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Current Situation of Power System and Electric Railway in Brazil
Joao Victor Pinon Pereira Dias,김형철(Hyungchul Kim) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.11
Growth of international interest on Brazil leads to question about the infrastructure characteristics of the nation, called a continental country. Brazil has unique aspects, giving focus in the main points of the power system and the railway in Brazil. The history of these systems is discussed to explain the present stage and the future.
Computer Model for Railway Inductive Power Supply Using the Valtchev Model
Dias, Joao Victor Pinon Pereira,Kim, Hyung-Chul,Jang, Dong-Uk Journal of International Conference on Electrical 2012 Journal of international Conference on Electrical Vol.1 No.1
This paper presents contactless power supply systems using the Valtchev model in transportation systems. The major drawback of contactless systems is that the efficiency is lower than that of contact systems. The coupling coefficient of the contactless transformer is the most influential parameter on the system efficiency. Here, a new computer model for the contactless transfer system developed in the Korea Railroad Research Institute is presented. Also, simulations of the old model and the new model are compared with the prototype measurement to assure the model validity.
Analysis of Inductive Power Transfer according to Resistance loads and air gaps at 50 kHz Frequency
Jang, Dong-Uk,Dias, Joao Victor Pinon Pereira,Chang, Sang-Hoon,Kim, Hyung-Chul 대한전기학회 2013 The Journal of International Council on Electrical Vol.3 No.3
Contactless systems use electromagnetic fields to transport power from railway substation to the traction system. The proto type of inductive power transfer (IPS) system has been developed in order to use train power feeding. It is based on a contactless transformer with a fixed coreless primary and different secondary core like E shape and U shape. The primary coil is supply with 50 kHz current which produces a magnetic flux in the secondary core. Further this flux induces a current in the secondary coil. This paper presents results of experiment for developed inductive power transfer system experiments. The IPS has a large air gap, so it is required a high magnetization current and compensate the leakage flux of primary and secondary coil. The proto type IPS has an air gap with range 1 to 5 mm and core material is ferrite with maximum power of 5 kW. The power supply to IPS is designed by constant current control inverter with compensation capacitance. We measure inductance of IPS and coupling coefficient in order to calculate the compensation parameter according to variable air gap. The analysis of output for the proto type IPS is performed regarding different loads.
장동욱(Dong-Uk Jang),Joao Victor,김형철(Heol-Cheol Kim),이동수(Dong-Su Lee),정상용(Sang-Yong Jung) 한국철도학회 2011 한국철도학회 학술발표대회논문집 Vol.2011 No.10
Contactless systems use electromagnetic fields to transport power from railway substation to the traction system. In Korea Railroad Research Institute KRRI the RIPS (Railway Inductive Power Supply) has been developed. The RIPS is based on a contactless transformer with a fixed coreless primary and a moving core compared with E shape and U shape in the secondary. The primary coil is supply with 20 kHz current which produces a magnetic flux in the secondary core. Further this flux induces a current in the secondary coil.
de-Azevedo-Vaz, Sergio Lins,Machado, Joao Victor Pereira,Pereira, Teresa Cristina Rangel,Freitas, Deborah Queiroz Korean Academy of Oral and Maxillofacial Radiology 2019 Imaging Science in Dentistry Vol.49 No.1
Purpose: To determine whether calcified carotid atherosclerotic plaques(CCAPs) and mineralized laryngeal cartilages (MLCs) were more frequently detected on digital or film-based panoramic radiographs. The clinical relevance of this question is that some radiopacities seen on digital radiographs may correspond to medium-density tissues that are not necessarily mineralized. Materials and Methods: Data were collected from panoramic radiographs and the respective reports issued by 2 private oral radiology centers. A total of 388 radiographs and reports were divided into film-based (group A) and digital (group D) radiographs. The frequencies of CCAPs and MLCs were analyzed using the Fisher exact test, and odds ratios were also calculated (${\alpha}=1%$). Results: The mean age of patients whose reports and radiographs showed CCAPs and/or MLCs ranged from 50.1 to 54.1 years. There was a predominance of females. A higher frequency of CCAPs and MLCs was observed in group D than in group A at both centers(P<0.01). CCAPs and MLCs were detected 4 times more frequently in group D than in group A at one of the centers. Conclusion: CCAPs and MLCs were more frequently detected on digital than on film-based panoramic radiographs. Further studies are needed to determine whether such radiopacities do indeed correspond to mineralized, rather than medium-density, tissues.