if (document.images) {
  image1on = new Image();
  image1on.src = "/.include/button/e/top_home_on.png";
  image2on = new Image();
  image2on.src = "/.include/button/e/top_ae2_on.png";
  image3on = new Image();
  image3on.src = "/.include/button/e/top_asca_on.png";
  image4on = new Image();
  image4on.src = "/.include/button/e/top_ginga_on.png";
  image5on = new Image();
  image5on.src = "/.include/button/e/top_sitemap_on.png";
  image6on = new Image();
  image6on.src = "/.include/button/e/top_japanese_on.png";

  image7on = new Image();
  image7on.src = "/.include/button/e/operation_on.png";
  image8on = new Image();
  image8on.src = "/.include/button/e/instrument_on.png";
  image9on = new Image();
  image9on.src = "/.include/button/e/result_on.png";
  image10on = new Image();
  image10on.src = "/.include/button/e/gof_on.png";
  image11on = new Image();
  image11on.src = "/.include/button/e/process_on.png";
  image12on = new Image();
  image12on.src = "/.include/button/e/catalog_on.png";
  image13on = new Image();
  image13on.src = "/.include/button/e/bib_on.png";

  image1off = new Image();
  image1off.src = "/.include/button/e/top_home_off.png";
  image2off = new Image();
  image2off.src = "/.include/button/e/top_astroe_off.png";
  image3off = new Image();
  image3off.src = "/.include/button/e/top_asca_off.png";
  image4off = new Image();
  image4off.src = "/.include/button/e/top_ginga_off.png";
  image5off = new Image();
  image5off.src = "/.include/button/e/top_sitemap_off.png";
  image6off = new Image();
  image6off.src = "/.include/button/e/top_japanese_off.png";

  image7off = new Image();
  image7off.src = "/.include/button/e/operation_off.png";
  image8off = new Image();
  image8off.src = "/.include/button/e/instrument_off.png";
  image9off = new Image();
  image9off.src = "/.include/button/e/result_off.png";
  image10off = new Image();
  image10off.src = "/.include/button/e/gof_off.png";
  image11off = new Image();
  image11off.src = "/.include/button/e/process_off.png";
  image12off = new Image();
  image12off.src = "/.include/button/e/catalog_off.png";
  image13off = new Image();
  image13off.src = "/.include/button/e/bib_off.png";
}

function turnOn(imageName) {
  if (document.images) {
    document[imageName].src = eval(imageName + "on.src");
  }
}

function turnOff(imageName) {
  if (document.images) {
    document[imageName].src = eval(imageName + "off.src");
  }
}