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 1970s, Lee deepened his investigation into perception and the act of painting itself. Moving away from the sharp, metallic density of his early cylinders, he adopted softer tonal gradations and diagonal arrangements that emphasized rhythm, subtlety, and sensation. His process—rooted in repetition, surface refinement, and the corporeality of painting—aligned conceptually with contemporaneous Dansaekhwa while remaining distinct in its unwavering focus on the “nucleus” as a condensed form of perception. During this period, his works reflected a phenomenological sensibility, presenting illusion not as representation but as an exploration of presence, rhythm, and spatial vibration.

Nucleus 73-18 (1973) presents a tightly ordered field of diagonally aligned cylinders, executed in a restrained monochromatic palette. The careful modulation of light and shadow lends each tubular form a sense of tangible weight, yet as they multiply across the canvas they dissolve into an undulating optical continuum. The work embodies Lee’s interest in tension between figure and ground, where individual forms oscillate between solidity and immateriality. With its stark visual lucidity and almost musical regularity, Nucleus 73-18 situates perception itself as the subject, exemplifying Lee’s mid-1970s pursuit of subtle rhythm and structural clarity.