International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

This work presents a combined experimental and simulation study of resist profile evolution in electron beam lithography (EBL) using poly(methyl methacrylate) (PMMA) resist. The influence of key process parameters, including exposure dose, electron beam energy, and resist thickness on the resist profile formation, sidewall shape, and feature fidelity is systematically investigated. Particular attention is given to proximity effects caused by forward and backscattered electrons, which lead to dose redistribution and profile distortions. Experimental results show a strong dependence of PMMA resist profiles on lithographic conditions, affecting sidewall angle and linewidth variation. Bilayer PMMA systems are also examined to evaluate improvements in profile control and undercut formation for lift-off processes. Simulation of resist development is employed to model resist profile evolution and predict structural changes under varying conditions. The comparison between experimental and simulated results demonstrates good agreement, confirming the validity
of the modeling approach. The study provides deeper insight into PMMA resist behavior and supports optimization of EBL process parameters for improved nanoscale patterning accuracy.

This study presents and validates a method for achieving positioning accuracy comparable to standalone GPS (approximately 10 m) using a proprietary Sigfox WiFi positioning system that transmits only two MAC addresses per message. Due to Sigfox’s severe payload limitations, conventional positioning attempts often fail or yield significant errors. Our approach introduces continuous scanning on the device to dynamically collect up to four MAC addresses, paired with meticulous backend analysis and filtering of MAC address quality using a custom Here API Validation Tool. The proposed method effectively addresses these limitations, demonstrating a 100% location acquisition rate and a median positional error of 19 meters, making it highly effective for both stationary and dynamic mobile tracking.

This study examines the effects of light-emitting diode (LED) lanterns and partition colors on the psychological condition of individuals in evacuation shelters. A previous questionnaire survey involving 193 participants evaluated emotional responses to four LED colors (yellow, green, blue, and red). Yellow light was most frequently perceived as calming and comfortable, whereas red light was strongly associated with tension and anxiety. Building on these emotional findings, we investigated environmental factors through an experiment involving blue, pink, and green partitions. The participants stayed inside each partition for 25 min, and their vital signs, including body temperature, pulse rate, and blood pressure, were measured every 5 min. The results indicate that blue partitions produced the most stable physiological responses, including lower systolic blood pressure and steady pulse rates, reflecting parasympathetic nervous system activation. In contrast, the pink and green partitions increased pulse rates and led to greater fluctuations, indicating higher stress. These findings demonstrate that appropriate lighting and partition colors can promote psychological stability and improve shelter environments. This study also highlights the importance of simple, low-cost environmental design strategies for stress reduction during prolonged evacuations.

Two-dimensional (2D) materials such as graphene and tungsten disulfide (WS₂ ) are promising candidates for gas sensors due to their unique electrical and surface properties. Graphene exhibits high conductivity and mechanical strength, while its oxidized or functionalized forms enhance chemical reactivity and gas adsorption. WS₂ , a semiconducting transition metal dichalcogenide, shows strong surface interactions with gases, enabling sensitive detection even at room temperature.
In this work, graphene and WS₂ thin films were characterized to evaluate surface morphology, uniformity, and structural quality. Graphene films were prepared by chemical vapor deposition (CVD) and transferred onto SiO₂ /Si substrates, while WS₂ films with thicknesses of 20 nm and 50 nm were obtained via CVD and sputtering. Surface analysis using scanning electron microscopy (SEM) and 3D laser microscopy revealed that graphene films are highly uniform and smooth, whereas WS₂ films exhibit thickness-dependent surface roughness and texture. These findings provide insights into the relationship between film morphology and gas sensing performance, highlighting the potential of both materials for sensor applications.

Considerable research has been conducted on measuring maximum tongue pressure, which is an index of tongue muscle strength that includes the relationship between tongue strength and swallowing function. Tongue pressure is the force with which the tongue presses a bolus of food against the palate and sends it into the pharynx. A low tongue pressure makes the aspiration of food more likely. In this study, we investigated the age-dependence of human swallowing function, as well as the swallowing function of female high school students in different courses, one in physical education and one in health and nursing.

