To provide a power steering device capable of increasing the degree of freedom in the layout of the various elements, stabilizing the surface of the oil and preventing air from being included or mixing foreign materials with the oil in the oil tank. Also envisioned are compositions comprising cultured NK cells and therapeutic uses thereof. Also provided are methods and compositions for the treatment of obesity and OB resistance. Thereafter the cooled exhaust air flows through a cooler or condenser where the temperature of the cooled exhaust air is further lowered to between about 100\xb0 F.