Electrical energy can be converted into heat energy through ohmic joule heating. Metallic materials are typically used in electrical heating elements because of their great electrical conductivity. However, metallic materials have several weaknesses, such as corrosion susceptibility, heavy weight, high manufacturing costs, and electromagnetic wave emissions [1,2]. To resolve these problems, carbon materials with good electrical conductivity, such as carbon fibers, graphite fibers, carbon nanotubes, and carbon black, have been examined as heating materials [3,4]. Among these carbon materials, graphite fibers possess many advantages compared to carbon fibers such as good mechanical and electrical properties, excellent chemical stability, high thermal conductivity, and so on [5-7].