• Journal of the Korea Institute of Information Security & Cryptology
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• v.9 no.4
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• pp.23-36
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• 1999

As the blind signature(10) does not reveal any information about the message or its signature it has been used for preventing the information leakage and for providing the anonymity in secure electronic payment systems. Unfortunately this perfect anonymity could be misused by criminals as blind signatures prevent linking the withdrawal of money nd the payment made 표 the same customer. Therefore we should provide publicly verifiable mechanism if it is required for the judge to trace the blackmailed messages. In this paper we propose a modified blind signature scheme which additionally provides the role of message recovery after analyzing the existing meta-ELGamal scheme(12) suggested by Horster. And we suggest a new fair blind multi-signature scheme based on the oblivious transfer protocol with which a judge can publicly verify its fairness and correctness if needed. Proposed scheme can also applicable to the diverse electronic payment applications.

• Journal of Computing Science and Engineering
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• v.5 no.4
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• pp.324-330
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• 2011

To avoid collisions, IEEE 802.11 medium access control (MAC) uses predetermined inter-frame spaces and the random back-off process. However, the retransmission strategy of IEEE 802.11 MAC results in considerable time wastage. The hidden node problem is well known in wireless networks; it aggravates the consequences of time wastage for retransmission. Many collision prevention and recovery approaches have been proposed to solve the hidden node problem, but all of them have complex control overhead. In this paper, we propose a fast retransmission scheme as a recovery approach. The proposed scheme identifies collisions caused by hidden nodes and then allows retransmission without collision. Analysis and simulations show that the proposed scheme has greater throughput than request-to-send and clear-to-send (RTS/CTS) and a shorter average waiting time.

• Journal of Computing Science and Engineering
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• v.11 no.3
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• pp.92-99
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• 2017

Memcached, commonly used to speed up the data access in big-data and Internet-web applications, is a system software of the distributed-cache mechanism. But it is subject to the severe challenge of the loss of recently uncommitted updates in the case where the Memcached servers crash due to some reason. Although the replica scheme and the disk-log-based replay mechanism have been proposed to overcome this problem, they generate either the overhead of the replica synchronization or the persistent-storage overhead that is caused by flushing related logs. This paper proposes a scheme of backing up the write requests (i.e., set and add) on the Memcached client side, to reduce the overhead resulting from the making of disk-log records or performing the replica consistency. If the Memcached server fails, a timestamp-based recovery mechanism is then introduced to replay the write requests (buffered by relevant clients), for regaining the lost-data updates on the rebooted Memcached server, thereby meeting the data-consistency requirement. More importantly, compared with the mechanism of logging the write requests to the persistent storage of the master server and the server-replication scheme, the newly proposed approach of backing up the logs on the client side can greatly decrease the time overhead by up to 116.8% when processing the write workloads.

• The Transactions of the Korea Information Processing Society
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• v.7 no.8
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• pp.2497-2504
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• 2000

This paper is aimed at defining items of fault, and then constructing rules of fault diagnosis and recovery using INBANCA technology for the purpose of managing the weh server. The fault items of web server consist of the process fault, server overload, network interface fault, configuration and performance fault. Based on these items, the actual fault management is carried out fault referencing. In order to reference the fault, we have formulated the system-level fault diagnosis production rule and the service-level fault diagnosis rule, conjunction with translating management knowledge into active network. Also, adaptive recovery mechanism of web server is applied to defining recovery rule and constructing case library for case-based web server fault recovery. Finally, through the experiment, fault environment and applicability of each proposed production rule and recovering scheme are presented to verify justification of proposed diagnosis rules and recovery mechanism for fault management. An intelligent case-based fault management scheme proposed in this paper can minimize an effort of web master to remove fault incurred web administration and operation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7A
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• pp.1028-1035
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• 1999

To increase the throughput of data transmission in burst-mode TDMA communication systems and also to get a good BER performance at the same time, it is essential to rapidly acquire the carrier while keeping the desirable tracking performance. To achieve this goal, in this paper, a new decision-directed carrier recovery algorithm is presented. The proposed scheme does not incorporate the PLL and suppress the Gaussian random process of input noise by the pre-stage low pass filter so as to get both the fast acquisition and a good performance. Through computer simulations, the performance of the scheme is analyzed with respect to the acquisition time and bit error rate. The cycle slip in the proposed scheme is seldom observed at very low SNR environment in contrast to the previous proposed one. Because of this merit, it is not required to do the differential encoding and decoding in the proposed scheme.

