• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.6
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• pp.2873-2892
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• 2019

Reducing the interference to the licensed mobile users and obtaining the energy efficiency are key issues in cognitive heterogeneous networks. A corresponding rate loss constraint is proposed to be used for the sensing-based spectrum sharing (SBSS) model in cognitive heterogeneous networks in this paper. Resource allocation optimization strategy is designed for the maximum energy efficiency under the proposed interference constraint together with average transmission power constraint. An efficiency algorithm is studied to maximize energy efficiency due to the nonconvex optimal problem. Furthermore, the relationship between the proposed protection criterion and the conventional interference constraint strategy under imperfect sensing condition for the SBSS model is also investigated, and we found that the conventional interference threshold can be regarded as the upper bound of the maximum rate loss that the primary user could tolerate. Simulation results have shown the effectiveness of the proposed protection criterion overcome the conventional interference power constraint.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.986-989
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• 2000

The traditional method to construct Geographic Information System (GIS) is to scan the published maps, then the important and difficult step is to digitize the maps data. It costs a lot of time and human resource. Because a Global Positioning System (GPS) can offer high accurate digital signal directly, we developed a new method that uses the GPS to construct the GIS.

• Korean System Dynamics Review
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• v.9 no.2
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• pp.129-154
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• 2008

As a practical means to upgrade urban sustainability, this paper focuses on resource cyclical systems concerned with the waste of electric and electronic equipment (WEEE) in Korea. Borrowing System Dynamics concepts and approaches, it examines behavioral changes of WEEE dynamics to observe whether the existing management methods can be readjusted. The measurement is based upon both reuse and material and thermal recycle simulation works in the individual stage of WEEE discharge, collection, and treatment, going beyond the traditional recycle-only customs. This research estimates that the newly introduced Extended Producer Responsibility (EPR) system would definitely exert a significant impact on the final stage of WEEE treatment, decreasing the final treatment volume in the first half of the research period. The trend, nonetheless, would be reversed in the second half, mainly owing to the additional waste volume originated from the local government and recycling center. Sensitivity analysis poses, among others, that the local government-supported reuse center should take charge of a pivotal role in the long run. The research also shows that sufficientand necessary conditions for the WEEE management and treatment should be given to the combined efforts, both from the private sectors and the public domains. Based on these research findings, the paper recommends that key stakeholders including the producer and the public organizations should devise how to jointly carry out specific agenda centered around partnership or network buildings.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.9
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• pp.103-108
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• 2014

In the virtualized server systems, a scheduler in a hypervisor is responsible to assign physical resources for virtual machines. However, the traditional scheduler is hard to provide optimized resource allocation considering the amount of I/O requests. Especially, the drawback hinders performance of software load balancer which runs on virtual machines to distribute I/O requests from the clients. In this paper, we propose a new architecture to improve the performance of software load balancer using multiprocess. Our architecture aims to improve hardware resource utilization and overall performance of the server systems which utilize virtualization technology. Experimental results show the effectiveness of the proposed architecture for the various cases.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.12
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• pp.2957-2986
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• 2013

The traditional approach of fixed spectrum allocation to licensed networks has resulted in spectrum underutilisation. Cognitive radio technology is envisioned as a promising solution that can be used to resolve the ineffectiveness of the fixed spectrum allocation policy by accessing the underutilised spectrum of existing technologies opportunistically. The implementation of cognitive radio networks (CRNs) faces distinct challenges due to the fact that two systems (i.e., cognitive radio (CR) and primary users (PUs)) with conflicting interests interact with each other. Specially, in self-organised systems such as ad-hoc CRNs (AHCRNs), the coordination of spectrum access introduces challenges to researchers due to rapid utilisation changes in the available spectrum, as well as the multi-hop nature of ad-hoc networks, which creates additional challenges in the analysis of resource allocation (e.g., power control, channel and rate allocation). Instead, game theory has been adopted as a powerful mathematical tool in analysing and modelling the interaction processes of AHCRNs. In this survey, we first review the most fundamental concepts and architectures of CRNs and AHCRNs. We then introduce the concepts of game theory, utility function, Nash equilibrium and pricing techniques. Finally, we survey the recent literature on the game theoretic analysis of AHCRNs, highlighting its applicability to the physical layer PHY, the MAC layer and the network layer.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.1013-1014
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• 2015

