• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.4
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• pp.87-98
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• 2002

Software has been developed very fast as information has become important value. Illegal software copy has been the main problem of developing software business. Recently used protecting lock system for software copy has not guaranteed perfectly from easily cracked-defense system. This paper, therefore, proposes 96-bit block cipher with 112-bit length to replace a DES(Data Encryption Standard) algorithm. Security chip by ASIC(Application Specific Integrated Circuit) security module is presented for software copy protection. Then, an auto block protecting algorithm is designed for the security chip. Finally, controlling driver and library are built for the security chip.

• Proceedings of the Korean Society of Computer Information Conference
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• 2014.07a
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• pp.241-244
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• 2014

본 논문에서는 HDFS(Hadoop Distributed File System)에서 문제되고 있는 복제정책의 개선을 위해 HMM(Hidden Markov Model)을 이용한 동적 데이터 복제본 삭제 전략을 제안한다. HDFS는 대용량 데이터를 효과적으로 처리할 수 있는 분산 파일 시스템으로 높은 Fault-Tolerance를 제공하며, 데이터의 접근에 높은 처리량을 제공하여 대용량 데이터 집합을 갖는 응용 프로그램에 최적화 되어있는 장점을 가지고 있다. 하지만 HDFS 에서의 복제 메커니즘은 시스템의 안정성과 성능을 향상시키지만, 추가 블록 복제본이 많은 디스크 공간을 차지하여 유지보수 비용 또한 증가하게 된다. 본 논문에서는 HMM과 최상의 상태 순서를 찾는 알고리즘인 Viterbi Algorithm을 이용하여 불필요한 데이터 복제본을 탐색하고, 탐색된 복제본의 삭제를 통하여 HDFS의 디스크 공간과 유지보수 비용을 절약 할 수 있는 전략을 제안한다.

• Journal of the Korea Society of Computer and Information
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• v.26 no.4
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• pp.75-84
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• 2021

In this paper, we introduce InfoDID, a robust user information management service based on DID that manages user information reliably. Since blockchain technology provides an environment in which data can be handled transparently on a decentralized basis, various services using blockchain are currently being developed As the importance of user's personal information has recently emerged, the DID technology is receiving attention. The technology allows a user to control his or her information through decentralized identifiers, and various information management services are being tried based on the technology. Using blockchain-based DID technology, InfoDID reliably controls personal information requested frequently, helping users to provide their information to other services more conveniently. In addition, to support service continuity, InfoDID uses BR2K technique that provides robust execution of blockchain application services, so that even partial service failures can be systematically recovered. To facilitate this operation, we present a replication status monitoring tool that can continuously check the replication states of blockchain application services running in association with the BR2K technique such as InfoDID.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.2
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• pp.367-374
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• 2017

This paper discusses management problems of Hadoop distributed node, which is a platform for big data processing, and proposes a novel technique for enabling flexible node management of Hadoop Distributed File System. Hadoop cannot configure Hadoop cluster dynamically because it judges temporarily unavailable nodes as a failure. Delayed block replication scheme proposed in this paper delays the removal of unavailable node as much as possible so as to be easily rejoined. Experimental results show that the proposed scheme increases flexibility of node management with little impact on distributed processing performance when the cluster size changes.

• Journal of the Korea Society of Computer and Information
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• v.25 no.10
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• pp.77-86
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• 2020

In this paper, we propose a technique for blockchain service replication and recovery using kubernetes(BR2K) that robustly executes blockchain services based on replication and supports systematic recovery in case of the service failure. Blockchain services are being developed and applied in various fields such as administration, finance, and medical systems based on the features of blockchain, such as decentralization, high security, and data integrity. In such areas where service continuity is important, it is necessary to provide robustness for execution of blockchain services, and a recovery plan for service failure is also required. To this end, BR2K provides an execution replication technique that systematically supports the sustainable execution of blockchain application services. Also, it introduces a robust container registry based on the blockchain service registry, systematically supporting the recovery of service failures by using it. In addition, Truffle, a blockchain service development framework, is extended to utilize the Kubernetes container management tool, and BR2K provides a technique for rapidly deploying blockchain services using the extended framwork.

• Journal of the Korea Society of Computer and Information
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• v.15 no.5
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• pp.49-56
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• 2010

In this paper, we implement a Hadoop based cluster for cloud computing and evaluate the performance of this cluster based on application characteristics by executing RandomTextWriter, WordCount, and PI applications. A RandomTextWriter creates given amount of random words and stores them in the HDFS(Hadoop Distributed File System). A WordCount reads an input file and determines the frequency of a given word per block unit. PI application induces PI value using the Monte Carlo law. During simulation, we investigate the effect of data block size and the number of replications on the execution time of applications. Through simulation, we have confirmed that the execution time of RandomTextWriter was proportional to the number of replications. However, the execution time of WordCount and PI were not affected by the number of replications. Moreover, the execution time of WordCount was optimum when the block size was 64~256MB. Therefore, these results show that the performance of cloud computing system can be enhanced by using a scheduling scheme that considers application's characteristics.

