Go schools directors are usually strong players too!
There are lot of strong amateurs in Korea, who never played in Go tournaments.
I will introduce you one of them - "yurim". His real name is Son Yibom and he
is able to keep 7-dan rank on Dashn with 50-50 score. He works as kids Go club director in Seoul.
In this game he crushed "haoda3" - Park Heeche, 7-dan who was in best 10 in Korea in the middle of 90's
That time he won several important amateur tournaments. Nowadays Park works as a go teacher.