Abstract: A public key cryptosystem is used for the authentication of a personal station (PS) which subscribes for a plurality of radio communication exchange systems. A public key of PS is registered into a public key DB of a public key management device. A private key is registered into PS. When PS moves into a service area of a certain radio communication exchange system, an exchange in that radio communication exchange system requests the public key management device for a public key of PS and makes a check for authentication of PS based on the public key cryptosystem by use of the received public key. Thereafter, when PS moves into a service area of another radio communication exchange system, an exchange in the other radio communication exchange system similarly requests the public key management device for a public key of PS and receives the same public key.

Abstract: A hydraulic drive system for the pitch cylinders (4A, 4B) of a bulldozer blade apparatus can include (a) main hydraulic pumps (30A, 30B) and an assistant hydraulic pump (31) to make up the assistant hydraulic circuit, (b) variable displacement hydraulic pumps (21A, 21B), or (c) fixed displacement hydraulic pumps (30A, 30B) and a plurality of solenoid selector valves such that the pitch cylinders can be connected in series. The assistant hydraulic pump (31) is connectable to delivery lines of the main hydraulic pumps through an assistant solenoid selector valve (32) which is controlled by an external signal. The blade (10) can be formed so that a line (14) tangential to the lower edge of the curved panel of the blade is inclined rearwardly with respect to the front face (13) of the blade edge member (12). Earth-moving work can be performed by inclining the blade (10) rearwardly by an angle (.theta..sub.

Abstract: A hydraulic drive system for the pitch cylinders (4A, 4B) of a bulldozer blade apparatus can include (a) main hydraulic pumps (30A, 30B) and an assistant hydraulic pump (31) to make up the assistant hydraulic circuit, (b) variable displacement hydraulic pumps (21A, 21B), or (c) fixed displacement hydraulic pumps (30A, 30B) and a plurality of solenoid selector valves such that the pitch cylinders can be connected in series. The assistant hydraulic pump (31) is connectable to delivery lines of the main hydraulic pumps through an assistant solenoid selector valve (32) which is controlled by an external signal. The blade (10) can be formed so that a line (14) tangential to the lower edge of the curved panel of the blade is inclined rearwardly with respect to the front face (13) of the blade edge member (12). Earth-moving work can be performed by inclining the blade (10) rearwardly by an angle (.theta..sub.

Abstract: A method of manufacturing a semiconductor device according to the present invention includes a process of introducing impurities into a semiconductor layer with a gate electrode and a resist film as a mask after a resist film is formed on the top and the side of the gate electrode by soaking the gate electrode on a semiconductor layer in an electrolyte containing resist and applying voltage to the gate electrode.

Abstract: An impact ripper (2) mounted on the rear portion of a construction machine, such as a bulldozer (1), for digging a hard soil layer is automatically controlled to reduce the operator's fatigue, to improve operability with regard to the posture of the impact ripper during operation of its vibrating mechanism (3), and to prevent breakdown of the impact ripper caused by wasteful striking. A vehicle tractive force and a vehicle speed required by digging resistance applied to a blade end (2a) of the impact ripper (2) are detected and signals obtained from the detections are inputted to a controller (4). When an automatic strike switch is on, an activating signal is outputted from the controller (4) to the vibrating mechanism (3) of the impact ripper (2) regardless of a vehicle body tractive force when a vehicle speed is less than a predetermined value.

Abstract: A direct driven shock ripper device according to the present invention is capable of efficiently transferring blows of a hydraulic breaker (10) to a base rock. It includes a bracket (2) which can be affixed to the rear end of a construction machine vehicle, a beam (4) on which a shank (8) and a breaker mount bracket (9) supporting the hydraulic breaker (10) are mounted, the beam (4) being disposed to the rear of the bracket (2), an arm (6) which couples a lower portion of the bracket (2) to a lower portion of the beam (4), a tilt cylinder (5) which couples an upper portion of the bracket (2) to an upper portion of the beam (4), and a lift cylinder (16) which couples an upper portion of the bracket (2) to a lower portion of the beam (4). A pair of link members (7) are provided between the beam (4) and the shank (8) to pivotally support the shank (8) on the beam (4) and thereby form a quadric linkage.