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An ionic-polymer–metal composite (IPMC) consists of an ionic polymer membrane and metallic electrodes plated on both surfaces. When it bends, a voltage is generated between the two electrodes across the membrane. Since it works not only in aqueous solution similar to in vivo but also in air, it can be used for embedded biomedical as well as surface-mounted sensors. The present study investigates the effect of solvent evaporation and mechanisms of electrode degradation of an IPMC when it is operated as a sensor. The output voltages and electrode resistances were measured with several cyclic bending motions applied on the sensor in both aqueous solution and air. There was a good correlation between the sensor voltage and the bending angle when the sensor was tested in aqueous solution. The sensor worked for a long time without attenuation in the output voltage in an aqueous solution. The output voltage, however, decreased rapidly when the sensor was operated in air. The results of resistance measurement showed that the electrode on the compressive side deformed more and generated more cracks than on the tensile side. Optical microscopic images taken on the electrode surfaces validated the results. The results provided very useful information needed to understand electrode degradation and solvent evaporation and to improve the performance of IPMC sensors.

BackgroundHousehold waste collectors (HWCs) are exposed to hazardous conditions. This study investigates the patterns of workplace injuries and work-related illnesses of HWCs.MethodsThis study uses cases of workplace injuries and work-related illnesses of HWCs that occurred between 2010 and 2011. We analyzed 325 cases of injuries and 36 cases of illnesses according to the workers' age, length of employment, size of workplace, injured part of body, day and month of injury, type of accident, agency of accident, and collection process.ResultsThere were significant differences in the effect of workers' length of employment, injured part of body, type of accident, agency of accident, and collection process. Results show that most injuries occur in workers in their 50s and older. This study also shows that 51.4% of injuries occur at businesses with 49 employees or fewer. Injuries to waste collectors happen most often when workers are electrocuted after slipping on the ground. The second most prevalent form of injury is falling, which usually happens when workers hang from the rear of the truck during transportation or otherwise slip and fall from the truck. Work-related illnesses amongst waste collectors are mostly musculoskeletal conditions due to damaging postures.ConclusionThese findings will be instructive in devising policies and guidelines for preventing workplace injuries and work-related illnesses of HWCs.

Patient appointment scheduling (AS) in outpatient clinics is a widely studied subject and plays an important role in facilitating the efficient use of clinical resources and patients' timely access to quality care. This paper considers two AS systems: open access (OA) and overbooking (OB). Clinics make strategic decisions on selecting an AS system and then make tactical decisions on the efficient or optimal use of the system based on the selection. This study proposes some guidelines for the strategic choice of an AS system. For this purpose, we conduct a discrete-event simulation to compare the two AS systems under various environments. We employ four performance measures for the comparison: overtime work, the proportion of unmet demand, in-clinic waiting times, and the use of appointment time slots. For the analysis, we devise an integrated measure representing a linear combination of the four measures. We divide the analysis into two phases. In the first phase, well-performed OA and OB policies are separately identified, and in the second phase, the two scheduling systems with the identified policies are compared. We find overbooking is more robust to various clinic environments and performs better than open access in general. Along with that result, we additionally suggest some rules for determining best open access and overbooking policies.

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BackgroundTruck driving is known as one of the occupations with the highest accident rate. This study investigates the characteristics of traffic collisions according to road types (expressway and rural road).MethodsClassifying 267 accidents into expressway and rural road, we analyzed them based on driver characteristics (age, working experience, size of employment), time characteristics (day of accident, time, weather), and accident characteristics (accident causes, accident locations, accident types, driving conditions).ResultsWhen we compared the accidents by road conditions, no differences were found between the driver characteristics. However, from the accident characteristics, the injured person distributions were different by the road conditions. In particular, driving while drowsy is shown to be highly related with the accident characteristics.ConclusionThis study can be used as a guideline and a base line to develop a plan of action to prevent traffic accidents. It can also help to prepare formal regulations about a truck driver's vehicle maintenance and driving attitude for a precaution on road accidents.

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