A new circulatory system besides blood and lymph vessels was discovered by Bong-Han Kim in early 1960 s. However, his claim has not been reproduced by other groups and thus was forgotten for a long time. Recently the Bong-Han duct, i.e., the new circulatory path was partially confirmed in animals such as rabbits and rats.

This new circulatory net of Bong-Han duct is an anatomical substance of acupuncture meridian, and it can open a new road toward scientific investigation of acupuncture effects. Furthermore the flowing path from a specific point in skin to its corresponding internal organ can be used for an efficient drug delivery path which is expected to be especially useful for cancer therapy.