Abstract: In an issuing subsystem is stored a first set of authorization data including information on matching between an operator and a group the operator belongs to, and information on matching between a group and commands authorized for operators belonging to the group. As an operator enters a command, the issuing subsystem references the first set of authorization data, judges whether or not the operator is to be authorized to execute the command and, if it is judged that he or she is to be authorized, augments the command with information identifying the group to which the operator belongs, the augmented command being transmitted to an executing subsystem. The executing subsystem stores a second set of authorization data including information on matching between a group and commands authorized for execution in response to an execution request from the group.

Abstract: The impurities of molten pig iron produced by a blast furnace are removed exclusively in a converter, according to the conventional steelmaking refining method.The desulfurization and dephosphorization, which have been conventionally achieved in a converter, are replaced by the desulfurization and dephosphorization during the pretreatment of the molten pig iron, according to recently developed steelmaking methods. In the multi-step steelmaking refining method, such oxygen-blowing as that employed for the conventional converter would result in a rather violent spitting and reduction in recovery of iron.It is an object of the present invention to provide a multi-phase steelmaking refining method, in which decarburization is carried out without causing the disadvantages in the prior art.