• Journal of the Korean Solar Energy Society
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• v.31 no.2
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• pp.82-88
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• 2011

The artificial increase in the solar intensity incident on solar cells using lenses or mirrors can allow solar cells to generate equivalent power with a lower cost. There are two types of concentration optics for solar energy conversion. One is to use mirrors, and the other is to use Fresnel lenses. The gains that can be achieved with a Fresnel lens or a parabolic mirror are compared. The result showed the gains are comparable and the two configurations were developed competitively. In application areas of Fresnel lenses as solar concentrators, several variations of design were devised and tested. Some PV systems still use commercially available flat Fresnel lenses as concentrators. A convex linear Fresnel lens to improve the concentration ratio and the efficiency is devised and flat linear Fresnel lens in thermal energy collection is utilized. In this study, we designed and optimized flat Fresnel lens and the 'light pipe' to develop 500X concentrated solar PV system. In the process, we compare the transmission efficiencies according to groove types. We performed rigorous ray tracing simulation of the flat Fresnel lenses. The computer aided simulation showed the 'grooves in case' has the better efficiency than that of 'grooves out case'. Based on the ray-trace results we designed and manufactured sample Fresnel lenses. The optical performance were measured and compared with ray-trace results. Finally, the optical efficiency was measured to be above 75%. All the design and manufacturing were performed based on that InGaP/InGaAs/Ge triple junction solar cell is used to convert the photon energy to electrical power. Field test will be made and analyzed in the near future.

• Korean Chemical Engineering Research
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• v.57 no.4
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• pp.539-546
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• 2019

Global warming has mentioned as one of the international problems and these researches have conducted. Carbon Capture, Utilization and Storage (CCUS) technology has improved due to increasing importance of reducing emission of carbon dioxide. Among of various CCUS technologies, mineral carbonation can converted $CO_2$ into high-cost materials with low energy. Existing researches has been used ions extracted solid wastes for mineral carbonation but the procedure is complicated. However, the procedure using seawater is simple because it contained high concentration of metal cation. This research is a basic study using seawater-based wastewater for mineral carbonation. 3 M Monoethanolamine (MEA) was used as $CO_2$ absorbent. Making various concentrations of seawater solution, simulated seawater powder was used. Precipitated metal carbonate salts were produced by mixing seawater solutions and $rich-CO_2$ absorbent solution. They were analyzed by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Thermogravimetric Analysis (TGA) and studied characteristic of producing precipitated metal carbonate and possibility of reusing absorbent.

• Journal of Climate Change Research
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• v.4 no.4
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• pp.349-358
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• 2013

In this study, the newest technology available to reduce GHG emissions, which can be applicable in energy industries of the future that has large reduction obligations by energy target management and large intensity of GHG emissions, has been investigated by searching the technical characteristics of each technology. The newest technology to reduce GHG emissions in the field of power generation and energy can be mainly classified into the improvement of efficiency, CCS, and gas combined-cycle technology. In order to improve the reliability of the GHG emission factor obtained from the investigation process, it has been compared to the technology-specific GHG emission factor derived from the estimated amount of emissions. Then the GHG abatement measures, using the derived estimation of factor, by using the newest technology to reduce GHG emissions have been predicted. As a result, the GHG reduction rate by technology of CCS development has been expected to be the largest more than 30%, and the abatement rate by technology of coal gasified fuel cell and pressurized fluidized-bed thermal power generation has been showed more than 20%. If the effective introduction of the newest technology and the study of its characteristics is continued, and properly applied for future GHG emissions, it can be prospected that the national GHG reduction targets can be achieved in cost-efficient way.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.626-631
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• 2019

The policy-making and technological development for the supply expansion of eco-friendly automobiles has been continuing, but the internal combustion engines still accounts for about 95%. Also, in order to meet the stricter emission regulations of internal combustion engines based on fossil fuels, the proportion of after-treatments for vehicles and (ocean going) vessels is gradually increasing. This study is a basic study for the post-Euro-VI exhaust response of CNG buses, and it is to investigate the basic characteristics according to Pd substitution transition metal effect, catalyst volume effect and space velocity. A catalysts was prepared and tested using a model gas reactor. The NGOC catalyst with 3Pd exhibited the highest catalytic activity with 22% at $300^{\circ}C$, 48% at $350^{\circ}C$ and about 75% at $500^{\circ}C$. 3Co NGOC containing 3wt% of transition metal was excellent in oxidation ability, and it was small in size of 2nm, and the degree of catalyst dispersion was improved and de-NO/CO conversion was high. The volume of the NGOC-LNT-SCR catalyst system was optimal in the combination of 1.5+0.5+0.5 with a total score of 165, considering $de-CH_4/NOx$ performance and catalyst cost. For SV $14,000h^{-1}$, the $CH_4$ reduction performance was the highest at about 20%, while the SV $56,000h^{-1}$ was the lowest at about 5%. If the space velocity is small, the flow velocity decreases and the time remaining in the catalyst volume become long, so that the harmful gas was reduced.

