Abstract: Disclosed herein is a fastening structure which enables objects to be easily coupled to or removed from each other, and which enables the relative positions between the objects to be changed in the longitudinal position of zipper rails. The fastening structure includes a first zipper rail unit which is provided on a planar portion of a first object and has zipper rails arranged parallel to each other, and a second zipper rail unit which is provided on a planar portion of a second object and has zipper rails arranged parallel to each other. While the zipper rails of the first zipper rail unit are individually coupled to the corresponding zipper rails of the second zipper rail unit in a female-male engagement manner, relative positions between the first object and the second object can be changed in the longitudinal direction of the zipper rails.

Abstract: Disclosed herein is a fastening structure which enables objects to be easily coupled to or removed from each other, and which enables the relative positions between the objects to be changed in the longitudinal position of zipper rails. The fastening structure includes a first zipper rail unit which is provided on a planar portion of a first object and has zipper rails arranged parallel to each other, and a second zipper rail unit which is provided on a planar portion of a second object and has zipper rails arranged parallel to each other. While the zipper rails of the first zipper rail unit are individually coupled to the corresponding zipper rails of the second zipper rail unit in a female-male engagement manner, relative positions between the first object and the second object can be changed in the longitudinal direction of the zipper rails.

Abstract: A circuit for converting a voice coding mode of a basic rate interfacing (BRI) card in an ISDN (Integrated Service Digital Network) keyphone system according to a voice coding mode of an office exchange. A PCM (Pulse Code Modulation) coding conversion circuit between an ISDN keyphone system and an office exchange, including an A/&mgr;-Law converter for converting the voice coding mode of the PCM data output from the ISDN keyphone system to an A-Law voice coding mode or a &mgr;-Law voice coding mode according to a coding mode of the office exchange and for converting the voice coding mode of the PCM data input to the ISDN keyphone system to an A-Law voice coding mode or a &mgr;-Law voice coding mode according to a coding mode of the ISDN or keyphone system, in response to a control signal output from a central processing unit so that a voice coding mode of the office exchange is matched to a voice coding mode of the ISDN keyphone system.

Abstract: A circuit for preventing data stored in a memory of a telephone system from being corrupted including: a memory for receiving a plurality of control signals from the processor and for storing received data; a decoder connected to a chip enable terminal of the memory, for receiving a plurality of control signals from the processor and for generating a memory enable signal during a normal operation voltage range of the processor, and for placing the memory in an inactive state by supplying a disabling signal to the chip enable terminal of the memory during an abnormal operation voltage range of the processor; a voltage sensing circuit, connected to a chip enable terminal of the decoder, for generating a high level during the normal operation voltage range of the processor, and for generating a low level during the abnormal operation voltage range of the processor for controlling the decoder; and a battery power source supplier for supplying power to the memory and the decoder.