• Journal of Energy Engineering
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• v.29 no.3
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• pp.86-90
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• 2020

This paper examines a blockchain network-based transaction system using location proofing in power direct transactions between networked energy clouds, energy communities, and prosumer machines participating in smart cities. It utilizes location-based blockchain network technology, which enables long-distance travel with recharging by power purchases during autonomous movements, autonomous electric vehicles that can purchase and sell electricity, and solar street lights that can be produced and sold in fixed form. In addition, it is possible to provide optimum power transaction matching and settlement reliability between machines without human intervention in power transactions between electric chargers. It also introduces a business-to-object business model between autonomous machines that exist in multiple and different spaces and through energy clouds that are expected to be scattered with various transaction prices, policies, and incentives.

• Journal of the Korea Convergence Society
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• v.11 no.2
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• pp.109-116
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• 2020

Social media is growing rapidly as a means of promoting artists' artworks and a channel for sales. However, since social media is not fundamentally a platform designed for trading, it has various limitations that make it difficult to ensure trust and security in carrying out transactions. In this paper, it is proposed interoperability between social media and blockchain-based smart contract system that can record and preserve the artist's profile, information related to artworks and details of the contract on the blockchain. The proposed interoperability allows artwork trading participants on social media to maintain mutual trust and to conduct the contract transparently. Also, the proposed interoperability consists of an API provided by the social media developer or an open source API without having to modify existing social media. This study is expected to contribute to the growth of the art trading market on social media by complementing the art trading practices on social media.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.2
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• pp.299-308
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• 2019

As the utilization value of personal information becomes higher, discussions about providing personal information are being conducted actively. One of the most common methods of providing personal information is that a group obtains a personal information with a consent of individual. However, the above method has 2 problems. First, more information is exposed than the information required by organization for utilization of personal information. Second, trusted party should provide organization with an authentication of personal information whenever they require personal information. To solve these problems, we propose a personal information management system with blockchain using zk-SNARK(zero-knowledge Succinct Non-interactive ARgument of Knowledge) for privacy. Our proposal enables individuals to guarantee reliability of their information and protect their privacy concurrently using zk-SNARK when they provid organization with their personal information. In addition, it is possible to manage the personal information data while ensuring the integrity of the data using blockchain and it is possible to share the personal information more conveniently than existing systems.

• Journal of Convergence for Information Technology
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• v.9 no.7
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• pp.14-24
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• 2019

It is necessary to look into multiple subjects, such as effectiveness, laws and polices of blockchain in order to easily accept blockchain technology in small and mid-sized enterprises(SME). This study analyzes the positive effects of applying the block chain to SMEs, examines the laws and policies required to apply them, and identifies the tasks. As a result, we confirmed that it can create positive effects such as optimizing supply chain management, simplifying import and export process documents, improving product quality, facilitating flow of funds, and improving transaction reliability. Also, we confirmed that it is necessary to improve the basic law of electronic transaction, electronic commerce law, electronic financial transaction law, personal information protection legislation, and needs policy supplement for platform development, education system for SMEs, transaction standardization guidelines, tax reduction policy, and block chain research and development. More extensive practical research and specific individual legal studies are needed in the future.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.1
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• pp.264-284
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• 2021

As the next-generation network architecture, software-defined networking (SDN) has great potential. But how to forward data packets safely is a big challenge today. In SDN, packets are transferred according to flow rules which are made and delivered by the controller. Once flow rules are modified, the packets might be redirected or dropped. According to related research, we believe that the key to forward data flows safely is keeping the consistency of flow rules. However, existing solutions place little emphasis on the safety of flow rules. After summarizing the shortcomings of the existing solutions, we propose FRChain to ensure the security of SDN data forwarding. FRChain is a novel scheme that uses blockchain to secure flow rules in SDN and to detect compromised nodes in the network when the proportion of malicious nodes is less than one-third. The scheme places the flow strategies into blockchain in form of transactions. Once an unmatched flow rule is detected, the system will issue the problem by initiating a vote and possible attacks will be deduced based on the results. To simulate the scheme, we utilize BigchainDB, which has good performance in data processing, to handle transactions. The experimental results show that the scheme is feasible, and the additional overhead for network performance and system performance is less than similar solutions. Overall, FRChain can detect suspicious behaviors and deduce malicious nodes to keep the consistency of flow rules in SDN.

