• Composites Research
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• v.32 no.5
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• pp.237-242
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• 2019

In this research, a capacitive pressure sensor (Piezocapacitive Sensor) was fabricated using carbon black powder containing poly-dimethylsiloxane (PDMS) with micro-grid patterned surface. To investigate the effect of carbon black powder and micro-grid pattern on the sensor's performance, various sensors were fabricated with different carbon black powder concentration and grid pattern density. The performances of the developed sensors were compared in terms of operating range and sensitivity.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.7
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• pp.1032-1038
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• 2017

Recently, regulation on carbon emissions has been strengthened according to the new climate change convention (COP21) held in Paris, and then Korea has decided to reduce CO2 emissions by 37% until 2030. As one of countermeasures, the government has energetically performed demonstration projects of island micro-grid including solar power, wind power and energy storage system. However, in order to smoothly introduce island micro-grid, it is a critical issue to carry out the economic evaluation for power utility aspect and independent power producer aspect. Therefore, this paper proposes economic evaluation algorithms of island micro-grid which are based on the present worth method, considering cost and benefit factors in the aspect of both sides. Firstly, in case of power utility this paper proposes algorithm to estimate a period of return on investment according to the introduction capacity of distributed generators replacing diesel generator. And also, in case of independent power producer, this paper proposes evaluation algorithm to estimate weighting factor of SMP and benefit rate based on break-even point related with cost and benefit. From a case study result on real island micro-grid model, it is confirmed that proposed algorithms are useful and practical for the economic evaluation of island micro-grid.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.1
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• pp.63-71
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• 2013

This paper describes the coordinated droop control method for stand-alone type DC micro-grid to improve reliability and utilization of distributed generations and energy storage. The stand-alone type DC micro-grid consists of several distributed generations such as a wind power generation, solar power and micro-turbine, and energy storage. The proposed method which is based on autonomous control method shows high reliability and stability through coordinated droop control of distributed generations and energy storage and also capability of battery management. The operation of stand-alone type DC micro-grid was analyzed using detail simulation model with PSCAD/EMTDC software. Based on simulation results, a hardware simulator was built and tested with commercially available components and performance of system was verified.

• Journal of radiological science and technology
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• v.41 no.2
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• pp.149-155
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• 2018

Quantitative analysis was performed to confirm that moire artifact was removed without loss of image when using grid suppression software in the diagnosis of micro lesions. we showed that grid suppression images can be morphologically different from original images as they are significantly lower than those of the optimized grid in the similarity analysis with reference images in mammographic phantom images. We were confirmed that images of microcalcification with smaller signal than noise were lost because the pixel values of all lesions increased significantly after the grid suppression, The change in contrast using the NORMI 13 X-ray test phantom was reduced to 30% of the reference image, This result was significantly lower than the 90% when using the optimized grid. In conclusion, the use of grid suppression software in clinical images should be carefully considered because of the possibility of misdiagnosis due to micro lesion loss and morphological changes.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.8
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• pp.24-32
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• 2005

Micro-source units having power ratings in thousands of watts can provide power quality with higher reliability and efficiency than the conventional large scale units. Since these units are small and easy to install, they are clustered with loads creating micro-grid services to customer sites such as office buildings, industrial parks and homes. Micro-sources adopt voltage source inverter to ensure the power quality of sensitive loads. This paper deals with the connection of micro-sources into the system grid EMTDC modeling of the grid connected micro-sources at the power frequency range are proposed and the characteristics of the control system parameters are investigated. Simulation results show that the micro-grid system with two micro-sources has good dynamic characteristics.

• 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 the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.10
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• pp.52-58
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• 2009

In this paper, we propose a probability method to determine minimum capacity of energy storage system(ESS) for Micro-grid Because of high capital cost of ESS, It's very important to determine optimal capacity of ESS and for stable operation of Micro grid(MG), we should determine minimum capacity of ESS. The proposed method has abilities to consider forced outage rate of generators and intermittent of non-dispatchable generators and minimum capacity make MG keep energy balancing by oneself.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1328-1334
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• 2015

A new system for evaluating the voltage management errors of distribution equipment is presented in this paper. The main concept of the new system is to use real distribution live-line voltage to evaluate and correct the voltage measurement data from distribution equipment. This new approach is suitable for a new Distribution Management System (DMS) which has been developed for a distribution power system due to the connection of distributed generation growth. The data from distribution equipment that is installed at distribution lines must be accurate for the performance of the DMS. The proposed system is expected to provide a solution for voltage measurement accuracy assessment for the reliable and efficient operation of the DMS. An experimental study on actual distribution equipment verifies that this voltage measurement accuracy assessment system can assess and calibrate the voltage measurement data from distribution equipment installed at the distribution line.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.3
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• pp.486-492
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• 2017

In recent years, renewable energy sources have been mentioned as solution to environmental regulation and energy supply-demand. Energy storage systems are needed to mitigate the intermittent output characteristics of renewable energy sources and to operate micro grid efficiently using renewable energy generation systems. However, despite the necessity of energy storage system, this cannot secure the economical efficiency of the energy storage system by high initial cost. In this paper, a micro grid is constructed to supply electric power to industrial customers by using solar power generation system and energy storage system among renewable energy generation power sources and operated to improve energy independence. In the case study, we use photovoltaic system which is representative renewable energy generation system. Unlike conventional photovoltaic system, this system uses floating photovoltaic system with the advantage of having high output and no land area limitations. It is operated for the purpose of improving energy independence in the micro grid. In order to secure economical efficiency, the energy storage system operates a micro grid with a minimum capacity. Finally, this paper calculates the appropriate subsidy for the energy storage capacity.

• Journal of radiological science and technology
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• v.40 no.4
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• pp.575-580
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• 2017

Because moire artifacts overlap with fine lesions and frequency bands, image processing software that removes moire artifacts can lead to loss of micro lesions. In this study, microscopic lesions such as microcalcification and microfracture were randomly formed on SD (Sprague Dawley) rats and image and optimized grid images were compared and analyzed using reference image and grid suppression software. The images were read by two consecutive radiologists using a McNemar's test. Among the 73 microcalcifications, in the 13 cases after grid suppression, the image of the optimized grid shows the loss of image in 3 cases, and the image after grid suppression shows statistically significant image loss (p=0.021). In all 53 fracture lines, there were 19 cases of image loss after the grid suppression, and only one case of the optimized grid showed no image loss. Therefore, the use of grid suppression software to remove moire artifacts should be carefully considered in the diagnosis of micro lesions.