Design thinking

• The Reflective Practitioners by Donald A. Schon
• Design Thinking by Nigel Cross
• Designerly Ways of Knowing by Nigel Cross
• Frame Innovation by Dorst

Service Design

• Designing the Invisible by Lara Penin (also in Korean & Japanese)
• Service Design: From Insight to Inspiration by Andy Polaine, Ben Reason, and Lavrans (also in Korean)

New Design

• In the Bubble by John Thackara (probably also in Korean)
• Leading Public Sector Innovation by Christian Bason
• Acting in an uncertain world by Callon, Lascoumes, and Barthe
• Legible Practices by Boyer, Cook, and Steinberg (online) also see their earlier case studies

Graphic Design Basics

• Stop Stealing Sheep and find out how type works (also in Korean)
• Grid Systems by Muller Brockmann (also in Korean)

Philosophy

• A Survey of Some Fundamental Problems by Karl Popper

Design History

• Pioneers of Modern Design by Nikolaus Pevsner