• Review of KIISC
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• v.28 no.3
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• pp.47-52
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• 2018

암호화폐가 세계적으로 주목받으며 핵심기술인 블록체인에 대한 관심이 증가하고 있다. 블록체인은 블록을 P2P 방식을 기반으로 생성된 체인 형태의 연결고리로 분산 저장되어 있으며 임의로 수정할 수 없고 누구나 변경의 결과를 열람가능하다. 블록체인의 공개 형태에 따라 공개형 블록체인과 허가형 블록체인으로 나뉘어 연구되고 있다. 이 논문에서는 세대별 블록체인의 개발 현황과 특징에 대해서 알아본다. 또한 블록체인 공개형태에 따른 특징과 보안성에 대하여 알아보고자 한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.6
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• pp.795-801
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• 2020

In the event of a fatal infectious disease in the country, it is very important that the government respond quickly and prevent the secondary infection of the people to prevent the subsequent spread of damage. However, in order to detect infectious diseases in existing medical institutions, and to reach the KCDCP(Korea Centers for Disease Control and Prevention) a total of four steps must be taken. In this paper, we simplifies the existing reporting process using the open blockchain. In addition, not only infectious disease related organizations share infectious disease information on the blockchain, but also grant access to the blockchain to ordinary citizens. By sharing information quickly and transparently revealing the process, we can add credibility to the response to the outbreak and official announcements. The public can also build efficient next-generation defense systems by checking information on the blockchain to prevent secondary infections.

• Journal of Internet Computing and Services
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• v.21 no.3
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• pp.1-9
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• 2020

Along with the growth of Blockchain, DApp (Distributed Application) is getting attention. As interest in DApp grows, market size continues to grow and many developers participate in development. Many developers are using API(Application Programming Interface) services to mediate Blockchain nodes, such as Infura, for DApp development. However, when using such a service, there is a serious risk that the API service operator can violate the user's privacy by 1 to 1 matching the account address of the Transaction executed by the DApp user with the IP address of the DApp user. It can have an adverse effect on the reliability of public Blockchains that need to provide users with a secure DApp service environment. The proposed Blockchain platform is expected to provide user privacy protection from API services and provide a reliable DApp use environment that existing Blockchain platforms did not provide. It is also expected to help to activate DApp and increase the number of DApp users, which has not been activated due to the risk of an existing privacy breach.

• The Journal of the Convergence on Culture Technology
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• v.7 no.1
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• pp.608-614
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• 2021

Currently, blockchain-based public cryptocurrency (hereinafter referred to as cryptocurrency) cannot acquire status as a currency for transaction due to the economic policies of each country, but it is used as an alternative currency transaction method due to individual circumstances of some Internet users. With this trend, it is predicted that such cryptocurrency can be used in real life beyond the Internet in the near future. In this paper, a technical method for designing a cryptocurrency payment system based on LoRaWAN that can easily build a wireless Internet network infrastructure at low cost as a way to activate the use of cryptocurrency in real life is presented based on the LoRaWAN standard.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.1
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• pp.55-60
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• 2020

In this paper, we propose an access control system using cryptography as a method to protect personal data in public blockchain. The proposed system is designed to encrypt data according to the access policy, store it in the blockchain, and decrypt only the person who satisfy the access policy. In order to improve performance and scalability, an encryption mechanism is implemented outside the blockchain. Therefore, data access performance could be preserved while cryptographic operations executed Furthermore it can also improve the scalability by adding new access control modules while preserving the current configuration of blockchain network. The encryption scheme is based on the attribute-based encryption (ABE). However, unlike the traditional ABE, the "retention period", is incorporated into the access structure to ensure the right to be forgotten. In addition, symmetric key cryptograpic algorithms are used for the performance of ABE. We implemented the proposed system in a public blockchain and conducted the performance evaluation.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.1
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• pp.149-156
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• 2023

