function preload() {
 var img01 = new Image();
 var img02 = new Image();
 var img03 = new Image();
 var img04 = new Image();
 var img05 = new Image();
 img01.src = "/images/nav_top-page_h.png";
 img02.src = "/images/nav_cms_h.png";
 img03.src = "/images/nav_price_h.png";
 img04.src = "/images/nav_faq_h.png";
 img05.src = "/images/nav_company_h.png";
}