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Influence of Electrolytic and Crevice Corrosion on Mechanical Resistance of Porcelain Insulators
Matheus Rabelo,Simpy Sanyal,Taeyong Kim,Ju-Am Son,In-Hyuk Choi,Junsin Yi 한국신재생에너지학회 2021 한국신재생에너지학회 학술대회논문집 Vol.2021 No.7
Porcelain insulators are widely used in transmission lines; however, their durability and considerable overall maintenance cost have become problems over the years. In this work, porcelain insulators were collected from various locations in South Korea and classified according to their length of service. Mechanical and electrical load tests were performed, and the failure load and damaged region were recorded for each specimen. The fast degradation of the pin in porcelain insulators exceeding 50 years in operation was notable because there was no pin breakage among the samples in service for less than 50 years. Moreover, the failure of 73.68% of all porcelain insulators in service for 54 years occurred in the pin. The average failure load of these samples was 14% lower than that of samples in use for 45 years. To confirm the pin’s deterioration mechanism over time, a mechanical analysis of the reduction in the pin cross-section was performed using the finite element analysis method. Accordingly, a novel degradation mechanism is proposed in this study. Previous studies that focused on the critical areas of the porcelain insulator found that the exposed pin side was easily damaged by the external load. The current findings revealing an unfamiliar porcelain deterioration mechanism may aid in the formulation of a better design to mitigate the problems described above.
Investigation of EVA Accelerated Degradation Test for Silicon Photovoltaic Modules
Jaeun Kim,Matheus Rabelo,Markus Holz,Eun-Chel Cho,Junsin Yi 한국신재생에너지학회 2021 신재생에너지 Vol.17 No.2
Renewable energy has become more popular with the increase in the use of solar power. Consequently, the disposal of defective and old solar panels is gradually increasing giving rise to a new problem. Furthermore, the efficiency and power output decreases with aging. Researchers worldwide are engaged in solving this problem by developing eco-module technologies that restore and reuse the solar panels according to the defect types rather than simple disposal. The eco-module technology not only solves the environmental problem, but also has economic advantages, such as extending the module life. Replacement of encapsulants contributes to a major portion of the module maintenance plan, as the degradation of encapsulants accounts for 60% of the problems found in modules over the past years. However, the current International Electrotechnical Commission (IEC) standard testing was designed for the commercialization of solar modules. As the problem caused by long-term use is not considered, this method is not suitable for the quality assurance evaluation of the eco-module. Therefore, to design a new accelerated test, this paper provides an overview of EVA degradation and comparison with the IEC and accelerated tests.
A Brief Review on III-V/Si Tandem Solar Cells
Sheng Yu,Matheus Rabelo,이준신 한국전기전자재료학회 2022 Transactions on Electrical and Electronic Material Vol.23 No.4
Single-junction (SJ) silicon (Si)-based solar cells are currently widely used in the photovoltaic (PV) industry due to their low cost and rapid industrialization, but their low efficiency (theoretical efficiency limit of 29.4%) is the most significant factor preventing their further expansion. Multi-junction (MJ) solar cells may be a key way to break the effi ciency limit of SJ Si-based solar cells since the approach can take full advantage of different PV materials. To overcome the disadvantages of other types of solar cells and improve the cell efficiency of solar cells, a new MJ solar cell, the III-V/Si tandem solar cell, was fabricated. This article reviews the development of III-V/Si tandem solar cells and briefly describes the three major terminal confi gurations and the three growth mechanisms of III-V compounds on Si substrates. Finally, we present four methods that characterize the performance of III-V/Si tandem solar cells and compare the advantages and disadvantages of these four methods.
Agrawal Khushabu,Patil Vilas,Ali Fida,Rabelo Matheus,우원종,조은철,Yi Junsin 한국물리학회 2021 Current Applied Physics Vol.26 No.-
The HF treatment removes the native oxide and lays behind the dangling bonds over the Si surface which causes the increment in density of interface traps (Dit) through the direct deposition of high-k dielectric on Si. Here, we propose the facile method for reduction of interface traps and improvement in barrier height with the (NH4)2S treatment on Al2O3/Si interfaces, which can be used as the base for the non-volatile memory device. The AFM was used to optimize the treatment time and surface properties, while XPS measurements were carried out to study the interface and extract the barrier height (ΦB). The short period of 20 s treatment shows the improvement in the barrier height (1.02 eV), while the one order reduction in the Dit (0.84 × 1012 cm2/eV) of sulfur passivated Al/Al2O3/Si MOS device. The results indicate the favorable passivation of the dangling bonds over the Si surfaces covered by sulfur atoms.
Integration of Subcells in III-V//Si Tandem Solar Cells
한승용,Suresh Kumar Dhungel,박소민,Matheus de Assis Rabelo,Duy Phong Pham,김영국,이준신 한국전기전자재료학회 2023 Transactions on Electrical and Electronic Material Vol.24 No.2
Tandem solar cells with four and two terminals fabricated with III-V on Si have achieved 35.9% conversion efficiency, which goes beyond the S-Q limit of single junction silicon solar cells. Compared to perovskite tandem solar cells, III-V//Si tandem solar cells have proven their high stability and reliability, which makes them potential candidates for commercialization in future for terrestrial applications. For the proper integration of III-V top and intermediate subcells with silicon bottom subcell, different approaches are being investigated globally. Mechanical bonding is an important approach that utilizes appropriate materials of high transmittance and conductance and hence it is being experimented globally except in the case of direct epitaxial growth of III-V materials on silicon. This review article presents a comprehensive description of diff erent approaches adopted for the integration of subcells in tandem architecture.