Sneaker Foam Maker Joins Ranks Of Korea’s 50 Richest After Jumping Into EV Batteries After decades of making chemicals used to make plastic foams for sneakers, Korea-listed Kumyang jumped into the hot battery business last year. The move sent shares of the company soaring by more than 1,000% since and catapulted Kumyang’s CEO, Ryu Kwang-ji, onto the Korea’s 50 Richest list.