• Ceramist
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• v.21 no.4
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• pp.312-330
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• 2018

Energy storage/conversion has become crucial not only to meet the present energy demand but also more importantly to sustain the modern society. Particularly, electrical energy storage is critical not only to support electronic, vehicular and load-levelling applications but also to efficiently commercialize renewable energy resources such as solar and wind. While Li-ion batteries are being intensely researched for electric vehicle applications, there is a pressing need to seek for new battery chemistries aimed at stationary storage systems. In this aspect, Zn-ion batteries offer a viable option to be utilized for high energy and power density applications since every intercalated Zn-ion yields a concurrent charge transfer of two electrons and thereby high theoretical capacities can be realized. Furthermore, the simplicity of fabrication under open-air conditions combined with the abundant and less toxic zinc element makes aqueous Zn-ion batteries one of the most economical, safe and green energy storage technologies with prospective use for stationary grid storage applications. Also, Zn-ion batteries are very safe for next-generation technologies based on flexible, roll-up, wearable implantable devices the portable electronics market. Following this advantages, a wide range of approaches and materials, namely, cathodes, anodes and electrolytes have been investigated for Zn-ion batteries applications to date. Herein, we review the progresses and major advancements related to aqueous. Zn-ion batteries, facilitating energy storage/conversion via $Zn^{2+}$ (de)intercalation mechanism.

• Journal of Wind Energy
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• v.14 no.3
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• pp.14-24
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• 2023

The significance of renewable energy has been on the rise, as evidenced by the 3020 renewable energy plan and the 2050 carbon neutrality strategy, which seek to advance a low-carbon economy by implementing a power supply strategy centered around renewable energy sources. This study examines the wind resources on the west coast of South Korea and confirms the potential for wind power generation in the area. Wind speed data was collected from 22 automatic weather system stations and four light house automatic weather system stations provided by the Korea Meteorological Administration to evaluate potential sites for wind farms. Weibull distribution was used to analyze the wind data and calculate wind power density. Annual energy production and capacity factors were estimated for 15-20 MW-class large wind turbines through the height correction of observed wind speeds. These findings offer valuable information for selecting wind power generation sites, predicting economic feasibility, and determining optimal equipment capacity for future wind power generation sites in the region.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.6
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• pp.551-561
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• 1991

The probabilistic generation simulation plays a key role in power system expansion and operational planning especially for the calculation of expected energy, loss of load probaility and unserved energy expected. However, it is crucial to develop a probabilistic generation simulation algorithm which gives sufficiently precise results within a reasonable computation time. In a previous paper, we have proposed an efficent method using Fast Hartley Transform in convolution process for considering the thermal and nuclear units. In this paper, a method considering the scheduling of pumped-storage plants and hydro plants with energy constraint is proposed. The method also adopts FHT techniques. We improve the model to include multi-state and multi-block generation. The method has been applied for a real size model system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.5
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• pp.596-603
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• 2013

The increase of distributed power generation is closely related to interest in microgird including renuable energy sources such as photovoltaic (PV) systems and fuel cell. By the growing interest of microgrid all over the world, many studies on microgrid operation are being carried out. Especially operation technique which is core technology of microgrid is to supply heat and electricity energy simultaneously. Optimal microgrid scheduling can be established by considering CHP (Combined Heat and Power) generation because it produce both heat and electricity energy and its total efficiency is high. For this reason, CHP generation in microgrid is being spotlighted. In the near future, wide application of microgrid is also anticipated. This paper proposes a mathematical model for optimal operation of microgrid considering both heat and power. To validate the proposed model, the case study is performed and its results are analyzed.

