• 전자통신동향분석
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• 제33권1호
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• pp.45-56
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• 2018

A Blockchain is a type of distributed ledger system that consists of a large number of nodes. A block is a container in which transactions are included, and the transactions can be recorded in chronological order by chaining blocks. To work properly, it is essential that the nodes in the Blockchain system have the same image of the chained-blocks. Blockchain systems use various types of consensus algorithms to achieve the same states among the nodes, and the fundamental elements in these algorithms are proof of work and the main chain selection policy, particularly in permissionless Blockchain systems. However, consensus algorithms for permissioned Blockchain systems can be completely different from those of permissionless blockchain systems. In this paper, we overview the basic working mechanism of consensus algorithms, and briefly introduce a few that are currently being applied.

• Journal of Contemporary Eastern Asia
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• 제18권2호
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• pp.1-8
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• 2019

The blockchain is still new and unfamiliar. But blockchain appears to shake an entire technology innovation system. Blockchain is rapidly drawing attention in that it will be able to fundamentally revolutionize industry ecosystem. While cryptocurrency transactions and market capitalization have been popular in mass media, several platform operators in non-cryptocurrency areas such as jewelry, social networks, and entertainment, are also moving to introduce blockchain technology in full swing. In this brief note, we intend to present integrated theoretical strands to summarize various prospects for blockchain technology. Further, we want to provide a reflection as to whether this new technology gives opportunities, challenges, or risks to future society. Particularly, we point out one of its alternative and promising adoption that gives way to new forms of decentralized and autonomous organizations (DAOs).

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권3호
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• pp.1280-1300
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• 2020

In the modern financial sector, interest in providing financial services that employ blockchain technology has increased. Blockchain technology is efficient and can operate without a trusted party to store all transaction information; additionally, it provides transparency and prevents the tampering of transaction information. However, new security threats can occur because blockchain technology shares all the transaction information. Furthermore, studies have reported that the private keys of users who use the same signature value two or more times can be recovered. Because private keys of blockchain identify users, private key leaks can result in attackers stealing the ownership rights to users' property. Therefore, as more financial services use blockchain technology, actions to counteract the threat of private key recovery must be continually investigated. Private key recovery studies are presented here. Based on these studies, duplicated signatures generated by blockchain users are defined. Additionally, scenarios that generate and use duplicated signatures are applied in an actual bitcoin environment to demonstrate that actual bitcoin users' private keys can be recovered.

• International journal of advanced smart convergence
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• 제9권2호
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• pp.157-163
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• 2020

Recently the blockchain technology has been actively studied due to its great potentiality. The smart contract is a key mechanism of the blockchain system. Due to the short history of the smart contract, many issues have not been solved yet. One main issue is vulnerability and another main issue is cost optimization. While the vulnerability of smart contract has been actively studied, the cost optimization has been rarely studied. In this paper, we propose two cost optimization methods for smart contracts running on the blockchain system. Triggering a function in a smart contract program code may require costs and it is repeated continuously. So the minimization of costs required to trigger a function of smart contract while maintaining the performance equally is very important. The proposed two methods minimize the usage of expensive permanent variables deployed on the blockchain system. We apply the proposed two methods to three prevalent blockchain platforms: Ethereum, Klaytn and Tron. Evaluation experiments verify that the proposed scheme significantly reduces the costs of functions in the smart contract written with Solidity.

• 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.

• 지식경영연구
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• 제19권4호
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• pp.187-201
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• 2018

This paper explores the potential of Blockchain technology in enabling a panacea for health equity. Since Satoshi Nakamoto first described Blockchain technology in 2008 pseudonymous paper, that distributed ledger system is empowered and ranging from finance to law to another sector and beyond. Also impacting healthcare sector and life science. In other words, there are many usage cases being researched in healthcare and Blockchain has shown its considerable special side in recent years. But this paper aims to the distributed ledger that is the special side of Blockchain technology is potentially can panacea for some global health equity issues such as patient data, counterfeit drug and hospital payment management.

• International Journal of Internet, Broadcasting and Communication
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• 제13권4호
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• pp.1-10
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• 2021

The purpose of the study is to contribute to the positive development of blockchain technology by providing data to examine security vulnerabilities and threats to blockchain-based services and review countermeasures. The findings of this study are as follows. Threats to the security of blockchain-based services can be classified into application security threats, smart contract security threats, and network (P2P) security threats. First, application security threats include wallet theft (e-wallet stealing), double spending (double payment attack), and cryptojacking (mining malware infection). Second, smart contract security threats are divided into reentrancy attacks, replay attacks, and balance increasing attacks. Third, network (P2P) security threats are divided into the 51% control attack, Sybil attack, balance attack, eclipse attack (spread false information attack), selfish mining (selfish mining monopoly), block withholding attack, DDoS attack (distributed service denial attack) and DNS/BGP hijacks. Through this study, it is possible to discuss the future plans of the blockchain technology-based ecosystem through understanding the functional characteristics of transparency or some privacy that can be obtained within the blockchain. It also supports effective coping with various security threats.

• International Journal of Advanced Culture Technology
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• 제8권4호
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• pp.242-248
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• 2020

Most works of art are done through brokers, and transaction details are not disclosed to the public and are always at risk of tampering. To solve these problems, many Artworks Blockchain Platforms that apply blockchain technology to art transactions are being used. Several companies are currently operating these platforms, but since various blockchain platforms are operated according to the content, the operating methods of each platform are different, and a related model is needed to solve these problems due to compatibility issues between platforms. In this paper, we collect the latest Artworks Blockchain Platforms data, and based on this, we will create and analyze the Color Petri net model of Artworks Blockchain Platform.

• Journal of information and communication convergence engineering
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• 제19권1호
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• pp.8-15
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• 2021

The Fourth Industrial Revolution is currently leading humanity into a super-connected, super-intelligent, and super-converged society through key technologies such as artificial intelligence, the Internet of Things (IoT), and big data. Blockchain technology has the potential to lead social innovation that will improve the mutual harmony and understanding of the complex structures of human society as well as various phenomena (e.g., antagonism, confrontation, and ideological conflict). With such progress in social innovation, blockchain technology will result in a fairer and more transparent human society. In addition, blockchain technology is emerging as a core infrastructure technology, and its growth and expansion are expected to bring about revolutionary improvements to nearly all fields of development and research. In this paper, we briefly outline the main features of blockchain technology. Through a further analysis of its ecosystem, we intend to offer suggestions for a more robust and efficient development of blockchain-related industries.

• 시스템엔지니어링학술지
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• 제19권1호
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• pp.1-13
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• 2023

Transportation of goods by rail in border areas requires considerable time, money, and human resources. Therefore, in this study, a blockchain-based non-stop passing system is proposed to solve this problem. In this study, each transit station and train are designated as one network node, and the corresponding node participates in the blockchain network to record and verify data. In the process, we will design a blockchain network using Docker and design a network interface. Without changing the data and information generated in the existing legacy clearance system, it is possible to configure a blockchain network to ensure the integrity and reliability of the data and to minimize the consumption of time and human resources. The railroad non-stop passing system aims to change the existing legacy system to a blockchain-based non-stop passing system.