ABSTRACT
Slip resistance between the footwear and underfoot surface is of great importance for preventing fall accidents and has been measured as a form of coefficient of friction (COF). The COF measurement between the shoe and floor was adopted to determine whether a slip is to occur, however, there has been ambiguity in the interpretation of the results. Importantly, its measurements and interpretations have been misguided in much research and practice for fall safety measures. That is, any slip resistance measurements have: (1) characteristics peculiar to a specific combination of the shoe-floor-environment; and (2) changed during entire service periods. Although the concept of friction is relatively simple and straightforward, its measurement, analysis, and interpretation in the solution of real-world problems are a quite challenging task. However, one of the most important aspects to address is that the COF measure is not a constant because friction measures are intrinsically noisy and continuously change as a function of a complex array of tribophysical phenomena between the shoe and floor (Kim and Smith 2000, 2003). In addition, friction phenomena observed at the sliding interface between the shoe heel and floor surface are diverse and combine various submechanisms (Kim and Smith 2000, 2003; Kim 2004a). Hence, there is an inherent risk in relying upon a single COF threshold to provide an indication of the fall safety.
