RESUMEN
In this study, an unmanned aerial vehicle (UAV) with a camera and laser ranging module was developed to inspect bridge cracks. Four laser ranging units were installed adjacent to the camera to measure the distance from the camera to the object to calculate the object's projection plane and overcome the limitation of vertical photography. The image processing method was adopted to extract crack information and calculate crack sizes. The developed UAV was used in outdoor bridge crack inspection tests; for images taken at a distance of 2.5 m, we measured the crack length, and the error between the result and the real length was less than 0.8%. The developed UAV has a dual-lens design, where one lens is used for bridge inspections and the other lens is used for flight control. The camera of the developed UAV can be rotated from the horizontal level to the zenith according to user requirements; thus, this UAV achieves high safety and efficiency in bridge inspections.
RESUMEN
OBJECTIVES: Employees in printing industries can be exposed to multiple solvents in their work environment. The objectives of this study were to investigate the critical components of chemical solvents by analyzing the components of the solvents and collecting the Safety data sheets (SDSs), and to evaluate the hazard communication implementation status in printing industries. METHOD: About 152 printing-related industries were recruited by area-stratified random sampling and included 23 plate-making, 102 printing and 27 printing-assistance companies in Taiwan. We analyzed company questionnaires (n = 152), SDSs (n = 180), and solvents (n = 20) collected from this sample of printing-related companies. RESULTS: Analytical results indicated that benzene and ethylbenzene, which were carcinogen and possibly carcinogen, were detectable in the cleaning solvents, and the detection rate were 54.5% (concentrations: <0.011-0.035 wt%) and 63.6% (concentrations: <0.011-6.22 wt%), respectively; however, neither compound was disclosed in the SDS for the solvents. Several other undisclosed components, including methanol, isopropanol and n-butanol, were also identified in the printing inks, fountain solutions and dilution solvents. We noted that, of the companies we surveyed, only 57.2% had a hazard communication program, 61.8% had SDSs on file and 59.9% provided employee safety and health training. We note that hazard communication programs were missing or ineffective in almost half of the 152 printing industries surveyed. CONCLUSIONS: Current safety information of solvents components in printing industries was inadequate, and many hazardous compounds were undisclosed in the SDSs of the solvents or the labels of the containers. The implementation of hazard communications in printing industries was still not enough for protecting the employees' safety and health.
