• KIPS Transactions on Software and Data Engineering
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• v.11 no.1
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• pp.19-28
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• 2022

Recently, cryptocurrency has attracted much attention, and price prediction studies of cryptocurrency have been actively conducted. Especially, efforts to improve the prediction performance by applying the deep learning model are continuing. LSTM (Long Short-Term Memory) model, which shows high performance in time series data among deep learning models, is applied in various views. However, it shows low performance in cryptocurrency price data with high volatility. Although, to solve this problem, new input features were found and study was conducted using them, there is a lack of study on input features that drop predictive performance. Thus, in this paper, we collect the recent trends of six cryptocurrencies including Bitcoin and Ethereum and analyze effects of input features on the cryptocurrency price predictive performance through statistics and deep learning. The results of the experiment showed that cryptocurrency price predictive performance the best when open price, high price, low price, volume and price were combined except for rate of closing price fluctuation.

• International Journal of Computer Science & Network Security
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• v.22 no.3
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• pp.364-374
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• 2022

Health information systems (HIS) are facing security challenges on data privacy and confidentiality. These challenges are based on centralized system architecture creating a target for malicious attacks. Blockchain technology has emerged as a trending technology with the potential to improve data security. Despite the effectiveness of this technology, still HIS are suffering from a lack of data privacy and confidentiality. This paper presents a blockchain-based data storage security architecture integrated with an e-Health care system to improve its security. The study employed a qualitative research method where data were collected using interviews and document analysis. Execute-order-validate Fabric's storage security architecture was implemented through private data collection, which is the combination of the actual private data stored in a private state, and a hash of that private data to guarantee data privacy. The key findings of this research show that data privacy and confidentiality are attained through a private data policy. Network peers are decentralized with blockchain only for hash storage to avoid storage challenges. Cost-effectiveness is achieved through data storage within a database of a Hyperledger Fabric. The overall performance of Fabric is higher than Ethereum. Ethereum's low performance is due to its execute-validate architecture which has high computation power with transaction inconsistencies. E-Health care system administrators should be trained and engaged with blockchain architectural designs for health data storage security. Health policymakers should be aware of blockchain technology and make use of the findings. The scientific contribution of this study is based on; cost-effectiveness of secured data storage, the use of hashes of network data stored in each node, and low energy consumption of Fabric leading to high performance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.7
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• pp.1060-1070
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• 2022

With the development of information technology, the size of the system has become larger and diversified, and the existing role-based access control has faced limitations. Blockchain technology is being used in various fields by presenting new solutions to existing security vulnerabilities. This paper suggests efficient role-based access control in a blockchain where the required gas and processing time vary depending on the access frequency and capacity of the storage. The proposed method redefines the role of reusable units, introduces a hierarchical structure that can efficiently reflect dynamic states to enhance efficiency and scalability, and includes user-centered authentication functions to enable cryptocurrency linkage. The proposed model was theoretically verified using Markov chain, implemented in Ethereum private network, and compared experiments on representative functions were conducted to verify the time and gas efficiency required for user addition and transaction registration. Based on this in the future, structural expansion and experiments are required in consideration of exception situations.

• Convergence Security Journal
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• v.22 no.1
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• pp.121-127
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• 2022

Recently, social issues related to cryptocurrency mining are continuously occurring at the same time as cryptocurrency prices are rapidly increasing. In particular, since cryptocurrency can be acquired through cryptographic operation, anyone with a computer can easily try mining, and as the asset value of major cryptocurrencies such as Bitcoin and Ethereum in creases, public interest is increasing. In addition, the number of cases where individuals who own high-spec computers mine cryptocurrencies in various places such as homes and businesses are increasing. Some miners are mining at companies or public places, not at home, due to the heat problem of computers that consume a lot of electrical energy, causing various problems in companies as well as personal moral problems. Therefore, this study studies the technology to obtain evidence for the traces of mining attempts using the Windows artifacts of the computers that mined cryptocurrency. Through this, it is expected that it can be used for internal audit to strengthen corporate security.

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.3
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• pp.189-195
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• 2020

Smart contract, one of the applications of blockchain, is expected to be used in various industries. However, there is risks of damages caused by attacks on vulnerabilities in smart contract codes. Tool support is essential to detect vulnerabilities, and as new vulnerabilities emerge and smart contract implementation languages increase, the tools must have extensibility for them. We propose a design model for extensible architecture of smart contract vulnerability detection tools that detect vulnerabilities in smart contract source codes. The proposed model is composed of design pattern-based structures that provides extensibility to easily support extension of detecting modules for new vulnerabilities and other implementation languages of smart contract. In the model, detecting modules are composed of independent module, so modifying or adding of module do not affect other modules and the system structure.

