Since January 2020, risk management against the novel coronavirus disease （COVID-19） has become an urgent social issue. Ergonomics can contribute to reducing social anxiety under the chemical, biological, radiological, nuclear and explosive （CBRNE） disasters through risk communication. This paper discusses ergonomic research issues for crisis and emergency risk communication （CERC） among stakeholders to promote appropriate understanding and behavioral change against social anxiety caused by the COVID-19 outbreak. Finally we summarized ergonomic research issues from following four perspectives: 1） CERC factors in CBRNE disasters, 2） action-oriented communication mitigating social anxiety, 3） ergonomic theory and practice against the public health crisis of COVID-19, and 4） academic role of human factors and ergonomics communities.
In Safety-1, safety is defined as having as few as possible negative outcomes, and in Safety-2, safety is defined as having as many success outcomes as possible. In this study, we aimed to experimentally verify the effectiveness of using Safety-1 mode and Safety-2 mode properly according to the situational variability, and to derive a quantitative indicator of the situational variability that should switch between both modes. The following was clarified from the result of the simulation experiment which assumed fire extinguishing activity. 1） The larger the situational variability, the more cases will be switched from Safety-1 mode to Safety-2 mode, but switching to the Safety-2 mode is a minority, as long as the situation does not change by more than 15 times the steady state. 2） The larger the situational variability, the more successful outcomes will be in the Safety-2 mode than in the Safety-1 mode, and an indication of better switching timing to achieve a successful outcome is that the magnitude of the situational variability 4-6 times relative to steady state.
Generally, non-contact gaze input devices require calibration before using. However, it is difficult for people with severe multiple disabilities who is mentally challenged and have difficulty in moving their bodies as they wish, to move their eyes according to the instructions. It takes time and effort to use a dedicated device, which makes them difficult to express intentions by looking. In this study, we constructed a real-time gaze area estimation system that does not require calibration while maintaining the resolution required for challenged people. Using a usual web camera, gaze area estimation was realized by learning eye and facial appearance with Convolutional Neural Network （CNN）. Next, 36 gazing points were set on the screen, and the evaluation experiments were performed by changing the relative distance between the camera and the face, and the posture angle of the face. In conclusion, it was confirmed that practical accuracy of the basic posture was maintained up to 1,200 mm for the distance, 100 mm downward in terms of position. The results for the posture angle were obtained for one subject only, but it was shown that the accuracy was maintained up to 10 degrees for the yaw, 15 degrees for the pitch, and 15 degrees for the roll angle, respectively.
In focusing on the manner in which drivers recognize extraordinary events occurring in front of them, visual searching is crucial. The purpose of this study is to investigate effective visual searching in recognizing extraordinary events based on the eye movements of drivers. One hundred twenty one drivers of a railway company participated in our study. An experiment was conducted using a railway driving simulator with eye tracker. The given driving scenario was a multi-task scenario in which the main task was to stop the simulated train before a ground device malfunction. The important sub-task was to recognize an extraordinary event, which was a subsidence of railway track on their right. Participants who stopped the simulated train before passing the subsidence were identified as part of the Recognizing Group; participants who passed the subsidence were identified as part of the Non-recognizing Group. Visual behaviors of both groups were analyzed. The findings revealed that total of gaze duration in ahead area by the Recognizing Group was longer than that by the Non-recognizing Group. Each gaze duration in ahead area by the Recognizing Group was also longer than that by the Non-recognizing Group.
This study aimed to clarify the effects of floor and air temperature change during floor heating onset on physiological and psychological responses in the human body. The experiments were conducted in an experimental house with 8 healthy young women wearing winter clothes（0.9clo）. The participants were exposed to 4 conditions with different heating rates at floor heating onset for 210 min including a 30 min rest, while sitting on a chair. Skin and core temperatures were measured, and the participants were asked to report thermal sensation and comfort. As a result, when floor temperature was increased rapidly during floor heating onset, the change in skin temperature was delayed, and core temperature decreased. In addition, the participants tended to feel more comfortable when their rating of thermal sensation was high as they continued to feel warm despite the high floor temperature of approximately 40℃. We found that not only sole and mean skin temperature but also the decrease of core temperature was related to thermal sensation. These findings suggest that setting the floor temperature based on thermal sensation and comfort during floor heating onset may lead to excessive heating.
The two approaches as the concepts to ensure safety of the complicated socio-technical systems have been proposed by Hollnagel. They are the safety concepts called “Safety-I” to reduce risks and “Safety-II” to expand successes. The resilience engineering is suggested as the methodology to achieve Safety-II. The study analyzes the recovery of the water injection of Unit 3 based on the resilience engineering, focusing on the fact that Fukushima Daiichi Nuclear Power Plant prevented further deterioration of the accident case, rather than the aspect that it has been evaluated for extracting risk factors. Based on those results, the study clarifies the method of learning to enhance safety which has a different view from existing accident investigation.
