President Park Geun-hye called for police Thursday to redouble efforts to eradicate four major \"social ills,\" such as school violence and sexual violence, saying she is committed to building a nation where the law serves as a shield for the socially weak. \"I promised before the people that I will certainly root out the four major social ills, which are sexual violence, school violence, domestic violence and substandard food, and will make a nation where law becomes a shield for the socially weak,\" Park said in a speech at the graduation ceremony of the Korea National Police University.