Well, I kind of gave my boss an ultimatum yesterday, after last weekend's depressing, discouraging experience (which was, admittedly, entirely subjective).
I told him that I wasn't very happy, and that I would like to negotiate an early end to my contract, but that I was uncomfortable with just cutting and running, as another foreign teacher at Hugok did only two weeks ago (he simply disappeared, cleared out of his apartment and sent an email, "bye"). This is not uncommon among some of the lower echelon foreign workers who come to Korea and end up disillusioned or frustrated by one aspect or another of the experience. But I don't want to be like that, I said.
We talked for a while. And here's where things stand. I will not take work home with me, ever. That's clearly not good for my personality type and for my ability to survive. I must get better at making clear when things I "must do" will not, realistically, get done in the time I have to spend on them at work–especially correcting student papers. In exchange, when I do have such unfinishable piles, I can count on him or someone to help me try to work through them somehow.
And, if that doesn't make things survivable over the contract term, he will give me a "letter of release" if I still want to leave at the end of a term–as long as I give sufficient notice and as long as it's at a good boundary between student terms. The first such stopping place is near the beginning of December. The "letter of release" will mean I cannot be "blacklisted" by Korean Immigration and thus I will be free to remain in Korea, seek another job here, etc., per whatever I might choose to do.
This seems like a very fair and reasonable basis upon which to proceed. And in good faith, I will probably be working exactly the full open hours of the academy for at least a while. Which means 11:30 to 11:30, roughly.