*4.2. Prototype Implementation and Field Test*

Based on DiverPAD's prototype as shown in Figure 13, a pre-production sample test was conducted to examine the problems that may occur in the development process. In addition, an optimization method was derived by reviewing the product prototype, and conducting product assessment by repeatedly comparing the test results. Figure 14 shows that field tests were conducted on DiverPAD prototype to make the display and button operating parts waterproof through arranging insulated touch panel.

**Figure 13.** Prototype of DiverPAD.

**Figure 14.** Field test of DiverPAD.

In the field tests, information such as temperature and distance depending on water depth can be checked on the touch screen of the DiverPAD. Measured values of temperature and depth on the DiverPAD can be analyzed for errors through Wavelet technique. In the fabrication of the DiverPAD, the distinctive features are an electrical insulator based capacitive touchscreen device that enables drawing and writing in the water, and modules for control and communication functions. The DiverPAD is manufactured using sensor devices that are the same with conventionally used diver computers. Therefore, it is less possibility that there is an error in the measurement value depending on the water depth compared to the existing diver computer. In addition, when comparing the two devices (i.e., DiverPAD in water, it was confirmed that there was no difference in measured values.

### **5. Conclusions**

In this paper, we proposed a new product that is anticipated to provide a strong foundation for future technological advancements in marine environment communication, and to be used widely in marine leisure activities, including scuba diving. Figure 15 shows that the proposed DiverPAD

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will result in making marine leisure activities safer, more diverse, and systematic, especially with the rapidly growing number of divers every year. It is expected that the marine leisure industry will expand its accessibility.

**Figure 15.** Application areas of DiverPAD.

**Author Contributions:** Conceptualization, J.L.; methodology, J.L.; software, J.L.; validation, D.J.; formal analysis, J.L.; writing—original draft preparation, J.L.; writing—review and editing, D.J.; supervision, D.J. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.
