How does Korean people address a doctor?

[seasurfer]

In English, we call Dr.(Last name), what about in korean?

[steved]

If the doctor is the owner of the clinic then you could call him 원장 선생님 but you would formally address any doctor as "의사 선생님." You really wouldn't need to use a last name at all unless they were practicing in a group practice. You could also use the specialty title along with "선생님" like a dentist would be 치과 선생님 in a multi-disciplinary clinic but if he was in solo practice then you would call him 원장 선생님.
Does that help or is that confusing?

[aerojoeyseo]

You can even get rid of 의사 and just call them 선생님 when you're addressing them.

However, addressing a doctor simply as 의사 is generally not acceptable for it is considered rude.

선생님 technically means 'teacher' but people add it after the title to express their respect for that person or simply to be polite. e.g. 의사 선생님 (doctor), 작가 선생님 (writer)

Hope it helps.

[dewnyc]

If you want to address someone or refer to someone as "Mr. (Last name)", such as when you don't know either the person's given name or his profession, or if you want the attention of (or on) a particular person in a group (in a business or more formal setting), would (Last name) + 선생님 also be used in such cases? Same for a woman, for example "Ms." or "Mrs."?

[hyunwoo]

If you want to address someone or refer to someone as "Mr. (Last name)", such as when you don't know either the person's given name or his profession, or if you want the attention of (or on) a particular person in a group (in a business or more formal setting), would (Last name) + 선생님 also be used in such cases? Same for a woman, for example "Ms." or "Mrs."?

Yeah some people use the word "선생님" to address others regardless of the profession, but this is very subtle. For example, I've never called anybody ㅇㅇ 선생님 when they are not teachers, but I wouldn't feel weird either if I had to.