Safety is the top priority for commercial transportation, not just for aircraft. In commercial aviation, where the entire system is complex, factors that compromise safety must be completely eliminated during the planning phase of airport construction. Subsequently, reliable procedures are required throughout the design and construction phases of the project. Deficiencies creep in and remain hidden throughout the planning, design, and construction phases and are only revealed when an accident occurs. However, by that point, damage has already occurred, and it is too late to take action. A prime example is the Jeju Air accident involving a low-cost carrier that occurred at Muan International Airport in the Republic of Korea on December 29, 2024. This study focuses on airport structures in light of this accident, unraveling latent issues across the planning, design, and construction phases, and clarifying aviation safety based on questions posed to aviation experts.

We hypothesize that JR-West’s failure of the organizational management is an important cause of the Fukuchiyama-Line Derailment Accident, though it is widely pointed out that the major causes are the operator’s human error and the organizational climate of JR-West. This study focused on Shared Mental Models （SMMs）of operators and verified that the skill development which includes interactions of operators is the most effective for prevention of organizational accidents isomorphic to the accident. Concretely, we simulated how SMMs of operators behave to observe operators’ micro behavior in the organizational macro view. As the results of the simulations, it was turned out that isomorphic accidents can occur if companies adopt other skill development types than the most effective type. These results suggest that JR-West of the day could not have the appropriate managerial cognition about what the optimum skill development type is such as subordinationtype is suitable, as an important cause of the accident.

This study investigates the ignition risk and discharge energy associated with abnormal discharges from a handheld electrostatic powder spray gun. A newly developed compact spark ignition test apparatus was used to simulate worst-case discharge conditions and assess explosion safety. Discharge behavior was analyzed through current waveform measurements, and the largest abnormal discharge was observed at an 18 mm discharge gap. Ignition tests were conducted using methane–air mixtures at various concentrations. No ignition occurred under 12 vol% methane, but since this corresponds to an ignition energy of approximately 5 mJ, compliance with the EN 50050-2 standard̶which defines 2 mJ as the safety threshold̶could not be confirmed. Additional tests with more sensitive gas concentrations (11.5% and 5.8% methane) showed no ignition in any trial, suggesting the abnormal discharge energy was below 2 mJ. By varying the methane concentration and determining the ignition boundary, the discharge energy was estimated to lie between 0.56 and 1.06 mJ. Although 1.06 mJ represents the highest estimated value obtained in this study and a small uncertainty may remain, the results indicate that the discharge energy is unlikely to exceed the 2 mJ safety threshold defined in EN 50050-2. Therefore, further clarification of the test conditions and their consistency with the stated safety threshold would be beneficial for more accurate risk assessment.

Since children have immature bodily functions, they may be more susceptible to damage from indoor product incidents than adults. In this study, the disability-adjusted life year was employed as a common index for equivalent risk conversion to quantify the expected risk value of indoor product incidents. The estimated incident rate and the expected risk value of children's indoor incidents were evaluated in comparison with socially established risk-based management levels such as the guidelines for drinking water quality of the World Health Organization. The estimated incident rate and the expected risk value had median values of 5.36 × 10 ^-6 (incidence / population / year) and 4.23 × 10 ^-5 (lost-years per person / year), which exceeded the reference level of 10 ^-7 (incidence / population / year) and 10 ^-6 (lost-years per person / year) by more than an order of magnitude in many cases. It was also found that the age group of 4 years and younger was at particularly higher risk compared to other age groups, both in terms of the incident rate and the expected risk value. Compared to the reference levels, the incident rate was 84 times higher and the total expected risk value was 127 times higher.