• Journal of Korea Multimedia Society
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• v.23 no.5
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• pp.658-666
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• 2020

PGP is an encryption software designed to provide information protection, security and authentication services for online communication systems. The characteristic of behavior done on the Internet is that you don't know the other person. It is very important to protect information from someone you cannot trust. So identification of the other person is an important task. PGP uses an digital signature algorithm to verify the identity of the other party. However, it is not accurate to check the other party's credibility. PGP increases trust as other users sign more on public keys of user. In other words, credibility is not perfect. In this paper, PGP certification system that key management in Ethereum blockchain, one of the blockchain platforms, is proposed. Key management in blockchain ensures data integrity, transparency and reliability.

• International journal of advanced smart convergence
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• v.9 no.2
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• pp.157-163
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• 2020

Recently the blockchain technology has been actively studied due to its great potentiality. The smart contract is a key mechanism of the blockchain system. Due to the short history of the smart contract, many issues have not been solved yet. One main issue is vulnerability and another main issue is cost optimization. While the vulnerability of smart contract has been actively studied, the cost optimization has been rarely studied. In this paper, we propose two cost optimization methods for smart contracts running on the blockchain system. Triggering a function in a smart contract program code may require costs and it is repeated continuously. So the minimization of costs required to trigger a function of smart contract while maintaining the performance equally is very important. The proposed two methods minimize the usage of expensive permanent variables deployed on the blockchain system. We apply the proposed two methods to three prevalent blockchain platforms: Ethereum, Klaytn and Tron. Evaluation experiments verify that the proposed scheme significantly reduces the costs of functions in the smart contract written with Solidity.

• Proceedings of the Korean Society of Computer Information Conference
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• 2018.07a
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• pp.297-298
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• 2018

본 논문에서는 모듈형 NVIDIA Jetson TX2 임베디드 제품에서 채굴을 통해 블록체인의 적합성 여부를 보인다. 범용성과 적합성의 평가기준은 TPS (Transactions Per Second), 블록생성시간(Block Generation Time)과 확정시간(Confirmation Time)이다. 채굴 준비 시 TX2 임베디드 제품의 특성상 하드웨어 드라이버를 자립적으로 설치 할 수 없기 때문에 HOST PC와 함께 사용하였다. HOST PC는 TX2 제품과 호환성이 높은 OS인 Ubuntu 14.04를 사용했으며, 하드웨어 드라이버 설치를 위해 NVIDIA 공식 TX2 제품 소프트웨어 중 JetPack 3.1 Release Version 을 사용하였다. 코인은 이더리움(Ethereum), 라이트코인(Litecoin)과 제트캐쉬(Zcash) 총 3종 코인으로, 채굴 시 나온 결과물로 TX2 제품에서 블록체인의 적합성 여부를 보였다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2018.07a
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• pp.69-72
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• 2018

국내 뿐 아니라 세계적으로 디지털 기반의 공유경제 서비스와 관리에 대하여 많은 관심을 두고 있다. 공유경제로 인하여 새로운 경제패러다임으로 높은 가능성이 있고 정부와 시민이 편익차원에서 많은 예산 절감이 가능하기 때문이다. 우버, 에어 비엔비 등의 사업이 활성화 되고 있는 상황에서 디지털 콘텐츠 역시 활용 공유 가능한 재화로써 공유경제에 참여하고 신뢰기반의 효과적 거래가 가능하다. 이 논문에서는 디지털 콘텐츠를 공유경제로 활용함에 있어 위 변조 및 해킹 가능성을 줄이고 투명한 거래가 가능하여 디지털 콘텐츠의 유통이 활성화 될 수 있는 방법으로 블록체인 활용기법을 제안하였다. 스마트 유통과정에서 이더리움의 스마트 컨트랙트 방법을 적용하고 디지털 콘텐츠 저작권을 보호하기 위한 머클트리 해싱방법과 암호화방법을 수정함으로써 디지털 콘텐츠가 공유경제로써 발돋움하고 활성화될 수 있을 것이다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2018.07a
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• pp.73-75
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• 2018

디지털 콘텐츠의 영역을 확장하여 발달된 기술을 반영한 다양한 디지털 콘텐츠 기술이 발달하고 있다. 가상현실, 증강현실, 컴퓨터그래픽, 홀로그램, 오감 인터랙션, 지능형 스마트 미디어 유통기술이 그것인데 이 중 지능형 스마트 미디어 유통기술이란 IoT, 클라우드, 빅데이터 기반 개인 맞춤형 콘텐츠 유통기술, 영상정보를 검색하여 방송, 모바일 등 연관콘텐츠를 제공하는 유통기술(Visual Browsing) 등을 말한다. 이 논문에서는 디지털 콘텐츠 중 지능형 스마트 미디어 유통기술을 안전하게 개발하고 발전시키기 위하여 블록체인 방법을 활용한 스마트 미디어 유통기술에 대하여 연구하였다. 블록체인 기반 기술을 통하여 스마트 미디어 유통 시 해킹으로부터 데이터 원본 보호의 안전함을 제공하고 유통 시 필요한 저작권관리 및 유통 기록을 위 변조 없이 관리할 수 있다.