• The Journal of the Convergence on Culture Technology
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• v.8 no.1
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• pp.583-590
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• 2022

With the release of the Bitcoin source in 2009, cryptocurrencies are continuously developing and expanding the market. Recently, new applicability is expanding centered on NFT coin and metaverse payment service. In particular, the Central Cryptocurrency Exchange actively supports relay transactions between cryptocurrencies or between traditional fiat currencies and cryptocurrencies. The cryptocurrency trading market based on such a central exchange encouraged speculative factors of cryptocurrencies, strongly arousing speculation and futility of cryptocurrencies. In addition, the central cryptocurrency exchange induces the centralization of users and virtual assets, thereby hindering the decentralization and security enhancement strategies of the block chain. Therefore, this study describes the current status and problems of centrally controlled centralized cryptocurrency exchanges in service, and presents a distributed cryptocurrency exchange modeling strategy and major issues as a decentralization model of the exchange. This research can strengthen the anonymity, decentralization, and autonomy of cryptocurrency based on blockchain.

• Proceedings of the Korea Information Processing Society Conference
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• 2019.10a
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• pp.97-100
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• 2019

사용자가 보유하고 있는 토큰은 기존 중앙화된 암호 화폐 거래소를 통해 교환 할 수 있다. 그러나 암호 화폐 거래소를 이용한 토큰 교환은 높은 수수료, 암호 화폐 거래소 해킹 가능성, 해당 거래소 내 등록된 암호 화폐에 대해서만 교환이 가능하다는 문제점이 존재한다. 이더리움 플랫폼에 배포된 스마트 컨트랙트는 블록체인 기반으로 다양한 형태의 계약을 조건이 만족할 시 자동으로 이행한다. 본 연구는 스마트 컨트랙트를 이용하여 기존의 중앙화된 암호 화폐 거래소 기반 토큰 교환 문제점을 해결하면서 이더리움 지갑 내 토큰을 사용자가 원하는 ERC-20 토큰으로 자동 교환해 주는 분산형 토큰 교환 시스템을 제안한다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.1
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• pp.187-194
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• 2019

Ever since the world's largest Bitcoin Echange, (Mt. Gox), was closed in March 2014 due to the series of hacking, still many other Exchages incl. recent Coinale in Korea have been attacked. Those hacking attempts never stopped and have caused significant threats to the overall industry of Crypto Currency and resulted in the loss of individual investors' asset. The DEX (Decentralized Exchange) has been proposed as a solution to fix the security problem at the Exchange, but still it is far away to resolve all issues. Therefore, this paper firstly analyzes security threats against existing Crypto Currency Exchanges and secondly derives security requirements for them. To do that it proposes a secure and distributed Crypto Currency Transaction Model through Personal Security devices as a solution. The paper also proves this new attempt by demonstrating its unique modelling; ultimately by adopting this modeling into Crypto Exchange is to avoid potential security threats.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.1
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• pp.100-106
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• 2018

Since the concept of virtual currency called Bitcoin was announced in 2008, the blockchain technology, which is the basis of Bitcoin, is attracting attention as an important platform technology in the era of the 4th industrial revolution that can change our society in the future. Although Existing electronic financial transactions store and manage all transaction history at a reliable central organization such as government and bank, blockchain-based electronic financial transactions are composed of a distributed structure in which all participants participating in the transaction store and manage the transaction history, it is possible to secure transaction transparency while reducing system construction and operation costs. Besides the virtual currency that started with bit coins, the technology of these blockchains has been extended in various fields such as smart contracts and document management. The key technology area of this blockchain is security based on proven cryptographic technology to make it difficult to forge and hack, but there are security risks such as security vulnerabilities in the virtual currency trading service, We will discuss security risks in using virtual currency and discuss countermeasures. Especially security accidents of virtual currency exchanges are occurring frequently recently, the damage of users who trade the virtual currency is also increasing, we propose security threats and security countermeasures against virtual currency exchanges.

• Proceedings of the Korea Information Processing Society Conference
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• 2019.05a
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• pp.65-67
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• 2019

최근 비트코인(Bitcoin)과 이더리움(Etherium)과 같은 퍼블릭 블록체인(Public Blockchain) 사용자의 급격한 증가로 인하여 블록체인 지갑 사용자가 늘어나고 있다. 또한, 암호화폐 거래소의 거래량이 증가와 이로 인한 지갑의 잔액 조회와 코인 이체를 위한 트랜잭션이 빈번하게 이루어 지고 있다. 한편, 최신의 잔액 조회와 빠른 이체를 위하여 마이닝 풀(Mining Pool)에서 사용되는 노드(Node)를 사용하는 것 같이 트래픽이 일부 노드에 집중되는 현상이 발생하여 시스템의 성능이 저하되는 문제가 있다. 이러한 문제를 해결하기 위하여 본 연구에서는 아파치 카프카(Apache Kafka)를 이용하여 트래픽 분산처리를 통한 효율적인 시스템을 제안한다. 또한, 시스템의 구조 설계 및 상세 모듈 설계를 제안한다. 제안 시스템은 기존 블록체인 시스템과의 연계가 가능하며, 기존 시스템의 변경 없이 구축할 수 있다. 또한, 주키퍼(ZooKeeper)의 분산처리를 통해 고성능과 가용성 및 안정성을 확보할 수 있다.

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.1
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• pp.17-28
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• 2019

In the financial investment management strategy, the distributed investment selecting and combining various financial assets is called portfolio management theory. In recent years, the blockchain based financial assets, such as cryptocurrencies, have been traded on several well-known exchanges, and an efficient portfolio management approach is required in order for investors to steadily raise their return on investment in cryptocurrencies. On the other hand, deep learning has shown remarkable results in various fields, and research on application of deep reinforcement learning algorithm to portfolio management has begun. In this paper, we propose an efficient financial portfolio investment management method based on Asynchronous Advantage Actor-Critic (A3C), which is a representative asynchronous reinforcement learning algorithm. In addition, since the conventional cross-entropy function can not be applied to portfolio management, we propose a proper method where the existing cross-entropy is modified to fit the portfolio investment method. Finally, we compare the proposed A3C model with the existing reinforcement learning based cryptography portfolio investment algorithm, and prove that the performance of the proposed A3C model is better than the existing one.