function get_checked_count( elem_name )
{
	check_count = 0;
	if ( document.f.elements[elem_name].length ){
		for ( i = 0; i < document.f.elements[elem_name].length; i ++ ){
			if ( document.f.elements[elem_name][i].checked ){
				check_count ++;
			}
		}
	}
	else if ( document.f.elements[elem_name].checked ){
		check_count ++;
	}
	return check_count;
}

function something_checked( elem_name )
{
	ret = get_checked_count( elem_name );
	if ( 0 == ret ){
		alert( "１つ以上選択してください。" );
		return false;
	}
	return true;
}