Although several methods have been used to capture the motion of workers at construction sites to improve productivity or safety during construction projects, collecting data by image analysis and discriminating between motions are timeconsuming processes. Therefore, it is difficult to use such methods to detect the motion of several workers or over a long time period. The authors applied an accelerometer to capture motion; this apparatus has been used in the health and medical fields. A small, light accelerometer and a simple discrimination program allowed the authors to determine whether a worker was active or inactive based on a threshold of the sum of the signal amplitude areas. Experimental surveys were conducted at construction sites: first, for setting plasterboards for two detached house construction projects and, second, for setting rebar at a large office building site. The findings of this experimental study are as follows. First, an accelerometer can be used in congested construction sites, and data can be obtained continuously. Second, this simple identification of active/inactive workers allows for the measurement of performance and the detection of problems at construction sites. Third, from the data, the hypothesis regarding workers' tendencies can be tested, that is, how workers' skill levels may affect the fluctuation of activity intensity. Therefore, in future studies, by increasing the data on workers, researchers could develop methods to improve the performance of workers.

No abstract

This paper presents a bonding-less 5-GHz RFID tag module using an 85% downsized RFID tag chip and a 97% downsized antenna. Inductive (or magnetic) coupling between the antenna and the chip realizes low cost bonding-less implementation. Compared with a conventional module operating in the UHF band, the proposed module operating in the 5GHz range is downsized in terms of both the chip and the antenna sizes. The experimental results confirmed that the proposed RFID tag module successfully works at 20 cm away from a reader whose output power is 15 dBm, achieving the same figure of merit as a conventionally bonded module. Moreover, this paper confirmed that the misalignment tolerance of the inductive coupling can be up to 50 μm.

No abstract