I was wondering that above sentence on title, “Excuse me, Ms.” is rude or not. I’ve watched a video on youtube about English titles, but “Excuse me lady.” is very rude to get attention from women, and “Excuse me ma’am” is good for southern part of the U.S. whereas it sometimes feels uncomfortable in other area. I know that Sir. can use for all men regardless of age. I need native English speaker’s correct and clear answer. Additionally, my american professor who came from Nevada often says “Mr. Jaehyeon” Is it a way to call me friendly? I am Korean, and my first name is Jaehyeon, Family name is Kim. I can write my name in Korean “Kim Jaehyeon”. I need correct answer of English native speaker. Thank you !
It is true that you do not need to use a title when addressing a stranger, but the bare words 'excuse me' might be interpreted as abrupt or even rude. Consider "Excuse me! How dare you take my seat!".
As to what title to use, that is difficult and is subject to culture and perceived differences in social class. In BrE 'Sir' or 'Madam' (not "Ma'am, unless you are addressing the Queen) might work well, but if you reckon that you are on a par with the person you are speaking to "Mate" is fine to a man. 'Miss' is fraught with danger if the lady in question might think you were being sarcastic.
One way round the problem is to say something other than 'Excuse me' such as "I am sorry to trouble you but...".
The situation you describe is a fairly rare one: Speaking to a stranger. Moreover "excuse me" is used for multiple purposes: To apologise, to attract attention, or to ask for something.
But in most situations you can just say "Excuse me!" You would not need to address the person with "Ma'am" or "Sir" or "Miss". I would not use any title when saying "Excuse me". Especially when speaking to a woman, as there is no generally accepted alternative to "sir". So don't create a problem for yourself; just say "Excuse me."
You should be professionally called "Mr Kim", as "Mr" is not used with given names. I don't know why your Professor doesn't follow this standard. You could ask him.