function changeImage1(){
    document.myimg1.src="img/btn_home2.gif";
}
function changeImage2(){
    document.myimg1.src="img/btn_home.gif";
}
function changeImage3(){
    document.myimg2.src="img/btn_intro2.gif";
}
function changeImage4(){
    document.myimg2.src="img/btn_intro.gif";
}
function changeImage5(){
    document.myimg3.src="img/btn_imp2.gif";
}
function changeImage6(){
    document.myimg3.src="img/btn_imp.gif";
}
function changeImage7(){
    document.myimg4.src="img/btn_shinbi2.gif";
}
function changeImage8(){
    document.myimg4.src="img/btn_shinbi.gif";
}
function changeImage9(){
    document.myimg5.src="img/btn_white2.gif";
}
function changeImage10(){
    document.myimg5.src="img/btn_white.gif";
}
function changeImage11(){
    document.myimg6.src="img/btn_mail2.gif";
}
function changeImage12(){
    document.myimg6.src="img/btn_mail.gif";
}