public static function Substring($pValue = '', $pStart = 0, $pLength = 0)
    {
        if (self::getIsMbstringEnabled()) {
            return mb_substr($pValue, $pStart, $pLength, 'UTF-8');
        }

        if (self::getIsIconvEnabled()) {
            return iconv_substr($pValue, $pStart, $pLength, 'UTF-8');
        }

        // else substr
        return substr($pValue, $pStart, $pLength);
    }