• KIPS Transactions on Software and Data Engineering
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• v.8 no.5
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• pp.193-204
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• 2019

The explosion of data due to the improvement of sensor technology and computing performance has become the basis for analyzing the situation in the industrial fields, and various attempts to detect events based on such data are increasing recently. In particular, sound signals collected from sensors are used as important information to classify events in various application fields as an advantage of efficiently collecting field information at a relatively low cost. However, the performance of sound-event classification in the field cannot be guaranteed if noise can not be removed. That is, in order to implement a system that can be practically applied, robust performance should be guaranteed even in various noise conditions. In this study, we propose a system that can classify the sound event after generating the enhanced sound signal based on the deep learning algorithm. Especially, to remove noise from the sound signal itself, the enhanced sound data against the noise is generated using SEGAN applied to the GAN with a VAE technique. Then, an end-to-end based sound-event classification system is designed to classify the sound events using the enhanced sound signal as input data of CNN structure without a data conversion process. The performance of the proposed method was verified experimentally using sound data obtained from the industrial field, and the f1 score of 99.29% (railway industry) and 97.80% (livestock industry) was confirmed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.523-531
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• 2018

The purpose of this paper is to derive priorities and implications for the organic resource conservation policy in the livestock sector. We conducted a survey on the importance-performance of the organic waste resource reclamation of livestock sector using a 5-point Likert scale. The importance average for the resource recycling of livestock organic waste was 3.63 and the average of performance was 3.04. As a result of the IPA on livestock manure recycling measures, it is necessary to improve feed quality, establish a local recycling system, increase demand for compost and liquid, enhance customer linkages, and develop cost reduction technologies. It requires intensive support for promoting the spread of odor reduction technologies and integrated management of biomass. It is necessary to introduce mid- and long-term measures such as the revival of feed in tariff, promote by-product feeding, establish solid fuel process management standards, create hygiene safety standards, develop eco-beads and promotion of feed conversion. It is required to strengthen support for the development of odor reduction technologies and prepare consultative organizations among related departments, develop eco-friendly solid fuel technology, and support policies for renewable energy certification.

• Education of Primary School Mathematics
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• v.22 no.4
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• pp.261-280
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• 2019

This study is a qualitative study on the case of teaching mathematics between parents and children. 12 lesson units were applied to the 5th grade elementary school child for the first semester, 2019. The purpose of this study was to identify conceptual understanding in the area, the types of problems that child felt difficult during the learning and parents' advantages and difficulties in this setting. For this study, video recording and voice recording were collected for each lesson class. The concept of the area was recognized correctly, the awareness of reconstruction became clear, and the concept of partitioning, unit iteration and structuring an array was more clearly rebuilt. He showed difficulty in conversion between units of the area, in displaying height of the shape whose height is displayed outside and drawing type of figure with same area after the value of the area was offered. In the learning situation of parents and children, parents who are researchers have the advantage of being able to customize up to their children and being free from time and cost constraints. There were difficulties in controlling negative emotion toward the child, determining the level of the children, distribution the class time and deciding the degree of intervention. Furthermore, research on parenting and child-to-parent teaching in mathematics is recommended.

• Membrane Journal
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• v.30 no.6
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• pp.395-408
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• 2020

Polymer electrolyte membrane fuel cells (PEMFCs) have gained much attention as eco-friendly energy conversion devices without emission of environmental pollutant. Polymer electrolyte membrane (PEM) that can transfer proton from anode to cathode and also prevent fuel cross-over has been regarded as a key component of PEMFCs. Although perfluorinated polymer membranes such as Nafion® were already commercialized in PEMFCs, their high cost and toxic byproduct generated by degradation have still limited the wide spread of PEMFCs. To overcome these issues, development of hydrocarbon based PEMs have been studied. Incorporation of cross-linked structure into the hydrocarbon based PEM system has been reported to fabricate the PEMs showing both high proton conductivity and outstanding physicochemical stability. This study focused on the various cross-linking strategies to the preparation of cross-linked PEMs based on hydrocarbon polymers with ion conducting groups for application in PEMFCs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.279-290
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• 2021

This study evaluated the economic feasibility of facility farms according to the introduction of the ultra-high density pot cultivation (UHDPC) for mango. The basic model was selected as a representative farmhouse case in the Jeonnam region, and seven scenarios for conventional crops were tested. The economic feasibility of crop switching was analyzed through partial budget analysis (PBA). The PBA analysis results were supplemented by adding a sensitivity analysis and a break-even point (BEP) analysis. As a result of the analyses, it was found that crop conversion was economical because the increase in the profit coefficient was greater than the increase in the loss coefficient due to the introduction of mango for all conventional crops. The economics of introducing mango was more sensitive to changes in gross income than to changes in cost items. The results show the detailed conditions of crop selection according to the conditions and preferences of individual farms by presenting the direction of increase and decrease by budget item and information on the amount of increase or decrease. In particular, the BEP analysis result, which is about half of the farms case, is significant in that it presents the minimum target value according to production and market risks.

• Journal of Industrial Convergence
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• v.20 no.10
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• pp.87-94
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• 2022

This paper seeks to raise inflection points of battery manufacturing bases in Korea in the V4 region through the reorganization of new industrial technologies in accordance with ESG. As a result, the global supply chain market is cut off. The Russian-Ukraine war and the U.S.-China hegemony are competing in the economic crisis caused by COVID-19. It is showing diversification of new suppliers in an environment where mineral, grain procurement, gas, and even wheat imports from China and Russia are not possible. As a protective glocal, this area is used as a buffer zone(Pro-Russia, Hungary). to an isolated zone(anti-Russia, Poland) by war. In this paper, economic growth is expected to slow further due to the EU tapering period and high inflation in world countries. Due to these changes, the conversion of new tech industry and the contraction of Germany's structure due to energy supply may lose the driving force for economic growth over the past 20 years. This is caused by market disconnection(chasm) in the nominal indicators in this area. On the other hand, Korea should actively develop into the V4 area as an energy generation export (nuclear and electric hydrogen generation) area as a bypass development supply area due to the imbalance in the supply chain of rare earth materials that combines AI. By linking this industry, the energy platform can be scaled up and reliable supply technology (next generation BT, recycling technology) in diversification can be formed in countries around the world. This paper proves that in order to overcome the market chasm caused by the industries connection, new energy development and platform size can be achieved and reliable supply technology (next-generation battery and recycling technology, Low-cost LFP) can be diversified in each country.