• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.2
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• pp.271-277
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• 2022

PBFT (Practical Byzantine Fault Tolerant) is a consensus algorithm that can achieve consensus by resolving unintentional and intentional faults in a distributed network environment and can guarantee high performance and absolute finality. However, as the size of the network increases, the network load also increases due to message broadcasting that repeatedly occurs during the consensus process. Due to the characteristics of the PBFT algorithm, it is suitable for small/private blockchain, but there is a limit to its application to large/public blockchain. Because PBFT affects the performance of blockchain networks, the industry should test whether PBFT is suitable for products and services, and academia needs a unified evaluation metric and technology for PBFT performance improvement research. In this paper, quantitative evaluation metrics and evaluation frameworks that can evaluate PBFT family consensus algorithms are studied. In addition, the throughput, latency, and fault tolerance of PBFT are evaluated using the proposed PBFT evaluation framework.

• Journal of Internet Computing and Services
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• v.21 no.1
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• pp.17-31
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• 2020

With the rapid development of block chain technology, attempts have been made to put the block chain technology into practical use in various fields such as finance and logistics, and also in the public sector where data integrity is very important. Defense Operations In addition, strengthening security and ensuring complete integrity of the command communication network is crucial for operational operation under the network-centered operational environment (NCOE). For this purpose, it is necessary to construct a command communication network applying the block chain network. However, the block chain technology up to now can not solve the security issues such as the 51% attack. In particular, the Practical Byzantine fault tolerance (PBFT) algorithm which is now widely used in blockchain, does not have a penalty factor for nodes that behave maliciously, and there is a problem of failure to make a consensus even if malicious nodes are more than 33% of all nodes. In this paper, we propose a Adaptive Consensus Bound PBFT (ACB-PBFT) algorithm that incorporates a penalty mechanism for anomalous behavior by combining the Trust model to improve the security of the PBFT, which is the main agreement algorithm of the blockchain.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.01a
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• pp.193-194
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• 2020

블록체인의 활용이 다양해지며 블록체인을 통한 산업, 정부의 기술적용이 확산되고 있다. 특히 사물인터넷 등 빅데이터 관리를 위한 방법으로 블록체인과의 융합도 적지 않게 거론되고 있다. 사물인터넷과 같은 빅데이터를 효과적으로 관리하기 위해서는 수집 및 저장과정과 더불어 투명하고 정확한 신뢰기반의 데이터 관리가 필요하다. 현재 블록체인의 프라이빗 블록체인 플랫폼에서 가장 많이 제시되고 활용되는 합의알고리즘은 PBFT이다. PBFT의 경우 노드 증가에 따른 연산알고리즘의 과중으로 인한 속도저하가 문제가 될 수 있다. 본 논문에서는 PBFT의 합의과정에 대한 알고리즘을 수정하여 노드 증가 시에도 복잡도를 낮출 수 있는 방법을 제안하였다. 본 논문에서는 시뮬레이션을 통하여 노드 개수를 변형하며 기존 PBFT알고리즘 대비 제안 알고리즘의 우수성을 증명한다.

• Journal of Information Processing Systems
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• v.18 no.6
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• pp.741-754
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• 2022

Openstack is widely used as a representative open-source infrastructure of the service (IaaS) platform. The Openstack Identity Service is a centralized approach component based on the token including the Memcached for cache, which is the in-memory key-value store. Token validation requests are concentrated on the centralized server as the number of differently encrypted tokens increases. This paper proposes the practical Byzantine fault tolerance (PBFT) blockchain-based Openstack Identity Service, which can improve the performance efficiency and reduce security vulnerabilities through a PBFT blockchain framework-based decentralized approach. The experiment conducted by using the Apache JMeter demonstrated that latency was improved by more than 33.99% and 72.57% in the PBFT blockchain-based Openstack Identity Service, compared to the Openstack Identity Service, for 500 and 1,000 differently encrypted tokens, respectively.

• Annual Conference of KIPS
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• 2019.05a
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• pp.197-200
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• 2019

가상 화폐 분야의 핵심 기술로 소개된 블록체인(Blockcahin) 기술은 4차 산업혁명에서 중심이 되는 기술로 주목받고 있다. 본 논문에서는 블록체인 시스템의 구조도와 대표적인 합의 알고리즘, 즉 증명(PoW: Proof of Work), 지분증명(PoS: Proof of Stake) 그리고 PBFT (Practical Byzantine Fault Tolerance)을 조사하였다. 합의 알고리즘의 특성을 분석하기 위하여, 보안성, 에너지 소비량, 거래 처리속도를 지표로 세워서 합의 알고리즘들에 대하여 전체적으로 비교 및 분석을 하였다.

