• Journal of Industrial Convergence
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• v.16 no.1
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• pp.15-20
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• 2018

Along with the increase of internet shopping, crimes that exploited personal information on the invoice of goods are becoming more and more advanced and becoming more and more classified from the interception of goods through voice phishing attack, injury, sexual offense. Therefore, in order to guarantee the anonymity of the customer's delivery information, there is a need for a delivery tracking prevention system which keeps the route information of the product's destination secret among delivery companies. For this purpose, We suggest that delivery tracing protect model based smart contract for guaranteed anonymity to protect the anonymity by encrypting delivery information and by separation of payment and personal information using the anonymity technique of block chain-based cryptography. Our proposed model contributes to expansion of internet shopping based on block chaining by providing information about product sales to company and guaranteeing anonymity of customer's delivery information to customer.

• Smart Media Journal
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• v.12 no.7
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• pp.27-42
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• 2023

The development of cloud services and IoT technology has radically changed the cloud environment, and has evolved into a new concept called fog computing and F2C (fog-to-cloud). However, as heterogeneous cloud/fog layers are integrated, problems of access control and security management for end users and edge devices may occur. In this paper, an F2C-based IoT smart health monitoring system architecture was designed to operate a medical information service that can quickly respond to medical emergencies. In addition, a role-based service access control technology was proposed to enhance the security of user's personal health information and sensor information during service interoperability. Through simulation, it was shown that role-based access control is achieved by sharing role registration and user role token issuance information through blockchain. End users can receive services from the device with the fastest response time, and by performing service access control according to roles, direct access to data can be minimized and security for personal information can be enhanced.

• Journal of Convergence for Information Technology
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• v.9 no.1
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• pp.86-91
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• 2019

Block chains began by recognizing the danger of centralized control of financial systems after the 2008 financial crisis. From the beginning of 2008, blockchain has been developing a lot of attention and technology, starting with a tremendous innovation called cryptographic destruction based on technology, a block chain called Bitcoin. However, the vulnerability has also been discovered over time and the damage has been repeated. But in the fourth industry of the 21st century, many advances and technologies based on them are expected to emerge. Therefore, this paper proposes new analytical transaction protocols for vulnerabilities in cryptographic currency transactions. The proposed transaction protocol is a way to authenticate once again at the end of the transaction and the transaction is concluded with this authentication. It presents countermeasures by adding security elements between users to the transaction process rather than internal security to transaction vulnerabilities.

• 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.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.2
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• pp.83-88
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• 2022

The purpose of this study is to present an analysis and implications for the metaverse-based virtual real estate transaction service. Through blockchain-based technology and metaverse, the world we live in is expanding naturally. Therefore, changes in the environment and perceptions of market participants are also very important factors. The concept and thinking about the existing asset value change and investment are also changing. This means that you can generate profits through value and investment in intangible assets. The service user aspect is a case of investing in the future value of virtual real estate that if more users participate rather than the present value, the principle of supply and demand will be applied to increase the number of consumers and the price will naturally rise according to the principle of scarcity. The service provider provides a technical platform for the service to directly transact the portion of the virtual area considered of interest directly through the virtual real estate purchase business. As the number of participants increases as well as funds and transaction fees, various revenue models such as advertisements can be discovered and provided. It plays the role of providing jobs and information through new services. As a stakeholder, governments can exploit the emergence of new technologies and products to create people and services and secure economic benefits. Of course, various institutional supports should be provided so that new services can settle in the market while mitigating risk factors. This study is meaningful in that it contributes to the establishment of a domestic metaverse-based environment and related research and is utilized in the study of virtual space real estate services.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.5
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• pp.147-156
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• 2022

