In short--been there, DONE that, sadly DOES NOT WORK.
Suggestions and my answers(?).
*Use physical punishment like the Korean teachers:
Yep. And pretty much from day 1, those students were so awful.
There was my special stay-after room cleaning for the really bad table or group. Plus group or individual humiliation punishment of kneeling out in the halls or in front of the rest of the class.
* Be loud and be heard.
HENCE I used a mike.
Not only did I use a mike, but any instructions were also typed out and projected on the screen. With most the class talking non-stop over the mike even, you had to have 'visual' explanations of the instructions.
note: My instructions were never more than 5 minutes, if that even. So there was no excuse for "English is too hard/too long..." whatever.
I taught at ELEMENTARY level previous to the high school and they had no problem understanding my very basic instructions.
I had other things I tried out that I will not bother going into here because really, at the heart of the matter, lies a more insidious two fold problem. At the macroscopic level, fundamentally Korean society still views women as lesser. So you can swear and whack and punish all you want, but if you're not doing it in a pair of pants, you'll find yourself just doing it all over again the next week. At the more microscopic level, if your fellow teachers don't have the decency to show professional respect for you (and they don't), the kids won't either. They aren't stupid. Ignorant, yes, but not stupid. They can see how the Korean teachers, teachers THEY respect, treat the foreign teachers. If their native teachers show they don't care, the students follow suit and also do not care.
And that's it.
If you have any suggestions then leave a comment for the other victims of that place. It's highly likely I have already tried and done them, in which case I will note that and how it doesn't work when they are published.
But if you are smart, you won't even bother.
Take my advice--bypass Korea and head straight for a different country like I am.
Thanks again for stopping into my little corner of the 'net, and Happy Browsing!!