I've found a few new accounts, they created a junk post and used Tag #introduceyourself. They used that tag so as to get upvote of the whale. After claiming the reward, they use to Steempower to downvote on someone else's post. This is a serious problem. Need to carefully give upvote to the Steemian that uses the Tag #introduceyourself. This is not very convenient for all the Steemian.