Abstract: Disclosed is a bi-directional optical add/drop multiplexer connected to an optical fiber for transmitting optical signals multiplexed in a wavelength division multiplexing optical network and which performs adding/dropping of the optical signals. The optical add/drop multiplexer includes a first wavelength division multiplexer provided with a multiplexing port functioning as a path for forward or backward optical signals and with a plurality of demultiplexing ports, each functioning as a path of demultiplexed channels. A plurality of add/drop parts, each performing adding/dropping of preset channels, and connected with the demultiplexing ports of the first wavelength division multiplexer in one-to-one. A second wavelength division multiplexer connected with the plurality of add/drop parts in one-to-one, provided with a plurality of demultiplexing ports, each functioning as a path for demultiplexed channels and with a multiplexing port functioning as a path for forward or backward optical signals.

Abstract: A passive optical network (PON) for providing a large amount of data at high speed to subscribers is provided. In particular, a PON employing a multi-carrier CDMA in which a CDMA method is applied for an upstream signal is provided. The PON employing a multi-carrier CDMA includes: optical network terminals (ONTs) for transmitting CDMA-based data using multiple carriers to an optical line terminal (OLT) and for receiving Ethernet-based data transmitted from the OLT; the OLT for transforming CDMA-based data received from the ONT into Ethernet-based data, for transmitting the Ethernet-based data to a higher network, and for transmitting Ethernet-based date to the ONTs; and an optical coupler for coupling CDMA-based optical signals transmitted from the ONTs, for transmitting the coupled optical signal to the OLT, and for distributing an Ethernet-based optical signal transmitted from the OLT to the ONTs.

Abstract: A refrigerating system for a refrigerator is disclosed. The refrigerator includes a compressor that compresses refrigerant, a condenser connected to the compressor that condenses compressed refrigerant, an expansion valve connected to the condenser that expands condensed refrigerant, freezing chamber and refrigerating chamber evaporators connected to the expansion valve that cool air in a freezing chamber and a refrigerating chamber by using refrigerant, respectively, and a regulating valve between the condenser and the refrigerating chamber evaporator that regulates refrigerant supply to the refrigerating chamber evaporator, thereby providing a refrigerating system for a refrigerator having high efficiency.

Abstract: A passive optical network includes a central office and a subscriber-side apparatus connected with the central office through an optical fiber link. The subscriber-side apparatus performs communication with the central office based on wavelength-division-multiplexed optical signals. The central office has a routing section, provided with first to fourth multiplexing ports, for demultiplexing multi-wavelength light inputted from the fourth multiplexing port into a plurality of channels. Each of the demultiplexed channels is amplified and multiplexed for output through the first multiplexing port. Optical signals inputted through the third multiplexing port are demultiplexed and outputted upstream. The routing section also multiplexes channels for downstream optical signals, outputting the multiplexed channels through the second port. A splitting section, provided with first to third splitting ports and arranged on a loop optical waveguide connects the first and fourth multiplexing port with each other.

Abstract: A multi-wavelength light source unit for optical communication system is disclosed. The light source includes a demultiplexer for demultiplexing a multiplexed light signal into a plurality of lights having different wavelengths and a multiplexer that receives the demultiplexed lights and multiplexes the demultiplexed lights into the multiplexed light signal. Input ports of the multiplexer are respectively port-to-port connectable to each one of a plurality of output ports of the demultiplexer. The light source unit includes a plurality of semiconductor optical amplifiers amplifying the demultiplexed lights output form the demultiplexer, and a plurality of beam splitters for splitting the amplified demultiplexed lights into two parts, so as to provide the respective input ports of the multiplexer with a split part of the lights, while to transmit the other part of the lights out of the beam splitters.

Abstract: A wavelength-path-monitoring/correcting apparatus used in a transparent OXC is disclosed. The apparatus includes: a path-information-generating section for generating path-monitoring information; a plurality of optical couplers for coupling each output signal of the wavelength-division demultiplexers with the pertinent path-monitoring information; a plurality of optical switches for switching each optical signal inputted from the optical couplers; a plurality of wavelength-division multiplexers for multiplexing optical signals inputted through the optical switches; a path-information-detecting section for detecting the path-monitoring information from optical signals outputted from the wavelength-division multiplexers; and, a path-control section for comparing the path-monitoring information detected through the path-information-detecting section with predetermined optical-switching information and for correcting switched paths.

