## 4 Case Study: Project for Enhancing K1 Tank
### Main Battle Tank (MBT) Modeling  
Common platforms and the constituents of existing MBT are derived through hierarchical decomposition prior to use in the modeling process using CBR. Figure 6 illustrates the actions for the domain analysis.  
The decomposition is shown in the first part of the illustration, and the examples of the results for all K-series MBTs are provided in Table A3 of the Appendix A.  
The derived platforms, modules, and properties are modeled in mathematical structures, and can be found in the second part of the figure below. In order to re-express the existing weapon systems using the designed platforms and modules, an appropriate platform is selected and the weapons are then decomposed according to the platform structure. The weapon characteristics are reflected in the modules configuring the platform through the module design. The designed modules are classified as repositories. To design an actual weapon system, all design constraints among the actual parts need to  
Figure 5: Interactive simulation process.  
Figure 6: Flow of actions for the domain analysis.  
be satisfied, but in this study, the modules that have the same series are designed assuming that they are compatible with each other.  
The requirements for the tank to be designed to overcome the expected environmental constraints are assumed as the first part of Figure 7.  
The attribute-values to satisfy the requirements are given in the second part of the illustrations below. The modules, including properties corresponding to the requirements, are retrieved from the module repository, and they are added to the module list that is used to retrieve similar cases by comparing the platform, environmental conditions, and module configuration. Furthermore, the constraints for the environment and attribute-values are used as criteria for the addition, deletion, and replacement of the modules in the revision process.  
The previous case comprises environmental conditions, required functions, and a set of modules to support the conditions and functions. Each case is classified in the case base and is then used in the case retrieval process. As an example of a previous case, the construction of the K1 MBT case is depicted in the first part of Figure 8.  
Figure 8: Flow of actions for the modeling process part (b).  
Figure 7: Flow of actions for the modeling process part (a).  
The target case that is provided from the requirement analysis is used to retrieve similar previous cases from the case base. Previous cases with high values based on similarity scores were chosen. The similarity score is calculated based on the formulas in Section 3.2.3, and the results of the similarity evaluation between K-series MBTs and the target case can be found in the second part of the figure. The details of K-series MBTs re-expressed in the proposed form are shown in Table 10. In the retrieval process, cases having high similarity scores but failing to meet operational environmental constraints, such as maintenance support, are excluded. This is because such cases cannot fulfill the requirements solely through the modification of the chosen case. Furthermore, the most similar case cannot satisfy every requirement although it may have the highest similarity score. Thus, a revision process is required for the selected case. This is shown in the sixth part of the illustration below. Here, based on the revision process introduced in Section 3.2.3, the revised K1 case according to the given specifications is depicted in the last part of the figure. That is, by using the revision process, it is possible to design the weapon system model that fulfils the requirements.  
With regard to the three expected benefits mentioned in the introduction of the paper, this section confirmed the first and second benefits. First, the design methods of the generalized structures and modules for modeling are provided. Second, the intelligent modeling method that uses CBR provides a procedure for automatic modeling that satisfies the requirements.