Approximately 60％ of accidents that happen on railway platforms in Japan resulting in injury or deaths are caused by drunken passengers. This study was designed to identify patterns of falls from platforms experienced by drunken passengers, as well as premonitory behaviors before falls and before making contact with moving train cars. Images collected from security cameras recording such accidents were analyzed. Results indicated （1） patterns of falls experienced by drunken passengers just before accidents could be classified into three types. （2） Premonitory behaviors displayed by drunken passengers on platforms and in concourses before having an accident could be classified into five types, and we calculated the incidence of these behaviors. Furthermore, 90％ of drunken passengers fell, or made contact with moving train cars after a few seconds of commencing to walk. It is suggested that station staff who observes drunken passengers displaying premonitory behaviors should call out to them and ensure their safety.
This study examined subjective assessments to clarify how agents for assistance with driving are accepted. The assessors were of various ages, including some who were elderly people. Three kinds of agents were assessed: voice, virtual and robot agents. The results showed that both the elderly people and people in other age groups positively assessed robot agents on the item ‘Familiarity’. The results also indicated that robot agents received lower assessments on the item ‘Obstruction’ than did voice or virtual agents. From these findings, robot agents are considered to be well accepted and tend not to cause hindrances. Moreover, the results changed after repeated use of agents, suggesting that continued use has an impact. Therefore, future directions for research include the following: differences in reception depending on differences in the types of robot agents, changes in assessments when agents are used over a long period of time, and changes in behaviors after driving with the assistance of agents.
A fall accident from a stepladder is often due to loss of balance while in a working posture. The purpose of this study was to evaluate posture stability, while standing on a stepladder, based on working posture and maximum reach distance. Ten male subjects reached forward as far as possible on a stepladder at shoulder height. The test involved combinations of 4 standing positions and 5 reach directions. The maximum reach distance on the horizontal plane, working posture, center of pressure (COP) location, and subjective assessment on posture instability were recorded. The horizontal distance from the center of a stepladder to the index fingertip was defined as the maximum reach distance, while COP location at these extreme distances determined the stability limit. The results showed that stability limit at two-steps below the platform was longer than that at one-step below the platform or on the platform. Maximum reach distance had no significant difference between on the platform and at two-steps below the platform. These results suggest that posture stability was improved at two-steps below the platform without a decrease of maximum reach distance.
The comprehension of hierarchical GUI menu operations was investigated in children in the process of developing their cognitive functions. Participants were 120 children aged 3-6 years. They were asked to select a target item presented on a computer screen, according to figures, colors, and patterns on menus constructed of two and three hierarchical structures. Their degree of comprehension was estimated on the basis of the success rate of selection tasks. For 3- to 5-year-old children, the success rate significantly increased with the two-structure menu than with the three-structure menu. Limited processing capacity of their short term memories, difficulty of voice-encoding, and undeveloped verbalization might have influenced their low success rates in the three-structure menu. The 6-year-old children had a success rate near 100%, which suggests that hierarchical menu images can be constructed in 6-year-old children as well as in adults. The points at which the success rate increased rapidly were observed both in the two- and three-structure menus. This suggests the existence of a critical period in the comprehension of hierarchical menus.
The purpose of this study was to compare the features of joint angle and muscle activity of standing up movement from a chair in PD (Parkinson's disease) patients and healthy individuals, for design of the chairs assisting standing up movement of PD patients. Twelve PD patients and 12 healthy individuals participated in this study. We measured the joint angle and muscle activity (electromyogram) in the lower limbs, and the ground reaction force during standing up movement from an armchair. In terms of the timing of change of the joint angle and the working joint angle, no significant difference was found between the PD patients and healthy individuals. However, the timing of PD patients in the movement from the start point of the rectus femoris to the start point of the tibialis anterior was significantly shorter than that of the healthy individuals. These results show that PD patients have specific features of muscle activities in standing up movement from a chair.
The objective of this study was to investigate an optimum crutch handle bar diameter that is easy for grasping and leads less efforts by hands, wrists and fingers. Sixteen healthy young adult males walked with a right-leg-support, swing-through gait motion using one pair of standard axillary crutches with six handles having different diameters (25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, measured lengthwise from the center). During the gait, surface electromyography from flexor digitorum superficialis (FDS) and extensor digitorum communis, wrist posture (flexion and extension), the distribution of externally applied pressure on the palm and subjective evaluation were measured. The results showed that the thicker handle conditions (40 mm, 45 mm and 50 mm) led to a lower pressure on the palm. In addition, wrist posture was more extended in thicker handle conditions than in thinner ones. On the other hand, thinner handle conditions (25 mm and 30 mm) resulted in higher FDS activity. The subjective evaluation showed the 35 mm handle diameter was most suitable for grasping. In conclusion, the handle diameter 35～40mm, which is about 19～22％of hand length, is regarded as the optimum handle size of axillary crutches for young adult males.