• Journal of the Korean Society of Safety
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• v.27 no.5
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• pp.179-184
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• 2012

This study was performed to find out the measurement criteria of slip resistance from analysis of human gait and slips. Many kinds of slip resistance testers were developed based on mechanical friction testers. But, there are, as yet, no unambiguous slip resistance measurement methodologies and generally accepted safety criteria or safety thresholds for estimating slipping hazard exposures. Also, there are variety of measuring conditions between those testers. The measurement criteria should be tested within the range of human slipping conditions observed in biomechanical studies. It's results should clearly consider whether the devices reflect the human slipping conditions. In this study a dragsled type friction tester, which was constructed in accordance with ISO 15133 basically, was used. Test conditions were set in order to determine the range of measurement criteria. It is shown that drag velocity should be more than 1 m/s, acceleration be more than 10 $m/s^2$, contact time be less than 0.1sec, and contact pressure be within 350~400 kPa.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.89-94
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• 2006

The tire delivering power generated from engine to the ground pulls a vehicle to move. Radius of tires is changeable due to elasticity that depends on the speed of vehicle and traction force. The main objectives on this study are real time measurement of dynamic radius and slip ratio according to the speed and traction force. The dynamic radius is proportional to speed and traction force. According to measurement, the dynamic radius is increased about 3mm under 100km/h compared to stop. It is also increased about 1.5mm when a traction force is supplied as much as 4kN compared to no load state at low speed. There is no strong relationship between slip ratio and vehicle speed. The slip ratio is measured up to 4% under WOT at first stage gear. Through this research, the method of measuring dynamic radius and slip ratio is set up and is expected to be applied to the measurement of traction force in chassis dynamometer or accelerating and climbing ability.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.91-96
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• 2006

Presently, cycle-slip detection is done between adjacent two points in many cycle-slip methods. Inherently, it is simple wavelet analysis. A new idea is put forward that the number of difference point can adjust by a parameter factor; we study this method to smooth raw data and detect cycle-slip with wavelet analysis. Taking CHAMP satellite data for example, we get some significant conclusions. It is showed that it is valid to detect cycle-slip in GPS phase measurement based on this wavelet function, and it is helpful to improve the precision of GPS data pre-processing and positioning.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.219-223
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• 2009

This paper is the result of investigation of ONO PPSM(ONO PORTABLE SLIP METER) by way of experiment to see the validity as a slip meter, ONO PPSM is a portable slip meter which was made up for the weak points of O-Y PSM(ONO-YOSHIOKA PULL SLIP METER) which takes an accurate measurement of the slip resistance but very heavy and hard to operate. In order to know the stability of the measurement result of ONO PPSM, we measured the slip resistance against 4 different kind of floor materials. As a result of this, we found out that the coefficient of variability of CSR' is less than 0.05. Also, we verified the relation between CSR' and CSR. more specifically by doing the slip test against 7 different kinds of inorganic matter floor materials. We increased the usability of ONO PPSM as a slip meter by suggesting the method of sharing the evaluation index of slip of CSR' and C.S.R.

• Journal of Powder Materials
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• v.9 no.4
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• pp.251-260
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• 2002

In the viscosity measurement of PIM feedstock, slip correction methods require a number of experiments and produce a high level of error. In this study, a rotational rheometer with a parallel-discs configuration having different surface roughness was tried to minimize the effect of the slip phenomenon. Disc surface was prepared in 3 different roughness conditions - a smooth and 2 roughened surfaces. Results with the roughened surfaces were compared with the results obtained with a slip correction method. Relationship between powder characteristics such as size and shape and a surface roughness of the disc was examined for feedstock of 4 different powders with a same binder. As results, the effect of the slip phenomenon could be sufficiently minimized on the roughened surface in most cases. However, the effect of the slip phenomenon could not be sufficiently minimized for feedstock of a round-particular-shape powder and in the case of very narrow gap size.

• International Journal of Automotive Technology
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• v.7 no.6
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• pp.681-686
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• 2006

The current flat type side slip tester measures only the total side slip. Therefore, measurement techniques which can be used to determine the side slip for each alignment element were examined. Because the side slip related to the camber angle varies depending on the unit load per travel wheel while the side slip related to the toe angle does not on the unit per travel wheel, but depends only on the direction of the tire, the side slip for each alignment element can be determined separately.

