I. Introduction
Recently, the interest in the offshore plant industry to collect marine resources has been increasing due to the increase of resource consumption. Therefore, the importance of offshore plant safety and accident prevention measures is also growing. Since accidents occurring in offshore plants are difficult to obtain outside assistance, effective early response is important to minimize accident damage[1]. A positioning system is required to obtain the position information of the workers in order to promptly determine the initial response and instruct the workers in case of an accident.