A method of gas carburizing is carried out at a carburizing temperature which is not higher than a peritectic point temperature at which \u03b4 iron and liquid phase are transformed into \u03b3 iron and not less than a eutectic point temperature at which liquid phase is transformed into \u03b3 iron and cementite. A handle having a ratchet mechanism is connected to a first roller for turning the roller during pressing. The processing system includes a programmable reference signal selection circuit to maintain the reference voltage at a constant level. This can comprise, for example, controlling the switched voltage clamp in synchronicity with the pulsed x-ray source. The storage information may include information relating to periods when the rechargeable battery is not being actively charged or discharged.