Electromagnetic interference (EMI) shielding is an important issue in modern daily life due to the increasing prevalence of electronic devices and their compact design. This study estimated EMI-shielding effect (EMI-SE) of small (8–14×17 mm) Hanji (Korean traditional paper) doped with carbon nanotubes (CNTs) and compared to Hanji without CNT using 2H (92.1 MHz) and 23Na (158.7 MHz) nuclear magnetic resonance (NMR) peak area data obtained from 1 M NaCl in D2O samples in capillary tubes that were wrapped in the Hanji samples. The simpler method of using the variation of reflected power and tuning frequency by inserting the sample into an NMR coil was also tested at 242.9, 158.7, and 92.1 MHz. Overall, EMI shielding was relatively more effective at the higher frequencies. Our results validated that NMR methods to be useful to evaluate EMI-SE, particularly for small, flexible shielding materials, and demonstrated that EMI shielding by absorption is dominant in Hanji mixed with CNT.

Abstract
 1. Introduction
 2. Experimental
  2.1. Preparation and characterization of Hanjiwith CNT
  2.2. NMR experiments
 3. Results and Discussion
  3.1. Hanji sample properties
  3.2. NMR results
 4. Conclusions
 References

• Young Seok Byun(Western Seoul Center, Korea Basic Science Institute, Graduate School of Analytical Science & Technology, Chungnam National University)
• Shin Ae Chae(Western Seoul Center, Korea Basic Science Institute)
• Geun Yeong Park(Department of Carbon and Advanced Nanomaterials Engineering, Jeonju University)
• Haeseong Lee(Department of Carbon and Advanced Nanomaterials Engineering, Jeonju University) Corresponding Author
• Oc Hee Han(Western Seoul Center, Korea Basic Science Institute, Graduate School of Analytical Science & Technology, Chungnam National University, Department of Chemistry & Nano Science, Ewha Womans University) Corresponding Author