• Journal of KIISE:Databases
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• v.28 no.3
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• pp.494-511
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• 2001

In the environment that database management systems manage disk spaces for storing databases directly, this paper proposes a correct and efficient scheme of performing pending actions for the removal of database files. As for performing pending actions, upon performing recovery, the recovery process must identify unperformed pending actions of not-yet-terminated transactions and then perform those actions completely. Making the recovery process identify those actions through the analysis of log records in the log file is the basic idea of this paper. This scheme, as an extension of the execution of transactions, fuzzy checkpoint, and recovery of ARIES, uses the following methods: First, to identify not-yet-terminated transactions during recovery, transactions perform pending actions after writing 'pa_start'log records that signify both the commit of transactions and the start of executing pending actions, and then write 'eng'log records. Second, to restore pending-actions-lists of not-yet-terminated transactions during recovery, each transaction records its pending-actions-list in 'pa_start'log record and the checkpoint process records pending-actions-lists of transactions that are decided to be committed in 'end_chkpt'log record. Third, to identify the next pending action to perform during recovery, whenever a page is updated during the execution of pending actions, transactions record the information that identifies the next pending action to perform in the log record that has the redo information against the page.

• Journal of the Korea Society of Computer and Information
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• v.6 no.2
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• pp.27-33
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• 2001

In this thesis, we present a simple and efficient recovery method, called ARIES/SR(ARIES/Selective Redo) which is based on ARIES(Algorithm for Recovery and Isolation Exploiting Semantics) ARIES performs redo for all updates done by either nonloser transaction or loser transaction, and thus significant overhead appears during restart after a system failure. To reduce this overhead, we propose ARIES/SR recovery algorithm. In this algorithm, to reduce the redo operations, redo is performed, using log record for updates done by only nonloser transaction. Also selective undo is performed. using log record for update done by only loser transaction for reducing recovery operation.

• The KIPS Transactions:PartA
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• v.13A no.7 s.104
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• pp.607-614
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• 2006

The checkpointing schemes should reduce the process delay through managing the checkpoints of each node to fit the network load to enhance the performance of the process running on the cluster system that write the checkpoints into its global stable storage. For this reason, a cluster system with single IO space on a distributed RAID chooses a suitable checkpointng scheme to get the maximum IO performance and the best rollback recovery efficiency. In this paper, we improved the striped checkpointing scheme with dynamic stripe group size by adapting to the network bandwidth variation at the point of checkpointing. To analyze the performance of the multi striped checkpointing scheme, we applied Linpack HPC benchmark with MPI on our own cluster system with maximum 512 virtual nodes. The benchmark results showed that the multistriped checkpointing scheme has better performance than the striped checkpointing scheme on the checkpoint writing efficiency and rollback recovery at heavy system load.

• Journal of KIISE:Information Networking
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• v.30 no.3
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• pp.448-460
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• 2003

In this paper, we propose a network fault recovery algorithm based on a segment restoration scheme to reduce restoration time and restoration resource. The proposed segment restoration scheme is based on network partitioning which divides a large network into several small subnetworks. The restoration performance of the proposed segment restoration scheme depends on the size and the topology of subnetworks. Since most faults can be restored in a subnetwork, restoration time is reduced obviously. We compare and analyze restoration performance according to the size of subnetworks and restoration schemes. From simulation results, the proposed segment restoration scheme has the shortest restoration time compared with other restoration schemes. Especially the restoration performance of the proposed segment restoration scheme is better than the SLSP, which is also a segment-based restoration scheme, in terms of restoration time and required restoration resource capacity.

• Journal of Digital Convergence
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• v.20 no.3
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• pp.377-388
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• 2022

Various researches are actively studied to satisfy exponentially increasing the usage of the Internet as well as the diverse service demands. Especially the Optical Internet that delivers several Tbps through a single optical fiber requires the intelligence to satisfy the various types of survivability requirements. In the paper, a novel recovery scheme that satisfies the various restoration demands in IP over WDM networks is proposed. The scheme classifies the restoration services into three classes and applies dedicated protection and shared restoration scheme with different priorities for each class. Also, a configuration scheme for information database to support the scheme is proposed. This scheme satisfies the different degree of restoration demands in terms of restoration time, blocking rate and resource usage. With the scheme, medical data can be transmitted without loss.