R-Name is a free batch file renaming utility. You simply drag 'n drop files (or folders) onto R-Name and they are automatically renamed based on your settings. You can even preview the changes before actually renaming the files. The source code is available.
개발자는 더이상 연락이 안된단다 -_-;;;
그래도 소스가 있어서 컴파일된 놈이 돌아다닌다.