A brush seal unit can be formed in any size by coupling split brush-seal pieces, and the brush seal units can be easily stacked. The first magnet is mounted in a door half-latch position, and the second magnet is mounted in a door full-latch position. According to the apparatus, powdered or granular material is uniformly heated and dried and heating source for carrier gas is not necessary, thereby achieving improvement in energy efficiency and energy saving. Accordingly, when a jammed printing medium is removed, the printing medium is not crumpled or torn, parts of the image forming apparatus are not damaged, and the image forming apparatus does not malfunction. A bit line contact hole is formed in the inter-layer dielectric to expose the top of the first conductive layer. The process may include: contacting at least one C2 to C5 alcohol with an organic acid in the presence of an esterification catalyst to convert at least a portion of the at least one C2 to C5 alcohol and the organic acid to an ester; at least one of catalytically and thermally degrading the ester to form an organic acid and an olefin.