Abstract: Disclosed herein are an apparatus and method for converting a replication-based file into a parity-based file in an asymmetric clustering file system. The apparatus includes a reception unit, a control unit, a parity computation unit, and a chunk conversion unit. The reception unit receives a parity-based conversion request, information about the size of a stripe, and a list of new chunks from a metadata server. The control unit divides a replication chunk, selected from among a plurality of replication chunks corresponding to an original chunk of the replication-based file, into a plurality of data segments. The parity computation unit generates at least one parity segment by performing a parity operation on the plurality of data segments. The chunk conversion unit selects one of different data segments from the original chunk or one of the plurality of replication chunks, the different data segments having locations different from one another.

Abstract: Provided are an apparatus and a method for acquiring a consistent result even if one client accesses any metadata server in a circumstance that the cluster configuring many metadata servers exist. The apparatus as mentioned above includes a deletion file list unit that stores information about a deleted metadata during a predetermined period; and a metadata server selector that selects a metadata server to receive a operation request about a metadata among a plurality of metadata servers based on information from the deletion file list unit.

Abstract: A call connection method and apparatus in a communication system are provided, in which a call connection request message is received from each of first and second terminals, it is determined whether the first and second terminals are requesting a call connection to each other, one of the first and second terminals is selected if the first and second terminals are requesting a call connection to each other, the call connection request of the selected terminal is rejected, and a call is connected between the first and second terminals by performing a call connection to the selected terminal according to the call connection request of the non-selected terminal.

Abstract: Disclosed is a scaffold installed within a large structure such as a pressure vessel or a tank of a ship, and an insulation system construction method using the same. The scaffold for use in performing desired work within a large structure includes a supporting structure installed adjacent to both side surfaces and a top surface of the large structure, and a carrying unit installed movable along the supporting structure to allow materials to be carried or to provide a working space for a worker thereon, wherein the supporting structure is installed to be movable along a wall surface of the large structure.

Abstract: Disclosed is a scaffold installed within a large structure such as a pressure vessel or a tank of a ship, and an insulation system construction method using the same. The scaffold for use in performing desired work within a large structure includes a supporting structure installed adjacent to both side surfaces and a top surface of the large structure, and a carrying unit installed movable along the supporting structure to allow materials to be carried or to provide a working space for a worker thereon, wherein the supporting structure is installed to be movable along a wall surface of the large structure.

Abstract: Disclosed is a cloud storage managing a plurality of files, including: a plurality of metadata servers managing a plurality of metadata associated with the plurality of files; a plurality of data servers managing the data of the plurality of files; and a cluster management server managing the plurality of metadata servers and the plurality of data servers.

Abstract: Disclosed is a method of calculating parity. The method dividing, by a client system, a file which is to be stored into chunks of a preset size and distributively storing the chunks in a plurality of data servers; sending, by the client system, a data write complete notification message to a metadata server; storing, by the metadata server, a file sent through the data write complete notification message in a recovery queue; and sending, by the metadata server, a random data server a parity calculation request for the file stored in the recovery queue.

Abstract: Disclosed are an apparatus, a system, and a method for recovering meta data using fragmentary information. The system for recovering meta data includes: a data server storing recovery information for recovering at least one data file and meta data related to each of the data file; and a meta data server storing the meta data related to the data files and receiving the recovery information from the data server when the meta data are lost to recover the lost meta data. By this configuration, the exemplary embodiment of the present invention stably can the lost meta data of the meta data server by using the recovery the meta data and prevent the phenomenon that the meta data collides with each other on the same directory hierarchical structure.

Abstract: Provided is a hot data management method based on hit counter, which prevents loads from being concentrated on a specific data server due to hot data by efficiently managing the hot data in the asymmetric storage system. Each of data servers of an asymmetric storage system checks hit counter for data stored in the corresponding data server to maintain hit counter information on the data in a latest state. The data server transmits the hit counter information to a metadata server at predetermined intervals. The data server makes or deletes a copy of the data according to the determination of the metadata server whether the data is hot data.

Abstract: Provided is an apparatus for signal transmission in a Fast Frequency Hopping-Orthogonal Frequency Division Multiplexing (FFH-OFDM) communication system which divides all of the available frequency bands into a plurality of sub-carrier bands and includes a plurality of sub-channels each including at least one sub-carrier band.

Abstract: Provided are a file storage system, and a method for managing duplicate files in the file storage system. The file storage system that performs file duplication for error recovery includes a client for requesting generation of a duplicate file of a new file being stored, a metadata server for storing information associated with prestored duplicate files and determining whether a file that is identical to the new file is present among the prestored duplicate files, to limit a number of identical duplicate files to a preset number, and a data server comprising a file duplication unit and a storage unit for respectively performing file duplication and file storage under the control of the metadata server. Accordingly, file recovery can be performed while duplicate files in the system are minimized.

