Bellows expansion joints enhance the displacement performance of piping systems owing to their unique geometrical features. However, structural uncertainties such as wall thinning in convolutions, a byproduct of the manufacturing process, can impair their structural integrity. This study addresses such issues by conducting a global sensitivity analysis to assess the impact of these uncertainties on the performance of bellows expansion joints under monotonic loading. Global sensitivity analysis, which examines main and nth order interaction effects, is computationally expensive. To mitigate this, we employed a surrogate model-based approach using an artificial neural network. This model demonstrated robust prediction capabilities, as evidenced by metrics such as the coefficient of determination. The sensitivity indices of the main effect for the 2-ply and 3-ply bellows at the sixth convolution were 0.3340 and 0.3233, respectively. The sensitivity index of the sixth convolution was larger than that of other convolutions because the maximum deformation of the bellows expansion joint under monotonic bending load occurs around it. Interestingly, the sensitivity index for the interaction effect was negligible (0.01%) compared to the main effect, suggesting minimal activity between uncertainty factors across convolutions. Notably, bellows expansion joints under repetitive loading exhibit more complex behaviors, with the initial leakage typically occurring at the convolution. Therefore, future studies should focus on the structural uncertainties of bellows expansion joints under cyclic loading and employ a surrogate model for comprehensive global sensitivity analysis.

본 논문에서는 구조물이 다중 구조물로 연결되는 경우 연결부의 조인트 위치를 기존의 위상최적설계 기법을 활용해 설계하는 기법 을 개발하였다. 조인트는 길이가 0이고 강성이 매우 강한 스프링으로 모델링되었으며, 조인트는 유한요소 메시 형상과 무관하게 이동 할 수 있도록 모델링되었다. 최적화 과정에서 조인트가 서로 뭉치는 현상을 방지하기 위해 조인트 최소거리 조건을 추가해 조인트간 의 최소거리가 확보된 설계를 얻었다. 최적설계 시 목적함수로는 전체 구조물의 compliance 값이 사용되었으며, 조인트 최소거리 조 건에 따른 결과를 비교하기 위해 2개의 수치예제를 해석하였다. 위상최적설계 결과 조인트 최소거리 조건의 변화에 따라 조인트 및 구조물의 최적 형상을 얻을 수 있었다.

본 연구에서는 실대형 실험과 구조해석을 통하여 현장에서 사용되는 기둥-서까래-도리, 기둥-도리-방풍벽 접합부를 적용한 강관 골조 플라스틱 연동온실의 정적 구조 성능을 분석하였다. 실대형 재하실험 결과는 접합부를 강접합으로 가정한 구조해석 결과와 비교하여 구조물의 횡방향 강성과 각 부재의 하중분담률에서 많은 차이를 보였다. 동고 높이에서 측정한 수평변위는 실험과 구조해석의 차이가 40% 이었고 수직변위는 89%의 차이를 보였다. S3 부재의 발생응력을 기준으로 한 각 부재별 하중분담률을 비교한 결과 실험과 구조해석에서 두 배 이상의 차이를 보이는 부재가 있었으며, 하부측벽이음(S2), 기둥 상부(S7) 등 주요 부재의 실험결과가 구조해석의 하중분담률을 재현하지 않았다. 현장에서 사용하는 접합부가 충분한 강성을 확보하지 않음으로써 구조물에 작용하는 외력을 각 부재에 적절하게 전달하지 못했으며 이로 인해 구조물의 강성이 저하되는 현상이 나타났다. 설계 단계에서 일반적으로 구조 해석에 의해 결정되는 구조성능의 신뢰도는 접합부의 특성을 보다 면밀하게 고려했는지 여부에 따라 좌우 될 수 있다. 따라서 온실 구조 성능에 대한 신뢰성을 높이기 위해서는 온실에 사용되는 다양한 접합부를 고려할 수 있는 구조해석 기술의 개발이 필요하며 설계 기준에서 상세 설계 방법을 보다 명확히 규정해야 할 것으로 판단된다.

