Abstract: Method for diagnosing a pneumatic control valve by using a positioner model includes: establishing relational expression for outputting valve stem displacement according to control pressure, the relational expression including parameters for the characteristics of a positioner, an actuator, and a valve, determining initial parameter value by adjusting the values of the parameters until the difference between a measured value for a normal operation of the pneumatic control valve and output value obtained by the relational expression is smaller than predetermined error limit, determining diagnostic parameter value by adjusting the values of the parameters until the difference between a measured value for a diagnostic operation of the pneumatic control valve and an output value obtained by the relational expression is smaller than a predetermined error limit, and comparing the initial parameter value and the diagnostic parameter value so as to determine whether the pneumatic control valve has abnormality.

Abstract: The present invention provides a method for diagnosing a rotation device by means of a rotor-bearing-foundation model, the method characterized by utilizing the characteristics of a simulation rotor system. To this end, the present invention comprises the steps of: simulating a rotation device as a rotor system; forming a mathematical model for the rotor system; estimating the state of the rotation device by means of the mathematical model and a vibration measurement value of the rotation device; and diagnosing for abnormalities in the rotation device from the changes in an estimated value. Therefore, since a rotation device is diagnosed for abnormalities by means of forming a mathematical model for a rotor system, the present invention enables more accurate diagnosis of the rotation device.

Abstract: The present invention relates to an air foil journal bearing including a bearing housing having a hollow, in which a rotor is arranged, and a pair of top foils with different lengths formed inside the hollow, thereby enhancing assemblability since the lengths are reduced and increasing stability at the time of high speed rotation through position adjustment of a slot to which the top foils are inserted.

Abstract: Disclosed herein is an air foil bearing capable of adjusting stiffness of single bumps by varying widths of the single bumps. Since the bumps have the same height in an initial stage, a wedging effect is implemented only when a load is applied thereto by an oil film. Therefore, the air foil bearing is advantageous in terms of height management thereof. In addition, it is possible to stably dampen shocks applied in the direction of rotation of a rotor, to improve a support capability, and to reduce shocks due to damping. Therefore, it is possible to enhance durability of the air foil bearing.

Abstract: Disclosed herein is an air blower for a fuel cell vehicle using bearings. The air blower may include a volute casing, an impeller configured to include a hub and a plurality of wings formed on the outer circumferential surface of the hub and to compress air within the volute casing, a motor casing connected to the volute casing, and a motor configured to include a stator, a rotary shaft lengthily formed to penetrate the stator and configured to have a first side connected to the impeller, a rotator formed on the outer circumferential surface of the rotary shaft, a first bearing provided on the first side of the rotary shaft connected to the impeller, and a second bearing provided on a second side of the rotary shaft.