Acorus calamus, commonly known as calamus or sweet flag, is a tall perennial plant living in a wetland. Traditionally in Korea, on the day of Dano, which is the fifth day of May of the lunar calendar, ladies washed their hair and body with boiled water of calamus root to make the skin and hair soft and shiny. Indeed, calamus is widely employed in modern herbal medicine to treat skin eruptions, rheumatic pains, and neuralgia. Jeju Changpo uses calamus root from Jeju Island, and it has significant hair growth, skin brightening and anti-oxidant effects.

When the skin is constantly exposed to UV radiation, the biological clock plays a critical role in minimizing and repairing UV-induced damage. Skin cells possess their own internal clock systems that regulate various physiological activities, including cell proliferation and differentiation, moisture balance, pH regulation, and wrinkle formation. According to the researches conducted at GNS Research Center, it is confirmed that Jeju Changpo has the ability to recover and repair from UV damage by modulating time-keeping genes related to the skin's circadian rhythm.