2.1. Root cause exploration
In addition to mind maps, you can use other methods such as brainstorming. These methods generally classify associative words hierarchically, but the classification is not important here. The key is to think of associative (or related) elements and make connections. The root causes search result through the mind map of the Operation and Maintenance System for ROK Naval ships is shown in Fig. 2. Starting from the target system, the causal relationships of the associative elements are indicated by arrows. Among them, those that affect many factors (Failure Probability), those that affect the policy of the system (Maintenance policy), those that require a separate analysis independent of the system (Maintenance technology), and the academic theory (Schedule pressure) are root causes. It is necessary to reflect the expert’s domain knowledge rather than the analyst’s subjective judgment.