"nhmoose" is 100% correct. = The dung-heap is to stop the kimchi from freezing in the FRIGID Korean Winters.
(I suspect that a compost heap would work, too.)
Everyone that I've talked to, who made kimchi in Korea, says that you MUST have some cold weather to make decent kimchi.
(I've never figured out how to keep the fermenting kimchi consistently at the correct temperature here in South TX. = Just too variable temperatures here. = A week of COOL in the 40s-50s & 60s, often followed by a week of in the mid-70s, in what we laughingly call "Winter".)
One of the "inside jokes" in South TX is that Winter is "the 4 or 5 days each year when the Canadian tourists put a 'cover-up' over their bikinis, when 'out & about'."
yours, satx