These Are U.S. Defense Posters -- Inconceivable would be a war without posters. Like bands, parades, flags and patriotic speeches, they are designed to rouse peaceful citizens to deeds of daring and hard work. Since America's entry into World War II, posters are being hung in defense factories during workers to obey regulations work hard, keep their mouths shut, look out for fifth columnists and saboteurs. Creators of these new cartoon-posters are Cy Hungerford, famous cartoonist of the Pittsbu