This paper investigates the influence of hands-free device on the braking operation of drivers. In the driving simulator experiment, participants performed a simple driving task and talking task with four types of hands-free device. When participants recognized the cautionary voice of fellow passenger, they braked as soon as possible. We developed the measurement system to evaluate reaction time, which is from the generation of the cautionary signal to the beginning of braking. As a result of calculating the mean of reaction time, the smallest was the non-talking condition, followed in order by the bone conduction headset condition, the earphone headset condition, and the speaker condition. Moreover, there are significant differences between hands-free devices by one-way analysis of variance. In addition, the Shaffer's multiple comparison showed that some comparisons differed significantly. It is suggested that the bone conduction device has less influence on the delay of the brake pedal operation.

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[in Japanese]

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In industry plants, maintenance workers generally work using procedure manuals. To deal with maintenance problems in domestic nuclear power plants, the major factors related to preparing the procedure manuals should be identified, and improvement of the procedure manuals themselves should be undertaken, but no concrete improvement approaches have been proposed. Therefore, in order to explore concrete ways of improving the procedure manuals, we proposed a cognitive behavioral model when maintenance workers are using procedure manuals. In studying this model, we used the FRAM (functional resonance analysis method) to organize the information necessary for the procedure manuals and we extracted problems on the expression form of that information. In order to confirm the validity of the model, we carried out a basic experiment with a LEGO block assembly by a maintenance worker. In the experiment, we prepared two types of LEGO blocks, blocks with a meaningless form and blocks for an automobile form, and five kinds of procedure manuals. From the experimental results, we obtained useful knowledge about the occurrence numbers of human errors and procedure manuals.

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