byte[] sourceByte = System.Text.Encoding.GetEncoding("utf-8").GetBytes(dt.Rows[i][2].ToString());
byte[] aimByte = System.Text.Encoding.Convert(System.Text.Encoding.GetEncoding("utf-8"), System.Text.Encoding.Default, sourceByte);
MessageBox.Show(System.Text.Encoding.Default.GetString(aimByte));