Page 367 - Practical Design Ships and Floating Structures
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             Recently, Computer Integrated Manufacturing System (CIMS) for ship building has been studied (for
             example Ship & Ocean Foundation 1989-94) and now the concept is practically applied in the design
             and manufacturing process in many shipyards. Furthermore, the concept of the life cycle support such
             as CALS concept is proposed  in which not  only the effectiveness of the design and manufacturing
             processes but also the effective operation and maintenance of ships are considered.
             For  the  effective maintenance of  the  ship structures, a  new  concept of  an  information system  of
             damages of ship structures has been studied by the authors (Kawamura et al. 1998,2000). In this paper,
             we  firstly  describe about the concept of the information system and about  the object oriented  data
             model for crack damages used in the system. Second, the prototype system constructed on an object
             oriented  database on an engineering workstation  is demonstrated.  Thirdly,  based  on the  proposed
             information system, a ship inspection supporting system by  using a portable (wearable) computer and
             virtual reality technique is described.


             2  CONCEPT OF AN INFORMATION SYSTEM OF DAMAGES OF SHIP STRUCTURES
              The role of the information system of damages of ship structures can be considered as (1) management
              of the health of an individual ship, (2) storage of the information related to the damages of the ship,
              and  (3)  estimation  of  the  detected damages  for  the  appropriate countermeasure.  To  realize  such
              functions, we proposed a concept of an information system as shown in Fig.l(a). In this concept, the
              information about damages such as crack or corrosion obtained in surveys is stored in an Information
              Database.  Since the  detail  infomation  such  as the  location  or  the  condition of  the  damages  are
              important for the  evaluation of  damages,  not  only  the  information  of  damages  itself but  also the
              information about the 3-Dimensional (3D) hull structure of the ship is stored in the database. In the
              Assessment System for damages of ships, risk of the damages is assessed and repair plan or operation
              plan are drafted based on the information in the database.  It  is possible to say that the Information
              Database can be regarded such as a medical record for a certain ship and the Assessment System for
              damages of ships aids the evaluation and planning based on the information stored in the database. For
              the efficient use of the proposed information system, inspection with high detectability of damages and
              a convenient recording of the damages to the database are necessary. In this study, we also proposed 9
              ship inspection supporting system by using a portable (wearable) computer as shown in Fig.1 (b).


              3  PROTOTYPE SYSTEM OF THE INFORMATION SYSTEM

              3.1 Data Model for the Information System

              The prototype of the information system of damages of ship structures was constructed assuming that
              the information of a certain ship is managed in a certain organization. The target ship of the prototype
              system is assumed to be a single-hull tanker, and a simple structure with 4 transverse spaces including
              transverse bulkhead is considered in the prototype system. Since the object oriented data structure is
              generally used in development of product model, an object oriented database (OBJEZTIVII'Y  1993)  is
              used for the data model of the information system.
              As  defined  in the data model  of CIMS, the ship hull  structure is defined by  Member-objects  and
              Connect-objects which represent joint information such as weld or slots. For the damages, the data
              model for corrosion and crack was proposed by Kawamura et ul. (1998). To construct the data model
              for damages, we  consider that the data model can indicate (1)  the location of  the damage and the
              damaged structural members,  (2) the condition of the damage such as configuration of the damage,
              and (3) the time when the damage is detected. Here, the definition of the crack at the intersection of
              longitudinals and transverse members is described as an example of the data model.
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