Abstract: According to an embodiment of the present invention, an emergency core cooling system (ECCS) valve provided between a reactor vessel of a system-integrated modular advanced reactor (SMART) and a small containment vessel formed to surround the reactor vessel so that a coolant is filled in a space between the reactor vessel and the small containment vessel in the event of a loss of coolant accident (LOCA) includes an outer shell connected to the reactor vessel and formed to protrude toward the small containment vessel and having a connector formed therein so as to communicatively connect an inside of the reactor vessel to an inside of the small containment vessel, an inner shell provided inside the outer shell at a preset distance from an inner wall of the outer shell, a piston movably constrained and inserted through a piston opening formed in the inner shell at a position facing the connector of the outer shell to open and close the connector, and a spring provided on an outer circumferential surface of the p

Abstract: Provided are a method of low-complexity decoding based on soft decision and a computing device for performing the method. The method of low-complexity decoding based on soft decision, performed by a computing device, includes receiving a vector, in which a codeword is modulated, through a channel, determining a decoding result by sequentially applying the received vector to one or more decoding algorithms, and decoding the codeword based on an analysis on the decoding result of a detector corresponding to each of the one or more decoding algorithms.

Abstract: An optical transmitter, an optical receiver, a method of operating the optical transmitter, and a method of operating the optical receiver are provided. The optical transmitter includes a light source configured to output laser light, an intensity modulator configured to provide a pulse signal with a predetermined period using the laser light, an in-phase and quadrature (I/Q) modulator configured to generate a coherent modulated signal applying an I/Q signal to the pulse signal with the predetermined period, and a polarization controller configured to delay one of polarization components forming the coherent modulated signal.

Abstract: Provided are a method and an apparatus for optimizing the performance of an optical transceiver, and the gist is as follows: receiving an optical input and converting the optical input into electrical signals; receiving a performance value and a reference clock of the electrical signals from a DSP part; generating a plurality of clocks by using the reference clock; determining ADC sampling timings of a plurality of ADCs on the basis of phases of the plurality of clocks applied to the plurality of ADCs; and compensating, on the basis of the determined ADC sampling timings, for differences in physical length between output signals of the plurality of ADCs.

Abstract: Provided are a method and apparatus for registering a new terminal using chromatic dispersion distance estimation. The method of registering a new terminal, performed by a transport unit (TU), includes performing frame synchronization through a downstream packet received from a transport node (TN), identifying a position of a frequency of a spectral null and a number of frequencies of spectral nulls through analysis on a frequency spectrum of the received downstream packet, estimating a transmission distance of an optical fiber to the TN, based on the identified position of the frequency of the spectral null and the identified number of frequencies of spectral nulls, and determining a timing of transmitting a registration request message, based on the estimated transmission distance, where the discovery information message is received from the TN.

Abstract: Disclosed herein is an optical transmitter for generating a vestigial sideband (VSB) optical signal. The optical transmitter includes: a modulator configured based on a photonic integrated chip (PIC); an optical fiber block; and a lensed thin film filter implemented between the modulator configured based on the PIC and the optical fiber block. The PIC includes at least one grating coupler, and the lensed thin film filter is disposed so that an angle of an optical signal emitted from a first grating coupler of the PIC coincides with an angle of incident (AOI) of the lensed thin film filter to design the first grating coupler and the lensed thin film filter.

Abstract: Provided are an apparatus and method for parallel Reed-Solomon (RS) encoding. A parallel RS encoding apparatus includes a coefficient generator configured to calculate a parity symbol matrix and group coefficients of each row or each column of the parity symbol matrix to correspond to the number of parallel paths, a data delayer configured to delay a parallel input information symbol block including symbols of the number of parallel paths so that calculation of a parity symbol is processed in order, a parity symbol calculator configured to calculate, based on the grouped coefficients outputted from the coefficient generator and the parallel input information symbol block delayed by the data delayer, the parity symbol, and a parallel outputter configured to output a codeword generated based on the parity symbol outputted from the parity symbol calculator and the parallel input information symbol block delayed by the data delayer.

Abstract: A deinterleaving method and a deinterleaving system performing the same are disclosed. According to an example embodiment, a data processing method includes dividing data into first data blocks of a first number of bits, performing deinterleaving on the first data blocks, and dividing deinterleaved data into second data blocks of a second number of bits and outputting the second data blocks, wherein the first number of bits is determined based on a minimum switching unit of a deinterleaving operation and the second number of bits.

Abstract: A deinterleaving method and a deinterleaving system performing the same are disclosed. According to an example embodiment, a data processing method includes dividing data into first data blocks of a first number of bits, performing deinterleaving on the first data blocks, and dividing deinterleaved data into second data blocks of a second number of bits and outputting the second data blocks, wherein the first number of bits is determined based on a minimum switching unit of a deinterleaving operation and the second number of bits.

Abstract: An optical transmission method for processing a signal based on direct detection includes setting, by an equalizer, an adaptive equalization coefficient by performing an equalization process during a training symbol field section in a frame of a received signal, performing, by a channel estimator, channel estimation to perform an equalization process of a soft output maximum likelihood sequence equalizer (MLSE) during the training symbol field section, driving the soft output MLSE, and compensating for, by the soft output MLSE, distortion of the received signal during a data symbol field section in the frame on the basis of the adaptive equalization coefficient and an estimated result value of a channel, and recovering, by an error corrector which allows soft-decision processing to be performed, the received signal by performing error correction on the received signal in which the distortion is compensated for.

