• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.3
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• pp.1260-1283
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• 2019

Low earth orbit (LEO) satellite broadband network is a crucial part of the space information network. LEO satellite constellation design is a top-level design, which plays a decisive role in the overall performance of the LEO satellite network. However, the existing works on constellation design mainly focus on the coverage criterion and rarely take network performance into the design process. In this article, we develop a unified framework for constellation optimization design in LEO satellite broadband networks. Several design criteria including network performance and coverage capability are combined into the design process. Firstly, the quality of service (QoS) metrics is presented to evaluate the performance of the LEO satellite broadband network. Also, we propose a network stability model for the rapid change of the satellite network topology. Besides, a mathematical model of constellation optimization design is formulated by considering the network cost-efficiency and stability. Then, an optimization algorithm based on non-dominated sorting genetic algorithm-II (NSGA-II) is provided for the problem of constellation design. Finally, the proposed method is further evaluated through numerical simulations. Simulation results validate the proposed method and show that it is an efficient and effective approach for solving the problem of constellation design in LEO satellite broadband networks.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.491-497
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• 2018

This study analyzes the relationship between R&D input and performance using panel data from the defense industry. A research model is established based on the R&D logic model, and the study sample consists of a strongly balanced panel data (n=351) empirically analyzed using panel linear regression. Results identified that defense improvement expenditure has a positive influence on the R&D input, and R&D input positively affected patents using a 5-year time lag. In addition, R&D input positively impacts economic performance, including sales and profit. Hence, the major finding includes R&D inputs have statistically significant effects on economic outcome and the R&D logic model featuring a time-lag.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.10
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• pp.3538-3556
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• 2014

This paper proposes a novel video stitching method that improves real-time performance and visual quality of a multi-camera video surveillance system. A two-stage seam searching algorithm based on enhanced dynamic programming is proposed. It can obtain satisfactory result and achieve better real-time performance than traditional seam-searching methods. The experiments show that the computing time is reduced by 66.4% using the proposed algorithm compared with enhanced dynamic programming, while the seam-searching accuracy is maintained. A real-time local update scheme reduces the deformation effect caused by moving objects passing through the seam, and a seam-based local color transfer model is constructed and applied to achieve smooth transition in the overlapped area, and overcome the traditional pixel blending methods. The effectiveness of the proposed method is proved in the experiements.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.11 s.170
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• pp.1960-1969
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• 1999

This paper presents dynamic modeling and controller design of a tracked vehicle installed with the double rod type ERSU(electro-rheological suspension unit). A 16 degree-of-freedom model for the tracked vehicle is established by Lagrangian method followed by the formulation of a new sky-ground hook controller. This controller takes account for both the ride quality and the steering stability. The weighting parameter between the two performance requirements is adopted to adjust required performance characteristics with respect to the operation conditions such as road excitation. The parameter is appropriately determined by employing a fuzzy algorithm associated with the vehicle motion. Computer simulations are undertaken in order to demonstrate the effectiveness of the proposed control system. Acceleration values at the driver's seat are analyzed under bump road profile, while frequency responses of vertical acceleration are investigated under random road excitation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.11
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• pp.4311-4330
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• 2015

Cloud computing has become a new paradigm by enabling on-demand provisioning of applications, platforms or computing resources for clients. Workflow scheduling has always been treated as one of the most challenging problems in clouds. Commercial clouds have been widely used in scientific research, such as biology, astronomy and weather forecasting. Certainly, it is very important for a cloud service provider to pursue the profits for the commercial essence of clouds. This is also significantly important for the case of providing services to workflow tasks. In this paper, we address the issues of workflow scheduling in commercial clouds. This work takes the communication into account, which has always been ignored. And then, a topology-based workflow-scheduling algorithm named Resource Auction Algorithm (REAL) is proposed in the objective of getting more profits. The algorithm gives a good performance on searching for the optimum schedule for a sample workflow. Also, we find that there exists a certain resource amount, which gets the most profits to help us get more enthusiasm for further developing the research. Experimental results demonstrate that the analysis of the strategies for most profits is reasonable, and REAL gives a good performance on efficiently getting an optimized scheme with low computing complexity.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.2
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• pp.159-166
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• 2014

