• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.114-115
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• 2018

Recently in Bitcoin raising a social issue is sometimes called a horizontal and decentralized digital virtual currency utilizing the Blockchain technology such as a type of password currency. On the other hand, the Blockchain, which is a distributed ledger shared on P2P networks and it was first used in Bitcoin. These technologies are regarded as technologies that can be applied diversely in other fields, and are attracting high social interest. Looking at recent trends in the virtual currency market such as Bitcoin, price movements have increased since the Japanese government approved the virtual currency as a means of settlement last year. Therefore, we try to present theoretical practical suggestion through the viewpoint of the Blockchain technology which is core technology of Bitcoin based on innovative technology.

• The Journal of Society for e-Business Studies
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• v.24 no.3
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• pp.129-142
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• 2019

The interest in the blockchain technology has been increasing since its inception and it has been applied to many fields and sectors. The blockchain technology creates a decentralized environment where no third party controls the data and transaction. Mobile apps recommendation has been extensively used to recommend apps to mobile users. For example, Android-based recommendation applications have been developed to recommend other mobile apps for download depending on user's preferences and mobile context. These recommendations help users discover apps by referring to the experiences of other users. Due to the collection of a large amount of data and user information, there is a problem of insecurity and user's privacy that are prone to be attacked. To address this issue the blockchain technology can be incorporated to assure cryptographic safety. In this paper, we present a survey of the on-going mobile app recommendations and e-commerce technology trend to address how the blockchain can be incorporated into the collaborative filtering recommendation systems to enable the users to set up a secured data, which implies the importance of user privacy preference on personalized app recommendations.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.290-292
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• 2019

Since the advent of blockchain and bitcoin, decentralization has been accelerating around the world as a public blockchain ethereum with smartcontract has begun. Developers can use Ethereum's blockchain development platform to develop "distributed applications" (DApp) running on a decentralized P2P network, and various types of devices from IoT to mobile can participate in a block-chain distributed environment have. Using Ethereum's blockchain development platform, developers can develop "Decentralized Application (DApp)" that run on a decentralized P2P network and various types of devices from IOT to mobile can participate in distributed blockchain environments. There are many ways to interact with the blockchain and the smart contract, but users tend to prefer the mobile methods due to their convenience and accessibility advantages. Therefore, the author developed an Android based voting DApp and researched related issues. Since the current development methods of DApp are not adequately researched and standardized, efficient methods for developing user-friendly DApp were studied. Because DApp has to spend a certain amount of fees to interact with blockchain, it has intensively investigated the gas problem of Smart Contract code and the security problem of code, and author would like to introduce it in this paper.

• Journal of the Korea Society of Computer and Information
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• v.26 no.2
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• pp.229-235
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• 2021

Blockchain, recognized as one of the core technologies of the 4th industrial revolution, is an Internet-based distributed data management system which does not require centralized control. Blockchain is characterized by the integrity and reliability of information, and blockchains can be used where such characteristics are required. Typical applications of blockchain include finance, transaction, and evaluation management. In this paper, we designed a blockchain-based evaluation management system that allows users to freely create and manage evaluation instances. Evaluation managers can create an evaluation instance according to their purpose and allocate evaluation items and evaluators. When the evaluators finish evaluating the evaluation items, the evaluation manager can aggregate the evaluation results for the instance. Someone, who want to perform evaluation for various purposes but do not have an evaluation system, can implement the evaluation system relatively simply by using this system. In addition, due to the characteristic of the blockchain, evaluators cannot modify the evaluation scores they have already recorded, and neither the system administrator nor the evaluation administrator can modify the evaluation scores. For this reason, the reliability of the evaluation increases.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.5
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• pp.394-402
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• 2021

Electronic voting systems have been widely used in many countries around the world since the mid-1990s. In recent years, studies have applied blockchain to existing electronic voting systems in order to provide reliability, fairness, and transparency for voters. This approach is highly useful as a technology that promotes decentralized citizen participation. However, the existing electronic voting systems using blockchain have not sufficiently considered anonymity. Lack of anonymity acts as an important constraint in cases of small- and medium-sized voting, which is often required in decentralized citizen participation. In this study, we propose a model that provides anonymity to a voting system using blockchain by applying the concept of the master node in Dash cryptocurrency. First, we define the differences in the requirements of the transfer and voting systems in blockchain. We propose a parallel and autonomous model and algorithm to provide anonymity in the blockchain-that is, a decentralized development environment. In addition, a discussion of security and the environment for the proposed model is described.