Abstract: A wideband erbium-doped optical fiber amplifier is disposed among an optical fiber through which a first and second band-band optical signals (for example, the C-band and L-band) are transmitted and forms a first optical path and a second optical path parallel to each other. The wideband erbium-doped optical fiber amplifier comprising a first amplifying section disposed on the first optical path, including a first erbium-doped optical fiber to amplify the first-band optical signals, a filter to gain-flatten the amplified first-band optical signals, wherein a reflected portion of the first band optical signal by the filter is directed to the second optical path; and a second amplifying section disposed on the second optical path, having a second erbium-doped optical fiber to amplify received second-band optical signals, wherein the reflected first-band optical signal is used to pump the second erbium-doped optical fiber.

Abstract: A bidirectional WDM self-healing ring network is provided and includes an outer ring network and an inner network for processing N units of optical signals and for performing a protection switching by using the outer ring network when the inner ring network suffers a link failure.

Abstract: A WDM bidirectional self-healing optical ring network is provided in which an outer ring network and an inner ring network can both handle N optical signals. The network includes a node; an optical add/drop multiplexer having a 1×N demultiplexer and a 1×N multiplexer; a pair of optical switching devices each connected to an optical fiber link intervening between the optical add/drop multiplexer and another node on the both ends of the optical add/drop multiplexer; and, a pair of circulators each connected between the optical add/drop multiplexer and a particular optical switching device in the optical switching device pair, each circulator having three ports, two of the three ports being connected to a corresponding optical switching device and remaining one port being connected to the optical add/drop multiplexer.

Abstract: An optical switching device has a plurality of input ports, and a plurality of output ports, that uses only circulators and reflectors to perform optical switching. A plurality of circulators each having a plurality of ports while operating to output an optical signal are input to a higher-order port thereof, to a lower-order port thereof arranged adjacent to the higher-order port. Each of the circulators being connected at a highest-order port thereof to an associated one of the input ports, at a lowest-order port thereof to an associated one of the output ports, and at each intermediate port thereof to a corresponding intermediate port of another one of the circulators. A plurality of reflectors each of which is adapted to reflect an optical signal, inputted thereto, or to allow the optical signal to pass there through. Each of the reflectors being connected between two intermediate ports of every two of the circulators connected to each other at the two intermediate ports.

Abstract: Transmitting data in a synchronous Ethernet passive optical network employs a synchronous Ethernet for ensuring QoS during transmission of multi-media data, thereby specifying transmission of synchronous data and asynchronous data, respectively. The Ethernet passive optical network has an optical line terminal, which is a central base station, and a plurality of optical network units. The method includes the steps of forming a synchronous frame using the OLT to transmit synchronous data for the ONUs, forming an asynchronous frame using the OLT to transmit asynchronous data for the ONUs, forming a super frame including the synchronous and asynchronous frames using the OLT, and transmitting the super frame using the OLT.

Abstract: Disclosed is a method of managing a Motion Picture Expert Group-2 Transport Stream (MPEG-2 TS) in an object unit of an MPEG-4 by efficiently matching the MPEG-4 with the MPEG-2 TS, in order to broadcast an internet protocol (IP). The method manages MPEG-4 object information in an MPEG-2 TS status, by adding the object information to a program map table (PMT) in the course of converting an MPEG-4 data into an MPEG-2 TS. The method includes the steps of: a) receiving an MPEG-4 SL (Sync Layer) to be transmitted as an MPEG-2 TS; b) acquiring an object information from the MPEG-4 SL; c) aligning the acquired object information corresponding to a program map table (PMT) of the MPEG-2 TS; and d) creating an MPEG-2 TS which has the PMT corresponding to the object information.

