Measures of Abnormal User Activities in Online Comments Based on Cosine Similarity

It is more important to ensure the credibility of internet media which influence the public opinion. However, there are vague suspicions in public from the examples of manipulation of onlin e reviews with anonymity. In this study, we explore the possibility of manipulating public opinion in online web sites. We investigate the characteristics of comments posted by users on web sites and compare each comments by using the cosine similarity function. Our result shows followings. First, we found a correlation between the similarities of comments and the article ranks in the web sites. Second, it is possible to identify abnormal user activities indicating excessive multiple posting, double posting and astroturf activities.Keywords: abnormal activities, cosine similarity, public opinio n, manipulation, astroturfing I.서 론 최근 사이버 상의 정보 획득의 기회와 활용이 증가됨에 따라 개인 및 대중의 의견 및 태도에 영향을 주는 매체의 신뢰성이 중요해지는 반면 인터넷 표현의 접수일(2013년 11월 8일), 수정일(2014년 1월 9일), 게재확정일(2014년 2월 7일)†주저자, chocowall@korea.ac.kr‡교신저자, sangjin@korea.ac.kr(Corresponding author)