Abstract: A communication system includes a communication management unit, an access point, and a plurality of traveling vehicles. The access point is connected to the communication management unit. Each vehicle includes a wireless communication unit. The communication system performs wireless polling communication between the communication management unit and the plurality of traveling vehicles via the access point at each predetermined polling cycle. In the communication system, a process including a wireless communication object addition step is performed to accept a new traveling vehicle as an object of wireless communication.

Abstract: A method for preventing microorganism multiplication, including using a gas containing a low concentration of ozone and a high concentration of ions, so that the multiplication of microorganisms can be safely and fully prevented by an additive effect of the ozone and ions. The generation of ozone is suppressed by reducing the discharge current in the ionization chamber using a pulse converter, which is provided to control the current flowing at the time of discharge, when generating the ions and ozone in the ionization chamber. Ions are produced in the ionization chamber in a high concentration to produce and supply ionized gas containing a low concentration of ozone and a high concentration of ions, which prevents microorganism multiplication on the objects.