## 4 Results and Discussion
### Potential Limitations and Future Study  
The performance analysis results discussed above demonstrated that the proposed SEM-LEWS was effective in providing useful and timely information associated with expected landslide type and hazard levels. However, to address potential limitations and overcome these issues in the future, it is necessary to reflect on the modeling effectiveness in terms of both the SEM-LEWS operation and historical landslide incidents during the study period. As a result, this study is considered to possess potential uncertainties and insufficiencies arising from the following three aspects. Firstly, the results of the temporal performance analysis of this study may not represent global performance, as the analysis was limited to a specific local region that includes the most landslide-prone areas in Busan. Given the limited accessibility to perfectly collected data on historical landslide incidents that actually took place within the entire Busan area, the performance analysis results can be refined by conducting sustained and thorough investigations to ensure that future landslide events are recorded in a systematic format over time, which can further improve the credibility of SEM-LEWS. Secondly, as [PERSON] et al. [24] highlighted, it was unfeasible to ensure truly complete examination of statistics associated with spatial false-warning (or false-positive) rates. This was due to the fact that it was almost impossible to find and collect historical data for all landslide incidents that could have actually taken place across the Busan area during the study period. Accordingly, this precluded the clarification of false-warning areas in which high warning levels were assigned but no landslide incidents occurred. However, considering that the fundamental purpose of landslide early warnings is directly connected to saving human lives, the tendency of the LEWS for spatial overestimations is an inevitable compromise to avoid missed-warning cases (landslides occurring without warnings). Therefore, in practice, it is desirable to consider the areas falsely warned with \"Alert\" and \"Emergency\" levels as areas with a high potential for slope failure or debris flow occurrences, respectively, which can be triggered at any moment in the near future. Thirdly, the introduced representative occurrence times of the 222 historical landslide data may not sufficiently take into account the general tendency of time lags between slope failure and debris flow incidents. From a theoretical perspective, under the condition of equal rainfall characteristics and subsurface hydrologic processes, shallow failures are supposed to occur at an earlier stage on steep slopes when a wetting front reaches shear planes. In contrast, debris flows are generally initiated at later stages on relatively gentle slopes in channelized concave terrain as potential shear masses tend to require excessive pore-water pressures on shear planes. As a matter of fact, for both of the two cases (aforementioned in Section 4.1.) in which multiple landslide timings were recorded within an IC zone at a particular rainstorm event date, the records preceding by about 1 h were slope failure types whereas the later records were debris flow types. Lastly, rainfall input data sourced from the historical records of the 17 KMA observatories may not have effectively reflected the pelt-points of localized intense rainfall during rainstorm events that took place in the Busan area within the study period. The spatial variability of rainfall over the distances between the observatories and historical landslide locations can diminish the reliability of the early warning modeling results. Moreover, the evolutions in early warning levels that occur within each hourly interval are not known due to the fact that hourly rainfall measurement data are the most fractionized historical records that are available from the KMA observatories.