[IEEE 2015 Annual Conference of the North American Fuzzy Information Processing Society (NAFIPS) held jointly with 2015 5th World Conference on Soft Computing (WConSC) - Redmond, WA, USA (2015.8.17-2015.8.19)] 2015 Annual Conference of the North American Fuzzy Information Processing Society (NAFIPS) held jointly with 2015 5th World Conference on Soft Computing (WConSC) - Analysis of Twitter hashtags: Fuzzy clustering approach