Abstract: A firearm detection system for inspecting whether a person passing through a gate positioned near a metal door is carrying a firearm is disclosed. The system comprises a door fixing device; a first sensor mounted on a doorframe to detect the entrance of a person into the door; a second sensor mounted on an entrance side of the gate to detect the entrance of the person into the gate; a third sensor mounted on an exit side of the gate to detect the exit of the person from the gate; and a microcomputer for controlling the operation of the door fixing device based on the detection results by the three sensors. The efficiency in use is maximized because a door fixing device operates to stop the movement of a door during the inspection procedure so as to prevent the generation of an electromagnetic field by the movement of the door made of similar material to the firearm, thereby preventing a false alarm signal from being generated by the movement of the door when a person carrying no firearm enters the gate.

Abstract: An object detecting apparatus for use in automobile is disclosed, and the apparatus includes ultrasonic wave transmitting and receiving units installed at a certain interval. Internally, the apparatus is provided with a single circuit which is capable of performing a functing of maintaining the safety distance with the car following behind during the normal running of the automobile, a function of detecting objects appearing behind during a reverse driving, and a function of making an exact close parking by reverse advancing. The circuit is divided into three sections: and ultrasonic wave transmitting section, a reflected wave receiving section, and a control device.