• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.4
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• pp.987-997
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• 2018

Blockchain has tamper-free, so many applications are developing to leverage tamper-free features of blockchain. MIT Media Labs proposed BlockCerts, educational certificate blockchain System, to solve problems of legacy certificate verifications. Existing educational certificate blockchain Systems are based on public blockchain such as bitcoin, Ethereum, so any entity can participate educational institute in principal. Moreover, the exisitng educational certricate blockchain system utilizes the integrity of blockchain, but the confidentiality of the educational certificate is not provided. This paper propose a digital certificate system based on private blockchain, name HyperCerts. Therefore, only trusted entity can participate in the private blockchain network, Hyperledger, as the issuer of digital certificate. Furthermore, the practical byzantine fault tolerance is used as consensus algorithm, HyperCerts reduce dramatically the latency of issuing digital certificate and required computing power. HyperCerts stores the hash value of digital certificate into the ledger, so breach of personal information by malicious entity in the private blockchain is protected.

• Journal of Multimedia Information System
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• v.6 no.3
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• pp.125-130
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• 2019

In this paper, Blockchain is mentioned as the next-generation core IT technology. As an immature technology, there are not many practical use cases, but it is expected to be widely applied in various industries such as cryptocurrency, finance, public, etc. to increase efficiency and enable new services that did not exist in the past. Nevertheless, the generalization of blockchain technology is still difficult. In particular, from the viewpoint of personal information protection, GDPR of Europe, etc., is becoming stronger. Considering that the core of the blockchain is the change of information sharing and processing method, it is very important how the blockchain can affect, especially from the viewpoint of privacy, and how the Privacy Act can be applied to the blockchain. However, the discussion on this part also seems to be insufficient. Therefore, in this paper, blockchain By analyzing the implications and implications of technologies and services using them from the perspective of the Privacy Act, we will discuss how the blockchain will be used to prevent leakage of privacy.

• 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.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.8
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• pp.3224-3242
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• 2020

Internet of Things (IoT) networks composed of a large number of sensors and actuators generate a huge volume of data and control commands, which should be enforced by strong data reliability. The end-to-end data reliability of IoT networks is an essential industrial enabler. Blockchain technology can provide strong data reliability and integrity within IoT networks. We designed a lightweight end-to-end blockchain network that applies to common IoT applications. Its enhanced modular architecture and lightweight consensus mechanism guarantee its practical applicability for general IoT applications. In addition, the proposed blockchain network is highly software compatible because it adopts the Hyperledger development environment. Directly embedding the proposed blockchain middleware platform in small computing devices proves its practicability.

• 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.

• Journal of Digital Convergence
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• v.16 no.8
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• pp.201-210
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• 2018

High expectations are posed on the blockchain-based internet of things (IoT), in which IoT and blockchain technology is combined to obtain trust in the Internet, where trust appears impossible to obtain. However, applications of current blockchain-based IoT technology to real-world scenarios appears to be significantly more difficult owing to limitations regarding scalability and security. In this paper, the difficulties to implement blockchain networking technologies for IoT and digital businesses are investigated and practical solutions such as sharding, off-chain, de-idetification and P2P crypto-currency exchange are explored. In further work, a blockchain platform for IoTs which provides scalability and security will be implemented according to this research results, and compared with conventional blockchain platforms.

• The Journal of Asian Finance, Economics and Business
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• v.6 no.3
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• pp.283-293
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• 2019

The purposes of the study are threefold: (1) develop key successful factors of blockchain platform for micro-enterprises based on Balanced Scorecard (BSC), (2) find out the correlation between the key successful factors of blockchain platform for micro-enterprises, and (3) understand the perception of micro-enterprise blockchain and the difference between theoretical guidance and practical application. This study combines Interpretative Structural Modeling Method, (ISM) and Decision-Making Trial and Evaluation Laboratory (DEMATEL) to analyze the causal relationships and hierarchical structures of the 12 key successful factors of blockchain platform for micro-enterprises and understand the correlation between factors. The 12 key successful factors developed based on the four perspectives of the Balanced Scorecard, and the questionnaire designs based on the concept of DEMATEL, and then analyzed data by DEMATEL and ISM methods to understand the correlation between key factors. The research results show that the key successful factors of blockchain platform for micro-enterprises include "brand equity", "security and anti-counterfeiting", "sales growth", "transparency and clear", "trust", "consensus mechanism", "traceability", "consistency", "tracking", "innovation management", "international", "organizational adaptation", in which consumer "trust" plays an important role. Micro-enterprises can use blockchain to expand the market, provide customers with better service quality, and bring sales growth to micro-enterprises.

• Journal of Practical Engineering Education
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• v.15 no.1
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• pp.133-142
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• 2023

This study aims to examine how blockchain technology is currently being applied in various fields, as well as the methods and limitations involved in constructing blockchain, and to gauge the potential future of blockchain technology. The success or realization of the technology's applications will depend on how quickly certain technical challenges can be overcome. This paper emphasizes that with the advancement of blockchain technology, when transparency and reliability are improved, it will become a significant force in changing not only the industrial sector but also the economic and political domains. Even if the problem awareness demonstrated by blockchain technology cannot be the most effective solution for solving real-world problems, the framework it presents will provide a significant window for us to understand the problems we face in reality.

• 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.

• Journal of Information Technology Services
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• v.16 no.2
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• pp.1-20
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• 2017

A bitcoin-based technology named blockchain is garnering attention in various industries as a cost-effective measure in strengthening security and a reliable technology medium. Blockchain technology will play a critical role in the Fourth Industrial Revolution, and IT technology is expected to bring fundamental changes. This study focuses on the characteristics of blockchain technology and the effects of the intention to accept its technology in an empirical manner. The aspects of the technology are organized by researching blockchain technology and theories of technology acceptability and previous studies were used as guidelines to create the research model and propose the hypothesis. The research model is based on UTAUT with a set-up of 5 factors for performance expectancy and effort expectancy. For empirical analysis, a survey was conducted on 283 IT workers in Korea, To examine the hypothesis structural equation modeling was used performance expectancy was influenced by security, reliability, diversity, and economic efficiency while effort expectancy was influenced by reliability and economic efficiency. Performance expectancy, social influence, facilitating conditions affect the intention to accept. Innovativeness of an organization and control effects are influenced as well. The present study aims to provide practical guidance as supplementary research in utilizing blockchain technology, and the limitations of the study and future research possibilities are discussed as well.