Short answers, pulled from the story.
The Korea Information Security Agency developed the SEED block cipher to replace weak 40-bit encryption standards in South Korea. This agency created its own standard to ensure robust security within the country.
SEED is a 16-round Feistel network with 128-bit blocks and a 128-bit key that uses two 8 × 8 S-boxes derived from discrete exponentiation. The structure resembles MISTY1 through its recursiveness and generates thirty-two 32-bit subkeys using rotations and round constants from the Golden ratio.
On the 1st of April 2015 the Ministry of Science, ICT and Future Planning announced its plan to remove ActiveX dependency. The target was to eliminate this requirement from at least 90 percent of the country's top 100 websites by 2017.
Mozilla decided to drop default support in Firefox 27 and above because SEED had no practical positive effect helping South Korea migrate away from ActiveX-based e-commerce. Other browsers were not offering any SEED-based cipher suites at that time.
SEED has been adopted by several standard protocols including S/MIME under RFC 4010 and TLS/SSL under RFC 4162. ISO/IEC 18033-3:2010 further formalized its use while NSS software security library implemented support for SEED.