일체식 교대 교량 공법은 1930년대부터 미국과 캐나다에서 적용되었으나, 국내에서는 공용 기간이 짧아 설계, 시공 및 유지관리 경 험이 부족하다. 또한, 장기 거동에 대한 추적 데이터가 부족해 설계 시 예측한 구조 거동의 안정성 검증이 필요하다. 본 연구는 국내 공 용 중인 일체식 교대 교량을 대상으로 장기 계측을 수행하고, 선행 연구에서 제안된 수치 해석 모델을 적용해 구조 안정성과 모델의 적용성을 검증하였다. 계절적 온도 변화에 따른 변위 값의 크기와 변화 형상을 정성적으로 평가하고, 실측과 수치 해석 변위 값을 t 검 정으로 비교해 정량적 검증을 수행하였다. 분석 결과, 대상 교량들은 예측 값과 실측 값이 큰 오차 없이 안정적인 구조 거동을 보였다. 일부 교량에서는 교대 밀림으로 인한 신축 이음 축소와 교대 벽체 및 거더부 협착이 관찰되었다. 모델링 정확도를 높이기 위해 지반- 교대 스프링 강성과 교좌 전단 강성을 설계 값보다 높게 반영하는 것이 필요하다.

본 연구에서는 상용 폴리염화비닐을 개질하여 두 종류의 PVC 기반 이온교환용 고분자를 성공적으로 제조하였다. 이후 개질된 두 이온교환 고분자를 활용한 전기방사 공정과 열 압착 공정을 거쳐 2차원 계면(2D-PVC-BPM)과 3차원 접합부 (3D-PVC-BPM)를 갖는 바이폴라막(BPM)을 제조하였다. 제조된 3D-PVC-BPM은 2D-PVC-BPM에 비해 우수한 물 분해 효율 및 안정성을 보였다. 구체적으로, 300 mA cm-2의 고전류 밀도에서 3D-PVC-BPM은 2D-PVC-BPM가 나타낸 전위보다 4.4 V 낮은 8.05 V의 막 전위를 나타냈다. 더욱이, PVC 주쇄가 가진 내화학성 덕분에 3D-PVC-BPM은 가혹한 조건에서도 높은 화 학적 안정성을 보였고, 이는 4 M H2SO4 및 4 M NaOH 용액에 28일간 침지한 후 관측된 질량 손실이 각각 2.8%와 2.1%에 그친 것을 통해 입증되었다. 끝으로, 3차원 접합부가 3D-PVC-BPM에 맞물림(interlocking) 효과와 넓은 계면면적을 제공해준 덕분에 3D-PVC-BPM의 인장 강도는 36 MPa를 초과했고 신장률 또한 약 50%에 이르는 등 우수한 기계적 물성을 나타냈다.

This study investigates the structural stability of a telescopic arm designed for a painting robot through finite element analysis (FEA). As factory automation progresses, robots are increasingly used to replace hazardous tasks like painting. However, the heavy weight of telescopic arms poses significant control challenges. This research specifically examines the structural stability of a 7.4-meter telescopic arm, designed for use in a 14m x 14m large-scale block painting environment. The telescopic arm consists of six steel links, each ranging from 700 mm to 1500 mm, and supports a 50 kg painting robot mounted at the end of Link 6. Using Dassault System’s Abaqus2022 software, simulations were performed in both stretched and rotated modes to analyze self-weight effects and structural stability. The results revealed maximum deflection of 92.3 mm in stretched mode and 127.3 mm in rotated mode, with the highest stress concentration of 416.8 MPa occurring at the Link 3 and Link 4 connection. To improve stability, additional reinforcement materials and an increase in connector thickness from 40 mm to 80 mm were applied, successfully reducing maximum stress to 94.3 MPa. These findings suggest an effective enhancement in the stability of the telescopic arm under various operational modes.

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.