• Journal of the Korea Society of Computer and Information
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• v.27 no.2
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• pp.125-134
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• 2022

In this paper, we propose an extension method of the BR2K technique for enhancing the robustness of blockchain application services. The BR2K (Blockchain application, Replication & Recovery technique using Kubernetes) technique was recently developed to support the robustness of blockchain services through service replication and rapid restart. The proposed technique extends the existing BR2K technique to provide a state version, which is meta-information about the service state, and a method for safely managing it, and use the state version to determine the timing for service state recovery. Also, the technique provides systematic service state backup for service recovery and joining of new service nodes by utilizing the version information and the service registry which acts as a service recovery center in the BR2K technique. Based on this, it is possible to support new service nodes to join the replication service with consistency. As a result, new service nodes can be quickly added to the BR2K service in operation, enhancing the robustness of the BR2K service. In addition, the extended method is applied to the pilot blockchain application service and tested in a Kubernetes environment composed of virtual machines to confirm the validity of service replication consistency and rapid service recovery in the event of node failures.

• Annual Conference of KIPS
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• 2012.11a
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• pp.274-277
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• 2012

중복 제거(De-duplication) 기법은 파일시스템 내에서 동일한 내용의 데이터 블록이나 파일의 중복을 제거하여 유일한 내용만을 보관함으로써, 저장장치의 낭비를 막을 수 있다. 상반된 개념으로 결함극복을 위하여 동일한 파일시스템이나 시스템 구성요소를 복제(이중화)함으로써, 일부 시스템 결함시 복제(이중화)된 다른 시스템을 이용하여 신뢰성과 가용도를 향상시킬 수 있다. 그러나 결함 극복을 위한 파일시스템의 이중화는 저장장치의 낭비화 복제된 파일시스템의 일치성 유지에 비용이 소요된다. 본 논문에서는 일정 수준의 가용도를 유지하기 위한 중복제거 기법을 제안하고 성능을 평가하였다. 제안하는 고가용도 중복제거 기법에서는 요구되는 가용도를 유지할 수 있는 범위내에서 중복을 제거하며, 필요에 따라 선택적으로 중복을 유지할 수 있도록 한다.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2008.10b
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• pp.87-90
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• 2008

디지털 워터마킹은 디지털 콘텐츠에 워터마크를 삽입함으로써 불법적인 복제를 방지하고, 지적재산권 및 저작권을 보호하며, 소유권을 주장할 수 있는 근거를 제시하는 기술이다. 기존의 워터마킹 기법에서는 워터마크를 삽입함으로써 데이터 왜곡과 품질 저하가 불가피하다는 단점이 있다. 이를 극복하기 위하여 원래 데이터를 변경하지 않는 제로-워터마킹 기법들이 제시되고 있다. 이 논문에서는 VQ(Vector Quantization) 방식의 블록 효과를 줄이고, 압축 비율과 품질을 향상시킨 SMVQ(Side Match Vector quantization) 방식에 대한 제로-워터마킹 체계인 CSMVQ(Chaotic SMVQ)를 제안한다. SMVQ 이미지 압축에서는 동일하게 두 이웃 블록의 접면 정보를 이용하기 위하여 좌측 상단에서 우측 하단으로 진행되므로, 임의의 순서로 블록을 선택하여 워터마크를 삽입하기 어렵다. CSMVQ에서는 이전에 부호화된 이웃 블록들의 접면 정보의 일치성을 동적으로 고려하여 부호화를 진행한다. 그러므로 무질서한 방식으로 워터마크가 삽입되도록 지원할 수 있다.

• Journal of the Korea Society of Computer and Information
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• v.25 no.3
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• pp.73-80
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• 2020

In this paper, we propose a robust execution scheme for Ethereum blockchain application services which provide continuous services and support recovery even in the case of failures of those services. As of now, blockchain services are rapidly expanding to all industries and being combined with various infrastructure services of public institutions. But if these services fail in disastrous situations such as earthquakes, floods and terrors or various hacking attacks, the aftermath is very serious and its side effects are difficult to assess. To resolve this issue, we develop the service registry as a smart contract of the Ethereum blockchain, which provides useful information on the services to users even in disasters. With the help of the service registry, we also present a method of replicating services on the basis of the ETCD distributed storage system. The proposed scheme is confirmed by the test service developed by the proposed techniques.