• Proceedings of the Korea Information Processing Society Conference
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• 2022.05a
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• pp.252-255
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• 2022

기존 블록체인 기술을 활용해 새로운 비즈니스 모델을 개발 및 투자하려는 기업들의 관심이 높아지고 있으나, 낮은 확장성으로 인해 기존 블록체인 기술만으로는 시장에서 활용되기 어렵다. 블록체인의 낮은 확장성을 해결하기 위해 검증된 참여자만 참여하는 프라이빗 블록체인과 프라이빗 블록체인 고속화를 위한 관련 연구가 같이 진행되고 있다. 삼성의 넥스레저는 하이퍼레저 패브릭의 다중 버전 동시성 제어(MVCC) 충돌로 인한 낮은 TPS 문제를 해결하기 위해 Accelerator를 추가하여 고속화를 진행하였다. 하지만 모든 트랜잭션을 수집하여 처리하는 방식인 Accelerator는 중앙화로 인해 악의적인 공격 타깃이 되어 단일 장애 지점 문제가 발생할 수 있으며, 공격으로 인해 위조되거나 분실된 데이터는 검증 없이 블록체인 블록에 반영되고, 한번 반영된 데이터는 수정이 어렵다. 본 논문에서는 이와 같이 프라이빗 블록체인 고속화 상황에서 발생할 수 있는 단일 장애 지점 문제를 해결하기 위해 CMT와 사기증명 기반의 고속화 하이퍼레저 패브릭 시스템을 제안했으며, 제안한 시스템을 구축하고 성능 테스트를 통해 CMT 하이퍼레저 패브릭 시스템 성능이 99.58% 유지됨과 사기증명이 가능함을 확인하였다.

• Journal of Convergence for Information Technology
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• v.9 no.11
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• pp.15-21
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• 2019

Allowing only authorized users to record and inquire in the ledger, private blockchain technology is attracting attention from institutions and companies. Based on distributed ledger technology, records are immutable. Because news via the Internet can be easily modified, the possibility of manipulation is high. Some false communication report systems are designed to prevent such harm. However, during the gap between the false communication report and verification time, contents on the website can be modified, or false evidence can be submitted intentionally. We propose a system that collects evidence using a headless browser for more accurate false communication management, and securely preserves evidence through a private blockchain and prevents possibilities of manipulation. The proposed system downloads original HTML, captures the website as an image, stores it in a transaction along with the report, and stores it in a private blockchain to ensure the integrity from acquisition to preservation of evidence.

• Journal of Internet of Things and Convergence
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• v.8 no.1
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• pp.11-16
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• 2022

Efforts to incorporate blockchain into various fields are continuing as cryptocurrency transactions become more active. Blockchain has the characteristic that once recorded facts cannot be modified or deleted. Due to these characteristics, the use in the field of recording and proving certain facts, such as voting or proof of ownership, is attracting attention. In this paper, users who want to participate in the transaction process using private blockchain, one of the types of blockchain, are divided into real estate brokers, building owners, and purchasers (lessors), and roles are assigned to each user. In addition, we would like to propose a system to increase reliability through the participation of institutions. Through this, we intend to not only present a real estate transaction system that prevents damage from real estate fraud related to false sales and fraudulent contracts, but also enhances reliability and contributes to finding ways to utilize blockchain in the future.

• Smart Media Journal
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• v.9 no.1
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• pp.9-15
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• 2020

Recently there have been increasing attempts to apply blockchains to businesses and public institutions. Blockchain is a distributed shared ledger with excellent transparency and security of data and through consensus algorithm, the same data can be shared to all nodes in order. In this paper, Modified PBFT which does not modify the PBFT consensus algorithm is proposed. MPBFT is able to tolerate Byzantine faults on a private blockchain on an asynchronous network. Even with the increase of participating nodes, the network communication cost can be effectively maintained. Modified PBFT takes into account the characteristics of an asynchronous network environment where node-to-node trust is guaranteed. In response to the client's request, PBFT performed the entire participation broadcast several times, but Modified PBFT enabled consensus and authentication through the 2 / N leader. By applying the Modified PBFT consensus algorithm, the broadcast process can be simplified to maintain the minimum number of nodes for consensus and to efficiently manage network communication costs.

