A trochanter belt with an elastic front portion 10 comprised of a soft inner surface which conforms to the body of the wearer. Text and a title thereof are recognized as a pair of documents, and multiple documents individually having the texts and the headings are prepared as retrieval-target documents. When each counter reaches a specified value, each mode is determined. The naphthene rich stream is reformed or dehydrogenated to convert the naphthene.