## 4 Conclusions  
This study experimentally analyzed differences in fire-resistance performance by adjusting the volume of firestop material in response to variations in penetrant and opening sizes for both metallic and nonmetallic pipes. The analysis was based on cross-sectional areas calculated from measured outer diameters, enabling quantitative comparisons among opening size, penetrant size, and firestop material volume. The influence of each component on fire-resistance performance was also classified and interpreted according to penetration type. The major conclusions are as follows:  
1. When the opening size was reduced, accompanied by a proportional decrease in firestop application area, the peak temperature either decreased or remained similar; no negative impact on fire-resistance performance was observed. This indicates that the current standard requiring a fixed amount of firestop material may be excessive for small penetrations, and that flexible application is feasible depending on conditions. 2. For nonmetallic pipes, which soften or collapse under high temperatures, fire-resistance performance was strongly influenced by total opening area and the degree of infill. Although an increase in penetrant area coincided with rising temperatures, this was due to experimental conditions in which both opening and penetrant sizes increased simultaneously. The penetrant size itself was unlikely to have been a major factor due to the pipe collapse at high temperatures. The impact of firestop volume was quantitatively evident in certain conditions. 3. For metallic pipes, which retain structural continuity and serve as direct heat-conduction paths, fire-resistance performance was more directly influenced by penetrant area or solid cross-section than by the opening size. Even under identical opening conditions, increasing the pipe size led to higher peak temperatures, empirically demonstrating that pipe diameter plays a critical role in determining fire resistance in metallic systems. This study provides experimental evidence identifying and analyzing structural factors that influence fire-resistance performance for both metallic and nonmetallic firestop configurations under several different conditions. Future research will investigate whether the outer cross-sectional area or actual solid cross-sections of metallic penetrants more directly impact fire performance. This will help establish differentiated performance-evaluation criteria based on penetration shape and component configuration. The findings are expected to serve as empirical data to enhance the stability and effectiveness of performance-based design standards and certification systems for firestop assemblies. This study did not aim to define the minimum possible volume of firestop material, but rather to evaluate whether sufficient performance could be secured through a simplified application method--specifically, with a single circumferential layer around small penetrations. With further accumulation of data with progress in research, this approach may lead to generalized volume criteria and potentially support the development of simplified predictive formulae for performance-based design. The present study also has certain limitations. Specifically, future work should consider additional variables that were not covered in this study. The use of other firestop materials such as mortars, putties, and wraps, different structural substrates beyond autoclaved lightweight concrete, and vertical installation orientations warrant investigation. These factors may significantly influence fire-resistance behavior and are important in the validation and generalization of the proposed approach. Conceptualization, H.-B.C. and J.-O.P. ; methodology, H.-B.C. and J.-O.P. ; software, H.-D.L. and S.-Y.H. ; validation, A.-Y.J. and J.-O.P. ; formal analysis, H.-B.C. and S.-Y.H. ; investigation, A.-Y.J. and J.-O.P. ; resources, A.-Y.J. and J.-O.P. ; data curation, H.-B.C. and S.-Y.H. ; writing--original draft preparation, H.-B.C. ; writing--review and editing, A.-Y.J.