The study is conducted on the subject of optimization of components sizing for series hybrid electric propulsion systems. The components sizing of series type hybrid system is very important because each component of series type is larger than the corresponding component of the parallel type or series-parallel type. If the components sizing is greater or less than what is required to this system, the performance of the system is getting worse. The methodology for the sizing of a driving motor is introduced based on the foundation of determined system configuration and performance target. And the sizing of an engine/generator and a battery is achieved based on simulation results using Dynamic Programming. It is possible to find the optimal sizing of these components by comparing fuel efficiency of hybrid electric propulsion system for 8 driving cycles.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.47 no.3
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• pp.75-85
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• 2024

Airpower is a crucial force for suppressing military threats and achieving victory in wars. This study evaluates newly introduced fighter forces, considering factors such as fighter performance and power index, operational environment, capacity of each airbase, survivability, and force sustainment capability to determine the optimal deployment plan that maximizes operational effectiveness and efficiency. Research methods include optimization techniques such as MIP(mixed integer programming), allocation problems, and experimental design. This optimal allocation mathematical model is constructed based on various constraints such as survivability, mission criticality, and aircraft's performance data. The scope of the study focuses the fighter force and their operational radius is limited to major Air Force and joint operations, such as air interdiction, defensive counter-air operations, close air support, maritime operations and so on. This study aims to maximize the operational efficiency and effectiveness of fighter aircraft operations. The results of proposed model through experiments showed that it was for superior to the existing deployment plan in terms of operation and sustainment aspects when considering both wartime and peacetime.

• Journal of Aerospace System Engineering
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• v.11 no.2
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• pp.1-8
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• 2017

Delivering clear requirements of the military in the defense acquisition process is a key activity for successful weapon acquisition. In the field of defense, Operational Requirements Documents (ORDs) are prepared to derive and deliver the requirements of the military. In this study, we compare and analyze the form and content of the recent domestic ORD with reference to the US Department of Defense (DoD) ORD. As a result of the study, it is found that the domestic ORD form needs to be supplemented with in accordance with the purpose of the operation, while the requirement parameter, which is a core item of ORD, is insufficient. In order to address these issues, detailed contents of the ORD form suitable for the purpose of this study are presented. Also, we provide clear definitions, explanations, and examples of the operational system's key performance parameters and suggest ways to clearly communicate the requirements of the military.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.3
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• pp.299-310
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• 2019

Increase of combat capability through the lightweighting of vehicles has been internationally issued. One of the methods for lightening is applying high hardness armor(HHA) steel which is outstanding ballistic performance and protection performance compared to weight. Development of HHA steel is currently completed in America, United Kingdom, Australia and Germany. It is used for not only combat vehicle, but also various combat device. Korea is developing new material of HHA steel according to this trend. When such HHA steel is applied to structure, welding process is used for connection of the structure. Cracks from hydrogen embrittlement and cold cracking are easily generated in welds of HHA steel and it greatly affects the strength of all structure. Decrease of strength from welding defect is critical to combat capability. Therefore, welding process optimization is important for performing the role of structure. In this study, international welding technology is reviewed through scientific research paper and patent.

• Journal of Korean Society for Quality Management
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• v.47 no.1
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• pp.163-186
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• 2019

Purpose: The purpose of this study was to present a methodology for assessing the efficiency of supply chain quality management considering characteristics of defense industries to provide academic and policy implications for strengthening quality competitiveness of military supplies. Methods: Using the defense industry's empirical data, conduct an efficiency evaluation by utilizing a multi-stage DEA/Entropy Model for defense industries subject to the quality level survey of military goods manufacturers in 2017. Results: The results of this study are as follows; the first step of the multi-stage DEA model, Quality Management Performance Efficiency Analysis, shows that the CCR model and the BCC model are more efficient than the parent company. the second stage of the multi-stage DEA model showed that the CCR model was slightly more efficient than the parent company and the BCC model was more efficient than the parent.the overall efficiency value of the multistage DEA model, calculated by multipointing the efficiency value of the first stage by the second stage, was more efficient than the parent. Conclusion: The results of this study show that the efficiency of supply chian quality management performance and profitability in the defense industry can be analyzed for the first time using the multistage DEA/Entropy model to identify specific inefficiencies and support objective decision making.