We investigated the six remaining Yang-cheon-cheoks (量天尺), which were first described in the Veritable Record of King Sukjong (肅宗實錄). These woodblock sundials from Korea are structurally very similar to a Gyupyo (圭表, gnomon) or an altitude sundial and are light, compact, and portable. The front side of a Yang-cheon-cheok has two holes for styluses and several hour-lines. We compared the intervals of the hour-lines from the originating point of the stylus placement on all Yang-cheon-cheoks and found that two of the relics had the same hour-lines using the standard of the unit of 1 chon (寸). These two were actually the same sundial although the physical size was different. In spite of the lack of time accuracy, we hypothesize that various-sized Yang-cheon-cheoks were made and widely distributed throughout the public in the late Joseon Dynasty.

1. INTRODUCTION
 2. RECORDS AND RELICS OF YANG-CHEON-CHEOK
  2.1 Historical Records
  2.2 Relics
 3. THE YO-SEON-YANG-CHEON-CHEOK
  3.1 Structure
  3.2 Measurements
 4. ANALYSIS OF THE RELICS
 5. CONCLUSIONS
 ACKNOWLEDGMENTS
 REFERENCES

• Yong Sam Lee(Department of Astronomy and Space Science, Chungbuk National University, Cheongju 28644, Korea)
• Byeong-Hee Mihn(Korea Astronomy and Space Science Institute, Daejeon 34055, Korea, Korea University of Science & Technology, Daejeon 34113, Korea, Department of Astronomy and Space Science, Chungbuk National University, Cheongju 28644, Korea) | Byeong-Hee Mihn1,2,3
• Sang Hyuk Kim(Korea Astronomy and Space Science Institute, Daejeon 34055, Korea, Korea University of Science & Technology, Daejeon 34113, Korea) Corresponding Author