Many cave-in accidents occur during trench excavations, leaving digging workers buried in collapsed soil even in shallow depths. A main cause of such accidents is the misunderstanding of stability. Typical earth support systems are heavy and stiff structures, so these are seldom used for shallow excavations. This study proposes a personal soil guard system to prevent labor accidents. This system has a simple structure with two sets of crossing frames and a pair of vertical sheets on located on either side to bear horizontal earth pressure from collapsed soil. This provides a protective space for personnel. It can be easily placed in trenches. Full scale model tests were carried out to investigate the function that blocks collapsed soil. An earth pressure from collapsed soil was measured at five different heights on a vertical wall that was placed at a distance from a model trench wall. The acting load after creep failure did not increase to a value that would cause failure of the frames and the sheets. And the supporting the shoulders and the toes by beams induced ductile failure, so the peak value of earth pressure on the sheets reduced. This study discusses a developed unique protection system for safer trench excavations in shallow depths.

As wind power generation increases and wind turbines become larger, the number of lightning strikes on wind turbines increases, and damage to blades in particular causes significant losses. Now, the main lightning protection method for blades is a receptor, which is a conductor attached to the tip of the blade to capture lightning, but there have been cases where lightning is not captured and strikes outside the receptor. Therefore, there is an urgent need for a method that can guide the lightning current to the receptor without damage when lightning strikes outside the receptor, and we are focusing on paint coatings in this study. Coatings are classified into two types according to the conductivity of their surface, and each type has a different protection system. The conductive coating enables protection by mitigating the electric field concentration and quickly completing the formation of a discharge path inside the coating. On the other hand, the nonconductive coating enables protection by accelerating the propagation of surface streamers, which is the precursor to the formation of a creeping discharge path. Considering environmental load, the nonconductive coating is suitable for actual applications.

Preventive measures for mental health problems are still uncommon in small enterprises with less than 50 employees. For increasing the number of employers who have a concrete image of countermeasures, we attempted to promote science-based, self-learning information and communication technology (ICT) mental health tools to small businesses. We considered their implementation strategies by using the framework of implementation science. Based on the framework of the Consolidated Framework for Implementation Research (CFIR), “lack of knowledge and interest of employers” was one of the obstructive factors. In response to the identified obstructive factors, it may be suitable to approach them from various support organizations (e.g., chambers of commerce and industry, labor and social security attorneys) that are familiar consultation services for them on daily basis. The level of activity of the organization differs (e.g., just diffuse the information, explain the contents, provide consultation), and it is important for us to prepare the contents of the distribution according to their levels. In the effort to improve social issues in the workplace, it is important to carefully consider the strategy that fits the issues before starting implementation. Our considering process can be applied to different settings and issues.

The implementation of risk assessment (hereafter, “RA”) at the design stage is essential for preventing workplace accidents related to the use of machines. However, among small and medium-sized machine manufacturers and in tegrators in particular, the dissemination and establishment of RA are impeded by the difficulty of performing “hazard identification” which is regarded as the most important step in the RA process. To establish an effective method for supporting machine designers who lack experience performing RA, the authors previously proposed a hazard identification support method based on the requirements stated in industrial standards related to machinery safety. This concept was inspired by the application of type-C machine safety standards to obtain a presumption of conformity with the applicable European directive(s), e.g., Machinery.

This report describes the results of an effectiveness evaluation of the proposed support method on the basis of subjective impressions of 12 designers working at small and medium-sized machine manufacturers, with a prototype software tool designed to assist with the hazard identification process. The results indicate that the designers viewed the proposed support method favorably and that it was effective to a certain extent in providing support to inexperienced machine designers.

This study aimed to clarify the relationship between requests for workplace improvement and work engagement among office workers in a transportation-related company depending on their level of stress coping ability. An anonymous, self-administered questionnaire survey was conducted on 52 office workers at a transportation company in Japan. Question items included attributes, the Mental Health Improvement & Reinforcement Research of Recognition (MIRROR), the Japanese Utrecht Work Engagement Scale (UWES-J), and the Japanese Sense of Coherence Scale (SOC). In the case of the high SOC group, among the items of MIRROR, those who requested “Supervisors are not too busy, so that they have time to listen to their subordinates,” “An assistant to act as their direct supervisor who is very busy has been appointed” had higher UWES-J scores. In the low SOC group, those who demanded “Coordination and cooperation with other groups are going well.,” “I do not have significant workload problems that affect my core responsibilities” had higher UWES-J scores. These results suggest that, when considering workplace improvement, there are items that should be considered not only from the number of requests but also from the viewpoint of work engagement.

Many crane overturning accidents are caused by the failure of the ground where the crane is placed. When considering the stability of such cranes, there is little information on the strength and deformation characteristics of Kanto loam, which is generally in an unsaturated condition. The authors conducted unconfined compression test and unsaturated triaxial compression tests under the same conditions using specimens made of Kanto loam to examine the results of bearing capacity tests on a model ground. As a result, the ultimate bearing capacity calculated using the unconfined compression strength was underestimated by about half of the bearing capacity test results. On the other hand, the ultimate bearing capacity obtained by using the strength parameters from the unsaturated triaxial compression test was estimated to be 20% smaller than the experimental bearing capacity, but the influence of the bearing width could be estimated. Also, the analytical and experimental values of the ultimate bearing capacity were almost equal in the range where the deformation modulus was similar between the bearing capacity test and the unsaturated triaxial compression test, suggesting that the influence of the increase in foundation width extends in the direction of the ground depth. In addition, it was reported that the choice of Poisson’s ratio has a significant influence on the prediction of settlement, which determines the stability of the machine.

Wire rope slings are heavily used in the manufacturing and construction industries as lifting implements for hoist-suspended loads with cranes. Wire rope slings are often dragged during movement because they are heavy due to being made of steel. As a result, wire rope slings are susceptible to damage. Wire ropes and wire rope slings must be disposed of or replaced depending on the degree of this damage. The disposal criteria for wire rope slings exhibiting various types of damage, such as the number of broken wires, kinks, and corrosion, are specified in JIS B 8836. In the present paper, it is shown that the degree of damage of wire rope slings used for a long time in the manufacturing industry is notable, as investigated based on JIS B 8836. In addition, as an evaluation of the residual strength of damaged wire rope slings, the breaking force of damaged wire rope slings is experimentally obtained and compared to the breaking force of new wire rope slings. For example, the breaking force of wire rope is demonstrated to decrease due to flattening, which is a type of damage.