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 G-99 (1969) represents an early yet confident refinement of Lee’s cylindrical vocabulary. Awarded the Special Prize at the 18th National Art Exhibition, the painting arranges tightly stacked tubular forms into a dynamic optical field that oscillates between solidity and void. Subtle gradations of metallic tones—achieved through his characteristic use of the flat brush and subsequent surface sanding—heighten the illusion of density and depth, while flashes of color punctuate the rhythmic order with precise tension. The work captures Lee’s transition from the experimental beginnings of Nucleus 10 toward the structural clarity that would anchor his practice through the 1970s, situating his pipes as both the vehicle of optical illusion and the locus of perceptual inquiry.