• Smart Media Journal
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• v.12 no.9
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• pp.95-102
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• 2023

As the utilization value of personal information increases, discussions on how to provide personal information are active, but information required by institutions to utilize personal information is being exposed more than necessary. Therefore, personal privacy protection is essential to overcome the problems and limitations of personal information protection. In this study, a decentralized identity information management model that overcomes the problems and limitations of the centralized identity management method of personal information and manages and selectively provides personal information by the information owner himself and demonstrates the excellence of personal information by implementing the Smart Personal Information Provision System (SPIPS) in the PBFT consensus algorithm through experiments.

• Journal of the Korea Society of Computer and Information
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• v.25 no.4
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• pp.47-53
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• 2020

Blockchain is a distributed shared ledger that transparently manages information through verification and agreement between nodes connected to a distributed network. Recently, cases of data management among authorized agencies based on private blockchain are increasing. In this paper, we investigated the application cases and technical processes of PBFT, the representative consensus algorithm of private blockchain, and proposed a modified PBFT algorithm that enables efficient consensus by simplifying duplicate verification and consensus processes that occur during PBFT processing. The algorithm proposed in this paper goes through the process of selecting a delegation node through an authoritative node and can increase the safety of the delegation node selection process by considering an efficient re-election algorithm for candidate nodes. By utilizing this research, it is possible to reduce the burden on the network communication cost of the consensus process and effectively process the final consensus process between nodes.

• Annual Conference of KIPS
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• 2021.11a
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• pp.334-336
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• 2021

허가형 블록체인 기반 데이터 공유 시스템은 분산 환경에서 신뢰 수준을 구축하고 일관된 메시지를 기록 및 공유함으로써 서비스의 상호 운용성을 가능하게 한다. 그러나 허가형 블록체인은 종종 탈중앙화, 보안 및 상호 운용성과 충돌한다. 이는 중앙 집중식 시스템으로 돌아가거나 데이터의 독점 및 남용 및 오용으로 이어질 수 있다. 따라서 CAP (Consistency, Availability, Partition tolerance)에 이론 검증에 따라 메시지 공유, 비잔틴 내결함성 및 메시지 일관성을 고려하고 적용해야 한다. 기존의 PBFT(Practical Byzantine Fault Tolerance) 합의 알고리즘는 노드의 증가시, 장애내성을 갖기위해 계산되어야 할 합의 처리시간이 증가하며, DPOS(Delegated Proof of Stake) 알고리즘은 보상, 리더 선출의 공정성 문제 등에 따라 허가형 블록체인에서의 적합한 방식이 연구되고 있다. 본 논문에서는 서비스의 상호 운용성과 과제에 대해 논의하고 허가된 블록체인의 합의 개선을 통한 데이터 공유 시스템을 제안한다.

• Journal of Korea Society of Digital Industry and Information Management
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• v.19 no.3
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• pp.37-44
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• 2023

In the future society, a means to verify the identity of the information owner is required at the beginning of most services that the information owner encounters, and the emergence and gradual spread of digital identification that proves the identity of the information owner is essential. In addition, as the utilization value of personal information increases, discussions on how to provide personal information are active. Therefore, there is a need for a personal information management method necessary for building a hyper-connected society that is safe from various hacking, forgery, alteration, and theft by allowing the owner to directly manage and provide personal information management. In this study, a decentralized identity information management model that overcomes the problems and limitations of the centralized identity management method of personal information and manages and selectively provides personal information by the information owner himself and implemented a smart personal information provision system(SPIPS: Smart Personal Information Provision System) using a smartphone.

• International Journal of Computer Science & Network Security
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• v.23 no.6
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• pp.181-192
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• 2023

Blockchain system brought innovation in the area of accounting, credit monitoring and trade secrets. Consensus algorithm that considered the central component of blockchain, significantly influences performance and security of blockchain system. In this paper we presented four consensus protocols specifically as Proof of Work (PoW), Proof of Stake (PoS), Delegated Proof of Stake (DPoS) and Practical Byzantine Fault-Tolerance (PBFT), we also reviewed different security threats that affect the performance of Consensus Protocols and precisely enlist their counter measures. Further we evaluated the performance of these Consensus Protocols in tabular form based on different parameters. At the end we discussed a comprehensive comparison of Consensus protocols in terms of Throughput, Latency and Scalability. We presume that our results can be beneficial to blockchain system and token economists, practitioners and researchers.