• 전기학회논문지
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• 제60권3호
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• pp.625-631
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• 2011

This paper presents a discrete-time output feedback consensus algorithm for Multi-Agent Systems (MAS). Under the assumption that an agent is aware of the relative state information about its neighbors, a state feedback consensus algorithm is designed based on Linear Matrix Inequality (LMI) method. In general, however, it is possible to obtain its relative output information rather than the relative state information. To reconcile this problem, an Unknown Input Observer (UIO) is employed in this paper. To this end, first it is shown that the relative state information can be estimated using the UIO and the measured relative output information. Then a certainty-equivalence type output feedback consensus algorithm is proposed by combining the LMI-based state feedback consensus algorithm with the UIO. Finally, simulation results are given to illustrate that the proposed method successfully achieves the state consensus.

• Journal of information and communication convergence engineering
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• 제17권3호
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• pp.167-173
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• 2019

This study investigates the problem of leader-following consensus for multi-agent systems with output saturations. This study assumes that the agents are described as a neutrally stable system, and the leader agent generates the bounded trajectory within the saturation level. Then, the objective of the leader-following consensus is to track the trajectory of the leader by exchanging information with neighbors. To solve this problem, we propose an observer-based distributed consensus algorithm. Then, we provide a consensus analysis by applying the Lyapunov stability theorem and LaSalle's invariance principle. The result shows that the agents achieve the leader-following consensus in a global sense. Moreover, we can achieve the consensus by choosing any positive control gain. Finally, we perform a numerical simulation to demonstrate the validity of the proposed algorithm.

• International Journal of Computer Science & Network Security
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• 제23권6호
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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.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권4호
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• pp.1389-1408
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• 2021

Proof-of-Work (PoW) is the first and still most common consensus protocol in blockchain. But it is costly and energy intensive, aiming at addressing these problems, we propose a consensus algorithm named Proof-of-Work-and-Block-Compression (PoW-BC). PoW-BC is an improvement of PoW to compress blocks and adjust consensus parameters. The algorithm is designed to encourage the reduction of block size, which improves transmission efficiency and reduces disk space for storing blocks. The transaction optimization model and block compression model are proposed to compress block data with a smaller compression ratio and less compression/ decompression duration. Block compression ratio is used to adjust mining difficulty and transaction count of PoW-BC consensus protocol according to the consensus parameters adjustment model. Through experiment and analysis, it shows that PoW-BC improves transaction throughput, and reduces block interval and energy consumption.

• 한국컴퓨터정보학회논문지
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• 제25권4호
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• pp.71-77
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• 2020

블록체인의 핵심기술인 합의알고리즘을 통하여 연결 노드 간 동일한 데이터를 정확하게 공유한다. 사용자 및 활용 환경을 고려한 적절한 합의 알고리즘 사용은 데이터 무결성 및 정확성 등을 효율적으로 유지하도록 한다. 본 논문에서는 프라이빗 블록체인 플랫폼의 특징을 고려하여 허가된 노드 간 합의 알고리즘 효율적 선정을 위한 성능평가방법을 제시하였으며 권위를 가진 연결노드의 수를 고려하여 해당 항목을 기존 공개된 수식에 변형하여 적용하였다. 이러한 과정을 통하여 노드 간 안정성을 고려한 합의과정의 단순화가 가능하였다. 제안한 연구내용을 통한 적절한 합의 알고리즘 선정을 통하여 합의 과정의 안정성을 높일 수 있다.

• Journal of Information Processing Systems
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• 제14권1호
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• pp.101-128
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• 2018

Thanks to its potential in many applications, Blockchain has recently been nominated as one of the technologies exciting intense attention. Blockchain has solved the problem of changing the original low-trust centralized ledger held by a single third-party, to a high-trust decentralized form held by different entities, or in other words, verifying nodes. The key contribution of the work of Blockchain is the consensus algorithm, which decides how agreement is made to append a new block between all nodes in the verifying network. Blockchain algorithms can be categorized into two main groups. The first group is proof-based consensus, which requires the nodes joining the verifying network to show that they are more qualified than the others to do the appending work. The second group is voting-based consensus, which requires nodes in the network to exchange their results of verifying a new block or transaction, before making the final decision. In this paper, we present a review of the Blockchain consensus algorithms that have been researched and that are being applied in some well-known applications at this time.

