• 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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.8
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• pp.2989-2998
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• 2010

This study proposes the DMA(District Metered Area) operation technologies to reduce water losses in water supply network, such as development of DMA control and monitoring system and analysis method of DMA water flow and pressure analysis. DMA boundary analysis and control and monitoring systems of J city was studied in advance, and some problems to be improved was presented. Water losses analysis program was developed to assess the effects of this study.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.345-352
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• 2006

The purpose of this paper is to evaluate the efficiency of two yard layout of HSS at container terminal, one is that the container yard blocks are placed horizontally in parallel with berth, the other is that the yard blocks are arranged vertically in perpendicular to the berth. In stevedoring system of container terminal, stacking and transport performance are influenced according to block arrangement type of yard. Therefore, efficient design that can improve stacking and transport performance is required. In this paper, we compared their efficiency of two block arrangement concepts in terms of storage capacity, productivity, facility investments, truck service level.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.873-879
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• 2020

The importance of data as a core resource of the 4th industrial revolution is emerging, and companies illegally collect and use personal data. In the financial sector, active research is conducted to safely manage personal data and provide better services using blockchain, big data, and AI technology. In this paper, we propose a system that can safely manage personal data by using blockchain technology, which can be used without changing the existing system. The composition of this system consists of a blockchain, blockchain linkages, a service provider, and a user (i.e., an app). Blockchain can be used regardless of its type and form, and services are provided by classifying blockchains and services in the blockchain linkages. Service providers can access personal data only after requesting and receiving delegated permission from users. Existent MyData services store all data in a user's mobile phone, so information may get leaked due to jailbreaks or rooting. But in the proposed system, personal data are stored in blockchain so information leakage can be prevented. In the future, we will study ways to provide customized services using personal data stored in blockchain.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.07a
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• pp.227-228
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• 2019

현실 세계에서 진행되는 투표는 시간과 공간이라는 자원들을 낭비하면서 진행이 된다. 그에 따른 보완책으로 온라인 투표 시스템을 제안할 수 있지만, 이 경우 데이터를 저장한 중앙 서버가 해킹당할 경우 데이터의 무결성 이 훼손되는 문제점을 야기할 수 있다. 본 논문에서는 이러한 문제점을 보완하기 위하여 블록체인 네트워크를 활용한 투표 시스템을 제안한다. 블록체인 투표 시스템을 응용하면 온라인으로 투표를 진행하여 시간과 공간이라는 자원을 절약할 수 있고 보안의 3요소 중 하나인 데이터의 무결성을 유지하여 투표 시스템의 투명성을 향상 킬 수 있다.

• The Journal of the Korea Contents Association
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• v.20 no.5
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• pp.11-22
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• 2020

The academic credit banking system is an educational system to implement a lifelong learning society. Students who meet the requirements of this system can achieve academic degrees equivalent to those of junior colleges or four-year universities. Credits and degree information of these students are recorded and managed by the central institution. However, this system can cause security problem such as hacking due to centralized management. In this paper, we propose an academic credit banking system which can manage credits and degree information based on blockchain technology. In the proposed system, credits and degree information are stored in block and managed in the public ledger in a permanent manner. Blocks are connected in the form of blockchain on a distributed network to improve security problems such as hacking and manipulation. Also, the efficiency of credit bank management can be increased because the functions of the central institution are distributed to the network participants. The prototype of the proposed system was implemented on the Go-Ethereum platform and experimentally verified the blockchain information among participating organizations using smart contracts.

• Journal of Internet of Things and Convergence
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• v.6 no.4
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• pp.65-72
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• 2020

In this paper, we developed a web-based DApp system based on a private blockchain by applying machine learning techniques to automatically identify Android malicious apps that are continuously increasing rapidly. The optimal machine learning model that provides 96.2587% accuracy for Android malicious app identification was selected to the authorized experimental data, and automatic identification results for Android malicious apps were recorded/managed in the Hyperledger Fabric blockchain system. In addition, a web-based DApp system was developed so that users who have been granted the proper authority can use the blockchain system. Therefore, it is possible to further improve the security in the Android mobile app usage environment through the development of the machine learning-based Android malicious app identification block chain DApp system presented. In the future, it is expected to be able to develop enhanced security services that combine machine learning and blockchain for general-purpose data.

• Journal of Software Engineering Society
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• v.29 no.2
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• pp.7-12
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• 2020

A project to establish an information system with a project cost of more than 500 million won at a local public firm is subject to the Information System Audit (hereinafter referred to as IS Audit), and the IS Auditor shall conduct audit according to the audit criteria. Recently, as blockchain technology has been applied to various fields such as manufacturing, healthcare, distribution, and public sectors beyond the financial industry, the development of systems that apply blockchain technology is increasing. The use of Hyperledger Fabric, a private blockchain, is on the rise to utilize blockchain technology in public firms and private firms. However, the newly emerging blockchain-based system is not sufficient to carry out auditing with existing audit check items, so it has no choice but to make and use audit items individually. Therefore, a need for verified audit items for systems that base on blockchain technology has emerged. In this study, we customized the Delphi process to derive audit items suitable for the system development project using the blockchain technology, and verified the completeness and accuracy of the audit items derived through a survey by the IS Auditor. This research will be of direct help to the IS Auditor, and it is expected that operators and organizers who provide services through the blockchain-based system will also contribute to improving the quality of the system.

• The Journal of the Korea Contents Association
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• v.21 no.6
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• pp.1-11
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• 2021

The Neis System is a system integrating administrative information that was operated in elementary and secondary schools in Korea. Currently, this system is operated by a central server method and contains school administration information and important educational information of students. Among student information, the student life record contains important information for a student to advance to a higher level institution, but problems such as information leakage or manipulation may occur due to malicious attacks. In this paper, we propose a hybrid blockchain system that combines the server and blockchain technology managed by the existing Neis system. The proposed system records the query information of the database in a block when student information is accessed. When a request for correction of student information or issuance of a certificate is received, the query of the blockchain, the information in the database, and the student's key value are checked to determine whether the information has been leaked or manipulated, and only if the data is normal, the request for revision of the record is performed. This process is more secure than the existing central server because it checks the manipulation of data through the blockchain. The proposed system was implemented on the Ethereum platform, and the query information of the blockchain was experimentally verified using smart contracts. This study contributes to enhancing the reliability of the Nice system by strengthening the security against forgery and alteration of student data by combining the existing Nice system with a block chain.

• Tunnel and Underground Space
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• v.25 no.5
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• pp.450-461
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• 2015

Extensive numerical experiments have been carried out to investigate effect of block size and fracture geometry on hydraulic characteristics of fractured rock masses based on connected pipe flow in DFN systems. Using two fracture sets, a total of 72 2-D fracture configurations were generated with different combinations of fracture size distribution and deterministic fracture density. The directional block conductivity including the theoretical block conductivity, principal conductivity tensor and average block conductivity for each generated fracture network system were calculated using the 2-D equivalent pipe network method. There exist significant effects of block size, orientation, density and size of fractures in a fractured rock mass on its hydraulic behavior. We have been further verified that it is more difficult to reach the REV size for the fluid flow network with decreasing intersection angle of two fracture sets, fracture plane density and fracture size distribution.