function detectDevice(){
    $nu = new Net_UserAgent_Mobile();
    $su = new SC_SmartphoneUserAgent_Ex();
    $retDevice = 0;
    if ($nu->isMobile()) {
        return DEVICE_TYPE_MOBILE;
    } elseif ($su->isSmartphone()) {
        if ($_GET['display_mode'] === "2") {
            return DEVICE_TYPE_SMARTPHONE;
        } elseif ($_GET['display_mode'] === "10") {
            return DEVICE_TYPE_PC;
        } else {
            if ($_SESSION['pc'] === "10") {
                return DEVICE_TYPE_PC;
            } elseif ($_SESSION['pc'] === "2") {
                return DEVICE_TYPE_SMARTPHONE;
            } else {
                return DEVICE_TYPE_SMARTPHONE;
            }
        }
    } else {
        return DEVICE_TYPE_PC;
    }
}