1st to 3rd Degree — Assistant Instructor: Bu Sa Bum (부사범 / 副師範)
4th to 6th Degree — International Instructor: Guk Jae Sa Bum (국제사범 / 國際師範)
7th & 8th Degree — Master (Instructor): Sa Hyun (사현 / 師賢)
9th Degree — Grand Master (Instructor) Sa Sung (사성 / 師聖)

Sa Bum (사범 / 師範): 師 is teacher and instead of 師父, which is the typical terminology pair for teacher, 範 can mean example or demonstrate. So an Instructor does not only teach but also lead by example and as a role model. Bu (부 / 副) is simply assistant or vice.
Sa Hyun (사현 / 師賢) and Sa Sung (사성 / 師聖): Again, we begin with teacher. 賢 can mean virtuous, intelligent or sagacious. Simply, a Master has reached high moral values and wisdom. 聖 can mean sacred, holy, or a sage. A Grand Master has or should have become a human being with the highest standard of morality and wisdom. The Grand Master is a spiritual teacher to all and it can be said that he or she is the closest person to a saint.