• International Journal of Internet, Broadcasting and Communication
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• v.13 no.1
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• pp.26-36
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• 2021

The Internet was created as a decentralized and autonomous system of interconnected computer networks used for data exchange across mutually trusted participants. The element technologies on the Internet, such as inter-domain and intra-domain routing and DNS, operated in a distributed manner. With the development of the Web, the Web has become indispensable in daily life. The existing web applications allow us to form online communities, generate private information, access big data, shop online, pay bills, post photos or videos, and even order groceries. This is what has led to centralization of the Web. This centralization is now controlled by the giant social media platforms that provide it as a service, but the original Internet was not like this. These giant companies realized that the decentralized network's huge value involves gathering, organizing, and monetizing information through centralized web applications. The centralized Web applications have heralded some major issues, which will likely worsen shortly. This study focuses on these problems and investigates blockchain's potentials for decentralized web architecture capable of improving conventional web services' critical features, including autonomous, robust, and secure decentralized processing and traceable trustworthiness in tamper-proof transactions. Finally, we review the decentralized web architecture that circumvents the main Internet gatekeepers and controls our data back from the giant social media companies.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.10a
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• pp.235-237
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• 2018

The Internet has allowed many things to move fast, including sharing of data, files and others within a second. Many domains use applications range from IoT, smart cities, healthcare, and organizations to share the data when necessary. However, there are some challenges faced by existing systems that works on centralized nature. Such challenges are data breach, trustiness issue, unauthorized access and data fraud. Therefore in this work, we focus on using a smart contract which is used by blockchain platform and works on decentralized form. Furthermore, in this work our contract provides an access to the file uploaded onto the decentralized storage such as IPFS. By leveraging smart contract-role based which consist of a contract owner who can manage the users when access the certain resources such as a file and as well as use of decentralized storage to avoid single point of failure and censorship over secure communication channel. We checked the gas cost of the smart contract since most of contracts tends to be a high cost.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.60-66
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• 2021

Blockchain is a technology that enables trust-based consensus and verification based on a decentralized network. Distributed ID (DID) is based on a decentralized structure, and users have the right to manage their own ID. Recently, interest in self-sovereign identity authentication is increasing. In this paper, as a method for transparent and safe sovereignty management of data, among data pseudonymization techniques for blockchain use, various methods for data encryption processing are examined. The public key technique (homomorphic encryption) has high flexibility and security because different algorithms are applied to the entire sentence for encryption and decryption. As a result, the computational efficiency decreases. The hash function method (MD5) can maintain flexibility and is higher than the security-related two-way encryption method, but there is a threat of collision. Zero-knowledge proof is based on public key encryption based on a mutual proof method, and complex formulas are applied to processes such as personal identification, key distribution, and digital signature. It requires consensus and verification process, so the operation efficiency is lowered to the level of O (log_eN) ~ O(N²). In this paper, data encryption processing for blockchain DID, based on zero-knowledge proof, was proposed and a one-way encryption method considering data use range and frequency of use was proposed. Based on the content presented in the thesis, it is possible to process corrected zero-knowledge proof and to process data efficiently.

• KIPS Transactions on Computer and Communication Systems
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• v.9 no.12
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• pp.321-332
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• 2020

Decentralized approaches are extensively researched by academia and industry in order to cover up the flaws of existing systems in terms of data privacy. Blockchain and decentralized learning are prominent representatives of a deconcentrated approach. Blockchain is secure by design since the data record is irrevocable, tamper-resistant, consensus-based decision making, and inexpensive of overall transactions. On the other hand, decentralized learning empowers a number of devices collectively in improving a deep learning model without exposing the dataset publicly. To motivate participants to use their resources in building models, a decent and proportional incentive system is a necessity. A centralized incentive mechanism is likely inconvenient to be adopted in decentralized learning since it relies on the middleman that still suffers from bottleneck issues. Therefore, we design an incentive model for decentralized learning applications by leveraging the Ethereum smart contract. The simulation results satisfy the design goals. We also outline the concerns in implementing the presented scheme for sensitive data regarding privacy and data leakage.

• Smart Structures and Systems
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• v.12 no.3_4
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• pp.399-414
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• 2013

The smart sensor technology has opened new horizons for assessing and monitoring structural health of civil infrastructure. Smart sensor's unique features such as onboard computation, wireless communication, and cost effectiveness can enable a dense network of sensors that is essential for accurate assessment of structural health in large-scale civil structures. While most research efforts to date have been focused on realizing wireless smart sensor networks (WSSN) on bridge structures, relatively less attention is paid to applying this technology to buildings. This paper presents a decentralized damage detection using the WSSN for building structures. An existing flexibility-based damage detection method is extended to be used in the decentralized computing environment offered by the WSSN and implemented on MEMSIC's Imote2 smart sensor platform. Numerical simulation and laboratory experiment are conducted to validate the WSSN for decentralized damage detection of building structures.

