ARC Validity to travel to China

Hi,
I'm wondering if anyone can possibly tell my WHY my working status in korea SIX MONTHS FROM NOW has anything to do with me travelling to China for a holiday? Is this not a national sovereignty conflict?

I've already booked and paid for a trip to China on September 18th, but my ARC expires March 4th, 2014 (even though my visa is good until the end of april). Does this mean I cant go on my holiday??

(i've just read below that someone was able to get a certificate of employment from their workplace... is this what I need to do to be able to go?

Thanks so much, I'd really appreciate some advice!