## 2 Materials and Methods  
A survey was conducted among older adults who were users of six exemplary senior citizen centers in Yeongdo-gu, Busan, South Korea. The survey period was set from Monday to Friday, aligned with the typical weekly schedule. Two primary reasons informed the choice of this standard weekly schedule. First, this research aimed to encompass the entire week to accurately reflect older adults' daily rhythms and social activity patterns, thereby facilitating the comprehensive interpretation of a wide range of usage patterns and motivations. Second, weekdays are more likely to involve regular activities and participation in welfare programs, whereas weekends may be influenced by external factors such as visits from family or friends. Consequently, the survey period was evenly distributed throughout the week, excluding weekends, to ensure data representativeness and comprehensiveness. Given older adults' information and communication technology  
Figure 1: Variable settings (created by the research team). literacy, this study employed an on-site visit method, as field surveys are more effective than online surveys for collecting reliable data. Furthermore, to increase participation rates and ensure more accurate and reliable data, the survey was conducted between 10:00 and 16:00--the hours when older adults typically use these centers. The details of the survey schedule are shown in Figure 2 and Table 3.  
After determining the survey schedule, the main items of the questionnaire were designed based on the previously defined dependent and independent variables (Figure 1). In addition to the primary survey items, the respondents' initials, type of eldercare system, age group, gender, and frequency of use were also included. The initials served as identifiers to screen for duplicate survey data, while the type of eldercare system was used to facilitate group analysis. Age group and gender were considered demographic variables for analyzing differences in the motivation to use senior citizen centers, and frequency of use was expected to facilitate an understanding of the current utilization status of these centers. Once the survey was finalized, the researchers visited the six centers according to a pre-planned weekly schedule to distribute the questionnaires and collect individual responses from users (including members and non-members). During the survey process, the intent and content of the items were clearly explained to the participants to enhance their understanding, thereby improving the accuracy and reliability of the responses. If the participants encountered difficulties or had questions while completing the survey, the research team assisted them by recording responses on their behalf in strict compliance with research ethics guidelines. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Center** & **Survey Period** & **Survey Hours** & **Primary Target** \\ \hline YR & 1 July 2024–5 July 2024 & & Older adults \\ DS & 15 July 2024–19 July 2024 & & who visited \\ SS & 29 July 2024–2 August 2024 & & these centers \\ GJ & 12 August 2024–16 August 2024 & & (including \\ DW & 26 August 2024–30 August 2024 & & members and \\ ISD & 9 September 2024–13 September 2024 & & non-members) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Survey schedule for each senior citizen center in Yeongdo-gu, Busan. Figure 2: Location of the target sites (created by the research team): (**a**) administrative districts in Busan and survey site locations and (**b**) photos of the six senior citizen centers. In addition, a verification procedure was introduced to prevent duplicate responses to the same question, thereby ensuring data reliability and accuracy.