• Proceedings of the Korea Information Processing Society Conference
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• 2020.05a
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• pp.417-419
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• 2020

데이터 3법 시대에 접어들면서 기업들에는 가명화된 개인정보를 활용할 수 있는 길이 열렸다. 하지만 현 데이터 3법은 데이터를 생성하고 유통하며 활용할 기업들의 책임과 혜택에 내용이 맞춰져 있어 아쉬운 감이 있다. 개인의 기본권을 보장하면서도 마이데이터 유통 및 활용을 도울 방법은 없을까? 본 논문에서는 데이터의 주체인 개인이 데이터 주권을 행사하고 실질적인 혜택을 받는 마이데이터 서비스의 활성화를 위한 ID 관리 기술로 블록체인 기반 분산 ID(Decentralized Identification, DID)를 제안하고, DID 수용의도에 영향을 마치는 요인을 연구함으로써 마이데이터 서비스 개발 활성화를 위한 정책적, 실무적 시사점을 도출하고자 한다.

• Journal of Information Processing Systems
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• v.16 no.3
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• pp.699-717
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• 2020

Propagation time on permissionless blockchain plays a significant role in terms of stability and performance in the decentralized systems. A large number of activities are disseminated to the whole nodes in the decentralized peer-to-peer network, thus causing propagation delay. The stability of the system is our concern in the first place. The propagation delay opens up opportunities for attackers to apply their protocol. Either by accelerating or decelerating the propagation time directly without proper calculation, it brings numerous negative impacts to the entire blockchain system. In this paper, we thoroughly review and elaborate on several parameters related to the propagation time in such a system. We describe our findings in terms of data communication, transaction propagation, and the possibility of an interference attack that caused an extra propagation time. Furthermore, we present the influence of block size, consensus, and blockchain scalability, including the relation of parameters. In the last session, we remark several points associated with the propagation time and use cases to avoid dilemmas in the light of the experiments and literary works.

• Proceedings of the Korea Information Processing Society Conference
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• 2020.05a
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• pp.231-234
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• 2020

In the past few years, the industrial internet of things (IIoT) has received great attention in various industrial sectors which have potentially increased a high level of integrity, availability, and scalability. The increasing of IIoT is expected to create new smart industrial enterprises and build the next generation smart system. However existing IIoT systems rely on centralized servers that are vulnerable to a single point of failure and malicious attack, which exposes the data to security risks and storage. To address the above issues, blockchain is widely considered as a promising solution, which can build a secure and efficient environment for data storing, processing and sharing in IIoT. In this paper, we propose a decentralized, peer-to-peer platform for secure data storing in industrial IoT base on the ethereum blockchain. We exploit ethereum to ensure data security and reliability when smart devices store the data.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.6
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• pp.981-997
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• 2020

Blockchain technology can provide a high level security based on a decentralized distributed ledger and consensus-based structure. In order to increase the utilization of blockchain technology, it is necessary to find a way to use it in fields that require personal data processing such as health care and e-commerce. To achieve this goal, the blockchain based system should be able to comply with data privacy regulations represented by European Union(EU)'s GDPR(General Data Protection Regulation). However, because of the properties of the blockchain like the immutability and decentralized recorded data, it is difficult to technically implement the requirements of the existing privacy regulations on the blockchain. In this paper, we propose a multi-chain based access control system that can guarantee the rights of the personal data subject required by GDPR by utilizing Chameleon Hash and Attribute Based Encryption (ABE). Finally, we will show through security analysis that our system can handle personal data while maintaining confidentiality and integrity.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.260-263
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• 2023

Considering the growth of blockchain technology, the research aims to transform the efficiency of recommending optimal coffee suppliers within the complex supply chain network. This transformation relies on the extraction of vital transactional data and insights from stakeholders, facilitated by the dynamic interaction between the application interface (e.g., Rest API) and the blockchain network. These extracted data are then subjected to advanced data processing techniques and harnessed through machine learning methodologies to establish a robust recommendation system. This innovative approach seeks to empower users with informed decision-making abilities, thereby enhancing operational efficiency in identifying the most suitable coffee supplier for each customer. Furthermore, the research employs data visualization techniques to illustrate intricate clustering patterns generated by the K-Means algorithm, providing a visual dimension to the study's evaluation.