• Journal of the Korea Institute of Building Construction
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• v.9 no.5
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• pp.155-161
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• 2009

This paper is the result of an investigation of a PORTABLE SLIP METER(ONO PPSM) by means of an experiment to determine its validity as a slip meter. ONO PPSM is a portable slip meter that was designed to address the weak points of PULL SLIP METER(O-Y PSM), which can be used to obtain an accurate measurement of slip resistance, but is very heavy and difficult to operate. To determine the stability of the measurement result of ONO PPSM, we measured the slip resistance against 4 different kind of floor materials. Our findings showed that the coefficient of variability of CSR' is less than 0.05. Furthermore, we verified the relationship between CSR' and CSR. More specifically, by performing the slip test against 7 different kinds of inorganic matter floor materials, we increased the usability of ONO PPSM as a slip meter by suggesting a method of sharing the evaluation index of slip of CSR' and C.S.R.

• Journal of the Ergonomics Society of Korea
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• v.20 no.2
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• pp.47-57
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• 2001

To simulate an actual slip to measure floor slipperiness, slip resistance testers simulate slip in only forward direction because forward slip in the landing phase was found to be the most important factor for loss of balance. Backward slip in the take off phase was possible but was excluded in the friction test protocol because it was not dangerous. However, backward slip was tested in the friction test protocol without any theoretical background of the significance in generating dangerous slips and falls and was proven to be as good as forward slip in measuring floor slipperiness. Therefore, this study was designed to investigate the significance of backward slip in generating dangerous slips and falls with different combinations of floor and shoe sole. The results showed different tendency of backward slip in take off phase being significant in generating dangerous slips and falls because backward slip in the takeoff phase affected gait pattern disturbances seriously. resulted in dangerous falls. Fast toe velocity increased the severity of backward slip and confirmed the significance of backward slip in generating dangerous slips and falls. As a result, this study recommends the utilization of backward slip in the measurement of floor slipperiness.

• Journal of the Ergonomics Society of Korea
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• v.10 no.2
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• pp.51-55
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• 1991

Since slipping has been identified as a major hazard, it is important to understand the mechanism of a slip. Many researches, based on biomechanical studies, had been attempted to do that. Thowever, the correlation between the mechanism of a slip and psychophysical behaviors of people had rarely been verified. For example, the existence of small slips in a forward direction, which do not normally perceived by human subjects, has been established by several experimenters. However, the term "microslips are not perceived by the walkers[4]." has not been examined precisely by any experiments. The objective of this study is, using a Signal Detection Theory (SDT), to define a microslip and slip more quqntitatively with the biomechanical measurement of slip distance. The results showed that, the slip distance around the 3 centimeters, there was a obvious change in the accident detectability of the subject. The conclusion is that it is possible to identify the boundary of a microslip and slip around the 3 centermeters of slip distance.

• Journal of the Korean Society of Safety
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• v.27 no.5
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• pp.185-189
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• 2012

While there is no standards on slip risk for contaminants on surface, glycerol is described in standard contaminant for measuring coefficient of friction(COF) and slip resistance such as ISO 13287. But that is just used to measure the slip resistance of surface materials and shoes not to evaluate the contaminant materials. Therefore the objective of this study was to find out the relationship between standard contaminant and the contaminants used usually at the workplaces. For this, some measurement criteria were acquired from the analysis based on biomechanics and kinetics of human gait during slips. The slip resistance according to viscosity of the contaminants was measured applying the criteria and slip probability was determined by the gait analysis. Some factors which should be considered when measuring the slip resistance were identified. The velocity, acceleration, contact time and contact pressure should be 1 m/sec, 10 $m/sec^2$, 350 kPa and less than 0.5sec respectively. The variation of viscosity according to temperature for working oils was different from that of standard contaminant. The static coefficient of friction (SCOF) of working oils was almost 0.5 times as large as the SCOF of standard contaminant. So it was assumed to be difficult to compare the contaminants at the workplaces with the glycerol as a standard contaminant for estimating the slip risk.