Sangmukwan was founded by master Ko Baek-yong in 1987. Master Ko Baek-yong started learning hapkido in 1964 from kuksanim Myung Jae-nam and has been a student of him until kuksanim’s death in 1999.

In 2005 master Ko Baek-yong moved the gym from Incheon to Seoul to better accommodate foreign students. From a young age master Ko Baek-yong has been teaching foreigners. Already when he was just a highschool student did he teach hapkido at a American army base in Incheon. In 1989 he accompanied kuksanim Myung Jae-nam to the Netherlands where they introduced Hankido to members of the Dutch HKD Federation. This visit proofed to be the basis for a long time relationship between Sangmukwan and the Dutch HKD Federation.

In 2005 and 2006 master Ko Baek-yong published to DVDs about Hankido. When teaching master Ko Baek-yong’s focus in on the basic principles that form the core of all Hankido techniques and their application. His philosophy is that it isn’t about how many techniques you know, but how well you understand the basic techniques.

Since 2006 master Ko Baek-yong is assisted by his youngest son, master Ko Se-hwan. Master Ko Se-hwan started learning HKD from a young age at Sangmukwan.