Seok Lee
activation = nn.tf.relu==> activation = tf.nn.relu 
jupyter에서는 fig = plt.figure() 가 다른 행에 있으면, plot이 실행 안됨.  같은 행에 있어야만 실행되는데 왜 그럴까요?
 batch normazation을 해보려고 하는데, is_training은 어떻게 설정을 하나요?
otherwise, it's half done.
as title says, I want to know what TF/Keras version was by that time when you created this code.
Arguments: inputs -- shape of the input images (channel, cols, rows) """ is the channel first to feed the image?