Jong-Ho is his name, which is 종호.
In Korean, when you are calling someone, you say "<name> ya" or "<name> ah", depending on how the <name> ends; in Jong-Ho's case, it is "Jong-Ho ya".
Now, among close friends, mainly kids, it is somewhat of a trend to skip the first syllable and just say the last two; so instead of "Jong-Ho ya", a close friend would say "Ho ya".
Enigma solved?!
Also, Jong-Ho thought that "Hoya" was easy enough in English and in many other languages to be a well remembered method name. Smart guy.
This is pretty late but I recently switched to hoya, I averaged around 1:30 with yau and and now I am about averageing 1:20+ depending on parity, and I only switched yesterday.