The attacks and harms from virtual world : an exploration of cyberbullying and its prevention (U+865BU+64ECU+4E16U+754CU+7684U+653BU+64CAU+8207U+50B7U+5BB3U+FF1AU+521DU+63A2U+7DB2U+8DEFU+9738U+51CCU+73FEU+8C61U+8207U+9632U+5236U+7B56U+7565U+8A0EU+8AD6)