In recent years, natural disasters have occurred almost annually in Japan, causing great damage. Power outages in disasterstricken areas have occasionally forced victims to resort to outdoor campfires or indoor candles for lighting. Prolonged bad weather during such events makes it difficult to safely secure lighting, which could have a negative influence on people’s health. To address this issue, we used white light-emitting diodes (LEDs) as the light source and fabricated handmade lanterns by filling a 500 mL plastic bottle with tap water and adding 1–2 drops of milk. In this study, an LED light source casing was constructed using a three-dimensional printer, achieving a stable light scattering effect. Red, green, blue, and yellow LEDs were used for the lantern, considering people’s preferences for colored handmade lanterns. An additional light source case was easily made from cardboard, and a bamboo light source case was also constructed.

Plasma-based ion implantation (PBII) is a surface modification technique that applies a negative high-voltage pulse to a sample immersed in plasma. PBII is suitable for samples with complex geometries, as its ion sheath conforms to the sample’s shape, ensuring uniform ion implantation. Due to its precise controllability, PBII is widely used industrially for surface modification and has promising applications for sterilization. We previously used PBII with oxygen gas to successfully sterilize heat-resistant spore. Here, we evaluated the use of PBII with HHO as the process gas for sterilization. Sterilization exceeding 7D was achieved at 10 min and 3 Pa. The enhancement of the sterilization efficacy was attributed to the synergistic effect of plasma and thermal energy, which emerged as a consequence of a temperature increase exceeding 100°C due to adjustments in pulse width and delay time. These results indicate the possibility for temperature control in PBII technology, which has potential application in sterilization processes.

In this paper, a two-dimensional (2D) material graphene with exceptional electronic and mechanical properties is discussed as a promising candidate for chemiresistive sensor applications. High surface area and superior charge carrier mobility of graphene enable rapid and sensitive detection of gaseous analytes, making it an attractive alternative to conventional metal oxide semiconductor (MOS) sensors. The review of recent advancements in graphene-based chemiresistive gas sensors is done, highlighting their operational principles, fabrication techniques, and performance enhancements through material modifications such as reduced graphene oxide (rGO). Additionally, we examine the application of graphene sensors in environmental monitoring, where their ability to detect pollutants like NO₂ , NH₃ , and CO₂ with high sensitivity and low power consumption provides a significant advantage over traditional sensing technologies. Despite these advancements, challenges such as selectivity, standardization, and sensor stability remain critical areas for future research.

When location was estimated using Sigfox’s Atlas Wi-Fi, the estimation error is several hundred meters. Meanwhile, when location was estimated using the Wi-Fi media access control (MAC) address and HERE’s API, the estimation error was ~10 m. In an Internet of Things device that obtains the Wi-Fi MAC address, the combination of exp32 and 100a was ~1/5th of the combination of Arduino R4 and Sigfox Shield.

This paper presents a study on the current state of research and use of dichalcogenides of transition metals, particularly WS2. The properties of WS2 in the context of its application in sensor technology and highlight the anticipated advantages of nanostructured disulfides are discussed.

In recent years, natural disasters have frequently occurred in Japan, almost yearly, causing enormous damage. In Hiroshima Prefecture, heavy rains in August 2014 and July 2018 caused large-scale landslides. Power outages continued in the affected areas, and some survivors had been lighting campfires outdoors and using candles indoors. In times of disaster in which bad weather persists, it is difficult to safely secure lighting, which can adversely affect health. Lanterns can be created by putting a few drops of milk into a PET bottle filled with water and shining light from the bottle’s bottom. In this study, we used a light emitting diode (LED) as a light source to evaluate the luminance of handmade lanterns. Results suggested that when using tap water with one LED lamp and a 500 ml PET bottle, 1–2 drops of milk are suitable to achieve the optimal light scattering effect.

In this study, the Sigfox network and the Internet were employed to develop an Internet of Things device equipped with temperature, humidity, barometric pressure, and other sensors to measure different physical data. In addition, we attempted to control Sigfox communication by employing AT commands using the Arduino UNOR4 Sigfox module, and social implementation of the proposed system.