Jusung Engineering, which is the only producer outside China of a certain advanced type of solar manufacturing equipment, has seen its Kosdaq-listed shares climb about 80% since mid-April.

The stock surge has lifted the net worth of Hwang, 66, who owns 26% of the company, along with his wife, Kim Jae-ran, and son, Eun-seok, who hold a combined stake of just over 4%, to about $1.1 billion based on Monday’s closing price of 126,600 won ($87), Forbes reported.

Hwang Chul-joo, chairman and CEO of Jusung Engineering. Photo courtesy of Jusung Engineering

Its stock rise followed an April 21 Chosun Biz report citing Korea Investment & Securities analyst Chae Min-sook, who said Jusung Engineering "could effectively become the only alternative" if the Chinese government limits exports of an advanced solar technology known as heterojunction to the U.S.

Her comments followed a Reuters report that Chinese officials were considering export controls on advanced solar manufacturing equipment, including heterojunction technology, which is used to produce high-efficiency solar panels.

Jusung Engineering is also the world’s fourth-largest maker of atomic layer deposition equipment by market share, behind ASM International in the Netherlands, Tokyo Electron in Japan and Lam Research in the U.S., according to research firm Gartner.

The company reported a 67% drop in net income to 107 billion won in 2025, while revenue fell 24% year-on-year to 311 billion won. It attributed the decline to increased research and development investment.

Hwang, who holds a bachelor’s degree in electrical engineering from Inha University in Incheon, worked at Hyundai Electronics, now part of SK Hynix, and ASM International before founding Jusung Engineering in 1993 and taking it public in 1999.