1. Biomedical Physics Laboratory, School of Physics, Seoul National University, Seoul 151-747, Korea.
2. College of Veterinary Medicine, Seoul National University, Seoul 151-742, Korea.
3. Department of Acupuncture and Meridian, College of Oriental Medicine, Kyung Hee University, Seoul, Korea.
4. Department of Physiology and Pharmacology, Karolinska Institute, SE-171 77 Stockholm, Sweden.