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The characteristics of red pigments of the Gaya cultural circles, the ancient federation kingdom in the southern part of the Korean Peninsula, have been investigated using multiple analyses (SEM–EDS, XRD, Raman and Mössbauer spectroscopy). In results, reddish ochre- and pure hematite-based pigments were distinguished. In addition, as the redness of the pigment increased, the proportion of well crystalline and magnetically ordered α-Fe2O3 phase also increased, whereas the amorphous and superparamagnetic Fe2O3 phase were decreased. These results indicate that the ancient Gaya people produced various red pigments according to their use by thermal treatment of reddish ochre and high-purity iron compounds. [ABSTRACT FROM AUTHOR]

An arc fault is an electrical breakdown of the insulating medium in an electrical system. When arc faults occur, they cause electrical fires with local sparks and temperatures of over 5000 °C. A series arc is generated in series with a load due to an incomplete connection between cords or a loose connection between a cord and terminal. However, it is hard to detect series arc faults with arc protection devices because the fault current flowing by series arc in the circuit is not higher than the load current. Especially in Korea, preventing electrical fires by series arc is rarely applied because there is no national standard for arc fault circuit interrupters (AFCI) and arc fault detection devices (AFDD). Therefore, many studies for reliable arc detection and analysis are still necessary to prevent electrical fires. In this study, phase analyses of series arc signals for low-voltage electrical devices such as heaters, computers, refrigerators, and air conditioners were conducted. The arc generator was fabricated according to UL 6199 and an optimal filter was designed to detect series arc signals without any attenuation. The phase of detected series arc signals was analyzed according to load types and finally a new algorithm was proposed based on the result of phase-resolved series arc (PRSA) analysis to identify types of loads. [ABSTRACT FROM AUTHOR]