• Journal of the Korea Society of Computer and Information
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• v.26 no.12
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• pp.159-168
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• 2021

Building Information Modeling (BIM) data is a digitized construction design by worldwide construction design stands rules. Some research are being conducted to utilize blockchain for safe sharing and trade of BIM data, but there is no way to store BIM data directly in the blockchain due to the size of BIM data and technical limitation of the blockchain. In this paper, we propose a method of storing BIM data by combining a distributed file system and a blockchain. We propose two network overlays for storing BIM data, and we also propose generating the Level of Detail (LOD)-based merkle tree for efficient verification of BIM data. In addition, this paper proposes a system design for distributed storage of BIM data by using blockchain besu client and IPFS client. Our system design has a result that the processing speed stably increased despite the increase in data size.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.8 no.3
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• pp.895-905
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• 2018

Public opinion polls have a strong influence on modern society as a means of examining the tendency of social groups on specific issues. As the influence of the polls increases, the problem of forgery and falsification of the results becomes an important issue. So, to guarantee the reliability of the results, our society needs novel mechanisms. As one of such mechanisms, the Ethereum blockchain is an environment for developing decentralized applications with the reliable blockchain technology. Ethereum decentralized applications can utilize smart contracts to provide services for users in transparent and reliable ways. In this paper, we propose a polling method that guarantees reliability using the blockchain technology, which is a distributed ledger technique that makes forgery or falsification actually impossible. The proposed method provides a robust verification function on the results of the associated polls for individual voters and verification organizations. Also, we present a distributed opinion polling application running on our private Ethereum blockchain network, showing the effectiveness of the proposed method.

• Journal of Industrial Convergence
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• v.21 no.7
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• pp.41-49
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• 2023

In recent years, various educational institutions have used online certificate services to verify academic achievement related to graduation and grades. However, the certificate of the existing system has limitations in verifying and tracking whether it is true or not and detailed academic background. In this regard, cases of forgery/falsification of online/offline certificates continue to occur. This study proposes a blockchain-based verification method that is safe from forgery and alteration, focusing on university institutions. Necessary information such as detailed class categories for each department, attendance, and detailed grades was collected/analyzed to create a linkage relationship through blockchain. In addition, the system/network environment required for blockchain sharing was considered, and it was implemented as an extension module in the form of an independent web application. As a result of the block chain verification, it was proved that the safe trust verification of educational information and the relationship between detailed information can be traced. This study aims to contribute to the improvement of academic credential verification services and information security for Korean educational institutions in the future.

• Journal of Software Engineering Society
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• v.29 no.2
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• pp.7-12
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• 2020

A project to establish an information system with a project cost of more than 500 million won at a local public firm is subject to the Information System Audit (hereinafter referred to as IS Audit), and the IS Auditor shall conduct audit according to the audit criteria. Recently, as blockchain technology has been applied to various fields such as manufacturing, healthcare, distribution, and public sectors beyond the financial industry, the development of systems that apply blockchain technology is increasing. The use of Hyperledger Fabric, a private blockchain, is on the rise to utilize blockchain technology in public firms and private firms. However, the newly emerging blockchain-based system is not sufficient to carry out auditing with existing audit check items, so it has no choice but to make and use audit items individually. Therefore, a need for verified audit items for systems that base on blockchain technology has emerged. In this study, we customized the Delphi process to derive audit items suitable for the system development project using the blockchain technology, and verified the completeness and accuracy of the audit items derived through a survey by the IS Auditor. This research will be of direct help to the IS Auditor, and it is expected that operators and organizers who provide services through the blockchain-based system will also contribute to improving the quality of the system.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.11a
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• pp.348-351
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• 2021

본 논문에서는 지속적으로 늘어나고 있는 내부의 유출자를 탐지하기위해 컨소시엄 블록체인 기술을 활용하여 기업간 직원의 PC사용 행위 로그 데이터를 가명처리하여 블록에 기록하여 네트워크에 참여한 다른 기업들간의 안전한 공유를 통해 내부자 유출 데이터 및 시나리오의 확장하여 내부에서의 유출을 탐지할 수 있는 데이터 셋을 확보하는 연구를 제안한다. 현재 내부자 위협탐지의 한계점중 가장 큰 요소를 차지하는 부족한 실제 사례의 내부자 유출 데이터 셋의 문제점을 본 연구를 통해서 네트워크 참여 기업간의 내부자 유출 데이터를 확장하고 타기업의 유출 사례를 활용해 기업에서 발생할 수 있는 내부자 유출을 미연에 방지할 수 있다.