Lee Seung Jio (1941–1990) was a pioneering figure in postwar Korean geometric abstraction and a founding member of the avant-garde groups Origin (1962–) and AG (1969–1975). Amid Korea’s rapid modernization, Lee developed a distinctive visual language through his iconic Nucleus series—often referred to as his “pipe” paintings—where cylindrical forms dissolve the boundary between two-dimensional plane and three-dimensional space. Executed with flat brushes, masking tape, and sandpaper, his precise, rational compositions stood apart from the gestural energy of Korean Art Informel and the later material focus of Dansaekhwa, establishing him as a singular voice who translated industrial aesthetics into a rigorous painterly vocabulary.

In the late 1960s, Lee began developing his Nucleus series, which became the foundation of his practice for more than two decades. Drawing inspiration from the technological spirit of the space age as well as his own phenomenological experiences—such as fleeting impressions of landscapes glimpsed from a moving train—Lee sought to articulate the mechanics of perception through repeated tubular motifs. While these forms resonate with the illusionistic clarity of Op Art, they also reflect his deeper engagement with phenomenology and structural abstraction. His sustained dedication to the nucleus as both a visual and conceptual device earned him critical recognition, including multiple prizes at the National Art Exhibition between 1968 and 1971.

Nucleus PM-76 (1969) demonstrates Lee’s bold experimentation with color and structure at the close of the 1960s. Departing from the straight, horizontally stacked pipe configurations, this work introduces vibrant blue gradations across diagonally arranged tubular forms, generating an optical rhythm that conveys both solidity and movement. The alternating alignment of cylinders produces a jagged, architectural effect, while stark passages of white and deep black anchor the composition through spatial contrast. With its interplay of chromatic intensity and structural layering, Nucleus PM-76 reflects Lee’s ambition to expand the perceptual possibilities of the pipe motif, situating his practice firmly within the experimental spirit of Korea’s postwar avant-garde.