$Zr_{0.9}Ti_{0.1}Cr_{0.9}Fe_{1.1}$ 금속간화합물의 수소 흠수 - 방출 싸이클링에 의한 Intrinsic degradation 에 관한 연구A study on the intrinsic degradation of $Zr_{0.9}Ti_{0.1}Cr_{0.9}Fe_{1.1}$ intermetallic compound upon thermally induced hydrogen absorption - desorption cycling