated. In 1963, Choi became the first Chairman of the Korea Kido Association (Daehan Ki Do Hwe; ) and appointed one of his most senior students, Kim Jeong-Yoon (; also rendered Kim Jung-Yun) as secretary general. Later, Kim separated from the hapkido organizations to form his own Han Pul Hapkido organization, although his art remains firmly based in the teachings of Choi Yong-sool. Another prominent top student who became crucial to the survival of Doju Choi's full system was Chinil Chang, the personally chosen second Doju (Grandmaster) and the only man awarded the 10th Dan and the title of Doju directly from Doju Choi. Students of importance who were trained by Choi during the later periods of his teaching were Kim Jeong-yoon, Kim Yoon-Sang () who later went on to form his own offshoot Hapki yusul organization to fabricate and support his erroneous and misguided claims of being the surviving grandmaster of hapkido. and