• Korean Chemical Engineering Research
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• v.58 no.3
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• pp.381-389
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• 2020

This study analyzed the optimal electricity cost of a 100% renewable energy source (RES) based system. Especially energy storage system (EES) and supplementary biopower system as well as photovoltaic (PV) and wind power component were included in the proposed RES-based system to overcome the intermittence of RESs and to efficiently balance energy supply and demand. To comparatively analyze the levelized cost of electricity (LCOE) of different RES-based systems, six scenarios were developed according to the involved RESs: PV, wind, PV/wind, PV/biopower, wind/biopower, and PV/wind/biopower systems. We then applied the proposed systems to build a 100% RES-based system in Jeju Island, Korea. As a result, the single component based system, PV and wind power system of 0.18 and 0.28 $/kWh, respectively, cannot compete with the economics of existing electricity grid. However, the optimal LCOE of the hybrid system where PV and wind power are used as main supply options and biopower as supplementary option was identified to be 0.08 $/kWh, which can compete with the economics of an existing electricity grid.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.1
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• pp.153-162
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• 2018

The importance of energy harvesting technique is increasing due to the elevated level of demand for sustainable power sources for wearable device applications. In this study, we developed an Energy Harvesting wearable Platform(EH-P) architecture which is used in the design of a multi-energy source based on TENG. The proposed switching circuit produces power with higher current at lower voltage from energy harvesting sources with lower current at higher voltage. This can powers microcontrollers for a short period of time by using PV and TENG complementarily placed under hard conditions for the sources such as indoors. As a result, the whole interface circuit is completely self-powered with this makes it possible to run of sensing on a Wearable device platform. It was possible to increase the wearable device life time by supplying more than 29% of the power consumption to wearable devices. The results presented in this paper show the potential of multi-energy harvesting platform for use in wearable harvesting applications, provide a means of choosing the energy harvesting source.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1714-1728
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• 2016

This paper presents improved harmonics extraction based on Adaptive Linear Neuron (ADALINE) algorithm for single phase photovoltaic (PV) shunt active power filter (SAPF). The proposed algorithm, named later as Improved ADALINE, contributes to better performance by removing cosine factor and sum of element that are considered as unnecessary features inside the existing algorithm, known as Modified Widrow-Hoff (W-H) ADALINE. A new updating technique, named as Fundamental Active Current, is introduced to replace the role of the weight factor inside the previous updating technique. For evaluation and comparison purposes, both proposed and existing algorithms have been developed. The PV SAPF with both algorithms was simulated in MATLAB-Simulink respectively, with and without operation or connection of PV. For hardware implementation, laboratory prototype has been developed and the proposed algorithm was programmed in TMS320F28335 DSP board. Steady state operation and three critical dynamic operations, which involve change of nonlinear loads, off-on operation between PV and SAPF, and change of irradiances, were carried out for performance evaluation. From the results and analysis, the Improved ADALINE algorithm shows the best performances with low total harmonic distortion, fast response time and high source power reduction. It performs well in both steady state and dynamic operations as compared to the Modified W-H ADALINE algorithm.

• Journal of the Korea Convergence Society
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• v.12 no.6
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• pp.139-150
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• 2021

Currently, the RPS(Renewable Portfolio Standard) is the policy which supplies new and renewable energy. Power generation companies with large capacity should produce renewable energy or secure through the purchase of REC (Renewable Energy Certificates) as mandatory. The government has revised the REC weight several times, which weights each energy source by evaluating the economic and social value of renewable energy sources, and revised the mandatory supply ratio to gradually increase. This study helps to find the impact of policies on related industries. In this study, time-series analysis and regression analysis on the capacity of PV(Photovoltaics) facilities as a dependent variable were performed to analyze the effect of the revision of the REC weight for photovoltaic power generation and the amount of mandatory supply for renewable energy. As a result, it was statistically assessed that the revision of the REC weight and the increase in the mandatory supply has a significant effect on the increase in the amount of PV facilities.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.6
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• pp.291-297
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• 2003

This paper presents a current-source-inverter based on a buck-boost configuration and its application for residential photovoltaic system. The proposed circuit has five switches. Among them, only one switch acts as chopping, and the other determine the polarity of output; therefore, it can reduce the switching loss. Because the input inductor current is operated on the discontinuous conduction mode, high power factor can be achieved without additional input current controller. So the overall system shows a simple structure. The operational modes are analysed in depth, and then it was verified through the experimental results using a 150 [W] prototype equipped with digital signal processor TMS320F241.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05a
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• pp.57-61
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• 2002

This paper presents a current-source-inverter based on a buck-boost configuration and its application for residential photovoltaic system. The proposed circuit has five switches. Among them, only one switch acts as chopping, and the other determine the polarity of output; therefore, it can reduce the switching loss. Because the input inductor current is operated on the discontinuous conduction mode, high power factor can be achieved without additional input current controller. So the overall system shows a simple structure. The operational modes are analysed in depth, and then it was verified through the experimental results using a 150 W prototype.

