---
node: jeong_yak_yong
type: person
slug: jeong_yak_yong
title: "Jeong Yak-yong"
lead: "Jeong Yak-yong (1762–1836), pen name Dasan, was the greatest scholar of Silhak, Joseon's school of practical learning. During eighteen years of exile he wrote the classics of Korean reform thought, including the Mongmin Simseo."
published: 2026-07-09
updated: 2026-07-09
---


## Who they were

A favorite of King Jeongjo, he designed the geojunggi pulley-crane used in building the Hwaseong Fortress at Suwon (1794–96), today a UNESCO World Heritage site. His family's Catholic connections made him a target after Jeongjo's death.

## What they did

He spent eighteen years in exile at Gangjin (1801–1818), where he wrote prodigiously — a corpus traditionally counted at around five hundred volumes. It includes the Mongmin Simseo ("Admonitions on Governing the People"), the classic of ethical local administration, and the Gyeongse Yupyo on institutional reform.

## Legacy

He stands at the summit of Joseon reform scholarship. "Dasan" names research institutes today, and his ideas are quoted by modern reformers of every stripe.