<form class="form-horizontal" action="" method="POST" role="form">
    <input type="hidden" name="<?php echo $this->security->get_csrf_token_name(); ?>" value="<?php echo $this->security->get_csrf_hash();?>" />
    <h2>회원가입</h2>
    <?php echo validation_errors(); ?>
    <div class="form-group">
     <label for="IDtext" class="col-lg-2 control-label">ID</label>
     <div class="col-lg-10">
      <input type="text" class="form-control" name="identifyname" value="<?php echo set_value('identifyname'); ?>" id="IDtext" size="24" minlength="6" maxlength="24" placeholder="아이디 (6자부터 24자까지, 영문, -, _ 포함)" required="required" />
     </div>
     <span class="okay">사용하셔도 좋습니다.</span>
     <span class="ng">이미 사용중이거나, 사용이 제한된 아이디입니다.</span>
    </div>
    <div class="form-group">
     <label for="Password" class="col-lg-2 control-label">비밀번호</label>
     <div class="col-lg-10">
      <input type="password" class="form-control" name="password" value="<?php echo set_value('password'); ?>" id="Password" size="24" minlength="8" maxlength="24" placeholder="비밀번호 (대소문자 구분없이 8자부터 24자까지)" required="required" />
     </div>
     <span class="okay">사용하셔도 좋습니다.</span>
     <span class="ng">비밀번호는 8자부터 24자까지 입력해주시기 바랍니다.</span>
    </div>
    <div class="form-group">
     <label for="PasswordRe" class="col-lg-2 control-label">비밀번호 다시 입력</label>
     <div class="col-lg-10">
      <input type="password" class="form-control" name="password_re" value="<?php echo set_value('password_re'); ?>" id="PasswordRe" size="24" minlength="8" maxlength="24" placeholder="비밀번호 재입력" required="required" />
     </div>
     <span class="okay">비밀번호가 일치합니다.</span>
     <span class="ng">비밀번호가 이전에 입력한 값과 일치하지 않습니다.</span>
    </div>
    <div class="form-group">
     <label for="Nickname" class="col-lg-2 control-label">닉네임</label>
     <div class="col-lg-10">
      <input type="text" class="form-control" name="nickname" value="<?php echo set_value('nickname'); ?>" id="Nickname" size="16" minlength="2" maxlength="16" placeholder="닉네임 (<, >,등 특수문자를 제외한 최소2글자부터 최대 16글자)" required="required" />
     </div>
     <span class="okay">사용하셔도 좋습니다.</span>
     <span class="ng">이미 사용중이거나 사용이 제한된 닉네임입니다.</span>
    </div>
   </form>

  $this->load->library('form_validation');
  if($this->input->post()){ // 회원가입 받았을경우
   if ($this->form_validation->run() == FALSE)
   {
    $this->load->view('register.php');
   } else {
    $this->load->view('register_complete.php');
   }
  } else {
   $this->load->view('register.php', $_MODEL);
  }

<?php

$config = Array(
 'member/register' => Array(
  array(
   'field' => 'identifyname',
   'label' => 'ID',
   'rules' => 'required|min_length[6]|max_length[24]|trim|strtolower|xss_clean|alpha_dash'
  ),
  array(
   'field' => 'password',
   'label' => '비밀번호',
   'rules' => 'required|min_length[8]|max_length[24]|trim|xss_clean'
  ),
  array(
   'field' => 'password_re',
   'label' => '비밀번호 확인',
   'rules' => 'required|min_length[8]|max_length[24]|trim|xss_clean'
  ),
  array(
   'field' => 'nickname',
   'label' => '닉네임',
   'rules' => 'required|min_length[2]|max_length[16]|trim|xss_clean|htmlentities'
  )
 )
);