• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권12호
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• pp.4759-4775
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• 2015

The reduction of power consumption in large-scale datacenters is highly-dependent on the use of virtualization to consolidate multiple workloads. However, these consolidation strategies must also take into account additional important parameters such as performance, reliability, and profitability. Resolving these conflicting goals is often the major challenge encountered in the design of optimization strategies for cloud data centers. In this paper, we put forward a data center monitoring strategy which dynamically alters its approach depending on the cloud system's current state. Results show that our proposed scheme outperformed strategies which only focus on a single metric such as SLA-Awareness and Energy Efficiency.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권1호
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• pp.466-482
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• 2015

IT is the key enabler of digital economy. Appropriate usage of IT can provide a strategic competitive advantage to a firm in a dynamic competitive environment. However, there has been a continuing debate on whether IT can actually enhance the productivity of firms. This concept is called IT productivity paradox. In this study, we analyzed the causality among appropriate indicators to demonstrate the real impact of IT on productivity. The 12,100 sample data from 2011 were used for analysis. As expected, the results indicated that mobile device usage, website adoption, e-commerce, open source, cloud computing, and green computing positively influence IT productivity. This unprecedented large-scale analysis can provide clarification regarding the ambiguous causal mechanism between IT usage and productivity.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2018년도 춘계학술발표대회
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• pp.85-87
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• 2018

Motivating by two promising technique of 5G, namely D2D and Edge computing, and the above mentioned problem of the current joint studies, We believe that more study is needed on the benefits of joining these two techniques in a single framework by more precisely taking into account the energy needed to computation, sending data, receiving data and as a result achieving more realistic energy efficiency in 5G cellular networks.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권3호
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• pp.1362-1376
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• 2016

A cloud computing system can be characterized by the provision of resources in the form of services to third parties on a leased, usage-based basis, as well as the private infrastructures maintained and utilized by individual organizations. To attain the desired reliability and energy efficiency in a cloud data center, trade-offs need to be carried out between system performance and power consumption. Resolving these conflicting goals is often the major challenge encountered in the design of optimization strategies for cloud data centers. The work presented in this paper is directed towards the development of an Energy-efficient and Performance-aware Cloud System equipped with strategies for dynamic switching of optimization approach. Moreover, a platform is also provided for the deployment of a Wind Farm CMS (Condition Monitoring System) which allows ubiquitous access. Due to the geographically-dispersed nature of wind farms, the CMS can take advantage of the cloud's highly scalable architecture in order to keep a reliable and efficient operation capable of handling multiple simultaneous users and huge amount of monitoring data. Using the proposed cloud architecture, a Wind Farm CMS is deployed in a virtual platform to monitor and evaluate the aging conditions of the turbine's major components in concurrent, yet isolated working environments.

• 한국산학기술학회논문지
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• 제12권5호
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• pp.2353-2359
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• 2011

최근 그린 IT의 요구와 컴퓨터 자원에 대한 효과적인 사용요구가 증가되면서 클라우드 컴퓨팅에 대한 필요성이 날로 증가되어 가고 있다. 2009년 버클리 대학에서는 클라우드 컴퓨팅을 위협하는 10대 요소를 발표하였으며 그 중에서 보안과 관련된 사용자 인증에 대한 문제가 가장 시급하게 해결되어야만 한다. 이에 본 논문에서는 클라우드 컴퓨팅 환경에서 효과적인 사용자 인증 프로토콜을 제안하고자 한다. 기존의 대표적인 사용자 인증 기법인 커베로스의 티켓 발행을 통해 사용자 인증에 대한 안전성을 보장하고, PKI의 사용자 인증을 통해 사용자 인증과 서비스 인증을 거치는 두 단계의 인증 처리 절차를 정의하였다. 제안한 인증 프로토콜에 대한 효율성과 안전성에 대한 검토 결과, 기존의 PKI 보다 구조적으로 복잡하지 않고 커베로스 보다 수행절차 및 시스템 구성을 간소화하여 응답시간을 줄였다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2013년도 추계학술대회
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• pp.675-677
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• 2013

