Park Jeong-Hwan (), who trained under Choi for only three years, is one of the later students that opened a Hapkido school in America, several of which still function today. Doju Choi made a special trip to the United States in 1982, several years prior to his death, to visit his highest ranked instructor Chinil Chang in New York City and to preside over the creation of the US Hapkido Association. Master Mike Wollmershauser, who was the only American to have trained under Choi Yong-sool himself, documented part of this historic visit on videotape, which is in the hands of Doju Chinil Chang. Doju Choi's final wishes were to spread Hap Ki Do all over the world as well as to unite the art as one family, although Doju Choi had realized at that point that the system had splintered into too many political and warring factions for that to ever happen. He also wished to keep his original system intact and for the lineage to be passed in a complete manner to his successor, which he accomplished. Master Wollmershauser attempted to spread this word of unity throughout the world until his death in December 2002. Doju Chang maintains the integrity and purpose of his mission while continuing to teach his students as he has since arriving in the United States decades ago. Controversy Choi's claims of being a student of Daito-ryu under Takeda Sokaku are contested and unsupported by the fee and attendance records of Takeda Sokaku that still exist today. However, according to Kisshomaru Ueshiba, son of Aikido founder Morihei Ueshiba, a young Korean was present at several of Takeda's seminars, suggesting that some Korean nationals had some formal training in Daitō-ryū Aiki-jūjutsu. One can only speculate as to why Choi's name is not on the otherwise meticulous records. The claim by some that the lack of documentation was due to his Korean ancestry is difficult to uphold since other Korean students are mentioned in the records. Others claim that, since Choi was Takeda's house servant, it is logical to assume he was trained by him or at least in his dojo. There is a strong similarity to the techniques taught in Daito-ryu and the techniques of Hapkido. The source of the name Hapkido is also disputed. Choi Yong-Sool's student, Ji Han-Jae, claims to have coined the name for the art. Seo Bok-Seob states in a 1980 interview