• The Journal of the Korea Contents Association
• /
• v.7 no.9
• /
• pp.89-99
• /
• 2007

With the development of the internet technology, network application services based on a large number of network nodes have been focused. However, such application services require much larger network size and traffic than current network. In order to develop them, efficient solutions as well as a simple improvement of network infra processing time are required. In this paper, to contribute a improvement of network computing technology, we design and implement the agent platform software based on the agent technology that performs works independently and asynchronously on a network and platform. The proposed agent platform software supports the scalability to accommodate the number of network hosts with rapid growth, the adaptability on a variable environments, and the availability for a fault-tolerance.

• Journal of KIISE:Computing Practices and Letters
• /
• v.14 no.5
• /
• pp.512-516
• /
• 2008

A conference-key agreement protocol is essential for computer network conferences that need secure communications. Especially, the fault-tolerant conference-key agreement can make a shared conference-key even if some make conferees disturb the key agreement processes. However, the performance of the previous fault-tolerant conference-key agreement protocols is decreasing significantly when the number of fake conferees is increasing. In this paper, we propose an efficient fault-tolerant conference key agreement protocol. Our scheme is based on the ID-based one round tripartite conference key agreement protocol. Simulation results show our scheme's efficiency against Yi's method especially when the number of fake conferees is large.

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

• The Transactions of the Korea Information Processing Society
• /
• v.7 no.9
• /
• pp.2969-2979
• /
• 2000

A mobile host has failure causes such as failure of the mobile host, disconnection of the mobile host, and wireless link failure that have not been seen in traditional computing environments. So far there have been few studies on fault tolerance of a mobile host in mobile computing environments. The Lazy scheme, a failure recovery technique of the mobile host, is a cost-effective one. However, this scheme has a defect that the mobile host cannot be recovered from failure of the base station with acheckpoint of the mobile host. In this paper, we propose and evaluate the Redundant Lazy scheme for performance improvement of the Lazy scheme.

• Journal of KIISE:Computer Systems and Theory
• /
• v.27 no.1
• /
• pp.53-60
• /
• 2000

The purpose of this paper is to propose new recovery algorithm for case of a system element raises communication obstacle due to faults in networks, Also we are simulate the algorithm using adjacency matrix. We recover one faulty node per each excution of proposed algorithm so that we can be reconstruct the faulty system gradually to communicatable network. For that, this paper propose a new recovery algorithm named MATRECO which connect the recovery process is simulated by use of adjacency matrix.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.1B
• /
• pp.13-23
• /
• 2002

A mobile host is prone to failure due to lack of stable storage, low bandwidth of wireless channel, high mobility, and limited battery life on the wireless network. Many researchers have studied to overcome these problems. For high level Availability in the cellular networks, it is necessary to consider recovery from the failures of mobile support stations as well as mobile as mobile hosts. In this paper, we present modified trickle scheme for recovery from failures of Mobile Support Station based on checkpointing scheme and analyze and compare the performance. We propose and analyze the performance of two schemes : one is waiting recovery scheme for the mobile support station having the last checkpoint and the other is searching the new path to the another mobile support station having the checkpoint.

• Convergence Security Journal
• /
• v.6 no.2
• /
• pp.81-89
• /
• 2006

System level diagnosis algorithms use the properties of t-diagnosable system where the maximum number of the faults does not exceed t. The existing diagnosis algorithms have limit when dealing with large fault sets in large multiprocessor systems. Somani and Peleg proposed t/k-diagnosable system to diagnose more faults than t (dimension) by allowing upper bounded few number of units to be diagnosed incorrectly. In this paper, we propose hypercube diagnosis algorithm using t/k-diagnosable system. When the number of faults exceeds t, we allow k faults to be diagnosed incorrectly. Simulation shows that the performance of the proposed algorithm is better than Feng's HADA algorithm. The proposed algorithm also gives similar performance compared to HYP-DIAG algorithm.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.17 no.4
• /
• pp.131-136
• /
• 2007

Ad hoc networks enable efficient resource aggregation in decentralized manner, and are inherently scalable and fault-tolerant since they do not depend on any centralized authority. However, lack of a centralized authority prompts many security-related challenges. Moreover, the dynamic topology change in which network nodes frequently join and leave adds a further complication in designing effective and efficient security mechanism. Security services for ad hoc networks need to be provided in a scalable and fault-tolerant manner while allowing for membership change of network nodes. In this paper, we investigate distributed certification mechanisms using a threshold cryptography in a way that the functions of a CA(Certification Authority) are distributed into the network nodes themselves and certain number of nodes jointly issue public key certificates to future joining nodes. In the process, we summarize one interesting report [5] in which the recently proposed RSA-based ad hoc signature scheme, called URSA, contains unfortunate yet serious security flaws. We then propose new scheme by fixing their security flaws.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.18 no.10
• /
• pp.1553-1571
• /
• 1993

A significant amount of research has focused on the development of highly parallel architectures to obtain far more computational power than conventional computer systems. These architectures usually comprise of a large number of processors communicating through an interconnection network. The VLSI (Very Large Scale Integration) and WSI (Wafer Scale Integration) cellular arrays form one important class of those parallel architectures, and consist of a large number of simple processing cells, all on a single chip or wafer, each interconnected only to its neighbors. This paper studies three fundamental issues in these arrays : fault-tolerant reconfiguration. functional reconfiguration, and their integration. The paper examines conventional techniques, and gives an in-depth discussion about fault-tolerant reconfiguration and functional reconfiguration, presenting testing control strategy, configuration control strategy, steps required f4r each reconfiguration, and other relevant topics. The issue of integrating fault tolerant reconfiguration and functional reconfiguration has been addressed only recently. To tackle that problem, the paper identifies the relation between fault tolerant reconfiguration and functional reconfiguration, and discusses appropriate testing and configuration control strategy for integrated reconfiguration on VLSI and WSI cellular arrays.

• Proceedings of the Korean Information Science Society Conference
• /
• 2004.04a
• /
• pp.925-927
• /
• 2004

침입감내기술이란 중요한 서비스를 제공하는 시스템에 의도적인 공격이나 의도적이지 않은 결함이 발생하더라도 정상적인 서비스를 제공할 수 있는 기술을 말한다. 즉 침입감내기술은 기존의 침입차단이나 탐지기술에 의하여 해결될 수 없었던 익명의 취약성을 이용하는 공격에 의해 발생하는 시스템의 피해를 방지하며 최소화하기 위한 기술이라 할 수 있다. 본 논문에서는 고속 네트워크와 이질적인 자원의 결합으로 구성되어 보안에 취약할 수밖에 없는 그리드 컴퓨팅 환경에서 기존의 정보보호기술과 결함허용기술을 이용하여 안전하게 서비스를 지속할 수 있는 그리드 시스템 모델을 제시하고 제안된 시스템의 타당성을 살펴보았다.