Abstract
In these days, more minors are using online communication services due to the popularity of mobile devices and smartphones. Even though they can deepen their relationships by such communication, online communication sites pose risks including cyber-bullying, sexual predators and so on. Such communication risks involving minors are social matters that must be detected automatically and prohibited. In this paper, we clarify communication behaviors by focusing on private chat systems, which are sometimes used to sexually entrap minors. In this research, we estimated the age group of users of social media without explicit age information. As a result, the estimation of the age group could be correctly performed with about 80% accuracy. By using the estimated age groups, we analyzed the characteristics of each age group regarding the use of private chat. By the analysis, we clarify the statistical features of utilization of minors, how to pair by age group and usage situations.
