An apparatus and method for generating high-speed clock signals using a voltage-controlled-oscillator device. The display control apparatus includes a storage storing predetermined attributes, and a converter for converting attributes of each of characters making up an input character string by referring to the storage so that characters making up a converted character string have the predetermined attribute. The first-layer core has an elliptical or rectangular cross section. Due to this structure, the third signal light is incident on the PIN-PD without the quantity thereof being varied depending on the polarization state of the first signal light. The text classifier controller also identifies keyword transition points in the text where the number of detected keywords in a particular category of keywords increases above a threshold number. The system also includes a threshold assembly having a self-articulating threshold cap configured to self-adjust toward the door sweep and interact therewith to form a sealing barrier when the door panel is in a closed position.