The purpose of this study was to investigate the effect of multi joint-joint position sense (MJ-JPS) training on joint position sense, balance, and gait ability in stroke patients. A total of 18 stroke patients participated in the study. The subjects were allocated randomly into two groups: an experimental group and a control group. Participants in the experimental group received MJ-JPS training (10 min) and conventional treatment (20 min), but participants in the control group only received conventional treatment (30 min). Both groups received training for five times per week for six weeks. MJ-JPS is a training method used to increase proprioception in the lower extremities; as such, it is used, to position the lower extremities in a given space. MJ-JPS measurement was captured via video using a Image J program to calculate the error distance. Balance ability was measured using Timed Up and Go (TUG) and the Berg Balance Scale (BBS). Gait ability was measured with a 10 m walking test (10MWT) and by climbing four flights of stairs. The Shapiro-Wilk test was used to assess normalization. Within-group differences were analyzed using the paired t-test. Between-group differences were analyzed using the independent t-test. The experimental group showed a significant decrease in error distance (MJ-JPS) compared to the control group (p<.05). Both groups showed a significant difference in their BBS and 10MWT results (p<.05). The experimental group showed a significant decrease in their TUG and climbing results (p<.05), but the control group results for those two tasks were not found to be significant (p>.05). There was significant difference in MJ-JPS and by climbing four flights of stairs on variation of pre and post test in between groups (p<.05), but TUG and BBS and 10MWT was no significantly (p>.05). We suggest that the MJ-JPS training proposed in this study be used as an intervention to help improve the functional activity of the lower extremities in stroke patients.

In this paper, a commercial multibody dynamics program ADAMS was utilized to investigate the model for the multi-joint boom conflicts. In this process, CATIA, ANSYS and ADAMS were used to develop the simulation. The addition of ADAMS made the system more accurate and improved precision of the system. In brief, the 3D CAD model of the structure was initially developed via CATIA. After this, the CATIA models were exported to ANSYS for creating flexible-body modeling by using formatted file. Subsequently, with ADAMS, the flexible body model was directly imported from ANSYS which performed the analyses of the dynamic collision of the nozzle boom conflicts. This contained the information regarding geometry and model shapes of the flexible body. Using ADAMS/Durability, it was possible to determine the strain energy for the nozzle configuration by crashing the contact structure that was created. Via this procedure, the acquired simulation analysis of nozzle showed interestingly good results with respect to the objectives of the study

In this paper, our aim is to develop a simulation model for Multi-joint demolition water vehicle. 3D model of vehicle is developed with CATIA. The rigid simulation model is built in ADAMS and the flexible simulation models are developed using ADAMS and ANSYS. The combination of the both ADAMS and ANSYS can improve the precision of system simulation. The rigid model with rigid multi-slide booms and rigid refracting booms, the hybrid model with flexible multi-slide booms and rigid refracting booms, and a flexible model with flexible multi-slide booms and flexible refracting booms are considered. The simulation analysis shows a good performance, and valuable results we are interested in are obtained.

This paper is to clarify the boundary condition of the joint connection in the multi-span vinyl greenhouse. It is carried out that experiments for the rotational stiffness of the joint connectors used in both the field and the guidelines of the greenhouse constructions.

Various driving mechanisms to adapt to uneven environment have been developed for many urban search and rescue (USAR) missions. A tracked mechanism has been widely used to maintain the stability of robot’s pose and to produce large traction force on uneven terrain in this research area. However, it has a drawback of low energy efficiency due to friction force when rotating. Moreover, single tracked mechanism can be in trouble when the body gets caught with high projections, so the track doesn’t contact on the ground. A transformable tracked mechanism is proposed to solve these problems. The mechanism is designed with several articulations surrounded by tracks, used to generate an attack angle when the robot comes near obstacles. The stair climbing ability of proposed robot was analyzed since stairs are one of the most difficult obstacles in USAR mission. Stair climbing process is divided into four separate static analysis phases. Design parameters are optimized according to geometric limitations from the static analysis. The proposed mechanism was produced from optimized design parameters, and demonstrated in artificially constructed uneven environment and the actual stairway.

Unlike robotic systems, humans excel at a variety of tasks by utilizing their intrinsic impedance, force sensation, and tactile contact clues. By examining human strategy in arm impedance control, we may be able to teach robotic manipulator's human's superior motor skills in contact tacks.This paper develops a novel method for estimating and predicting the human joint impedance using the electromyogram(EMG)signals and limb position measurements. The EMG signal is the summation of MUAPs(motor unit action potentials). Determination of the relationship between the EMG signals and joint stiffness is difficult, due to irregularities and uncertainties of the EMG signals. In this research, an artificial neural network(ANN)model was developed to model the relation between the EMG and joint stiffness. The proposed method estimates and predicts the multi joint stiffness without complex calculation and specialized apparatus. The feasibility of the developed model was confirmed by experiments and simulations.

본 연구에서는 댐군을 연계운영할 경우 발생하는 효과를 이수측면에서 평가할 수 있는 방법을 개발하여 한강수계 댐군 운영 실적의 평가에 적용하였다. 개발된 평가방법에서는 용수공급과 유황개선 부분에서 연계운영의 효과를 평가하기 위하여 평가지점에서 필요수량에 대한 충족률과 유황안정도를 평가지표로 사용하였다 발전 부분에서 연계운영의 효과는 댐군에 의해 생산된 총발전량을 평가지표로 사용하였다. 실제 운영실적은 공칭공급량을 공급하는 단독운영과 최적화 모형에 의한 평