Regardless of the strict enforcement of prevention education in accordance with the school facility management standard, safety accidents that lead to human and physical damages occur in current educational facilities because of teenagers with very low sense of responsibility and insensitivity toward fire and facility safety. To ensure educational facility safety, technology that will enable a fast work process and easy confirmation of electronic blueprints and related documents about the educational facility through smart devices at the site by various means is needed. This paper proposes a system design linked to the National Education Information System (NEIS) that uses the document conversion function, high efficiency resolution, and Internet of Things (IoT) to inspect and control the educational facility in the event of a safety accident through the Educational Facility Resource Management System (EFRMS) that manages the electronic blueprints, and various educational facility documents through various smart devices.

• 전자공학회논문지 IE
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• v.46 no.3
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• pp.42-47
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• 2009

In CDMA system, the call admission control method using the variable effective bandwidth concept is employed in this paper. The bandwidth for a new call and a handoff call is allocated by considering the number of mobile station being served and dynamically assigned by taking account of the blocking rate of new calls and the dropping rate of handoff calls. There is reserved resource for handoff call. In the case radio resource is insufficient, a new call and a handoff call stand by in buffer for constant time. When radio resource come about, the waiting call is allocated the resource. I analyze the performance of system according to existence and nonexistence of buffer by a simulation study.

• Journal of the Korean Solar Energy Society
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• v.31 no.6
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• pp.72-77
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• 2011

The purpose for installation of offshore weather station is a measurement of wind resources and so on. If weather station is operated, it will be possible to analysis for wind resource and arrangement of wind farm by using measured data. In this paper, we carried out the development of offshore wind resource measurement system for measuring offshore wind resource. Also, In order to monitor for real-time wind data with 1 Hz, we installed the wireless transmission system. All wind characteristic data are sent to the server PC through the this system is connected outport of DataLogger. Transmitted wind data were used in order to look at in the Web-page and tablet PC on a real time basis in a graph. In this paper, we will introduce about the wind resource measurement and remote monitoring system that is the result of study.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.1
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• pp.55-64
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• 2015

Wind turbine market is showed height growth rate of about 30% for year, and is increasingly growing. Total rate of domestic wind turbine installation is showing share of 0.2% of the global market that is 380MW. However, wind turbine installed in domestic are foreign product more than 90%. Similarly, Datalogger of pretest system for ocean wind turbine plant installation has been leaked huge cost to abroad by mostly abroad company product. In this paper, we proposed pretest weather resource measurement system for efficiency and investment cost cutting of wind turbine construction work. Preset weather resource measurement system is ocean weather resource measurement datalogger based on wireless communication(wifi) that have consist of hardware and software(wind rose) that is able to monitoring as datalogger of wireless bridge and battery state, wind direction, wind speed, temperature, humidity, radiation around weather tower and is able to analysis of measured data.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.4
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• pp.51-60
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• 2009

In radio frequency identification(RFID) systems, when an RFID reader uses the same or adjacent frequency with neighbor readers, the interference between the readers may occur, which causes the reader collision and errors in tag recognition. In the previous study on RFID reader anti-collision, the techniques based on Frequency Division Mutiplex(FDM) or Time Division Multiplex(TDM) are proposed. However in these paper, the problem on the condition of RFID reader-to-reader interference considering the distance between interfering readers, frequency and operating time is not define exactly. In this paper, the interference effect is analyzed through RFID reader interference model considering the TDM and FDM, and the optimization problem is defined. To solve this, genetic-resource allocation technique is proposed. Therefore the optimal resource allocation applied RFID environment faithfully is accomplished.