Munpia.com is doing very well in South Korea right now with web novel.
Many authors are making a full time living from it.
The premise is very simple.
First 30 chapters are free.
Each chapter after that is about 100 Gold Coin (100 won or $0.10) to read.
1000 paying readers = $100 in revenue per chapter.
So an author really need about 2000 paying readers to write full time.
http://www.novelupdates.com/opublisher/munpia/
Many of their novels are being translated.