• 경영정보학연구
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• 제13권3호
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• pp.141-163
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• 2011

인터넷을 중심으로 한 정보기술의 급격한 발전은 정보화 사회로의 패러다임 전환을 가져오면서 사회적 여론을 형성하는 과정에도 영향을 미치고 있다. 이에 따라 디지털 매체를 활용하여 온라인에서 정보를 생성하고 유통하며 사회적 합의에 이르는 정보처리 매커니즘의 변화에 대한 연구의 중요성이 증가하고 있다. 본 연구에서는 사회적 정보처리 과정의 고찰을 통하여 사회적 합의도출 및 제도화의 프로세스 모델을 도출하고 인터넷 매체에서의 정보처리 특성을 분석하였다. 정보처리 매커니즘의 변화를 분석하기 위하여 사회적 맥락 속에서 집단적 행동을 분석하는 질적 연구방법인 인류학적 접근법(ethnographic approach)을 적용하여 2가지 사례를 관찰 분석하였다. 사회적 컨센서스 형성과정은 사회적 의제의 제기, 여론 활동에서의 선택적 반영, 의제의 수용과 확산, 공론화와 사회적 합의, 제도화와 피드백이라는 5가지 단계로 구성되어진다. 인터넷 매체에서의 정보처리 특성은 사건에의 능동적 반응, 오피니언 리더의 역할 전이, 발의와 분석의 탄력성, 높은 확장성, 합의도출에의 적합성, 제도화와 상호작용 등 6가지로 제시하였다. 본 연구에서는 사회구성원의 정보를 공유하고 사회적 여론을 이끄는 과정을 설명하는 모텔을 제시함으로써 정보처리 구조를 사회적 네트워크 관점에서 고찰할 수 있는 이론적 기반을 마련하였다. 또한 그리고 인터넷 매체의 사회적 효용을 사회적 정보처리라는 새로운 기준으로 분석하여 정치, 커뮤니케이션 경영분야에서의 미디어 활용 및 의사결정의 합리성 제고에 기여할 것으로 보인다.

• 유통과학연구
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• 제15권2호
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• pp.7-14
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• 2017

Purpose - This study attempts to extend the research in responsible luxury by identifying contexts where Corporate Social Responsibility (CSR) can promote luxury brands' evaluation. It contributes to the literature on consumer responses to CSR, and to responsible luxury in particular and demonstrates how dispositional consensus and luxury-CSR information of luxury brands affects consumers' evaluation of brand. Research design, data, and methodology - An experiment was conducted to test the relationship between brand evaluation and responsible luxury brands' CSR information using collected data through a survey in a large university of South Korea. Study conditions were manipulated with various product types to analyze the relationship in different product domains. Results - When consensus regarding sincere and altruistic motive of companies for CSR activity is high, the perceived fit between luxury brand and the type of CSR has no effect on brand evaluation. But, in case of lower consensus regarding the benevolent company motives, higher fit enhances evaluation than lower fit. Conclusions - In using consensus as a guiding factor to choose the type of charity with favorably view, the level of irrespective fit can help luxury firms to enjoy the benefits of better image. In case of low consensus donating to charities that are closely related to the brands' product or area of business seems to be fruitful.

• 한국통신학회논문지
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• 제39B권5호
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• pp.323-325
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• 2014

컨센서스 알고리즘은 노드의 커버리지가 넓어질수록 협력하는 이웃 노드 수가 증가하여 빠르게 수렴하지만, 분산 무선 네트워크에서는 커버리지가 넓어지면 증가한 협력 이웃 노드 간에 접속 충돌로 인하여 정보 공유 지연이 증가한다. 따라서 노드 커버리지의 크기에 따라 컨센서스 알고리즘의 수렴 속도와 네트워크상의 정보 공유 지연 간에 트레이드오프가 존재한다. 본 논문에서는 이러한 트레이드오프 관계를 고려하여 네트워크 규모에 따라 컨센서스 달성 시간을 최소화하는 커버리지 제어 방법을 제시한다.

• Asia pacific journal of information systems
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• 제15권4호
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• pp.27-60
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• 2005

The purpose of this study is to call attention to the consensus of stakeholders of corporate e-Learning system for the sake of its success. We identified the critical success factors(contents, technical features, management, and organizational support) as major components of corporate e-Learning systems and questioned whether stakeholders' consensus on the importance of these components facilitates the successful implementation of these components. We also questioned whether the influence of these components on user satisfaction could be moderated by contextual factors. Based on empirical testing of 18 e-Learning user companies, we verified that the consensus of stakeholders regarding the importance of content, technological features, and organizational support has a positive influence on the perceived quality of these factors in their e-Learning systems, which in turn is positively related to user satisfaction. The learning subjects and learning style did significantly moderate the influences of these perceived qualities on user satisfaction.