1. [1] T. Aoki, M. Yamasaki, T. Takeda, H. Harada, and K. Nakamura, “Guidelines for power-supply systems for datacom equipment in NTT,” Proc. INTELEC'02, pp.134-139, 2002.
2. [2] A. Pratt, P. Kumar, and T.V. Aldridge, “Evaluation of 400V DC distribution in telco and data centers to improve energy efficiency,” Proc. INTELEC'07, pp.40-45, Oct. 2007.
3. [3] K. Hirose, T. Takeda, and S. Muroyama, “Study on field demonstration of multiple power quality levels supply in Sendai,” Proc. INTELEC'06, pp.256-261, 2006.
4. [4] Ministry of Economy, Trade and Industry, Japan, “Green IT initiative 2007,” 2007.
5. [5] H. Ikebe, “Power systems for telecommunications in the IT age,” Proc. INTELEC'03, pp.1-8, Oct. 2003.