Abstract: A method of configuring system layers for a synchronous Ethernet is provided. In the method, a physical layer takes charge of input and output of an Ethernet frame in direct relation to hardware, an xMII (x Media Independent Interface) layer connects the physical layer to a data link layer. The data link layer has a sync frame processor for processing a synchronous frame and an async frame processor for processing an asynchronous frame. A parser and multiplexer (MUX), included in the x MII layer, construct a super frame with a synchronous frame and an asynchronous frame, transmit the super frame through the physical layer, parse a received super frame into a synchronous frame and an asynchronous frame, and transmit the synchronous and asynchronous frames to the data link layer.

Abstract: A method of enabling transmission of a time-critical control signal event in a sync frame period, such as a pause signal that is generated when the receive buffer of an Ethernet switch is filled with packets beyond a threshold due to congestion of uplink asynchronous data, is disclosed. To transmit time-critical information in a synchronous Ethernet system, a current transmission period is checked upon detection of a time-critical event. If the current transmission period is a sync frame period, time-critical control information is generated, inserted into the first sub-sync frame after the time-critical event, and transmitted. If the current transmission period is an async frame period, a control frame including the time-critical control information is generated and transmitted.

Abstract: Disclosed is a method for establishing a synchronization in a synchronous Ethernet system. Devices are classified according to the type of the devices, and a device having a highest class in the synchronous Ethernet system is detected, then it is determined if the device having the highest class is able to serve as the timing master. If so, the device having the highest class is able to serve as the timing master if only one such device is detected; otherwise, the timing master between devices having the highest class is selected through a collision algorithm.

Abstract: Disclosed is a method for estimating an available bandwidth of a network. A plurality of periodic time-stamp packets are transmitted to a receiving-party communication apparatus, which is connected to the network, through the network at a currently-set test transmission rate, and then a changing tendency of transmission delay time differences between the time-stamp packets is checked on the basis of reception times at which the receiving-party communication apparatus have received the respective time-stamp packets. When the transmission delay time differences are located outside a stable range and show a tendency to increase, the test transmission rate is set to a decreased value and the time-stamp packets are repeatedly transmitted at the decreased rate and when the transmission delay time differences are located outside the stable range and show a tendency to decrease, the test transmission rate is set to be an increased value and the time-stamp packets are repeatedly transmitted at the increased rate.

Abstract: An optical add/drop multiplexer includes a multiplexing/demultiplexing unit having an input multiplexing port, an output multiplexing port and a plurality of demultiplexing ports each connected to a respective optical circulator. Each optical circulator includes a first port for internally inputting an added channel, a second port for outputting the added channel to a corresponding demultiplexing port and receiving a channel outputted by the corresponding demultiplexing port, and a third port for outputting the channel received from the second port.

Abstract: There is disclosed an optical source generator for wavelength division multiplexing optical communication systems.

Abstract: An optical cross-connect system is disclosed that use reduces the number of AWGs (Arrayed-Waveguide Grating) as compared to prior art systems so that the hardware complexity is reduced while simultaneously reducing its production costs. The optical cross-connect system includes N×N AWGs for performing multiplexing/demultiplexing functions, an optical circulator for transmitting bidirectional signals via the AWGs, an optical coupler for interconnecting N individual ports of the AWGs, and an optical switching block connected to the optical coupler. One of the optical signals branched from the optical coupler is input to the optical switching block having a corresponding wavelength and distributed to a desired output terminal, and the other one of the optical signals is input to an optical switching block being out of an operable wavelength range and filtered by the optical switching block.

Abstract: Disclosed is an optical add/drop multiplexer connected to an optical fiber for transmission of a multiplexed optical signal, and adapted to add a channel to the optical signal or to drop a channel from the optical signal. The optical add/drop multiplexer includes a wavelength division multiplexing/demultiplexing (WDM) unit connected to the optical fiber, having input and output ports providing a path for a multiplexed optical signal, and a plurality of demultiplexing ports respectively providing paths for demultiplexed channels. A plurality of add/drop multiplexer (ADM) units respectively connected to the demultiplexing ports of the WDM unit, each of the ADM units including first and second circulators each adapted to output a channel, input to a higher-order port thereof, to a lower-order port, and a reflector for passing or reflecting a channel inputted thereto. The first circulator receives a channel at a second port and outputs the channel to a third port connected to the reflector.