It's the most pressing problem, but fire-prone phones aren't the only challenge facing the world's leading seller of mobile phones. In Samsung's home country of South Korea, the conglomerate was already feeling the heat from investors, who want to streamline its complicated corporate structure, and from critics, who say it's not changing from its previously top-down, "militaristic" ways.In South Korea, Samsung's next moves matter. That South Koreans call their country the "Republic of Samsung" is no exaggeration. The conglomerate's electronics are known around the world, but in Seoul, Samsung is also behind everything from baked goods to ship-building to life insurance.