• The KSFM Journal of Fluid Machinery
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• v.4 no.3 s.12
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• pp.62-77
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• 2001

The modern wind turbines are widely used as important natural energy sources for the electric generation in western countries and some Asian nations. They are commercially matured and progressive and clear policy for the more development with higher technical purposes is maintained throughout the world. Modern wind turbines produce nearly 2000 kW output in their largest sizes and this trend increases up to more powerful power and ultimate utilization of wind energy favoured by clean natural energy. This article has the points of reviewing the states of the art of modern wind turbines with their present technical directions toward next generation version. Some descriptionsare given for easy understanding of the turbine components and related fluid mechanics concerned. The general outlines of policy taken over some countries are also introduced.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.367-372
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• 2001

A fuel cell is an electrochemical energy conversion device tint converts hydrogen and oxygen into electricity and heat for hot water and heating room A fuel cell provides a DC voltage tint can be used to power motors, lights or any number if electrical appliances. There are several different types if fuel cells, each using a different chemistry. Some types if fuel cells show promise for use in DC (distributed generation) because fuel cell is very clean and efficient energy device. CETI (Clean Energy Technologies, Inc.) is developing PEMFC and DMFC for residential power generation, portable and battery. It is anticipated tint RPG is advantageous over current power generation by utility In terms if economics assuming the lifetime of major components is at least five years.

• Journal of the Korean Solar Energy Society
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• v.29 no.1
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• pp.64-69
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• 2009

This paper aims at enhancing the electric production efficiency of photovoltaic(PV) system. The electrical power of PV system is proportional to light intensity on a PV module surface. In this paper, we apply two types of systems to enhance power generation efficiency. First, of all, concentring sunlight using specular surface and one-axis tracking system which traces the sun with vertical direction are applied in this project. From this, we analyze the fixed type method and power generation efficiency.

• International Journal of Air-Conditioning and Refrigeration
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• v.12 no.3
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• pp.141-147
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• 2004

Cogeneration has been widely introduced in many countries for use m industrial, commercial and residential applications. However, there have been few models with an output of less than 100kW. In the present study, a spark ignited gas engine with electric generation output of 10kW was developed for micro cogeneration package. Developed gas engine achieved following performance characteristics such as $26.7\%$ of electric generation efficiency, NOx emission less than 10 ppm at $13\%$ oxygen, 82 dB of noise level, and about 3 seconds of switching time from idling to nominal power.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.2
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• pp.106-117
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• 2022

Multiple output converters can be utilized when various output voltages are required in applications. Recently, one of the multiple output converters called fly-buck has been proposed, and has attracted attention due to the advantage that multiple output can be easily obtained with a simple structure. When constant on-time (COT) control is applied, the output ripple voltage must be treated carefully for control stability and voltage regulation characteristics in consideration of the inherent energy transfer characteristics of the fly-buck converter. This study analyzes the operation principle of the fly-buck converter with a ripple generation network and presents the design guideline for the improved output voltage regulation. Validity of the analysis and design guideline is verified using a 5 W prototype of the COT controlled fly-buck converter with a ripple generation network for telecommunication auxiliary power supply.

• Journal of the Korean Solar Energy Society
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• v.35 no.5
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• pp.57-65
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• 2015

The Potential Induced Degradation(PID) in PV module mainly affected by various performance conditions such as a potential difference between solar cell and frame, ambient temperature and relative humidity. The positive charges as sodium ions in front glass reach solar cell in module by a potential difference and are accumulated in the solar cell. The ions accelerate the recombination of generation electrons within solar cell under illumination, which reduces the entire output of module. Recently, it was generally known that PID generation is suppressed by controlling the thickness of SiNx AR coating layer on solar cell or using Sodium-free glass and high resistivity encapsulant. However, recovery effects for module with PID are required, because those methods permanently prevent generating PID of module. PID recovery method that voltage reversely applies between solar cell and frame contract to PID generation begins to receive attention. In this paper, PID recovery tests by using voltage under various outdoor conditions as humidity, temperature, voltage are conducted to effectively mitigate PID in module. We confirm that this recovery method perfectly eliminates PID of solar cell according to repeative PID generation and recovery as well as the applied voltage of three factors mainly affect PID recovery.