1. Zalman Tech Co., Ltd.,Seoul, 153-803, South Korea; School of Mechanical Engineering, Sungkyunkwan University, Suwon, 440-746, South Korea
2. School of Mechanical Engineering, Sungkyunkwan University, Suwon, 440-746, South Korea
3. Zalman Tech Co., Ltd., Seoul 153-803, South Korea
4. Mechanical, Aerospace, and Nuclear Engineering Department, Rensselaer Polytechnic Institute, Troy NY, 12180-3590