Abstract: Disclosed is an optical communication line monitoring apparatus comprising: an optical transceiver for transmitting management frames to remote devices connected to optical communication lines and receiving response frames transmitted from the remote devices; an optical time domain reflectometer (OTDR) for transmitting optical pulse signals to the optical communication lines and detecting reflection signals reflected from the optical communication lines, which have received the optical pulse signals; an optical switch for switching the optical transceiver and the OTDR at an input terminal thereof and switching each of multiple optical communication lines at an output terminal thereof; and a monitoring unit for determining whether or not a first optical communication line is abnormal based on a response frame transmitted from a first remote device, with the input terminal connected to the optical transceiver and the output terminal connected to the first optical communication line among the multiple optical co

Abstract: An ethernet-based communication system is provided. The communication system comprises: a first unit configured to generate a reference clock signal by using an input first ethernet signal, multiplex the first ethernet signal and a second ethernet signal in response to the reference clock signal, and output the multiplexed ethernet signals; a second unit configured to generate the reference clock signal by using the multiplexed ethernet signals, separate the second ethernet signal from the multiplexed ethernet signals in response to the reference clock signal, and output the first ethernet signal; and a transmission medium for connecting the first and second units and transmitting the multiplexed ethernet signals from the first unit to the second unit.

Abstract: The present invention relates to a passive wavelength division multiplexing device for automatic wavelength locking and a system thereof including an optical multiplexer, an optical filter, an integrated optical receiver monitor, and a tunable optical transmitter. Through wavelength locking that adjusts a wavelength of an optical signal, which changes according to an external environment such as a temperature change, into a wavelength of an optical signal having the maximum optical intensity, communication quality may be maximized by securing a stable communication channel, a locking time and a communication channel setting time may be reduced, and more robust locking may be guaranteed.

Abstract: The present invention relates to a passive wavelength division multiplexing device for automatic wavelength locking and a system thereof including an optical multiplexer, an optical filter, an integrated optical receiver monitor, and a tunable optical transmitter. Through wavelength locking that adjusts a wavelength of an optical signal, which changes according to an external environment such as a temperature change, into a wavelength of an optical signal having the maximum optical intensity, communication quality may be maximized by securing a stable communication channel, a locking time and a communication channel setting time may be reduced, and more robust locking may be guaranteed.

Abstract: A controller system for a CD-ROM drive or other slow access device such as a magneto-optical device using a conventional hard disk drive as a cache memory. In some embodiments, the hard disk cache is partitioned to use a portion thereof to clone the most often used data blocks on the CD-ROM disk such as the directory/file allocation table, while the balance of the hard disk is used to cache some or all of the balance of the CD-ROM disk using conventional cache memory least recently used rules. Three bus controllers for the host computer, CD-ROM drive and the hard disk cache are controlled by a microprocessor which runs a control program that implements the cloning and cache rules. The three bus controllers are connected by a DMA bus for faster transfer of data. The microprocessor controls the directions of the DMA transfers by data written to a control register.