Abstract: A refrigerant channel switching apparatus in an air conditioner having cooling and warming functions is provided. The apparatus includes a main valve body, a direction shifting chamber formed within the main valve body and having a four connecting ports connected to an output and an input of a compressor, an indoor heat-exchanger, and an outdoor heat-exchanger, respectively, an operating chamber formed in the main valve body having a plurality of connecting ports, an operational guide member contained in the operating chamber and disposed to rotate in the operating chamber, a partition formed with the operational guide member in a body and disposed to rotate within the direction shifting chamber of the main valve body, a pilot valve connected to the connecting ports of the operating chamber and causing the direction shifting chamber to switch a connection between a compressor, an indoor heat-exchanger, and an outdoor heat-exchanger.

Abstract: An off-track optimizing apparatus, disk, and method for raising track density of a hard disk drive using a magnetoresistive head. An optimal off-track amount is detected in an initial test process of a hard disk drive, and an additional position detection signal is written into a specific area of a disk. During track follow, the magnetoresistive head is on-tracked in a specific track by using the additional position detection signal.