public static function get_default_max_day($task_cash, $model_id, $min_day)
 {
     $max = kekezu::get_show_day(floatval($task_cash), $model_id);
     if ($max) {
         $max >= $min_day or $max += $min_day;
         return date('Y-m-d', time() + $max * 24 * 3600);
     } else {
         return false;
     }
 }
 public function get_defalut_max_day()
 {
     $std_obj = $this->_std_obj;
     $task_cash = intval($std_obj->_release_info['txt_task_cash']);
     return kekezu::get_show_day($task_cash, $this->_model_id);
 }