• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.2
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• pp.85-91
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• 2014

Cloud storage system uses a distributed file system for storing and managing data. Traditional distributed file system makes a triplication of data in order to restore data loss in disk failure. However, enforcing data replication method increases storage utilization and causes extra I/O operations during replication process. In this paper, we propose a data replication method using erasure codes in cloud storage system to improve storage space efficiency and I/O performance. In particular, according to data access frequency, the proposed method can reduce the number of data replications but using erasure codes can keep the same data recovery performance. Experimental results show that proposed method improves performance in storage efficiency 40%, read throughput 11%, write throughput 10% better than HDFS does.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.4
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• pp.210-219
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• 2023

The decline in the rural populace and an aging workforce have led to fatalities due to worsening environments and hazards within vinyl greenhouses. Therefore, it is necessary to automate crop cultivation and disease detection system in greenhouses to prevent labor loss. In this paper, an object detection-based model is used to detect diseased crop in greenhouses. In addition, the system proposed configures the environment of the artificial intelligence model in the cloud to ensure stability. The system captures images taken inside the vinyl greenhouse and stores them in a database, and then downloads the images to the cloud to perform inference based on Yolo-v4 for detection, generating JSON files for the results. Analyze this file and send it to the database for storage. From the experimental results, it was confirmed that disease detection through object detection showed high performance in real environments like vinyl greenhouses. It was also verified that efficient monitoring is possible through the database

• The Korean Journal of Archival Studies
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• no.66
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• pp.5-35
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• 2020

In the digital age, the most basic unit of records management is a document file. Depending on whether each document file is produced in an open standard format or an exclusive proprietary format, there is a cost difference in the process of use and long-term preservation. As government agencies moved to cloud-based business management systems, web-based document editing software was newly adopted. They had the opportunity to select a new file format for web-based document editing software. This paper deals with strategies to maximize the advantages of open standard formats while considering the legacy public document production practices. It introduces ISO/IEC 26300:2006 ODF, ISO/IEC 29500:2008 OOXML, KS X 6101 OWPML, etc. as open standard formats, and looks at considerations when choosing a format and web-based document editing software. In addition, it proposes a strategy to maintain the format of document files shared in cloud storage as an open standard format.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.95-96
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• 2009

클라우드 컴퓨팅은 대규모의 분산 시스템을 기반으로 페타바이트급 이상의 처리가 가능해진 최근에 각광받고 있는 기술이다. 대부분 비 대칭 분산 구조로 객체기반 클러스터 파일 시스템으로 이루어져있다. 이런 환경에서 효율성과 신뢰성 등을 고려하여 많은 연구가 진행 중이다. 본 논문에서는 특정한 상황에서 병목현상과 메타 데이터 서버간의 부하분산을 처리함으로써, 한 특징인 효율적인 측면에서 향상이 가능한 기법을 제안하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.740-743
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• 2013

클라우드 컴퓨팅 환경에서는 사용자의 데이터를 수많은 분산서버를 이용하여 데이터를 암호화하여 저장한다. 구글, 야후 등 글로벌 인터넷 서비스 업체들은 인터넷 서비스 플랫폼의 중요성을 인식하고 자체 연구 개발을 수행, 저가 상용 노드를 기반으로 한 대규모 클러스터 기반의 클라우드 컴퓨팅 플랫폼 기술을 개발 활용하고 있다. 이와 같이 분산 컴퓨팅 환경에서 다양한 데이터 서비스가 가능해지면서 대용량 데이터의 분산관리가 주요 이슈로 떠오르고 있다. 한편, 대용량 데이터의 다양한 이용 형태로부터 악의적인 공격자나 내부 사용자에 의한 보안 취약성 및 프라이버시 침해가 발생할 수 있다. 특히, 하둡에서 데이터 블록의 권한 제어를 위해 사용하는 블록 접근 토큰에도 다양한 보안 취약점이 발생한다. 이러한 보안 취약점을 보완하기 위해 본 논문에서는 비밀분산 기반의 블록 접근 토큰 관리 기법을 제안한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.835-838
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• 2013

