# Location Optimization of Emergency Bell Based on Coverage Analysis for Crime Prevention
## 3 Materials and Methods
### Data Collection and Processing  
In this section, detailed descriptions of all datasets utilized in this study are provided.  
Data used for this study are as shown in Table 1. Particularly, data was collected from various sources, including Gwangju metropolitan city hall, Korea Telecom (KT), the national land information platform, and the statistical geographic information service. More precisely, the data analysis was conducted using open-source tools, including Python (Ver 3.9.7), QGIS (Ver 3.16), and RStudio (Ver 4.2.1). The Gwangju city hall provided data on the location of emergency bells and the cumulative status of five major crimes. These data were collected as of January 2022 and contained information on the models of emergency bells, their installation locations, and corresponding coordinates. The cumulative status of five major crimes was recorded from 2015 to September 2021, including information about the type of crime and the specific location where it occurred.  
Furthermore, since the address information provided in the five major crime datasets only allows for a limited specification of crime locations in the GIS program, geocoding was utilized to convert the address data into a coordinate form. Particularly, the transient  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Data** & **Source** & **Reference Date** & **Type** & **Description** \\ \hline \multirow{3}{*}{Emergency bell location data} & Gwangju Metropolitan City Hall & 2022 & csv & Emergency bell location by coordinate, address, district, administrative dong \\  & Gwangju Metropolitan City Hall & & & & CCTV camera’s location by coordinate, address, district, \\  & Gwangju Metropolitan City Hall & 2022 & csv & coordinate, address, district, \\  & Gwangju Metropolitan City Hall & & & & Crime occurrence location by address, district, \\  & Gwangju Metropolitan major crimes & City Hall & 2015\(\sim\)2021 & csv & administrative dong \\  & The status of the transient population & KT (Korea Telecom) & 2021 & csv & administrative dong, by \\  & The geographic information of administrative dong & Statistical Geographic Information Service & 2021 & ship & Geographic data of administrative dong \\  & National Land Information Platform & 2021 & ship & Geographic data of resident \\  & National Information Platform & & & & population data in \\  & National Land Information Platform & & & 100 \(\times\) 100 (m\({}^{2}\)) grid format \\  & National Land Information Platform & & & & Geographic data of building \\  & National Land Information Platform & & & & type by single-family building \\  & & Information Platform & & & and detached building in \\  & & & & & 100 \(\times\) 100 (m\({}^{2}\)) grid format \\ \hline \hline \end{tabular}
\end{table}
Table 1: List of dataset files and their descriptions.  
population status is a dataset that can be purchased from KT, a leading mobile telecommunications service provider in South Korea. Precisely, the information on the transient population status is classified by time zones for each administrative dong, and data from 2021 were used for the analysis. In addition, the total transient population was stratified by transient population between 18:00 and 6:00 and transient population between 7:00 and 17:00.  
Meanwhile, the data on resident population and building types were obtained from the national land information platform in the form of shp files. More precisely, the data for each 100 \(\times\) 100 (m\({}^{2}\)) grid in five districts in Gwangju were provided and combined with the above data using QGIS. The combined data was exported as a csv file and preprocessed using the R programming language. Subsequently, the final datasets for each grid and administrative dong were extracted. Finally, the EBMCLP and EBLSCP were considered by utilizing the variables such as the cumulative total of crimes, crime locations, and existing emergency bell locations to determine the optimal location for the emergency bells with Python (Ver 3.9.7).