http://cs231n.stanford.edu/slides/winter1516_lecture10.pdf
https://www.youtube.com/watch?v=Zt-7MI9eKEo
http://aikorea.org/blog/rnn-tutorial-1/
http://aikorea.org/blog/rnn-tutorial-3/
https://tensorflowkorea.wordpress.com/2016/05/04/stanford-cs231n-강좌가-닫혔습니다/
http://cs231n.github.io/classification/#validation-sets-for-hyperparameter-tuning