You Do Need power plug adapter while traveling from North Korea to Bhutan.

Here is Why You Need An Adapter

The outlet and plug type used in Bhutan are C, D and G and in North Korea is C. This is how they look like.

North Korea

In North Korea, outlets of type C are in use.

Type C

Bhutan

In Bhutan, outlets of type C, D and G are in use.

Type C

Type D

Type G