클라우드 컴퓨팅을 사용하면 컴퓨팅 자원을 구축하는 비용을 절감할 수 있다는 장점이 있다. 문제는 클라이언트가 데이터 센터와 서비스제공자를 완전히 신뢰할 수 없다는 것이다. 예를 들어, 클라우드에 저장된 파일이 손실되었을 때 서비스 제공자는 서비스의 신뢰도가 떨어지는 것을 막기 위해 이를 숨길 수 있다. 이때, 데이터가 저장 후에 손실되었다는 것을 증명하지 못하면, 그 피해는 클라이언트에게 돌아오게 된다. 따라서, 클라이언트의 데이터를 보호하기 위하여 무결성을 검증할 수 있는 적절한 기법을 적용하여야 한다. 기존 연구로는 homomorphic tags 기반의 기법들이 많이 제안되었으나 이 기법은 많은 지수연산을 필요로 하므로 상용화할 수 있을 만큼의 효율성을 가지지 못한다. 특히, 클라이언트가 증거 생성을 위해 많은 연산을 부담해야 한다. 본 논문에서는 효율성에 중점을 둔, 특히 클라이언트의 효율성에 중점을 둔 무결성 검증 기법을 제안한다. 제안하는 기법은 Modular arithmetic을 기반으로 설계되었으며, 무결성 검증뿐만 아니라 데이터가 자주 업데이트 되는 환경을 지원한다. Simulation result는 제안하는 기법이 기존 기법에 매우 효율적임을 보여준다.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.11
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• pp.403-410
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• 2022

Non-Fungible Tokens (NFTs) created on the basis of blockchain have their own unique value, so they cannot be forged or exchanged with other tokens or coins. Using these characteristics, NFTs can be issued to digital assets such as images, videos, artworks, game characters, and items to claim ownership of digital assets among many users and objects in cyberspace, as well as proving the original. However, interest in NFTs exploded from the beginning of 2020, causing a lot of load on the blockchain network, and as a result, users are experiencing problems such as delays in computational processing or very large fees in the mining process. Additionally, all actions of users are stored in the blockchain, and digital assets are stored in a blockchain-based distributed file storage system, which may unnecessarily expose the personal information of users who do not want to identify themselves on the Internet. In this paper, we propose an NFT platform using cloud computing, access gate, conversion table, and cloud ID to improve usability and privacy problems that occur in existing system. For performance comparison between local and cloud systems, we measured the gas used for smart contract deployment and NFT-issued transaction. As a result, even though the cloud system used the same experimental environment and parameters, it saved about 3.75% of gas for smart contract deployment and about 4.6% for NFT-generated transaction, confirming that the cloud system can handle computations more efficiently than the local system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.4B
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• pp.288-299
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• 2012

To ensure data confidentiality and fine-grained access control in business environment, system model using KP-ABE(Key Policy-Attribute Based Encryption) and PRE(Proxy Re-Encryption) has been proposed recently. However, in previous study, data confidentiality has been effected by decryption right concentrated on cloud server. Also, Yu's work does not consider a access privilege management, so existing work become dangerous to collusion attack between malicious user and cloud server. To resolve this problem, we propose secure system model against collusion attack through dividing data file into header which is sent to privilege manager group and body which is sent to cloud server and prevent modification attack for proxy re-encryption key using d Secret Sharing, We construct protocol model in medical environment.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.10
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• pp.429-436
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• 2017

There is a growing tendency to outsource sensitive or important data in cloud computing recently. However, it is very important to protect the privacy of outsourced data. So far, a variety of secure and efficient multi-keyword search schemes have been proposed in cloud computing environment composed of a single data owner and multiple data users. Zhang et. al recently proposed a search protocol based on multi-keyword in cloud computing composed of multiple data owners and data users but their protocol has two problems. One is that the cloud server can illegally infer the relevance between data files by going through the keyword index and user's trapdoor, and the other is that the response for the user's request is delayed because the cloud server has to execute complicated operations as many times as the size of the keyword index. In this paper, we propose an improved multi-keyword based search protocol which protects the privacy of outsourced data under the assumption that the cloud server is completely unreliable. And our experiments show that the proposed protocol is more secure in terms of relevance inference between the data files and has higher efficiency in terms of processing time than Zhang's one.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.5
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• pp.803-813
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• 2013

As the developments of smart devices and social network services, the amount of data has been exploding. The world is facing Big data era. For these reasons, the Big data processing technology which is a new technology that can handle such data has attracted much attention. One of the most representative technologies is Hadoop. Hadoop Distributed File System(HDFS) designed to run on commercial Linux server is an open source framework and can store many terabytes of data. The initial version of Hadoop did not consider security because it only focused on efficient Big data processing. As the number of users rapidly increases, a lot of sensitive data including personal information were stored on HDFS. So Hadoop announced a new version that introduces Kerberos and token system in 2009. However, this system is vulnerable to the replay attack, impersonation attack and other attacks. In this paper, we analyze these vulnerabilities of HDFS security and propose a new protocol which complements these vulnerabilities and maintains the performance of Hadoop.