• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권7호
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• pp.2914-2935
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• 2016

With the increasing popularization of cloud computing, how to reduce physical energy consumption and increase resource utilization while maintaining system performance has become a research hotspot of virtual machine deployment in cloud platform. Although some related researches have been reported to solve this problem, most of them used the traditional heuristic algorithm based on greedy algorithm and only considered effect of single-dimensional resource (CPU or Memory) on energy consumption. With considerations to multi-dimensional resource utilization, this paper analyzed impact of multi-dimensional resources on energy consumption of cloud computation. A multi-dimensional resource constraint that could maintain normal system operation was proposed. Later, a novel virtual machine deployment method (NVMDM) based on improved particle swarm optimization (IPSO) and Euclidean distance was put forward. It deals with problems like how to generate the initial particle swarm through the improved first-fit algorithm based on resource constraint (IFFABRC), how to define measure standard of credibility of individual and global optimal solutions of particles by combining with Bayesian transform, and how to define fitness function of particle swarm according to the multi-dimensional resource constraint relationship. The proposed NVMDM was proved superior to existing heuristic algorithm in developing performances of physical machines. It could improve utilization of CPU, memory, disk and bandwidth effectively and control task execution time of users within the range of resource constraint.

• International Journal of Naval Architecture and Ocean Engineering
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• 제4권4호
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• pp.488-503
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• 2012

The stern boat deployment system was investigated to evaluate the capability of launching and recovering rigid hull inflatable boat (RHIB) via the stern ramp. The main parameters to launch and recover RHIB were tested at the design stage. The combined hydrodynamic effect of the stern wake and the water jet flow made it difficult to maintain the maneuvering and sea-keeping ability of RHIB approaching to the stern ramp. The safe recovery course was proposed to maintain the directional control of RHIB and to reduce the combined hydrodynamic effect in the transom zone. To evaluate the feasibility of RHIB recovery, the stern sill depth was measured in various conditions and the ramp availability time was obtained. Also, the experimental percent time operability (PTO) test was performed by the number of successive launching and recovering operations.

• 한국수소및신에너지학회논문집
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• 제30권6호
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• pp.479-484
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• 2019

Environmental problems were related to human life from second industrial revolution. Recently, peoples are interested in solving global warming problem and improving air quality. Therefore, we request for eco-friendly vehicles such as fuel cell electric vehicles using eco-friendly hydrogen energy. In order to reduce particulate matter in Korea, we have established a plan to promote the deployment of eco-friendly vehicles. In this paper, we analyzed the average monthly charging status and hydrogen consumption by introducing fuel cell bus.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제15권4호
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• pp.255-259
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• 2009

본 논문에서는 동적으로 변하는 그리드 자원이 그리드 컴퓨팅 환경에 자동적으로 참여할 수 있는 미들웨어 시스템인 AGE(Automatic Grid Environments)를 소개하고자 한다. 기존의 시스템에서는 그리드 환경을 구축하기 위하여 각각의 그리드 노드들에 미리 필요한 미들웨어를 다운받아 환경을 설정하여야 하였지만, AGE는 노드가 그리드 환경에 참여하기 위하여 미들웨어를 자동적으로 설치하고 실행하는 기능을 제공한다. 또한 그리드 작업을 실행하기 위하여 필요한 응용프로그램을 사전에 설치하지 않고, 각 그리드 노드에서 실행될 때 다운로드받아 설치 및 실행되는 환경을 제공한다. 즉, 사용자는 그리드 환경의 구축에서부터 작업의 실행 및 구축된 그리드 환경을 제거하는 등의 모든 처리과정을 편리하게 이용할 수 있다.

• 한국컴퓨터정보학회논문지
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• 제13권5호
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• pp.69-76
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• 2008

본 논문에서는 컴포넌트의 단위인 클래스의 일관된 생성과정 및 정형화된 형식을 기반으로 클래스 코드생성을 위한 프로토타입을 구현하였다. 특히 컴포넌트의 기반이 되는 클래스간 연결관계와 집합관계 등을 객체지향언어로는 표현하기 어려운 문제들을 해결하기 위하여 관련성 규칙을 제안하였으며, 이를 통해서 일관성 있는 코드생성의 정형화가 가능하도록 하였다. 또한 코드 생성기를 이용해서 생성된 소스코드는 컴포넌트 모델 구축에 적용되며, 이후에 어플리케이션 개발 시 재사용 대상인 비즈니스 컴포넌트의 조립과 분배의 기반이 되도록 한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권1호
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• pp.277-290
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• 2019

The demand for indoor positioning is increasing day by day. However, the widely used positioning methods today cannot satisfy the requirements of the indoor environment in terms of the positioning accuracy and deployment cost. In the existing research domain, the localization algorithm based on three-dimensional space is less accurate, and its robustness is not high. Visible light communication technology (VLC) combines lighting and positioning to reduce the cost of equipment deployment and improve the positioning accuracy. Further, it has become a popular research topic for telecommunication and positioning in the indoor environment. This paper proposes a surface centroid TOA localization algorithm based on the VLC system. The algorithm uses the multiple solutions estimated by the trilateration method to form the intersecting planes of the spheres. Then, it centers the centroid of the surface area as the position of the unknown node. Simulation results show that compared with the traditional TOA positioning algorithm, the average positioning error of the surface centroid TOA algorithm is reduced by 0.3243 cm and the positioning accuracy is improved by 45%. Therefore, the proposed algorithm has better positioning accuracy than the traditional TOA positioning algorithm, and has certain application value.

