A relief valve coupled to a container is disclosed. The relief valve may include a valve body forming an internal chamber, an inlet portion connected to the chamber and configured to receive content flow from the container, a spring, a poppet including a seat disc, wherein a spring force exerted by the spring biases the seat disc towards the inlet portion, and a cap configured to include a plurality of passages.

The present invention relates to an inflator mounted on protective equipment, comprising: a main body (100) having a cylindrical structure that is open at the top and bottom thereof, wherein the main body (100) has a key-ball insertion hole (110) and a gas supply hole (120) that are formed on portions of a lateral side thereof, and a bomb (600) for storing compressed air is coupled to the lower side of the main body (100); an eccentric lever (200) that is rotatably coupled to the upper opening of the main body (100) through a rotation shaft (230) and includes a lever (210) that adjusts a downward pressure by rotating an eccentric drum part (220) having the shape of a circular plate; a perforation part (300) that provides a restoring force downward according to the pressure state of the eccentric lever (200) and perforates the bomb (600) to allow the gas in the bomb (600) to be supplied to a user's protective equipment through the gas supply hole (120); and a key-ball (400) that confines the movement of the perforation part (300) while being inserted into the key-ball insertion hole (110) and separates from the key-ball insertion hole (110) according to the state of the outside to operate the perforation part (300).

Disclosed is a sensor for monitoring a composite structure. The sensor includes multiple sensing elements of different sizes, each configured for different respective monitoring tasks. Also disclosed are methods of fabricating the sensor, designing and manufacturing the sensor, and attaching the sensor to the composite structure.