In a switching power converter, no-load condition is detected based on a variety of parameters including the output current, primary current, transformer reset time, and switching period. A system can include one or more moveable magnets adjacent to printed coils on a circuit. A separating and conveying apparatus separates and conveys the sheets contained in the temporary containing apparatus one by one. A vertical guide can be formed at the front side of the main chassis, and a protrusion formed on the front panel can be inserted into the vertical guide for controllably moving an upper portion of the front panel up and down. We describe a query-analysis process which receives a query as input and matches it to one or more of the question templates, where a priority algorithm determines which match is used if there is more than one. The image photographing apparatus may determine optimal composition information based on feature information that is detected from a photographed image and control a photographing parameter based on the determined optimal composition information.