A laser welding structure that is formed by joining a stranded wire of a signal line and a welding portion by locally applying a laser beam and thereby melting and solidifying the stranded wire of the signal line and the welding portion has the following features. Input audio streams are sample-rate converted to an intermediate sample rate derived from the internal oscillator, which may be an LC oscillator. A first insulating layer is formed on a surface of the magnetizable metal layer. Next, the learning curve value is determined based upon the recurring costs model and the nonrecurring costs value such that the sum of the recurring costs and nonrecurring costs at the determined learning curve value is minimized over the potential learning curve values. Applying the candidate query to the document collection.