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Baek B.K.,Korea Institute of Science and Technology | Baek B.K.,Yonsei University | La Y.H.,Korea Institute of Science and Technology | La Y.H.,Hanyang University | And 10 more authors.
Polymer Degradation and Stability | Year: 2016

For the first time, a kinetic study on the supercritical decrosslinking reaction of silane-crosslinked polyethylene (S-XLPE) in a continuous process was conducted. The decrosslinking reaction in a continuous process was corresponding to the first-order reaction model in which the reaction rate was linearly proportional to the gel content. The residual gel content exponentially decreased with reaction time. Reaction constant was observed exponentially related to the reaction temperature. The continuous decrosslinking reaction revealed kinetic constants of 1.355 ± 0.103, 2.715 ± 0.177, and 4.348 ± 0.218 min-1 at 360, 380 and 390 °C, respectively and activation energy of 132.36 kJ mol-1. © 2016 Elsevier Ltd.

Kong S.,KAIST | Kim J.J.,KAIST | Park L.,LS Cable and System Ltd. | Park U.,LS Cable and System Ltd. | Kim J.,KAIST
cccc2012 Asia-Pacific Symposium on Electromagnetic Compatibility, APEMC 2012 - Proceedings | Year: 2012

In this paper, we present the prediction model of the near-field intensity at the frequency of maximum power transfer in mutual-coupled rectangular coils for wireless power transfer (WPT) systems. When the current flows through the transmitter coil in mutual-coupled coils, the electromagnetic fields are radiated from both transmitter and receiver coil and interact with each other. The presented model enables to predict the near-field intensity of mutual-coupled rectangular coils reflecting an interaction between the transmitter and receiver coils such as a mutual coupling factor and an offset of electromagnetic fields radiated from each coil at the operating frequency that maximizes the power transferred. In order to validate the presented model, the test vehicles of the coupled rectangular coils are simulated with 3D EM solver and fabricated on printed circuit boards (PCBs). Lastly, it is experimentally verified that the presented model has a good prediction of the near-field intensity at the frequency of maximum power transfer in mutual-coupled rectangular coils for WPT systems. © 2012 IEEE.

Kong S.,KAIST | Hwang C.,KAIST | Kim K.,KAIST | Kim H.,KAIST | And 3 more authors.
2011 IEEE Electrical Design of Advanced Packaging and Systems Symposium, EDAPS 2011 | Year: 2011

In this paper, we propose an analytical model for predicting the EMF intensity from the circular coil in WPT systems while the current flows through the coil. Assuming the coil is a filament, we then calculate the magnitude of B-field of the circular coil from the vector magnetic potential. Through 3D EM simulations, it is verified that the proposed model well predicts the EMF intensity at various distance from the coil. As the proposed EMF intensity prediction model gives a fast, yet precise solution of the intensity, it can significantly reduce the design optimization time. © 2011 IEEE.

Baek B.K.,Korea Institute of Science and Technology | Baek B.K.,Yonsei University | Shin J.W.,LS Cable and System Ltd. | Jung J.Y.,Korea Institute of Science and Technology | And 5 more authors.
Journal of Applied Polymer Science | Year: 2015

This work demonstrates that extrusion process can be used as a continuous reactor for the recycling of crosslinked polyethylene (XLPE) via supercritical methanol decrosslinking reaction. The multistage single screw extruder (L/D = 36, D = 40 mm) with methanol injection pump was customized for the continuous supercritical decrosslinking reaction. Reaction temperature was ranged from 360C to 390C. The amount of methanol was varied from 0 to 7 mL/min. The extruder provided the crosslinked polymers with the supercritical conditions of methanol during continuous process. The gel content of XLPE decreased with the increase in the reaction temperature and methanol content. Although XLPE experienced supercritical methanol for less than 2 min retention time in the continuous supercritical extruder, it was completely decrosslinked above 390C at the methanol feeding rate of 7 mL/min. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41442. © 2014 Wiley Periodicals, Inc.

Kim S.H.,Gyeongsang National University | Choi J.H.,Gyeongsang National University | Kim W.J.,Gyeongsang National University | Kim K.L.,Korea University | And 4 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2012

A high-temperature superconducting (HTS) DC cable system has attracted a great deal of interest from the view point of low loss, dense structure and large capacity compared to HTS AC cable system. It has a HTS cable and a termination. A HTS DC cable system consists of a conductor, cooling system and electrical insulation. To realize the HTS DC cable system, it is important to study not only high current capacity and low loss of conductor but also optimum electrical insulation at cryogenic temperature. The electrical insulation technology of HTS DC cable and termination must be solved for the long life, reliability and compact of cable.In this paper, we will discuss mainly on the electrical insulation characteristics and the insulation design of 220 kV class HTS DC cable. Voltage-time (V-t) characteristics of laminated polypropylene paper (PPLP) in LN 2 were studied. Furthermore, the surface flashover characteristics of glass fiber reinforced plastic (GFRP) for termination insulators under DC and lightning impulse voltage were studied. © 2011 IEEE.

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