SemiconductorsPush toward more profitable advanced chips could cause DDR4 memory shortageSK Hynix, Samsung Electronics and Micron Technology control 90% of the global DRAM market. (Photo obtained by Nikkei)TOKYO -- Prices for standard DRAM, a widely used type of memory chip, remain high after doubling in just one month on speculation that Chinese manufacturers are phasing out production to focus on artificial intelligence chips and boost the country's self-reliance in semiconductors....