[计] effective time, operation use time, operational use time
yǒu xiào gōng zuò shí jiān ㄧㄡˇ ㄒㄧㄠˋ ㄍㄨㄥ ㄗㄨㄛˋ ㄕˊ ㄐㄧㄢ
有效工作时间