1. School of Mechanical and Advanced
Materials Engineering, Ulsan National Institute of Science and Technology,
Ulsan 689-798, Republic of Korea
2. School of Electrical and Computer
Engineering, Ulsan National Institute of Science and Technology, Ulsan
689-798, Republic of Korea
3. Low Dimensional Carbon Materials
Center, Ulsan National Institute of Science and Technology, Ulsan
689-798, Republic of Korea
4. Department of Civil Engineering,
Kyung Hee University, Yongin 446-701, Republic of Korea