how to increase the size of /dev/root in edison

I met a problem that the space of  /dev/root is not big enough. I want to increase its size.

I tried the Increasing the Root Partition Size , but it doesn't work. May be they are different things, or there is something wrong during my building?

Filesystem           1K-blocks      Used Available Use% Mounted on

/dev/root               475080    305328    133056  70% /