A diode comprises a substrate formed of a first material having a first doping polarity. To achieve the above objective, the present invention is configured such that before the electromagnetic drive mechanism supplies a drive force to a plunger which is electromagnetically driven by the electromagnetic drive mechanism, another displacement force situates the plunger in a specific position. The constraints are converted into a Boolean expression. A connector is removably coupled to each of the shoulder straps to pull the shoulder straps toward each other.