• The Plant Pathology Journal
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• v.29 no.4
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• pp.364-373
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• 2013

It has been known that most regulation of pathogenicity factor (rpf ) genes in xanthomonads regulates virulence in response to the diffusible signal factor, DSF. Although many rpf genes have been functionally characterized, the function of rpfE is still unknown. We cloned the rpfE gene from a Xanthomonas oryzae pv. oryzae (Xoo) Korean race KACC10859 and generated mutant strains to elucidate the role of RpfE with respect to the rpf system. Through experiments using the rpfE-deficient mutant strain, we found that mutation in rpfE gene in Xoo reduced virulence, swarm motility, and production of virulence factors such as cellulase and extracellular polysaccharide. Disease progress by the rpfE-deficient mutant strain was significantly slowed compared to disease progress by the wild type and the number of the rpfE-deficient mutant strain was lower than that of the wild type in the early phase of infection in the inoculated rice leaf. The rpfE mutant strain was unable to utilize sucrose or xylose as carbon sources efficiently in culture. The mutation in rpfE, however, did not affect DSF synthesis. Our results suggest that the rpfE gene regulates the virulence of Xoo under different nutrient conditions without change of DSF production.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.6
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• pp.853-858
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• 2010

The purpose of the study was to determine fat contents and fatty acid compositions of the lipids in sweetfish cultured in Korea and lipid oxidation during storage at refrigeration temperature ($2^{\circ}C$). Whole or minced sweetfish were vacuum-packaged or treated with ascorbic acid. Changes in thiobarbituric acid (TBA) values, peroxide values (PV) and free fatty acid (FFA) in the fish were determined. Sweetfish contained 72.5% moisture, 5.3% lipid and 1.1% ash. Palmitic acid was the highest (27.4% (w/w) of the total fatty acids) among the saturated fatty acids. Total monounsaturated fatty acids (MUFA) were 33.9% and oleic acid (21.0%) was the highest, followed by palmitoleic acid (7.8%). Total PUFA were 28.2%. Predominant PUFA were linoleic acid (8.1%), EPA (5.7%) and DHA (12.1%). TBA values and PV of the whole sweetfish treated with ascorbic acid and vacuumpackaged were not different from the control. TBA values of the minced sweetfish treated with ascorbic acid were significantly lower than the other groups (p<0.05). PV of the fish treated with ascorbic acid and vacuum packaging were significantly lower than the other groups (p<0.05). The result of this study suggests that cultured Korean sweetfish may be a good source of unsaturated fatty acids including EPA and DHA, and vacuum packaging and addition of ascorbic acid may protect lipids from oxidation.

• Journal of the Korean Society for Railway
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• v.19 no.5
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• pp.592-599
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• 2016

In the 21st yearly session of the Conference of the Parties (COP 21) of the 2015 United Nations Climate Change Conference, held in Paris, France, in December 2015, the "Paris Agreement" was negotiated; this is a new global agreement on the reduction of climate change, which encourages every country to participate in countermeasures for global climate change. Along with such movements, the electric railway sector has also been actively engaged in low carbon technology. This paper studied the building of a 1.5MW photovoltaic power generation system using the rooftop of the Gwangmyeong Station Building, which is the largest roof among the high-speed railway station buildings in Korea; this station has passenger traffic that reached about 7 million in 2014. For this study, we configured an optimized photovoltaic (PV) power generation system and then estimated the expected annual energy production by using PV system software; we also calculated the expected revenue that could be obtained by linking this source to the power distribution system. The obtained data were used to analyze the contribution of low-carbon energy that could be obtained by introducing a PV power generation system on the roof of an electric railway station building.

• Current Photovoltaic Research
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• v.4 no.2
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• pp.54-58
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• 2016

Laser-doped selective emitter process requires dopant source deposition, spin-on-glass, and is able to form selective emitter through SiNx layer by laser irradiation on desired locations. However, after laser doping process, the remaining dopant layer needs to be washed out. Laser-induced melting of pre-deposited impurity doping is a precise selective doping method minimizing addition of process steps. In this study, we introduce a novel scheme for fabricating highly efficient selective emitter solar cell by laser doping. During this process, laser induced damage induces front contact destabilization due to the hindrance of silver nucleation even though laser doping has a potential of commercialization with simple process concept. When the laser induced damage is effectively removed using solution etch back process, the disadvantage of laser doping was effectively removed. The devices fabricated using laser doping scheme power conversion efficiency was significantly improved about 1% abs. after removal the laser damages.