This research tried to develop an ESS electricity trading system linked with blockchain for energy participation consumers. For the purpose of publishing renewable energy ESS power amount and demand information, we will build a smart contract system on the blockchain DB, utilize the blockchain DB data of energy prosumers and consumers, and expand the power trading market flexibly. to provide realistic solutions. Therefore, the main contents of the development of the ESS power trading system linked to the blockchain are cloud-based web construction for ESS management, coin issuance and exchange registration for activating the blockchain, and to reflect the blockchain technology, building a blockchain database for collecting and supplying ESS-based production demand data, selecting a blockchain-based platform and building a foundation, and creating a smart contract, etc.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.2
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• pp.51-58
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• 2022

Blockchain technology is a system in which data from users participating in blockchain networks is distributed and stored. Bitcoin and Ethereum are attracting global attention, and the utilization of blockchain is expected to be endless. However, the need for blockchain data privacy protection is emerging in various financial, medical, and real estate sectors that process personal information due to the transparency of disclosing all data in the blockchain to network participants. Although studies using smart contracts, homomorphic encryption, and cryptographic key methods have been mainly conducted to protect existing blockchain data privacy, this paper proposes data privacy using matrix character relocation techniques differentiated from existing papers. The approach proposed in this paper consists largely of two methods: how to relocate the original data to matrix characters, how to return the deployed data to the original. Through qualitative experiments, we evaluate the safety of the approach proposed in this paper, and demonstrate that matrix character relocation will be sufficiently applicable in private blockchain environments by measuring the time it takes to revert applied data to original data.

• The Journal of Society for e-Business Studies
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• v.22 no.1
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• pp.51-64
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• 2017

After Bitcoin was proposed by Satoshi Nakamoto in 2009, studies have been carried out to apply the Block Chain technology in various environment, which was applied as a distributed transaction of Bitcoin. Smart contracts, voting and proof of ownership of digital contents are typical applications of Block Chain. They used the feature that it is impossible to modify or delete once recorded facts. They also applied to prove relevant facts and to provide data integrity. The applied cases are mainly made in an environment where the data should or could be open to the public, and they have been proposed as solutions to solve the problems occurred in relations. This fact has led to the attention that Block Chain can be applied as a good alternative in similar circumstances. In this study, real estate market service was selected to expand the application range of Block Chain. Although there are about 250 applications and web services in total, the satisfaction is not high due to false offerings. Thus we propose a countermeasure against the problem by applying the Block Chain to the real estate market service, and investigate the research direction of the Block Chain in the future market.

• The Journal of the Convergence on Culture Technology
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• v.5 no.1
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• pp.451-456
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• 2019

Our students are shocked by the results that there is an inverse proportion between academic achievement and life satisfaction. Recently, the Organization for Economic Cooperation and Development (OECD) published the PISA 2015 Student Well-Being Report. According to the report, Korean students' education is the highest among OECD countries, but their life satisfaction is the 47th ranked among the 48 OECD and non-OECD countries.[1] This is the cause of the unilateral education using collective achievement in evaluation methods. Therefore, I propose a personalized integrated model utilizing block chain technology. I suggest a personalized education and evaluation system model using selective education and personal approval rather than from teachers' unilateral education. This will no longer open the student's achievement grade system to the public. This change will be accomplished utilizing block chain technology. This technology is characterized by security, transparency and dispersion. The result of this work can be used to improve students' quality of living through a management system of personalized education and evaluation, based on the nature of education.

• Smart Media Journal
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• v.12 no.2
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• pp.76-82
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• 2023

In the 4th industrial revolution, the blockchain that distributes and manages data through a P2P network is used as a new decentralized networking paradigm in various fields such as manufacturing, culture, and public service. However, with the advent of quantum computers, quantum algorithms that are able to break existing cryptosystems such as hash function, symmetric key, and public key cryptography have been introduced. Currently, because most major blockchain systems use an elliptic curve cryptography to generate signatures for transactions, they are insecure against the quantum adversary. For this reason, the research on the quantum-resistant blockchain that utilizes lattice-based cryptography for transaction signatures is needed. Therefore, in this paper, we propose a blind signature scheme for the blockchain in which the contents of the signature can be verified later, as well as signing by hiding the contents to be signed using lattice-based cryptography with the property of quantum resistance. In addition, we prove the security of the proposed scheme using a random oracle model.