South Korea will shut down some cryptocurrency exchanges!

https://www.bloomberg.com/news/articles/2017-12-28/bitcoin-drops-as-south-korea-says-exchange-closures-are-possible

South Korea is trying to protect its citizens from the impending collapse of bitcoins by shutting down some cryptocurrency exchanges.

I think South Korea government knows that the Japanese are trying to offload their bitcoins by finding suckers to buy over at a much higher price.  Therefore, the SK government has been taking further actions against bitcoins.