In this study, we developed a new electric low-height beds mechanism with a stable driven rack and pinion by analyzing the current state of existing beds development and supplementing shortcomings of the beds. Structural safety is evaluated through Finite-Element-Analysis using a simulation method applying existing elevate system types and a new type. Furthermore, we designed and manufactured a trial bed with increased variable height considering medical instrument standards to use both for home and hospital. The elevation mechanism suggested in this study could be valuable to electric beds development.

The cultural heritage of fortresses is often exposed to external elements, leading to significant damage from stone weathering and natural disasters. However, due to the nature of cultural heritage, dismantling and restoration are often impractical. Therefore, the stability of fortress cultural heritage was evaluated through non-destructive testing. The durability of masonry cultural heritages is greatly influenced by the physical characteristics of the back-fille material. Dynamic characteristics were assessed, and endoscopy was used to inspect internal fillings. Additionally, a finite element analysis model was developed considering the surrounding ground through elastic wave exploration. The analysis showed that the loss of internal fillings in the target cultural heritage site could lead to further deformation in the future, emphasizing the need for careful observation.

In a self-level riser, the piston rod generates hydraulic pressure while reciprocating along the pump rod, so components such as rods and valves require precise processing technology. Among them, the design of the pump rod was changed to a spiral groove method because there was a risk of poor operation during eccentricity. In this paper, the design and 3D modeling of the pump rod were conducted, and the structural stability of the core part according to the load change applied to the pump rod was confirmed.

The radioactive Sr-90, which is formed from beta decay, is well known as one of the most commonly detected nuclides in radioactive waste. In 2015, it was reported that Sr-90 was observed in some soil and metal wastes among the 516 drums of radioactive waste transferred from the decommissioning site of the Korea Research Reactor (in Seoul) to the disposal site (in Gyeongju). Decontamination and sequestration of radionuclides, including Sr, from nuclear waste is important because they are hazardous and harmful to the ecological environment. Immobilization of these nuclides using a zeolite framework is suitable and simple method that has been widely studied. Therefore, it is still necessary to continuously explore the thermal stability of various zeolites and environmental changes around adsorbed cations in zeolite pore for effective immobilization of these radionuclides. In this study, we observed the thermal stability in fully Sr-exchanged natrolite (Sr-NAT), one of small-pore zeolite, from room temperature to 350°C using the in-situ synchrotron X-ray powder diffraction and thermogravimetric (TGA) analysis. In addition, we investigated the structural changes in Sr-NAT during temperature increase by Rietveld analysis. Sr-NAT exhibited apparent zero thermal expansions (ZTE) with the thermal expansion coefficients of -3(1) × 10-6 at the initial stage of increasing the temperature due to dehydration process. In the section from 250°C to 300°C, a phenomenon like negative thermal expansion (NTE) occurs in which the unit cell volume of Sr-NAT decreases despite the increase in temperature. Sr-NAT maintained well its crystallinity up to 350°C, and it became amorphous at 350°C. In this study, we provide a fundamental understanding of the structural changes and thermal stability mechanism of Sr-exchaged zeolite natrolite with increasing temperature.

This paper is about structural, and vibration analysis for the development of Index chucks Structural and vibration analyses were performed using the ANSYS Mechanical program to evaluate the Index chuck's structural stability and vibration characteristics. As a analysis result, when the maximum load of 500N was applied to the Index chuck, the safety factors were 2.06, 2.09, and 2.60, respectively, when the thickness was 5mm, and the outer diameters were 70mm, 90mm, and 120mm, respectively. Structurally safe results were obtained. In addition, under load conditions of 300 N or less, structural safety was confirmed if the thickness is 3mm or more.