스마트 기기의 보급화로 인해 IT 생태계는 변하고 있으며, 이로 인해 기업들로 하여금 클라우드 컴퓨팅 분야가 이슈화 되고 있다. 클라우드 컴퓨팅은 IT 비용을 절감하며, 친환경적인 그린 IT를 지향한다. 또한, 모든 IT 기기를 지원하여 이동시에도 실시간으로 업무를 처리할 수 있다. 이러한 장점으로 인해 많은 기업들은 클라우드 컴퓨팅 서비스를 도입 및 검토 중에 있으며, 클라우드 도입시 저해되는 요인은 보안이다. 이에 본 논문에서는 클라우드가 갖고 있는 보안 문제점을 분석하고, 올바른 가이드라인을 제시한다. 이는 클라우드 컴퓨팅 시스템 및 서비스의 제공분야에 활용될 것으로 사료된다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권6호
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• pp.1892-1912
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• 2022

With the massive demand and growth of cloud computing, virtualization plays an important role in providing services to end-users efficiently. However, with the increase in services over Cloud Computing, it is becoming more challenging to manage and run multiple Virtual Machines (VMs) in Cloud Computing because of excessive power consumption. It is thus important to overcome these challenges by adopting an efficient technique to manage and monitor the status of VMs in a cloud environment. Reduction of power/energy consumption can be done by managing VMs more effectively in the datacenters of the cloud environment by switching between the active and inactive states of a VM. As a result, energy consumption reduces carbon emissions, leading to green cloud computing. The proposed Efficient Dynamic VM Scheduling approach minimizes Service Level Agreement (SLA) violations and manages VM migration by lowering the energy consumption effectively along with the balanced load. In the proposed work, VM Scheduling for Efficient Dynamically Migrated VM (VMS-EDMVM) approach first detects the over-utilized host using the Modified Weighted Linear Regression (MWLR) algorithm and along with the dynamic utilization model for an underutilized host. Maximum Power Reduction and Reduced Time (MPRRT) approach has been developed for the VM selection followed by a two-phase Best-Fit CPU, BW (BFCB) VM Scheduling mechanism which is simulated in CloudSim based on the adaptive utilization threshold base. The proposed work achieved a Power consumption of 108.45 kWh, and the total SLA violation was 0.1%. The VM migration count was reduced to 2,202 times, revealing better performance as compared to other methods mentioned in this paper.

• 전자통신동향분석
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• 제24권5호
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• pp.30-37
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• 2009

LED는 빛을 내는 반도체이다. LED는 백열전등에 비하여 전기 절감 효과가 높고, 형광 등에 비하여 수은을 사용하지 않아 친환경적이기 때문에 녹색성장의 대표주자 중 하나이다. 메모리 반도체와 전자통신 기기가 융합하여 지난 20년간 발전하여 왔듯이, 앞으로는 LED와 전자통신이 융합하여 새로운 형태의 융합 기술이 발전할 것이다. 현재 예상 가능한 LED 전자통신 융합 기술은 LED 조명과 동시에 통신을 할 수 있는 가시광 무선통신 기술과 감성 및 전기 절감을 실현할 수 있는 LED 조명 모듈간 유선 네트워킹 기술이다. 본 고에서는 LED 조명과 녹색성장이 연계된 배경, 가시광 무선통신의 국내 및 국제 표준 동향, LED 조명 네트워킹 기술을 설명한다. LED 융합 기술에 의하여 인간중심의 편리 시설을 제공하면서도 전기 절감 및 저탄소를 실현할 수 있다.

• 전자공학회논문지A
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• 제32A권12호
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• pp.55-63
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• 1995

By employing the concept of superimposing the induced current on partial scattere roled as a secondary source, matrix Green's function was derived. The procedure in the way of derivation presented here was based on the equivalence principle and the induction theorem and applying moment methods to the resulting electric field integral equation. As examples, the induced current on scatterers consisted of wire/plate conductor, the input impedance and gain patterns of corner reflector antenna were calculated. And computing times required for solving matrix equation were compared with those of conventional method.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.399-400
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• 2002

A numerical procedure for analyzing thermo-elastic contact applied to an automotive disk brake and calculating subsurface stress distribution has been developed. The proposed procedure takes the advantage of the simplex algorithm to save computing time. Flamant's solution and Boussinesq's solution are adopted as Green function in analysis. Comparing the numerical results with the exact solutions has proved the validity of this procedure.