A human being presence detection system automatically determines the presence of human beings without directly attaching sensors to the human body and detects human drowsiness. Twisting includes shuffling the arrays of biometric data and may include changing of values in these arrays. The heteropolyacid catalyst produced by the method exhibits excellent catalyst activity in terms of conversion rate, selectivity, and yield. The method simplifies the measurement process by extracting important feature information from the mesh. The three optical fibers form optical paths whose light outputs are caused to interfere. The chair according to the present invention comprises plural legs, at least one of which projects long to the backward, thereby obtaining sufficient stability even when the large load is applied toward backward of the chair.