• Proceedings of the Korea Society of Design Studies Conference
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• 1998.10a
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• pp.10-11
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• 1998

• Journal of the Korean Solar Energy Society
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• v.38 no.4
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• pp.55-66
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• 2018

nZEH (net-Zero Energy House) is defined as a self-sufficient energy building where the sum of energy output generated from new & renewable energy system and annual energy consumption is zero. The electricity generated by new & renewable energy system with the form of distributed generation is preferentially supplied to electrical demand, and surplus electricity is transmitted back to grid. Due to the recent expansion of houses with photovoltaic system and the nZEH mandatory by 2025, the rapid increase of distributed generation is expected. Which means, we must prepare for an electricity-power accident and stable electricity supply. Also electricity charges have to be reduce and the grid-connected should be operated efficiently. The introduction of ESS is suggested as a solution, so the analysis of the load matching and grid interaction is required to optimize ESS design. This study analyzed the load matching and grid interaction by expected consumption behavior using actual data measured in one-minute intervals. The experiment was conducted in three nZEH with photovoltaic system, called all-electric houses. LCF (Load Cover Factor), SCF (Supply Cover Factor) and $f_{grid}$ (Grid Interaction Index) were evaluated as an analysis indicator. As a result, LCF, SCF and $f_{grid}$ of A house were 0.25, 0.23 and 0.27 respectively; That of B house were 0.23, 0.23, 0.19, and that of C were 0.20, 0.19, 0.27 respectively.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.11
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• pp.2185-2191
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• 2009

Wind power and photovoltaic(PV) generation systems are the fastest growing sources of renewable energy. The nonlinear devices, such as power electronic converter or inverter, of wind power and PV generation systems are the source of harmonics in power systems. The harmonic-related problems can have significant detrimental effects in the power system, such as capacitor heating, data communication interference, rotating equipment heating, transformer heating, relay misoperation and switchgear failure. There is a greater need for harmonic analysis that can properly maintain the power quality. By measuring harmonics of existing wind power and PV generation systems as harmonics modeling, the studies were made to see the harmonic impact of grid-connected wind power and PV generation systems.

• Journal of Communications and Networks
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• v.14 no.6
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• pp.614-618
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• 2012

Smart grid is widely considered to be a next generation power grid, which will be integrated with information feedback communications.However, smart grid communication technologies are subject to inefficient spectrum allocation problems. Cognitive radio networks can solve the problemof spectrumscarcity by opening the under-utilized licensed bands to secondary users. In this paper, adaptive cognitive radio spectrum sensing and sharing algorithms are developed for smart grid environments. Simulation results are presented to demonstrate the effectiveness of the proposed scheme in comparison with other existing schemes.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.1112-1118
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• 2014

In island and backcountry areas, electrical power is usually supplied by diesel generators. It is difficult for small scale diesel generators to have an economy of scale owing to the usage of fossil fuels to produce electricity. Also, there is a problem of carbon dioxide emissions that brings some environmental pollution to the entire region of the area. For solving those, this paper proposes a design method of autonomous micro-grid to minimize the fossil fuels of diesel generator, which is composed of diesel generator, wind turbine, battery energy storage system and photovoltaic generation system. The proposed method was verified through computer simulation and micro-grid operation system.

• Journal of Integrative Natural Science
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• v.15 no.2
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• pp.89-97
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• 2022

This paper presents the comprehensive feasibility study of solar mini-grid project located in Bajhang District, Sudur Paschim Province, Nepal. The study has been conducted with the aim of developing a suitable size solar mini-grid system to meet electricity demand of proposed settlements of the village people. The study forecasts that the estimated average daily peak power consumption of load is about 20kW and average daily energy demand of load is about 100-150kWh/day in the base year 2022. The shared ratio of productive end uses is about 25% of the total power consumption and about 27% of the total energy demand, which will be used for small business/income generation activities and required 45kWp size solar power generation mini-grid system. The estimated project cost for the proposed 45kW solar mini-grid system technology, including 3 years of operation & maintenance, as well as power distribution network up to end user's premises is about 0.24 million USD. It is concluded that 45kWp photovoltaic mini-grid is feasible for the location.

• Progress in Superconductivity and Cryogenics
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• v.12 no.2
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• pp.17-20
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• 2010

A considerable amount of research material discussing designs and properties of High Temperature Superconducting Fault Current Limiter (HTS FCL) is available. However, a shortage of research concerning positioning of HTS FCL in power grid is felt. In this paper a feasibility study of HTS FCL positioning in Smart Grid through simulation analysis is carried out. A complete power network (including generation, transmission and distribution) is modeled in Simulink / SimPowerSystems. A generalized HTS FCL is also designed by integrating Simulink and SimPowerSystem blocks. The distribution network of the model has a wind turbine attached to it forming a micro grid. Three phase fault have been simulated along with placing FCL models at key points of the distribution grid. It is observed that distribution grid, having distributed generation sources attached to it, must not have a single FCL located at the substation level. Optimized HTS FCL location regarding the best fault current contribution from wind turbine has been determined through simulation analysis.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.9
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• pp.1560-1565
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• 2010

The renewable resource are getting more attentions with increased concerns on the depletion of fossil fuels and several environmental issues like emission problem. Wind power is a representative option among several renewable sources and the generation capacity using wind power is being increased. However, the wind generation is so volatile on its output characteristic, so it is required to assess the grid impact of wind power generation by measuring the fluctuation effect more precisely. This paper proposes the method for measuring the generation output according to IEC 61400-21(Measurement and assessment of power quality characteristics of grid connected wind turbines) to assess the power quality of wind turbine generation. In addition, it shows an application case to a small-scale wind power generator. In the case study, it suggests a structure design of the proposed measurement instrument both on hardware and software aspects, which is composed of a remote monitoring & data analysis program and an FPGA based real-time signal processing device.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.1
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• pp.1-14
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• 2006

This paper presents the techniques developed using the line source method to internally generate waves on an arc in a rectangular grid system. For five different types of wave generation layouts, quantitative experiments were conducted under the following conditions: the propagation of waves on a flat bottom, the refraction and shoaling of waves on a planar slope, and the diffraction of waves to a semi-infinite breakwater. Numerical experiments were conducted using the extended mild-slope equations of Suh et al. (1997). The fifth type of wave generation layout, consisting of two parallel lines connected to a semicircle, showed the best solutions, especially for a small grid size.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.1709-1718
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• 2017

This paper presents a hybrid stochastic deterministic multi-timescale scheduling (SDMS) approach for generation scheduling of a power grid. SDMS considers flexible resource options including conventional generation flexibility in a chance-constrained day-ahead scheduling optimization (DASO). The prime objective of the DASO is the minimization of the daily production cost in power systems with high penetration scenarios of variable generation. Furthermore, energy storage is scheduled in an hourly-ahead deterministic real-time scheduling optimization (RTSO). DASO simulation results are used as the base starting-point values in the hour-ahead online rolling RTSO with a 15-minute time interval. RTSO considers energy storage as another source of grid flexibility, to balance out the deviation between predicted and actual net load demand values. Numerical simulations, on the IEEE RTS test system with high wind penetration levels, indicate the effectiveness of the proposed SDMS framework for managing the grid flexibility to meet the net load demand, in both day-ahead and real-time timescales. Results also highlight the adequacy of the framework to adjust the scheduling, in real-time, to cope with large prediction errors of wind forecasting.