본 논문은 코시 모멘텀(Cauchy’s Momentum) 방정식을 이산화하기 위해 GC-LSM(Geometric Conservative Least Squares Method) 을 사용한 새로운 Meshless 방법을 제시한다. FEM(Finite Element Method) 방법이 구조해석에 널리 사용되고 있지만 무격자 기법은 격자를 이동해야 할 때 장점이 많기 때문에 개발되었다. 본 작업은 무격자 기반의 FSI(Fluid-Structure Interaction) 프로그램을 개발하 기 위한 기틀을 다지는 단계이다. 본 논문에서는 Cauchy’s Momentum 방정식을 GC-LSM을 사용하여 강형식 형태로 이산화하였고, 시간 적분을 위해 New Mark Beta 방법을 사용하였다. 개발된 기법은 1D, 2D 및 3D 벤치마킹 문제에서 검증했으며, 정적 해석 및 동적 해석 결과가 해석해와 비교시 매우 정확한 결과를 보여준다.

This paper proposes a method to evaluate the structural safety of a large wide-width greenhouse structure against wind load caused by a typhoon through a fluid structure interaction analysis technique. The conventional method consisted of roughly estimating the wind load based on the relevant laws and regulations, and determining safety through structural analysis. However, since the wind load changes nonlinearly according to the wind speed distribution and wind direction around the greenhouse and the external shape of the structure, there are many uncertainties in the existing structural safety evaluation method, and it is difficult to accurately determine the design margin. In this study, a systematic method was developed to accurately calculate the wind load acting on a greenhouse structure and evaluate structural safety by considering the characteristics of wind through a fluid structure interaction analysis using coupled computational fluid dynamics and computational structural mechanics. Using the proposed method, it is possible to significantly reduce the manufacturing cost because it is possible to obtain an optimal design that reduces the over-conservative design margin while securing the structural strength of the greenhouse.

The purpose of this study was to develop a side protection device for school buses for children. In the case of the door side impact beam, it plays a very important role because it protects passengers from external collisions. However, in the case of a school bus for children, the space between the door and the door trim is very narrow, unlike a general passenger car. So, as an alternative to this, we are trying to develop Rub Rail, which is compulsory for children's school buses in the United States. Based on the results of structural analysis according to the cross-sectional shape of the rub rail, we want to find out the appropriate shape of the rub rail.

In this study, a finite element analysis was used to analyze the stress state and vibration characteristics generated by continuous contact between wheels and rails when driving urban railway vehicles. The rails applied to the analysis were divided into straight and curved shapes, and three-dimensional modeling was performed to analyze the changes in structural characteristics of wheels and rails when driving on straight and curved rails. As a result of the analysis, the stress characteristics were up to 6.5 MPa on a straight rail and 9.81 MPa on a curved rail, and it is believed that this increase in stress will increase noise due to an increase in friction at the interface. The vibration characteristics of the wheels and rails showed similar behavior from the 3rd mode to the 9th mode of the rail to the intrinsic vibration characteristics from the 4th mode to the 6th mode of the wheel.

Recently, the construction of tall buildings utilized by high strength-concrete in the whole world is tending to be on the rise. The application of high-rise structural system in buildings results in the excellent cut-down effect in construction materials due to section reduction. Therefore, in order to investigate the CO2 and resource reduction effect for the high-rise structural system, comparisons of GWP and ADP in embodied energy of structural materlais between 4 type of high-rise structural system have been performed. As a result, GWP emission increased in the order of steel structure outrigger system, RC shear wall system, and RC outrigger system. On the other hand, ADP emissions increased in the order of RC shear wall system, RC outrigger system, and steel structure outrigger system.

The flange spreader has been used to withdraw gaskets and valves during butterfly valve maintenance. When using the conventional flange spreader, an excessive working space (pipe separation distance) appears, and the pipe and flange are damaged by the load. Also, the equipment can’t be operated safely when the pipe has eccentric fitting. To solve the problems, a valve easy out tool with collet was developed for safely fixing and spreading flange. By using Ansys Workbench 2021 R2, the structural analysis of the original collet was performed, and shape design of the collet was carried out to improve structural safety.

Structural characteristics have been analyzed for gear system in a commercial iron bending machine which is widely used at many building construction sites. This complicated gear system in the bending machine is fundamental power transfer unit from electrical motors, and it is composed of various configuration structure including various spur and helical gear assembly. Main structural characteristics of the gear system such as stress and deformation distributions are predicted with numerical simulation of FEM method for various operating conditions of torque and rotation speed. Results show that there is large deformation in lower region of driving gear, and high stress near those contact area which is greatly affected by motor torque. These results can be applied for the design improvement of efficient gear system in the iron bar bending machine.

본 논문에서는 축하중과 폭발하중을 동시에 받는 철근콘크리트 부재의 구조 거동을 분석하였다. 기본적인 폭발하중을 받는 패널 실험 데이터, 축하중과 폭발하중을 받는 철근콘크리트 기둥 실험데이터를 이용하여 비선형 동적해석 모델링을 검증하였다. 축하중의 적용에 있어서 Autodyn은 동적해석만을 위한 프로그램이기 때문에 축하중과 같은 정적 하중에 대한 초기 응력 상태를 모사하는 해석 절차를 제시하였다. 축하중비 0%~70% 구간과 TNT 등가량에 의존한 환산거리 1.1~2.0에 해당하는 매개변수를 선정하여 총 80개의 비선형 동적 유한요소해석을 진행하였다. 축하중비와 환산거리의 변화를 통해 손상정도와 최대 변위 및 회전각으로 구조 거동을 비 교 분석한 결과로 원거리 폭발하중에서 축하중을 받는 기둥의 강성 증가로 최대 변위가 감소한다. 결과적으로 축하중비 10%~30%, 30%~50%, 50% 이상의 영역 3가지로 구조적 거동 분류가 가능함에 따라 내폭 설계 모델 개발에 활용될 수 있을 것으로 보인다.