• Review of Korea Contents Association
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• v.16 no.2
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• pp.20-24
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• 2018

• 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.

• Journal of Industrial Convergence
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• v.18 no.6
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• pp.147-154
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• 2020

It is difficult to educate the overall operation of public and private blockchains with different characteristics. Recently, most education for blockchain is targeted at public blockchains such as Bitcoin and Ethereum. However, in an actual business environment, a private blockchain such as HyperLedger Fabric is used because access to corporate data is controlled through user authentication. In the case of HLF-based education, it is necessary to understand various components that are not in the public blockchain, such as peers, orderers, and channels. In this paper, a lab framework for HLF is designed for an efficient and systematic understanding of the functions and operations. The framework consists of HLF network, chaincode, and decentralized software control functions. Through the framework, the network configuration, distribution and activation of chaincode, and dApp execution process were checked step by step, and it was very easy to understand the overall flow for blockchain services. In addition, it is expected that a systematic understanding of the overall flow will be possible even in future network expansion.

• Journal of Internet Computing and Services
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• v.20 no.5
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• pp.121-132
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• 2019

As the 4th industrial age enters, the number of IoT devices is exploding. Accordingly, the importance of security is also increasing in proportion to the increasing number of security incidents of IoT devices. However, due to the limited performance of IoT devices, there are limitations to applying existing security solutions. Therefore, a new automatic firmware distribution solution is needed to solve this problem. To solve this problem, we propose a new automatic firmware update system that uses a hybrid blockchain that combines a public blockchain and a private blockchain. The public blockchain allows various firmware providers to distribute firmware using a common system. Private blockchain solves the transaction overload problem of the public blockchain and facilitates the management of IoT devices. It also uses distributed file storage to ensure high availability without failing. Therefore, this system is expected to be very effective for improving the security of IoT devices.

• Journal of the Korea Society of Computer and Information
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• v.26 no.2
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• pp.69-78
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• 2021

In this paper, we propose a implementation plan of the human resource pool recruitment system using private (permitted) blockchain. The term Human Resource has become commonly used and has come to recognize human resources as resources. Despite these changes, the use of human resource pools has been sluggish. Once entered, information is often not updated on a regular basis and does not provide sharing, searching, carrier management and anti-counterfeiting. In this research, in order to provide a human resource pool recruitment system that utilizes private (permitted) blockchain, we first used the blockchain network to enable sharing and searching of human resource pools, and to use keywords. Used to get results that meet certain conditions. Second, we added an institutional verification process to ensure the integrity of the input data and prepared preventive measures in the non-technical part by utilizing the structural characteristics of the blockchain to prevent counterfeiting and alteration. Third, we designed and implemented a Dapp (Decentralized application) that includes a Web UI so that each of the three groups can control the blockchain and the predefined processes and business logic.

• Journal of Internet of Things and Convergence
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• v.9 no.1
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• pp.33-39
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• 2023

As the number of people with chronic diseases increases due to an aging society, it is urgent to prevent and manage their diseases. Although biometric authentication methods and Telemedicine Systems have been introduced to solve these problems, it is difficult to solve the security problem of medical information and personal authentication. Since smart healthcare includes personal medical information of subjects, the security of personal information is the most important field. Therefore, in this paper, we tried to propose a Telemedicine System using a smart wearable device ECG in the form of a wristband and face personal authentication in a private blockchain environment. This system targets various medical personnel and patients with chronic diseases in all regions, and uses a private blockchain that can increase data integrity and transparency, ECG and face authentication that are difficult to forge and alter and have high personal identification to provide a system with high security and reliability. composed. Through this, it is intended to contribute to increasing the efficiency of chronic disease management by focusing on disease prevention and health management for patients with chronic diseases at home.