Abstract: Provided are a method and a system for managing a file metadata, which are independent of a address change of a data server and movements of a disk by using a location of disk where data exists actually as a location information of a file data. The method for managing the file metadata includes determining whether the request of the metadata is valid, verifying information of a disk storing a file data corresponding to the metadata and a data server address in which the file data exists, and transmitting the verified address of the data server to the client. According to the method and the system for managing the file metadata, data services can be continuously provided without modifications of a file metadata even if the data server address is changed.

Abstract: Provided is a system and method for updating a plurality of the same files consistently. The file update system comprises a first and a second data servers formed as pipe line type network for storing an original file and a duplicate file of the original file respectively, and for updating both the original file and the duplicate file in response to an update request, wherein the first and the second data servers mutually exchange file update information, correct the file update information so as to prevent overlapped update due to a plurality of update requests for the same file, and then update the original file or the duplicate file according to the corrected file update information.

Abstract: Provided are an apparatus and a method which can be easily implemented with flexibility enabling distributing all metadata of trees and files in an asymmetric distributed file system. The apparatus includes: a metadata storage unit storing metadata corresponding to a part of partitions of a virtual metadata address space storing metadata for directories and/or files for each of the partitions; and a metadata storage management unit controlling the metadata so that the metadata are stored in the metadata storage unit and manages a master map including information on the part of the partitions. Since all directories and files can be distributed to a plurality of metadata servers without a limitation, it is possible to prevent a load from being concentrated on a predetermined metadata server. Metadata roles of the metadata servers are very simply readjusted and as a result, the load can be easily distributed in a partition level.

Abstract: Provided are an apparatus and a method for acquiring a consistent result even if one client accesses any metadata server in a circumstance that the cluster configuring many metadata servers exist. The apparatus as mentioned above includes a deletion file list unit that stores information about a deleted metadata during a predetermined period; and a metadata server selector that selects a metadata server to receive a operation request about a metadata among a plurality of metadata servers based on information from the deletion file list unit.

Abstract: The present invention relates to an apparatus and method of performing an error recovery process in an asymmetric clustering file system that has higher efficiency in data recovery when a data server in an asymmetric clustering file system fails than a method of processing the data recovery in the metadata server. The present invention includes receiving a chunk list requiring recovery by a data server included in the other data server groups than a data server group including a failed data server among a plurality of data server groups, requesting chunk data necessary for recovering an erroneous chunk from a data server in the other data server groups to the other data servers than the failed data server in the data server group, and recovering the erroneous chunk based on the chunk data by the data server in the other data server group.

Abstract: An LNG storage tank comprises a heat insulating wall on an inner surface of the storage tank, a sealing wall contacting LNG on the heat insulating wall, and a structure to support the sealing wall. The structure comprises an anchor structure, which comprises an anchor member between the inner surface of the storage tank and the sealing wall to secure the sealing wall to the inner surface, and a heat-insulating material around the anchor member. The anchor member is coupled at several portions to the inner surface. The structure provides a simple configuration to the heat insulating wall and the sealing wall, and a simple connection therebetween, enabling convenient construction thereof while increasing sealing reliability. The structure simplifies an assembled structure and a manufacturing process, reducing a construction time of the tank while efficiently relieving stress on the tank.

Abstract: The present disclosure relates to a unit-wall structure for a liquefied gas storage tank on land, which enables rapid and easy construction of a cylindrical wall of the storage tank by stacking a plurality of pre-produced unit-wall structures to overlap one another. The unit-wall structure includes iron rods arranged lengthwise and breadthwise therein, wherein the unit-wall structure has an arc shape so that a plurality of unit-wall structures are stacked to form a cylindrical wall of the storage tank.

Abstract: The present disclosure relates to a method of constructing a liquefied gas storage tank on land, which enables rapid and easy construction of walls of a cylindrical storage tank by stacking a plurality of pre-produced unit-wall structures to be stacked or superposed with respect to one another. The method includes: producing unit-wall structures made of concrete and each having iron rods arranged lengthwise and breadthwise therein, stacking the unit-wall structures in a cylindrical arrangement, and connecting the unit-wall structures adjacent and in longitudinal and lateral directions with respect to each other to form a wall of the storage tank.

Abstract: An apparatus and method for Automatic Repeat reQuest (ARQ) in a Multi Input Multi Output (MIMO) system. The method includes computing weights of erroneous packets and weights of transmitting antennas by using channel information; sorting the weights of the erroneous packets in descending order; sorting the weights of the transmitting antennas in ascending order; and assigning the transmitting antennas to the erroneous packets according to sorting results.