function secBoard(n){
                var menus_childs = document.getElementById('jfdh_menu').children,
                    mains_childs = document.getElementById('jfdh_display').children;
                
                for(var i=0;i<menus_childs.length;i++){
                    menus_childs[i].className="button_jfgl";
                }
                menus_childs[n].className="button_jfgl_1";
                
                for(var i=0;i<mains_childs.length;i++){
                    mains_childs[i].style.display="none";
                }
                mains_childs[n].style.display="block";
            }