This comparative case study examined the experiences of urban and rural elementary school students in Korea using PengTalk, an AI-based English learning application. Using a mixed-methods approach, the study analyzed student surveys, usage records, and interviews. Quantitative data were examined through descriptive statistics and Mann-Whitney U tests, while qualitative responses were analyzed thematically. Both groups expressed positive perceptions, especially regarding PengTalk’s gamified and interactive features. Urban students outperformed their rural peers in average scores (82.5 vs. 75.8) and cumulative totals (28,224 vs. 12,369). However, gamification alone was insufficient to sustain engagement, particularly in the rural school. Major challenges included limited digital literacy and inadequate instructional support in the rural school, as well as technical issues such as voice recognition errors in the urban school. The findings indicate that student engagement with AI tools depends not only on application design but also on contextual factors such as access, support, and digital infrastructure. This study concludes with recommendations for more inclusive and equitable AI-assisted language learning environments.

Biosynthetic processing of fibrillar procollagens is essential for producing mature collagen monomers that polymerize into fibrils by a self-assembly process. The metalloproteinase ADAMTS-2 is the major enzyme that processes the N-propeptide of type I procollagen in the skin and also of type II and type III procollagens. Mutations in the ADAMTS-2 gene cause dermatospraxis in animals and Ehlers-Danlos syndrome VIIC in humans, both of which are characterized by the accumulation of type I pN-collagen and the formation of abnormal collagen fibrils in the skin. Despite its importance in procollagen processing, little is known about the regulation of ADAMTS-2 expression. Here, we demonstrate that ADAMTS-2 can be regulated by 1,25-dihydroxyvitamin D3, an inducer of type I procollagen synthesis. This steroid hormone induced ADAMTS-2 mRNA ~3-fold in MG-63 human osteosarcoma cells and MC3T3-E1 murine osteoblastic cells. This induction was dose- and time-dependent in MG-63 cells. In contrast, secreted ADAMTS-2 protein was increased only 1.4-fold with 1,25-dihydroxyvitamin D3. Finally, 1,25-dihydroxyvitamin D3 in the presence of ascorbate increased levels of secreted ADAMTS-2 1.9-fold over ascorbate treatment alone, which did not appreciably change ADAMTS-2 expression. These data indicate that the regulation of ADAMTS-2 is coupled with the synthesis of type I procollagen through 1,25-dihydroxyvitamin D3 signaling and may involve translational or posttranslational control.