Abstract: An optical transmission method for processing a signal based on direct detection includes setting, by an equalizer, an adaptive equalization coefficient by performing an equalization process during a training symbol field section in a frame of a received signal, performing, by a channel estimator, channel estimation to perform an equalization process of a soft output maximum likelihood sequence equalizer (MLSE) during the training symbol field section, driving the soft output MLSE, and compensating for, by the soft output MLSE, distortion of the received signal during a data symbol field section in the frame on the basis of the adaptive equalization coefficient and an estimated result value of a channel, and recovering, by an error corrector which allows soft-decision processing to be performed, the received signal by performing error correction on the received signal in which the distortion is compensated for.

Abstract: A method and apparatus for estimating a burst error. A burst error estimation method includes measuring a frequency of a spectrum null for an optical signal received through an optical receiver; determining whether the measured frequency of the spectrum null corresponds to an intermediate frequency of a baud rate; and estimating that a burst error occurrence condition is met when the frequency of the spectrum null is determined to correspond to the intermediate frequency of the baud rate.

Abstract: A method and apparatus for compensation of a chromatic dispersion through an optical compensation and an electronical compensation in optical communication. An optical communication method receives an optical signal, estimates a first transmission length based on a null component included in a frequency spectrum of the optical signal, optically compensates for a chromatic dispersion of the optical signal based on the first transmission length, estimates a second transmission length based on a null component included in a frequency spectrum of the compensated optical signal, and electronically compensates for a residual chromatic dispersion of the compensated optical signal based on the second transmission length.

Abstract: A method and apparatus for compensation of a chromatic dispersion through an optical compensation and an electronical compensation in optical communication. An optical communication method receives an optical signal, estimates a first transmission length based on a null component included in a frequency spectrum of the optical signal, optically compensates for a chromatic dispersion of the optical signal based on the first transmission length, estimates a second transmission length based on a null component included in a frequency spectrum of the compensated optical signal, and electronically compensates for a residual chromatic dispersion of the compensated optical signal based on the second transmission length.

Abstract: Disclosed is an optical receiver and an error correction method performed by the optical receiver, receiving, using a receiving antenna or a photodetector, a training signal in which an error occurs due to noise and distortion while being output from an optical transmitter and transmitted through a communication channel and identifying a hyperplane for classifying a probability that the received training signal is a training signal corresponding to a training signal output from the optical signal using a support vector machine (SVM) and learning a parameter of the identified hyperplane such that a classification error probability is minimized when the probability is extracted using the identified hyperplane, wherein the parameter of the identified hyperplane is used to correct an error occurring while a transmission signal output from the optical signal is received using the receiving antenna or the photodetector.

Abstract: An optical receiver and a method of controlling the optical receiver. The method may include setting, by a controller, a dispersion value of a dispersion compensator to compensate for a dispersion of an optical signal received through an optical fiber, compensating, by the dispersion compensator, for the dispersion of the optical signal based on the set dispersion value, performing, by the controller, an error correction with respect to the optical signal of which the dispersion is compensated and verifying a number of bit errors, and resetting, by the controller, the dispersion value of the dispersion compensator based on the verified number of bit errors.

Abstract: An apparatus and method for driving an optical source for an optical fiber link monitoring apparatus. The apparatus for driving an optical source for an optical fiber link monitoring apparatus includes a laser part configured to output probe light that corresponds to a bipolar code probe signal; an optical receiver configured to convert reflected light, which has travelled back from an optical fiber link after transmission of the bipolar probe light, into an electrical signal; and a direct-current (DC) canceller configured to remove a DC offset component from the electrical signal generated by the optical receiver.

Abstract: Disclosed is an optical fiber cable monitoring apparatus using a dual light source. The optical fiber cable monitoring apparatus includes: an optical transmitter configured to comprise a first light source and a second light source, which output light of different wavelengths, and to operate the first light source and the second light source to propagate first probe light and second probe light to an optical fiber cable; and an optical receiver configured to comprise a first light receiving module and a second light receiving module, each receiving first reflected light and second reflected light which are reflected from the optical fiber cable.

Abstract: An optical fiber link monitoring apparatus for detecting a failure in an optical fiber link by analyzing a trace of a received signal that has been transmitted to and reflected from said optical fiber link. The optical fiber link monitoring apparatus includes a variable gain amplifier (VGA), an analog/digital converter (ADC), and a controller. The VGA amplifies a gain of the received signal, for which the ADC converts the gain-amplified signal into a digital signal. The controller then analyzes a digital signal trace and adjusts the gain of the VGA according to the analysis result.

Abstract: A method for transmitting an orthogonal frequency division multiplexing (OFDM) signal in an optical network and apparatus therefor are provided. The method includes: converting a media access control (MAC) frame into an OFDM frame that contains a physical (PHY) level preamble, using the MAC frame which is transmitted from a MAC layer in a passive optical network (PON) to a PHY layer in an OFDM-PON; and transmitting the generated OFDM frame.