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Effectiveness in Preventing Malfunctions from Anti-Theft Systems
Effectiveness of the MG Vest in Preventing PM Malfunctions from Anti-Theft Systems
| Objective | Method | Results | Discussion | Conclusion |
Objective
This experiment evaluated whether the MG Vest can prevent pacemaker (PM) malfunctions caused by electromagnetic waves emitted from anti-theft systems.
Method
A human phantom equipped with a PM was used to conduct two types of tests: passing through the center of the anti-theft system gate (Figure 1), and facing directly toward the transmitting pillar under the worst-case scenario (Figure 2).
Figure 1: Gate Center Passage Test
Figure 2: Facing the Transmitting Pillar Test
Three anti-theft systems were tested, all installed in libraries. The frequencies emitted by each system were measured using an oscilloscope prior to testing.
Results
Out of the three anti-theft systems tested, malfunctions occurred in two of them. (Table 1)
| Anti-Theft System | Transmitter Side | Receiver Side | Number of PMs Tested | Malfunction Count |
|---|---|---|---|---|
| A | 14kHz | 14kHz | 5 | 2 |
| B | 200kHz | 200kHz | 5 | 3 |
| C | 7kHz | 5kHz | 10 | 0 |
▲ Table 1: Frequencies and Malfunction Counts of Anti-Theft Systems
The table below shows the distance at which malfunctions began and the malfunction distances while wearing the MG Vest for the systems where malfunctions occurred (Table 2). The MG Vest showed protective effect against System A (14kHz), but no protective effect was observed against System B (200kHz).
| Test Sample | Malfunction Occurrence Distance | Test Pattern | |
|---|---|---|---|
| Without Protection | Wearing MG Vest | ||
| A-1 | 10cm | - | Facing Transmitting Pillar |
| A-2 | 10cm | - | Facing Transmitting Pillar |
| B-1 | 30cm | 30cm | Gate Center Passage |
| B-2 | 30cm | 30cm | Gate Center Passage |
| B-3 | 30cm | 30cm | Gate Center Passage |
▲ Table 2: Distance and Malfunction Occurrence per Sample
Next, for System B (200kHz), the EMS Pad—a magnetic shielding material—was placed over the left shoulder area where the PM was installed, and the malfunction was eliminated. This suggests that electromagnetic interference entered from the upper shoulder area, affecting the PM. The 200kHz magnetic field likely has significant field wrapping and tends to be directed from top to bottom.
Discussion
Although direct-facing of the transmitting pillar was used as a test condition, this is a rare scenario in daily life. However, since anti-theft systems are increasingly camouflaged to preserve store aesthetics, or posters may cause people to stop nearby, simulating the worst-case scenario remains valid and meaningful for testing purposes.
Conclusion
The MG Vest demonstrated the ability to shield electromagnetic waves emitted by anti-theft systems operating at frequencies of 14kHz or higher, effectively preventing PM malfunctions. Retail stores such as bookstores, CD/video rental shops, and electronics retailers typically use systems operating at higher frequencies. However, some libraries use systems operating at lower frequencies (e.g., 200Hz), where electromagnetic waves can wrap around the shoulder and still affect the PM, even if the material provides shielding. This limitation may be due to the shape of the EMS Pad. Going forward, development of larger, thinner, and lighter shielding materials that can cover more of the body will be necessary.