• Journal of Creative Information Culture
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• v.5 no.2
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• pp.173-182
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• 2019

Recently, creative teaching methods have received a lot of attention in the university community. Creative teaching methods can maximize the effectiveness of the creative education through the voluntary participation of students. One of the most important skills in creative teaching methods is communication because many students are passive in their real classes. An economic reward system helps to improve students' communication skills because it motivates students to study harder. Therefore, a blockchain media based on an economic reward system can be useful teaching tools. This paper proposes a creative teaching method using blockchain media to improve communication skills. The proposed method consists of eight steps, and it was applied to classes for the last three years. The results show that the proposed method helps students improve their communication skills.

• Convergence Security Journal
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• v.22 no.1
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• pp.71-79
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• 2022

The smart grid system has emerged to maximize energy efficiency through real-time information exchange between power providers and consumers by combining information technology and power supply systems. The authentication schemes using blockchain in a smart grid system have been proposed, which utilize an edge server's architecture to collect and store electric power-related information and process data between a central cloud server and smart grid-IoT devices. Although authentication schemes are being proposed to enhance security in the smart grid environment, many vulnerabilities are still reported. This paper presents a new mutual authentication scheme to guarantee users' privacy and anonymity in a smart grid based on edge computing using blockchain. In the proposed scheme, we use the smart contract for the key management's efficiency, such as updating and discarding key materials. Finally, we prove that the proposed scheme not only securely establishes a session key between the smart grid-IoT device of the user and the edge server but also guarantees anonymity.

• KIPS Transactions on Software and Data Engineering
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• v.11 no.6
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• pp.267-272
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• 2022

Online exams are not limited by time and space. It has the advantage that it does not require a separate exam site for examinees, and there is no time and cost required to move to the exam site. However, the online exam has the disadvantage that various cheating is possible because the exam is conducted in an individual environment. In addition, there is a difficulty in detecting cheating due to the lack of exam supervision methods. In addition, since the exam process and result data exist only as digital data, it is inconvenient to check directly on the server where the exam result is stored in order to check whether the exam result is forged or not. If the data related to the exam is maliciously changed, the authenticity cannot be verified. In this study, we tried to increase the reliability of the online exam by developing a blockchain-based online exam cheating detection system that stores exam progress-related data in the blockchain to detect cheating. Through the experiment, it was confirmed that forgery and falsification are detected as a result of the exam.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.7
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• pp.946-954
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• 2021

Since COVID19 virus has been occured, variety steps of the quarantine guidelines were enacted. In step 2.5, eating in a cafe was prohibited and only takeout was permitted, but the government has changed several rules. So now people can have a dissert or coffee in the cafe. Though the government adviced available staying time as 1 hour, it is not obeyed often except superstore, and even the management depends on handwriting. In this paper, we implemented a blockchain system to use for this case. This system is implemented with using hyperledger fabric, the blockchain framework which is made by IBM. For a test, 1 organization is in the system and chaincode is installed to the organization to run the system. We expect the certain effect to the quarantine via this system. Moreover, we will develop an application by using this system as a backend.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.4
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• pp.462-469
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• 2019

According to the survey of Ministry of the Interior and Safety in Korea, The number of public and private CCTV reached over ten million and is still increasing. Also with improving Image Processing Technology, it is possible to obtain diverse information. Recently, various services using CCTV are being provided. Therefore it is necessary to ensure CCTV image integrity. However there is no system to prove events in film yet. In this paper, we suggest system model that can manage, use and authenticate CCTV. This model allows a CCTV film to be verified by other nearby CCTVs' data. This model ensures film's integrity by using blockchain. And also, It addresses privacy problem in CCTV and file size problem in blockchain by using not large film data but much smaller analyzed data.