Thanks to your reply, I could find a new solution "3DNA"( http://rutchem.rutgers.edu/~olson/3DNA/ ) It's free and has lots of function. Thank you again.
* I searched Nucgen at http://scholar.google.com and followed the first result. * This "3DNA" was among paper list which has cited the Nucgen article. Cheers, Hyun-Chul Kim Biomatics Lab. Department of Biosystems Korea Advanced Institute of Science and Technology Yusung-Gu, Taejon 305-333 Republic of Korea