function yang1()
{
window.open('yang1.html', 'yang', 'toolbar=no,menubar=no,scrollbars=no, resizable=yes,status=no,location=no,directories=no,top=0, left=0,fullscreen=no,height=550,width=520');
} 
function yang2()
{
window.open('yang2.html', 'yang', 'toolbar=no,menubar=no,scrollbars=no, resizable=yes,status=no,location=no,directories=no,top=0, left=0,fullscreen=no,height=550,width=520');
}
function yang3()
{
window.open('yang3.html', 'yang', 'toolbar=no,menubar=no,scrollbars=no, resizable=yes,status=no,location=no,directories=no,top=0, left=0,fullscreen=no,height=550,width=520');
}