Suppose you have repository C:\Repositories\REPO and folder /trunk/abc in this repository. See the sample steps to move folder /trunk/abc to another repository C:\Repositories\REPO2.
Ensure that all commits affecting /trunk/abc path and its descendants do NOT affect any other path. For example, there is no commit which adds files to /trunk/abc and */another_folder* at the same time or copy files from */another_folder* to /trunk/abc etc.
Create dump of the REPO repository:
svnadmin dump C:\Repositories\REPO > REPO.dump
Filter out unnecessary paths from the REPO.dump file:
svndumpfilter include /trunk/ABC < REPO.dump > filtered.dump
Create empty /loaded folder in the C:\Repositories\REPO2 repository.
Unlike svndumpfilter, svnsync will automatically translate copy operations with an unreadable source path into normal additions, which is useful if history involving copy operations needs to be filtered.