Acrich is Seoul Semi’s brand for mains voltage (120 and 230V) leds that are actually long strings with intermediate voltage taps. The ides is that they can be driven by switching in parts of the string at various points in the rectified input sinewave, which leaves a small (low wasted power) voltage drop across the …
This story continues at Seoul makes in-roads on flicker in drivers for Acrich serial leds,
Or just read more coverage at Electronics Weekly