• ETRI Journal
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• v.42 no.6
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• pp.846-858
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• 2020

The non-orthogonal multiple access (NOMA) technique offers throughput improvement to meet the demands of the future generation of wireless communication networks. The objective of this work is to further improve the throughput by including an underlay cognitive radio network with an existing multi-carrier NOMA network, using cooperative communication. The throughput is maximized by optimal resource allocation, namely, power allocation, subcarrier assignment, relay selection, user pairing, and subcarrier pairing. Optimal power allocation to the primary and secondary users is accomplished in a way that target rate constraints of the primary users are not affected. The throughput maximization is a combinatorial optimization problem, and the computational complexity increases as the number of users and/or subcarriers in the network increases. To this end, to reduce the computational complexity, a dynamic network resource allocation algorithm is proposed for combinatorial optimization. The simulation results show that the proposed network improves the throughput.

• International Journal of Computer Science & Network Security
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• v.22 no.5
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• pp.67-72
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• 2022

There has been a significant growth in global population and industrialization, as a consequence demand for electricity is increasing rapidly and the power systems need to increase the electricity generation. Currently, most of generated electricity is generated from fossil fuels. However, there are many financial and environmental concerns associated with the generation of electricity from such resource. Photovoltaic )PV) solar as a renewable resource is promising. The power output of PV systems is mainly affected by the solar irradiation and ambient temperature. This paper attempts at reducing the burden and improving the accuracy of the extensive simulations related to integrating PV systems into the electrical grid.

• Nuclear Engineering and Technology
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• v.43 no.4
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• pp.375-382
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• 2011

The prospects for growth of the nuclear power industry in Korea have improved remarkably as the demand for energy increases in stride with economic development. Meanwhile, as nuclear energy development is enhanced, nuclear technology has also improved evolutionarily and innovatively in the areas of reactor design and safety measures. As nuclear technology development in Korea advances, more human resources are required. Accordingly, the need for a well-managed program of human resource development (HRD) aimed at assuring needed capacities, skills, and knowledge and maintaining valuable human resources through education and training in various nuclear-related fields has been recognized. A well-defined and object-oriented human resource development and management (HRD&M) is to be developed in order to balance between the dynamics of supply and demand of the workforce in the nuclear industry. The HRD&M schemes include a broad base of disciplines, education, sciences, and technologies within a framework of national sustainable development goals, which are generally considered to include economics, environment, and social concerns. In this study, the projection methodology considering a variety of economic, social, and environmental factors was developed. Using the developed methodology, medium- and long-term nuclear human resources projections up to 2030 were conducted in compliance with the national nuclear technology development programmes and plans.

• Journal of Wind Energy
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• v.9 no.4
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• pp.65-71
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• 2018

To establish an offshore wind turbine test site, a wind resource assessment of the candidate site is required as a preliminary procedure. The wind resource assessment must be performed with at least one year of wind data. If the assessment is performed with short-term wind data, the results cannot validate the wind conditions of the candidate site. This study performs wind resource assessment of Kokunsangun-do to investigate the wind conditions of the candidate site. The wind data is measured by the Automatic Weather System (AWS) of the Korea Meteorological Administration, located at Maldo. The data is for five years, measured from 2013 to 2017. Measured wind data is statistically processed with a 10-minute average scheme to find out the dominant wind direction and wind power density, with yearly wind speed distribution (Weibull-based). This study contributes to build a database of wind energy resources around Maldo. Also, the results of this study could be used for the establishment of an offshore wind turbine test site.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.662-663
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• 2011

수요자원시장은 '08년 시범사업을 시행하고, '09년부터 본 사업을 시행하였고, '10년도에는 51.3만kW의 부하감축을 시행하였다. 본 논문에서는 우리나라 전력수요자원시장의 기본개념 및 운영경험을 설명하고, 향후 전력수요자원시장의 개선방향에 대해 언급하고자 합니다.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.420-422
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• 2005

This paper introduces a new paradigm for energy supply system in near future which produces electric and district heat cogeneration with dispersed power grid with small nuclear power units. Recently, in nuclear field, a lot of effort has been done in nuclear major countries to develop small and medium reactor for enhancement of nuclear peaceful use as like in district heating, electric power generation, seawater desalination or hydrogen generation.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1721-1723
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• 2002

In 3rd-generation mobile communication systems providing packet service, optimal scheduling algorithms we needed to increase service efficiency. In this paper, three scheduling algorithms (SP, EDF, and RPQ) which have been studied in the field of computer networks are applied with transmit power constraint to an interference-limited CDMA system, proving to be efficient.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.92-96
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• 2009

In this paper, economic analysis of Energy Storage System for power system is performed. Economic analysis is performed to show the benefits of Energy Storage System. Results illustrate the advantages of Energy Storage System not only acting as an alternative generation resource but also giving a better reliability and stability in power system.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.310-314
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• 2008

The exploitation of the wind energy resource is a rapidly growing area world-wide. The number of installed units is continuously increasing, and it is important to respect and to deal with the impact of wind turbine. This paper addresses the power quality characteristics of U57 Wind Turbine. 750kW gearless type wind turbine for low wind speed, named U57, is developed by UNISON. The power quality measurement system consists of measuring WTG output current, line-to line voltage and wind speed signal. With using measured data, power quality measurement is evaluated about maximum power, reactive power, voltage fluctuation, harmonics according to IEC 61400-21.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.704-711
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• 2013

Data center is an information hub and resource for information-centric society. Since data center houses hundreds to ten thousands servers, networking and communication equipment, and supporting systems energy saving is one of the hottest issues for green data center. Among several solutions for green data center this paper introduces higher voltage direct current (DC) power feeding system. Contrary to legacy alternating current (AC) power feeding system equipped with Uninterruptible Power Supply (UPS), higher voltage DC power feeding system is reported to be a more energy efficient and reliable solution for green data center thanks to less AC/DC and DC/AC conversions. Main focus of this paper is on reliability issue for reliable and continuous operation of higher voltage DC power feeding system. We present different types of configuration of the power feeding systems according to the level of reliability. We analyze the reliability of the power feeding systems based on M/M/1/N+1/N+1 queueing model. Operation of the power feeding system in case of failure is also presented.