Kim Mi Ja (pseudonym) is the first North Korean defector to be granted permanent U.S. residency under the North Korea Human Rights Act of 2004.  The details of this legislation can be found here (PDF) and on Wikipedia.

A reported 63 North Korean defectors are currently living in the U.S.  Most of them have reportedly applied for permanent residency.

Some North Korean refugees living both in China and South Korea quietly prefer a U.S. residency over South Korea and have placed hopes in this legislature.  However, as we reported before, those refugees who have already made it to South Korea, will find it difficult to seek residency elsewhere in the west.