1. Manufacturing and Engineering Technology, College of Engineering, Tennessee Technological Univ., 920 N. Peachtree Avenue, Lewis Hall 111A, Cookeville, TN 38505 US
2. Engineering Laboratory, National Inst. of Standards and Technology, Gaithersburg, MD 20899, US, e-mail: dkim@tntech.edu
3. Engineering Laboratory, National Inst. of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD, 20899 US (Corresponding author), e-mail: paul.witherell@nist.gov
4. Engineering Laboratory, National Inst. of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899 US