Industrial control systems that manage and maintain various industries were mainly operated in closed environment without external connection, but with the recent development of the Internet and the introduction of ICT technology, the access to the industrial control system of external or attackers has become easier. Such incorrect approaches or attacks can undermine the availability, a major attribute of the industrial control system, and violation of availability can cause great damage. In this paper, when issuing commands in an industrial control system, a verification group is formed using a random list to verify and execute commands, and a trust score technique is introduced that applies feedback to the verification group that conducted verification using the command execution result. This technique can reduce overhead generated by random generation in the process of requesting command verification, give flexibility to the verification process, and ensure system availability. For the performance analysis of the system, we measured the time and gas usage when deploying a smart contract, gas usage when verifying a command. As a result, we confirmed that although the proposed system generates a random list compared to the legacy system, there was little difference in the time when it took to deploy smart contract and that the gas used to deploy smart contract increased by about 1.4 times in the process of generating a random list. However, the proposed system does not perform random operations even though the operation of command verification and confidence score technique is performed together during the command verification process, thus it uses about 9% less gas per verification, which ensures availability in the verification process.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.8
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• pp.269-280
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• 2022

With the rise of a decentralized finance market (so called, DeFi) using blockchain technology, users and capital liquidity of decentralized finance applications are increasing significantly. The Automated Market Maker (AMM) is a protocol that automatically calculates the asset price based on the liquidity of the decentralized trading platform, and is currently most commonly used in the decentralized exchanges (DEX), since it can proceed the transactions by utilizing the liquidity pool of the trading platform even if the buyers and sellers do not exist at the same time. However, Automated Market Maker have some disadvantages since the cost efficiency of each transaction using Automated Market Maker depends on the liquidity size of some liquidity pools used for the transaction, so the smaller the size of the liquidity pool and the larger the transaction size, the smaller the cost efficiency of the trade. To solve this problem, some platforms are adopting Transaction Path Routing Algorithm that bypasses transaction path to other liquidity pools that have relatively large size to improve cost efficiency, but this algorithm can be further improved because it uses only a single transaction path to proceed each transaction. In addition to just bypassing transaction path, in this paper we proposed a Multi-Path Routing Algorithm that uses multiple transaction paths simultaneously by distributing transaction size, and showed that the cost efficiency of transactions can be further improved in the Automated Market Maker-based trading environment.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.2
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• pp.103-109
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• 2019

Due to the development of ICT technology, the IoT environment for connecting objects in the vicinity to networks and utilizing information about objects in various fields is getting attention, and security threats are also increasing. In order to solve the increasing security problem in IoT environment, we are studying methods that use certificate, encryption, hash calculation and block chain in the private sector. However, the security authentication method which overcomes the performance gap between devices and has compatibility with various devices It has not been proposed yet. In this paper, we propose an authentication method that can achieve wide compatibility by minimizing the influence of IoT device environment.

• Journal of Internet Computing and Services
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• v.21 no.6
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• pp.51-56
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• 2020

Cryptocurrencies, including Bitcoin, has decentralization, distribution and P2P properties unlike traditional currencies relies on trusted central party such as banks. All transactions are stored transparently and distributively, hence all participants can check the details of those transactions. Due to the properties of cryptographic hash function, deletion or modification of the stored transations is computationally not possible. However, cryptocurrencies only provide pseudonymity, not anonymity, which is provided by traditional currencies. Therefore many researches were conducted to provide anonymity to cryptocurrencies such as mix-based methods. In this paper, I will propose more efficient hybrid mix-based method for anonymity than previous mix-based one.

• International Journal of Contents
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• v.17 no.1
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• pp.1-10
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• 2021

Visual analytics is an emerging research field that combines the strength of electronic data processing and human intuition-based social background knowledge. This study demonstrates useful visual analytics with Tableau in conjunction with semantic network analysis using examples of sentiment flow and strategic communication strategies via Twitter in a blockchain domain. We comparatively investigated the sentiment flow over time and language usage patterns between companies with a good reputation and firms with a poor reputation. In addition, this study explored the relations between reputation and marketing communication strategies. We found that cryptocurrency firms more actively produced information when there was an increased public demand and increased transactions and when the coins' prices were high. Emotional language strategies on social media did not affect cryptocurrencies' reputations. The pattern in semantic representations of keywords was similar between companies with a good reputation and firms with a poor reputation. However, the reputable firms communicated on a wide range of topics and used more culturally focused strategies, and took more advantages of social media marketing by expanding their outreach to other social media networks. The visual big data analytics provides insights into business intelligence that helps informed policies.