A system and method are provided for mobile stations for enhancing the ease of use of a mobile station. The data is exchanged via a link operable to provide a first link mode in which at least a portion of the exchanged data may be lost. Therefore, it is possible to provide a variable hydraulic motor driving device which is capable of preventing braking operation from being excessively long and also capable of preventing a large shock from occurring at a time of stoppage due to a large braking force generated from an early stage of braking operation. Both methods may be applied with either a static or a dynamic implementation. The third layer is joined with at least one of the first layer and the second layer such that the second layer is positioned between the first layer and the third layer.