Optimize algorithm of the flow meter to Subaru environment

The flow meter has been showing "0" flow since it was attached to Subaru Cs flange. According to the chyan , the meter showed the proper value (~3.5 Hz), but decreased 0 soon. When we inspected the flow meter 8 June, it is fount that the flow is not too slow to detect the pulse with the current algorithm. Therefore, the algorithm should be optimized to detect slow pulse at Subaru telescope.

Besides, the unit of the flow, for which [ Hz ] used currently, should be changed to see the "flow" more directly. The calibration factor (K-factor) is written in the label of the device, according to the vendor's manual.