• Journal of Internet Computing and Services
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• v.17 no.2
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• pp.1-9
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• 2016

Users are provided infrastructure such as CPU, memory, network, and storage as IaaS (Infrastructure as a Service) service on cloud computing environments. However storage instances cannot support the maximum storage capacity that SQL servers can use, because the capacity of instances provided by service providers is usually limited. In this paper, we propose a method of securing mass storage capacity for SQL servers by sharing network disks with limited storage capacity. We confirmed through experiments that it is possible to secure mass storage capacity, which exceeds the maximum storage capacity provided by an instance with Amazon EBS on Amazon EC2 Windows environments, and it is possible to improve the overall performance of the SQL servers by increasing the disk capacity and performance.

• Electronics and Telecommunications Trends
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• v.24 no.4
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• pp.1-13
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• 2009

본 논문은 클라우드 컴퓨팅 기술 동향에 대한 분석서로 관련 기술과 주요 서비스 내용을 소개한다. 2006년 클라우드 컴퓨팅이란 용어가 처음 생겨난 이래, 2008년 글로벌 IT 기업 CEO들이 잇달아 차기 비즈니스의 핵심 기술로 클라우드 컴퓨팅을 지목한 이후, 전세계가 클라우드 컴퓨팅에 대한 관심이 집중되고 있다. 이에 클라우드 컴퓨팅의 대표 서비스 형태인 IaaS, PaaS, SaaS 서비스에 대한 개념을 설명하고, 각 서비스별 대표 기업들의 기술 동향을 살펴본다. IaaS 서비스에 대해서는 아마존의 EC2와 S3 서비스를, PaaS 서비스에 대한 Google의 AppEngine을, SaaS 서비스로 세일즈포스닷컴의 세일즈포스 서비스를 대표 기술로 소개하고 클라우드 컴퓨팅을 구성하기 위한 기술적인 요소들을 간략하게 언급하였다.

• Journal of KIISE
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• v.43 no.6
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• pp.621-626
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• 2016

Recursive query algorithm is used in many social network services, e.g., reachability queries in social networks. Recently, the size of social network data has increased as social network services evolve. As a result, it is almost impossible to use the recursive query algorithm on a single machine. In this paper, we implement recursive query on two popular in-memory distributed platforms, Spark and Twister, to solve this problem. We evaluate the performance of two implementations using 50 machines on Amazon EC2, and real-world data sets: LiveJournal and ClueWeb. The result shows that recursive query algorithm shows better performance on Spark for the Livejournal input data set with relatively high average degree, but smaller vertices. However, recursive query on Twister is superior to Spark for the ClueWeb input data set with relatively low average degree, but many vertices.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06a
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• pp.293-295
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• 2012

가상화 기술은 물리적 컴퓨팅 자원을 사용자에게 논리적으로 제공하여 시스템의 효율성을 높이고 유연성을 향상시키기 위한 기술로 서버 통합이나 아마존 EC2와 같은 클라우드 컴퓨팅 환경에서 사용되고 있다. 이러한 가상화 환경에서는 다수의 가상머신들의 동시적인 I/O 수행으로 인해 저장장치에 병목현상이 발생된다. 또한 각 가상머신들의 중복된 데이터들을 저장하기 위해 불필요한 쓰기 비용이 발생하여 시스템의 성능 저하가 발생하게 된다. 본 논문에서는 이러한 가상화 환경에서의 I/O비용을 감소시키기 위해 SSD를 캐시로 사용하는 중복 제거 기법을 제안한다. 제안된 기법은 중복된 데이터를 제거하여 불필요한 디스크에 대한 I/O 수행을 감소시키며, 중복 발생 패턴의 특성을 고려하여 SSD의 빠른 쓰기 성능을 효과적으로 사용할 수 있는 캐시 구조 모델을 통해 가상화 환경에서 I/O 성능을 향상 시킬 수 있음을 보인다.

• Journal of KIISE
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• v.42 no.9
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• pp.1175-1184
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• 2015

Recently, there has been an explosive increase in the volume of multimedia data that is available as a result of the development of multimedia technologies. More and more data is becoming available on a variety of web sites, and it has become increasingly cost prohibitive to have a single data server store and process multimedia files locally. Therefore, many service providers have been likely to outsource data to cloud storage to reduce costs. Such behavior raises one serious concern: how can data users be authenticated in a secure and efficient way? The most widely used password-based authentication methods suffer from numerous disadvantages in terms of security. Multi-factor authentication protocols based on a variety of communication channels, such as SMS, biometric, or hardware tokens, may improve security but inevitably reduce usability. To this end, we present a data block-based authentication scheme that is secure and guarantees usability in such a manner where users do nothing more than enter a password. In addition, the proposed scheme can be effectively used to revoke user rights. To the best of our knowledge, our scheme is the first data block-based authentication scheme for outsourced data that is proven to be secure without degradation in usability. An experiment was conducted using the Amazon EC2 cloud service, and the results show that the proposed scheme guarantees a nearly constant time for user authentication.