it is an object of the present invention to provide a simulation tool , which can overcome complications of examinations by simulations as described above and can provide a designer with easy examinations . a simulation based on a design parameter of a unit is implemented . furthermore , a simulation result implemented by the control device is output on a display screen as a graph . then , the unit design parameter is corrected in accordance with a correction in the graph displayed on the display screen . thus , the simulation can be retried easily .