When eccentric live loads are applied on the deck overhang of steel-box girder bridges, torsional moments, comprising pure torsional and distortional moments are generated on the box sections. The torsional moment on the bridge girders distorts the box girder cross-sections, inducing additional normal stress components and causing instability of the box girder sections in severe cases. Hence, it is essential to install intermediate diaphragms in the box sections to minimize distortional behaviors. Although the applied live loads are critical parameters that influence intermediate diaphragm spacings, the effects of live load combinations have rarely been addressed in the design of intermediate diaphragm spacings. Thus, load combinations should be evaluated to design the intermediate diaphragm spacing of the box girder bridges more thoroughly. In this study, the load combination effects on the distortional behavior and adequate intermediate diaphragm spacing were evaluated through a finite element analysis (FEA). Composite rectangular box girder bridges with different cross-sectional aspect ratios ($H/B$) and spans ($L$) were analyzed in the parametric study. It was found that the truck load, which represents the concentrated load, significantly influences the distortional warping normal stress, normal stress ratio, and intermediate diaphragm spacing. In addition, the FEA results showed that the controlling load combinations could be varied with the span.

A fabricated mobile scaffold has various components, including vertical members, horizontal members, braces, work plates, and castor wheels. In Korea, the structural performance of each member must be validated based on member-level structural safety criteria; this means that rigorous evaluation methods are required to secure the system-level structural safety of the fabricated mobile scaffold. To suggest rational system-level structural safety criteria and effective evaluation methods, the characteristics of the structural behaviors of the assembled structure must be investigated first. Unlike other temporary equipment, it is a product that requires convenience of use and ease of movement. Therefore, to secure the safety and usability of the structure, it is necessary to evaluate the ultimate behavior of a mobile scaffold fabricated with various material and structural types. In an experimental study, the ultimate mode and load-bearing capacity were investigated, and the appropriateness of the required performance of the mobile scaffold was reviewed. Three types of experimental test models with different materials (steel and aluminum) and stories (single-story and three-story erection) were selected and examined for vertical loads. Based on the experimental results, the ultimate behavior characteristics of the fabricated mobile scaffold were analyzed, and the ultimate load was identified.

At construction sites, various types of temporary equipment and structures are used for safety and work efficiency. However, various temporary equipment-related accidents frequently occur for many reasons, including inappropriate installation, usage, and material and structural imperfections. A mobile scaffold is one of the most commonly used indoor temporary equipment for work in high places. In general, the main structural members of the mobile scaffold, such as the mainframes, horizontal members, braces, caster wheels, outriggers, and handrails, are installed on the construction site for this purpose. This means that the load-carrying capacity of the equipment can vary depending on the assembly details. In Korea, there are safety certification standards applied for frequently used temporary equipment, such as scaffolds and shoring. However, the standards concern the strength criteria for the member itself, rather than the global load-carrying capacity. Therefore, it is difficult to review whether the fabricated mobile scaffold has sufficient load-carrying capacity, or to confirm the structural safety considering the various uncertainties affecting the structural performance. In this study, rational safety certification standards and evaluation methods are suggested for fabricated mobile scaffolds. The suggested safety certification standards present structure-level criteria for checking the load-carrying capacity, horizontal stiffness of the structure, and overturning risk. It is expected that the structural performance for safety can be directly checked based on the suggested safety certification standards and performance evaluation methods during the safety certification stage.

스마트 공장 및 제조공정의 혁신은 제조 데이터의 불균형을 가속화시키고 있으며, 이는 결함 진단 및 분석 프레임웍의 부정확성을 일으키고 있다. 본 연구에서는 이러한 제조 데이터가 가지는 불균형 문제점을 해소하기 위한 방법론으로 데이터 생성방법론인 생성적 적대 신경망 (Generative Adversary Network)을 고려한다. 생성적 적대 신경망이 가상데이터의 생성에 기여하는 동안, 실제 제조 데이터에 적용하기 위해서는 모델 붕괴 (Model Collapsing)과 같은 문제를 해소해야 한다. 모델 붕괴현상이란, 신경망에 목적함수에만 초점을 맞추어 데이터가 생성되어 각 속성값의 분포가 원래 데이터와 차이가 나는 현상을 의미한다. 본 연구에서는 생성적 적대 신경망의 기존 목적함수에서 실제와 가까운 데이터 생성을 위한 유도항을 추가하여 가상데이터를 합성하는 프레임웍을 제안한다. 생성된 가상데이터를 분류를 위한 훈련데이터로 사용함으로써, 데이터의 불균형 및 모델 붕괴현상을 동시에 해소토록 한다. 제안하는 프레임웍의 우수성을 증빙하기 위하여 불균형을 가진 실제 강판 품질 데이터를 사용하여, 기존의 여러 연구 방법론과 비교하고 분석한다.

Three-dimensional (3D) LiDAR is widely used because it can accurately measure 360° 3D depth. One of the most widely used sensors to this end is VLP-16, a 16-channel LiDAR manufactured by Velodyne. This 16-channel LiDAR provides dense 3D depth data in the horizontal direction. However, in the vertical direction, it provides only sparse depth data owing to the LiDAR architecture. We propose an upsampling method to obtain a dense 3D depth map from a 16-channel LiDAR by applying an edge-aware filter to the LiDAR data. A camera- LiDAR sensor system composed of a 16-channel LiDAR and six vision cameras is used for this purpose. First, the LiDAR depth data are projected onto the camera image coordinates to generate a 2.5D depth map. Next, bilinear interpolation and a weighted median filter are applied to upsample the original depth map. Compared with the original LiDAR data, we can generate an extremely dense depth map by using the proposed method. The results of quantitative analysis show that the proposed method can dramatically increase the number of 3D depth points and reduce the depth reconstruction error.

This study aims to investigate the structural behavior and load-carrying capacity of prefabricated shoring systems. The structural behavior and performance of shoring systems are influenced by the buckling of vertical members, where the compressive force acts as the main load. The buckling strength of a vertical member is sensitive to not only the material and geometrical properties of members but also the connection details between members, presence or absence of braces, and stiffness ratio between members. Therefore, in this study, the structural behavioral characteristics of the individual post member and the entire system are investigated by considering the structural details through eigenvalue and nonlinear finite element analyses. On the basis of the analytical studies, it was confirmed that the boundary condition of the vertical member, rotational and horizontal stiffnesses, and eccentricity condition of the end, which are directly affected by the compressive force acting on the prefabricated shoring system, have a direct effect on the elastic buckling strength. In addition, it was determined that factors such as whether the braces were installed, rotational stiffness of the vertical–horizontal member connection, and the number of installation stages affected the overall strength of the structure. According to the structural analysis results, the assembled structure was reduced by 92.9% and 82.2% compared to the elastic buckling strength of a single member as the height increased to two and three stories. In addition, when the bracing member was not installed, 12.1% and 23.6% strength reduction was confirmed as the elastic buckling strength increased by two and three stories compared to the case where the bracing member was installed. Consequently, the necessity of a whole structural performance evaluation technique was confirmed for a more practical structural performance evaluation.