function imgC(obj)
{
    var fpath = obj.src;
    if( fpath.match(/_on/) ){
        obj.src = fpath.replace(/_on/,'');
    }else{
        if( fpath.match(/png/) ){
            obj.src = fpath.replace(/.png/,'_on.png');
        }
        if( fpath.match(/jpg/) ){
            obj.src = fpath.replace(/.jpg/,'_on.jpg');
        }
        if( fpath.match(/gif/) ){
            obj.src = fpath.replace(/.gif/,'_on.gif');
        }
    }
}

/*
 * image changer for main navigation
 */
function imgCM( obj )
{
    if( key != obj.name )
    {
        imgC(obj);
    }
}

/*
 * image changer for sub navigation
 */
function imgCS( obj )
{
    if( keys != obj.name )
    {
        imgC(obj);
    }
}

/*
 * image changer for multi images
 */
function imgCN(imgPath,key){
    obj = document.images[key];
    on_image = new Image();
    on_image.src = imgPath;
    obj.src = on_image.src;
}

/*
 * initializer
 */
function init()
{
    obj = document.images[key];
    if( obj )
    {
        imgC(obj);
    }
    /*objs = document.images[keys];
    if( objs )
    {
        imgC(objs);
    }*/
}