• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.6
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• pp.1377-1383
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• 2015

As the cloud services users' increase, there are important files created by individual in cloud storage. Thus, investigation of cloud artifact should be conducted. There are two methods of analyzing cloud service, one is that investigates cloud server provider (CSP), and another is that investigates client. In this paper, we presents an automated framework to detect the altered artifact and developes a tool that detects the cloud artifact. We also developed Cloud Artifact Tool that can investigate client computer. Cloud Artifact Tool provides feature of collection and analysis for the services such as Google Drive, Dropbox, Evernote, NDrive, DaumCloud, Ucloud, LG Cloud, T Cloud and iCloud.

• Journal of The Korean Astronomical Society
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• v.40 no.4
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• pp.119-122
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• 2007

From the HCN observations of dense molecular cloud L694-2, Lee et al.(2007) determined internal distributions of density and velocity for the cloud. The density profile collaborates roughly with the Bonnor- Ebert gas sphere, but the velocity field departs significantly from the result of numerical simulations that are started from the BE sphere. Taking L694-2 as an example of collapsing clouds, we have performed a series of collapse simulations and determined initial configurations for the cloud in such a way that the resulting density and velocity profiles both match with the empirically deduced ones. Among many trial configurations the cloud which is initially uniform in density and bound by an expanding envelop depicts most closely the empirically obtained profiles of both density and velocity.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.106.2-106.2
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• 2011

The two competing theories of star formation are based on turbulence and ambipoar diffusion. I will first briefly explain the two theories. There have been analytical (or semi-analytic) models, which estimate star formation rates in a turbulent cloud. Most of them are based on the log-normal density PDF (probability density function) of the turbulent cloud without self-gravity. I will first show that the core (star) formation rate can be increased significantly once self-gravity of a turbulence cloud is taken into account. I will then present the evolution of molecular line profiles of HCO+ and C18O toward a dense core that is forming inside a magnetized turbulent molecular cloud. Features of the profiles can be affected more significantly by coupled velocity and abundance structures in the outer region than those in the inner dense part of the core. During the evolution of the core, the asymmetry of line profiles easily changes from blue to red, and vice versa. Finally, I will introduce a method for incorporating ambipolar diffusion in the strong coupling approximation into a multidimensional magnetohydrodynamic code.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.5-7
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• 2014

일반적인 가상화 플랫폼에서는 가상화 소프트웨어가 소프트웨어적으로 에뮬레이션하여 제공하는 가상 I/O 장치들을 가상 플랫폼에서 사용한다. 소프트웨어 에뮬레이션 기반 I/O 장치들을 사용하는 가상 플랫폼들은 성능이 떨어지고 고사양의 응용 프로그램을 지원할 수 없는 문제점을 가지고 있다. 본 논문에서는 해당 문제점을 극복하기 위해 PCI 기반 하드웨어 장치들을 가상 플랫폼에 직접 할당하여 고품질의 가상 플랫폼을 제공하는 기술을 설계 및 구현한다.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.1
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• pp.180-186
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• 2021

In cloud computing service it is important to share the system resource among multiple instances according to user requirements. In particular, the issue of efficiently distributing I/O resources across multiple instances is paid attention due to the rise of emerging data-centric technologies such as big data and deep learning. However, it is difficult to evaluate the I/O resource distribution of a Linux container, which is one of the core technologies of cloud computing, since conventional I/O benchmarks does not support features related to container management. In this paper, we propose a new I/O performance benchmarking framework that can easily evaluate the resource distribution of Linux containers using existing I/O benchmarks by supporting container-related features and integrated user interface. According to the performance evaluation result with trace-replay benchmark, the proposed benchmark framework has induced negligible performance overhead while providing convenience in evaluating the I/O performance of multiple Linux containers.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.280-283
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• 2014

Cloud Computing virtualizes logical resources like cpu, memory and disks etcs from physical machines. This virtualization technology increases computing resource utilization and supports dynamic resource allocations. Because of these benefits, global cloud computing services like Amazon AWS, Google Cloud and Apple iCloud are prevalent. With this cloud Computing services, there has been a request about cloud migration between different cloud environments. If one service which operates in a cloud computing environment wants to migrate to another cloud environment, there should have been a compitability between two different cloud environment. but even global cloud computing services do not support this compitability. In this paper, we suggest a process and technology to cloud migrations based on open sources.

• Korean Journal of Remote Sensing
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• v.15 no.1
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• pp.21-30
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• 1999

The CLW (Cloud Liquid Water) is a parameter of vital interest in both modeling and forecasting weather. In mesoscale models, the magnitude of latent heat effects corresponds to the amount of CLW, which is important in the development of a certain weather system. The goal of this study is the estimation of CLW by GMS-5 data which is compared with that of SSM/I data and GMR(Grounded Microwave Radiometer)data. First of all, we found out the relationship of cloud albedo to cloud thickness, and caculated the CLW using the result of the relationship. The CLW amount of SSM/I or GMR and that of GMS-5 were compared, respectively. The correlation coefficient was about 0.86 and RMSE was 9.23 mg/$cm^2$ between GMS-5 data and GMR data. And also the correlation coefficient was 0.84 and RMSE was 14.02 mg/$cm^2$ between GMS-5 data and SSM/I data.

• Journal of Information Technology Services
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• v.14 no.4
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• pp.221-236
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• 2015

Application software is delivered to customers as a form of service at cloud environment. A cloud service provider is a marketplace between supply side (application providers) and demand side (customers). Cloud service providers have to validate applications to be included in their service portfolio. Not only performance, security, networking, compliances should be checked but also business contract, authentication should be provided. Organization customers are more sensitive to these validation criteria and process. We study the Internet2 NET+, which is a successful cloud marketplace of applications for research and education organizations. This case study shows us three things : (i) a cloud marketplace's application management process : selection, validation, transition to service, customization of applications (ii) what a cloud marketplace has for its infrastructure like authentication, security, access control etc. (iii) what a cloud marketplace has as its governance structure. This case study will provide informative analysis of Internet2 NET, a profit-making vertical and buyer's marketplace (education industry). And we will get some strategic implications for planning and implementing cloud marketplaces.

• Journal of Information Processing Systems
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• v.14 no.1
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• pp.239-251
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• 2018

In existing cloud services, information security and privacy concerns have been worried, and have become one of the major factors that hinder the popularization and promotion of cloud computing. As the cloud computing infrastructure, the security of virtual machine systems is very important. This paper presents an immune-inspired intrusion detection model in virtual machines of cloud computing environment, denoted I-VMIDS, to ensure the safety of user-level applications in client virtual machines. The model extracts system call sequences of programs, abstracts them into antigens, fuses environmental information of client virtual machines into danger signals, and implements intrusion detection by immune mechanisms. The model is capable of detecting attacks on processes which are statically tampered, and is able to detect attacks on processes which are dynamically running. Therefore, the model supports high real time. During the detection process, the model introduces information monitoring mechanism to supervise intrusion detection program, which ensures the authenticity of the test data. Experimental results show that the model does not bring much spending to the virtual machine system, and achieves good detection performance. It is feasible to apply I-VMIDS to the cloud computing platform.

• 한국전산유체공학회:학술대회논문집
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• 2006.05a
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• pp.233-236
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• 2006

LES model of a cumulus cloud is developed in which the motion of a large number of water droplets are explicitly simulated. Model provides various important information of the cloud process such as entrainment and internal mixing, the distribution of droplets within cloud, and the evolution of particle size spectrum.