• 한국군사과학기술학회지
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• 제21권6호
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• pp.877-885
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• 2018

The anti-submarine helicopter is the most effective weapon system in anti-submarine warfare. Recently changes in the introduction of the anti-submarine warfare sonar system are expected to operate multi-static sonar equipment of the anti-submarine helicopter. Therefore, it is required to study the operational concept of multi-static of anti-submarine helicopter. This paper studies on the optimal search of multi-static based on anti-submarine helicopter considering Furthest On Circles(FOC). First, the deployment of the sensors of the anti-submarine helicopter is optimized using genetic algorithms. Then, the optimized model is extended to consider FOC. Finally, the proposed model is verified by comparing pattern-deployment the search method in Korean Navy.

• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1482-1494
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• 2022

Power conversion cycles (Subcritical Steam, Supercritical Steam, Open Air Brayton, Recuperated Air Brayton, Combined Cycle, Closed Brayton Supercritical CO₂ (sCO₂), and Stirling) are evaluated for land-based nuclear microreactors based on technical maturity, system efficiency, size, cost and maintainability, safety implications, and siting considerations. Based upon these criteria, Air Brayton systems were selected for further evaluation. A brief history of the development and applications of Brayton power systems is given, followed by a description of how these thermal-to-electrical energy conversion systems might be integrated with a nuclear microreactor. Modeling is performed for optimized cycles operating at 3 MW(e) with turbine inlet temperatures of 500 ℃, 650 ℃ and 850 ℃, corresponding to: a) sodium fast, b) molten salt or heat pipe, and c) helium or sodium thermal reactors, coupled with three types of Brayton power conversion units (PCUs): 1) simple open-cycle gas turbine, 2) recuperated open-cycle gas turbine, and 3) recuperated and intercooled open-cycle gas turbine. Aeroderivative turboshaft engines employing the simple Brayton cycle and two industrial gas turbine engines employing recuperated air Brayton cycles are also analyzed. These engines offer mature technology that can facilitate near-term deployment with a modest improvement in efficiency.

• Journal of Communications and Networks
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• 제13권4호
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• pp.345-359
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• 2011

Decode-and-forward relaying is a promising enhancement to existing radio access networks and is already standardized in 3rd generation partnership project (3GPP) as a part of long term evolution (LTE)-Advanced Release 10. Two inband operation modes of relay nodes are supported, namely type 1 and type lb. Relay nodes promise to offer considerable gain for system capacity or coverage, depending on the deployment prioritization, in a cost-efficient way. Yet, in order to fully exploit the benefits of relaying, the inter-cell interference which is increased due to the presence of relay nodes should be limited. Moreover, large differences in the received power levels from different users should be avoided. The goal is to keep the receiver dynamic range low in order to retain the orthogonality of the single carrier-frequency division multiple access system. In this paper, an evaluation of the relay based heterogeneous deployment within the LTE-Advanced uplink framework is carried out by applying the standardized LTE Release 8 power control scheme both at evolved node B and relay nodes. In order to enhance the overall system performance, different power control optimization strategies are proposed for 3GPP urban and suburban scenarios. A comparison between type 1 and type 1b relay nodes is as well presented to study the effect of the relaying overhead on the system performance in inband relay deployments. Comprehensive system level simulations show that the power control is a crucial means to increase the cell edge and system capacities, to mitigate inter-cell interference and to adjust the receiver dynamic range for both relay node types.

• 항공우주시스템공학회지
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• 제11권5호
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• pp.36-41
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• 2017

위성 궤도 내 우주 잔해가 늘어남에 따라 현재 운용 중인 위성들과 폐위성과의 충돌 위험이 지속적으로 증가하는 추세이다. 위 문제를 해결하기 위해 본 연구에서는 1 자유도의 간단한 메커니즘을 사용한 포획장치를 설계하였다. 포획장치는 net가 연결된 4개의 링크군으로 구성되었다. 또한 신뢰도를 높이기 위해 4개의 링크군을 하나의 구동부에 연결하여 자유도가 1이 되도록 설계하였다. 포획장치가 청소위성(janitor위성)의 임무수행에 영향을 끼치지 않도록 위성의 옆면에 수납하였다. 최종적으로 우주 환경에서의 전개 가능성을 파악하기 위해 미세중력 환경을 모사한 수중환경에서 포획장치 전개 실험을 수행하였다. 포획장치 전개실험 중 janitor위성과의 간섭 없이 전개완료 됨을 확인함으로써 대상 위성 포획에 대한 가능성을 검증하였다.