Howard,
Does your system use 선생님 (seon saeng nim) in reference to martial arts instructors or are you referring to normal teachers/professors? I don't read Hanja, only Hangul, so I'm not sure of the translation for those characters to Korean. I assume that the Korean pronunciation is the same as it is for 선생?
What would be the Hanja equivalent for Martial Arts instructor (사범님

?
I've actually never seen Koreans use the Hanja to refer to these. Does your style do this? If so, which style?
Sukerkin,
What I'm referring to....In the Korean language, there are many different words for teacher. Seon Saeng (선생님

refers to a school teacher or professor, while Sa Bom (사범님

refers to a martial arts instructor.
Does the same apply in Japanese?
Datflow, excuse my off topic comments....
Clarification....This is what I was referring to. The Korean language is very complex and uses both Korean characters (Hangul) and Chinese (Hanja). Generally the Hanja characters (the name for chinese characters when used in Korea....in Japan it is called Kanji) are used only in scholarly publications and some newspapers. The average high school student must learn around 10,000 chinese characters in addition to the Korean vocabulary. College students will learn many many more.
The term Seon Saeng is basically another way of saying "sir," "mister," or "teacher." Whereas the term Sa Bom refers specifically to a Martial Arts instructor. The nim (님

is just a "modifier" if you will simply to show respect to the person you're talking to (used when a younger person speaks to an older person).
This is the kind of stuff that you will generally only learn in a place like this or through personal study. If you intend to stay in the art for a long time and get truly serious, you may find yourself around older Koreans and this kind of stuff comes in handy. Just a Korean phrase book or Korean/English dictionary helps a lot sometimes, although it will not have any MA specific terms in it usually. As we've said, it is just a matter of how much you want to put into it. You can obviously still be a GREAT martial artist without knowing any of this stuff.