4.4.2. Sensitivity Analysis

#### - GEWPro work time of each work process

Sensitivity analysis regarding the work time of each work process of GEWPro was performed because it has a direct impact on work productivity, which in turn has a decisive effect on the result of LCC analysis. According to sensitivity analysis of the GEWPro work time of each work process, even if the time required for preparation and installation work process varies within the sensitivity range set in Table 8 (a), the use of GEWPro was deemed to be economical (Figure 6a). On the other hand, it was observed to be uneconomical if the speed of painting work drops below 5 m/min (Figure 6b) or if the time for each disassembly and horizontal moving work process exceeds 13 min (Figure 6c). Therefore, to secure the economic viability of GEWPro, it is recommended that the painting work process be maintained at least 5 m/min (currently, 6.2 m/min) while keeping the disassembly and horizontal moving work to be done within 13 min/process (currently, 8.4 min/process).

#### - GEWPro equipment projected expensess

Sensitivity analysis of the GEWPro equipment cost is essential to enhance the reliability of economic analysis because the projected expenses of GEWPro (i.e., initial cost, and maintenance cost) can vary according to the manufacturing process and the supply/demand of GEWPro (particularly the maintenance cost, because it can be generated randomly during the expected service life of GEWPro). The results of sensitivity analysis on the projected expenses of GEWPro equipment (Figure 6d,e) suggests that even if the GEWPro equipment projected expenses vary within the sensitivity range set in Table 8 (b), the use of GEWPro is economical.


In this study, LCC analysis was conducted using the interest rate derived from the average inflation rate over the last 10 years in South Korea. Because interest rates can fluctuate depending on the economic conditions at home and abroad, it is imperative that sensitivity analysis is performed to enhance the analysis reliability. As shown in Figure 6f, sensitivity analysis showed that even if the interest rate varies within the sensitivity range set in Table 8 (c), the use of GEWPro is economical.

**Figure 6.** Results of sensitivity analysis.
