A corona generating device, includes a conductor; a grid having a curved surface; and a frame for supporting the grid. The scan lines and the data lines are disposed over the substrate, therefore a plurality of pixel areas are defined. A model of an evolution of steam pressure in the tissue, caused by the ablation energy, as a function of time is estimated. When an HA that subscribes to the monitoring service registers, it is also redirected to the MA-SG, and a secure tunnel is established between the TMA and the HA and maintained by heartbeat messages. In the disclosure, the accommodating condition of the dust for the dust collecting unit can be easily shown.