1. Research & Development Center, Mitsubishi Hitachi Power Systems, Ltd., 832-2 Horiguchi Hitachinaka-shi, Ibaraki 312-0034, Japan e-mail:
2. Hitachi Gas Turbine Engineering Department, Mitsubishi Hitachi Power Systems, Ltd., 3-1-1 Saiwai-cho Hitachi-shi, Ibaraki 317-8511, Japan e-mail: