• Journal of Platform Technology
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• v.9 no.1
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• pp.46-57
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• 2021

Recently, research has been actively conducted to utilize blockchain technology in various fields. In particular, blockchain-based smart contracts are applied to various automation systems that require reliability as they have the characteristics of recording data in a distributed ledger environment to verify the integrity and validity of data. However, blockchain does not provide data access control and information security because data is shared among network participants. In this paper, we propose a user dynamic access control mechanism utilizing smart contracts in blockchain environments. The proposed mechanism identifies the user's contextual information when accessing data, allocating the user's role and dynamically controlling the data access range. This can increase the security of the system and the efficiency of data management by granting data access dynamically at the time of user authentication, rather than providing the same services in roles assigned to each user group of the network system. The proposed mechanism is expected to provide flexible authentication capabilities through dynamic data access control by users to enhance the security of data stored within blockchain networks.

• KNOM Review
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• v.22 no.3
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• pp.20-24
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• 2019

Blockchain is a distributed ledger-based technology where all nodes participating in the blockchain network are connected to the P2P network. When a transaction is created in the blockchain network, the transaction is propagated and validated by the blockchain nodes. The verified transaction is sent to peers connected to each node through P2P network, and the peers keep the transaction in the memory pool. Due to the nature of P2P networks, the number and type of transactions delivered by a blockchain node is different for each node. As a result, all nodes do not have the same memory pool. Research is needed to solve problems such as attack detection. In this paper, we analyze transactions in the memory pool before solving problems such as transaction fee manipulation, double payment problem, and DDos attack detection. Therefore, this study collects transactions stored in each node memory pool of Bitcoin and Ethereum, a cryptocurrency system based on blockchain technology, and analyzes how much common transactions they have using jacquard similarity.

• International Journal of Computer Science & Network Security
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• v.23 no.11
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• pp.128-132
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• 2023

Investment authorities are broad financial institutions that carefully manage investments on behalf of the national government using a long-term value development approach. To provide a stronger structure or framework for In-vestment Authorities to govern the distribution of funds to public and private markets, we've started research to create a blockchain-based prototype for managing and tracking numerous finances of such authorities. We have taken the case study of Oman Investment Authority (OIA) of Sultanate of Oman. Oman's wealth is held in OIA. It is an organization that oversees and utilizes the additional capital generated by oil and gas profits in public and private markets. Unlike other Omani funds, this one focus primarily on assets outside the Sultanate. The operation of the OIA entails a huge number of transactions, necessitating a high level of transparency and administration among the parties involved. Currently, OIA relies on various manuals to achieve its goals, such as the Authorities and Responsibilities manual, the In-vestment Manual, and the Code of Business Conduct, among others. In this paper, we propose a Blockchain based framework to manage the operations of OIA. Blockchain is a part of the Fourth Industrial Revolution, and it is re-shaping every industry. The main components of every blockchain are assets and participants. The funds are the major assets in the proposed study, and the participants are the various fund shareholders/recipients. The block-chain's transactions are all safe, secure, and immutable, and it's part of a trustless network. The transactions are simple to follow and verify. By replacing intermediary firms with smart contracts, blockchain-based solutions eliminate any middlemen in the fund allocation process.

• Journal of Korea Multimedia Society
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• v.21 no.12
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• pp.1448-1458
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• 2018

Vehicular Ad-Hoc Networks (VANETs) have become one of the active areas of research, standardization, and development because they have tremendous potentials to improve vehicle and road safety, traffic efficiency, and convenience as well as comfort to both drivers and passengers. However, message trustfulness is a challenge because the propagation of false message by malicious vehicles induces unreliable and ineffectiveness of VANETs, Therefore, we need a reliable reputation method to ensure message trustfulness. In this paper, we consider a vulnerability against the Sybil attack of the previous reputation systems based on blockchain and suggest a new reputation system which resists against Sybil attack on the previous system. We propose an initial authentication process as a countermeasure against a Sybil attack and provide a reliable reputation with a cooperative message delivery to cope with message omission. In addition, we use Homomorphic Commitment to protect the privacy breaches in VANETs environment.

• Journal of Industrial Convergence
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• v.20 no.6
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• pp.37-45
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• 2022

With the development of the Internet of Things (IoT), related network infrastructures require new technologies to protect against threats such as external hacking. This study proposes an L-PBFT consensus algorithm that can protect IoT networks based on a blockchain consensus algorithm. We designed a blockchain (private) model suitable for small networks, tested processing performance for ultra-small/low-power IoT devices, and verified stability. As a result of performance analysis, L-PBFT proved that at least the number of nodes complies with the operation of the consensus algorithm(minimum 14%, maximum 29%) and establishes a trust network(separation of secure channels) different from existing security protocols. This study is a 4th industry convergence research and will be a foundation technology that will help develop IoT device security products in the future.

