Abstract: Disclosed is an inner shell for safety helmets, which is massproduced and has a structure capable of efficiently absorbing and dispersing an impact, and a method of producing the same, which ensures the reduced material costs and the improved workability and productivity. The inner shell (10) includes a liner member (12) having openings at upper and lower parts thereof, and an impact absorbing member (14) surrounding a circumference of the liner member (12). The method includes injection-molding a molten plastic resin into a predetermined shape of liner member (12), putting the molded liner member (12) in a metal mold, forming the impact absorbing member (14) using a foamed resin, including Styrofoam, a polyethylene foam, and a urethane foam, in the metal mold after the metal mold is hermetically sealed, separating the inner shell (10) from the metal mold, and finishing the inner shell (10).

Abstract: A backpack for back-mounting a compressed-air cylinder, fastened to the backpack by a cylinder fastening belt, when a user wears harnesses and a waist belt. The backpack inlcudes a backboard (100) having support hooks (105) to support the compressed-air cylinder (50); a harness support (130) for the harnesses (30) coupled to the backboard (100) so as to rotate upwards and downwards around the center; a waist protector (120) coupled to the backboard (100) in the back of the harness support (130) so as to cover and protect the back of the user's waist; and a rotary unit for rotatably supporting both the harness support (130) and the waist protector (120) on the backboard (100). The waist protector and the harness support move separately from the backboard by the rotary unit, thus allowing the user to work without stressed by the waist belt or the harnesses.