유용도 함수(A)를 정확히 나타낸 수식은? (단, MTTR=mean time to repair, MTBF=mean time between failure, MTBM=mean time between maintenance, MTFF=mean time to first failure 이다.)
A = MTTR / MTTR+MTBF
A = MTFF / MTFF+MTTR
A = MTBF / MTBF+MTTR
A = MTBM / MTBM+MTTR
유용도 함수(A)를 정확히 나타낸 수식은? (단, MTTR=mean time to repair, MTBF=mean time between failure, MTBM=mean time between maintenance, MTFF=mean time to first failure 이다.)
A. A = MTTR / MTTR+MTBF
B. A = MTFF / MTFF+MTTR
C. A = MTBF / MTBF+MTTR
D. A = MTBM / MTBM+MTTR