• Korea Trade Review
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• v.47 no.6
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• pp.269-289
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• 2022

The COVID-19 pandemic has disrupted supply chains across the world. When the pandemic broke out, the disruptions were mainly due to the lockdowns imposed in various countries. The WTO has predicted that the pandemic might cause world trade to decline by 13 to 32 per cent in 2020. This paper will examine the implications of COVID-19 on digital trade, particularly the use of blockchain in the Asia Pacific. The Asia Pacific (particularly Singapore and Hong Kong) is a leader in the use of digital technologies. This paper will thus attempt to draw out lessons from the first movers for the rest of Asia. It will examine the bottlenecks in the application of this technology in the Asia Pacific countries, and the need for regulatory changes in the Asia-Pacific. It will trace the technology's barriers to adoption, both as regards interoperability, and regulatory framework. The advantages of blockchain technology in trade finance are clear; it can promote trade efficiency, mitigate risk and expand trade to other regions. However, earlier efforts to introduce digital technologies have failed. More collaborative efforts are required, so that networks can connect seamlessly on a single technology platform, and meet the demand for trade finance. The COVID-19 pandemic seems to have provided an enabling environment for the intensification of digital efforts, increasing their urgency; should these measures indeed successfully occur, they will improve the resiliency of supply chains across the region.

• The Journal of Bigdata
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• v.5 no.1
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• pp.89-96
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• 2020

Deep learning using an artificial neural network has been recently researched and developed in various fields such as image recognition, big data and data analysis. However, federated learning has emerged to solve issues of data privacy invasion and problems that increase the cost and time required to learn. Federated learning presented learning techniques that would bring the benefits of distributed processing system while solving the problems of existing deep learning, but there were still problems with server-client system and motivations for providing learning data. So, we replaced the role of the server with a blockchain system in federated learning, and conducted research to solve the privacy and security problems that are associated with federated learning. In addition, we have implemented a blockchain-based system that motivates users by paying compensation for data provided by users, and requires less maintenance costs while maintaining the same accuracy as existing learning. In this paper, we present the experimental results to show the validity of the blockchain-based system, and compare the results of the existing federated learning with the blockchain-based federated learning. In addition, as a future study, we ended the thesis by presenting solutions to security problems and applicable business fields.

• Journal of Korea Multimedia Society
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• v.22 no.5
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• pp.613-625
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• 2019

The rise of the Internet of Things (IoT) devices have greatly influenced many industries and one of them is healthcare where wearable devices started to track all your daily activities for better health monitoring accuracy and even down to tracking daily food intake in some cases. With the amounts of data that are being tracked and shared between from these devices, questions were raised on how to uphold user's data privacy when data is shared between these IoT devices and third party. With the blockchain platforms started to mature since its inception, the technology can be implemented according to a variety of use case scenarios. In this paper, we present a system architecture based on the healthcare system and IoT network by leveraging on multiple blockchain networks as the medium in between that should enable users to have direct authority on data accessibility of their shared data. We provide proof of concept implementation and highlight the results from our testing to show how the efficiency and scalability of the healthcare system improved without having a significant impact on the performance of the Electronic Medical Record (EMR) that mostly affected by the previous solution since these solutions directly connected to a public blockchain network and which resulted in significant delays and high cost of operation when a large amount of data or complicated functions are involved.

• KIPS Transactions on Software and Data Engineering
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• v.11 no.7
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• pp.283-290
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• 2022

Blockchain is a technology that secures integrity and transparency by distributing and storing transaction details within multiple node networks. Recently, research is being conducted to secure integrity by applying blockchain to Bill of Lading (B/L documents) of monetary value. In this paper, we study a blockchain-based bill of lading system to improve usability. The shippers register the issued bill of lading on the blockchain, and banks in each country read it to conduct L/C transactions. The consignees receive the goods after completing certification with a quick response code (QR) containing the bill of lading information. Through this, shippers enjoy merits in that they can shorten the time and cost of sending shipping documents by mail and prove the integrity of the documents. The consignees have the advantage of being able to check the documents at the same time as they are registered and trust the transaction. Finally, on the bank side, the security of shipping documents is ensured and verification can be done quickly.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.33 no.1
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• pp.371-401
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• 2022

If the blockchain means storing information in a distributed environment that cannot be forged or altered, it is mentioned that this is similar to what librarians collect, preserve, and share authoritative information. In this way, this study examined blockchain technology as a way to collect and provide reliable information, increase work efficiency inside and outside the library, and strengthen cooperative networks. This study attempted to propose various ways to utilize blockchain technology in book relations based on literature surveys and case studies in other fields. To this end, this study first analyzed the field and cases of blockchain application to confirm the possibility and value of blockchain application in the library field, and proposed 12 ways to utilize it based on this. The utilization model was proposed by dividing it into operation and service sectors. In the operation sector, it is a digital identity-based user record storage and authentication function, transparent management and traceable monitoring function, voting-based personnel and recruitment system, blockchain governance-based network efficiency function, and blockchain-based next-generation device management and information integration function. The service sector includes improved book purchase and sharing efficiency due to simplification of intermediaries, digital content copyright protection and management functions, customized service provision based on customer behavior analysis, blockchain-based online learning platforms, sharing platforms, and P2P-based reliable information sharing platforms.