“…As mentioned above, the height ratio of the tester to the chair for Figure 10 is 1.74, and the height ratio of the tester to the chair for Figure 12 is 2.12. In all test cases, since IFADS detects the change in the person's state, it can detect correctly even if the tester cannot be detected, because the human features of the falling tester cannot be found in Cases 14,15,16,17,20,21,22, and 23. In Cases 14,15,16,21,22, and 23, IFADS cannot detect the testers, because some of the testers' features are obscured by the chair.…”