Asan is a city in South Chungcheong Province, South Korea. It borders the Seoul Capital Area to the north. Asan has a population of approximat…Asan is a city in South Chungcheong Province, South Korea. It borders the Seoul Capital Area to the north. Asan has a population of approximately 300,000. Asan is known for its many hot springs and is a city of spas.