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seok [Korean, 섬/석 (石)]

In Korea, at least as early as the 17ᵗʰ century – 20ᵗʰ century, a unit of capacity, in the 20ᵗʰ century = 180.39 liters (about 5.12 U.S. bushels). Also romanized as sok, seom and som. Sŏk is the Sino-Korean pronunciation, sŏm the Korean, and in Chinese the unit is called shih.

It is often used as a unit of mass to measure quantities of rice, with differing values¹ for different types of rice:

for milled rice, 144 kilograms.
for brown rice, 155 kg.
for rough rice, 100 kg.

1. J. L. Maclean, D. C. Dawe, B. Hardy and G. P. Hettel.
Rice Almanac. 3rd edition.
IRRI, 2002.