2022년 기준 국내 폐타이어 발생량은 약 37만톤으로 그 중 88.9% 인 약 32만 9천톤이 재활용되는 것으로 조사되었다. 하지만 이 중 약 75%가 시멘트소성로용 등 열이용 분야에 사용되었다. 폐타이어는 대부분 고무와 플라스틱으로 이루어져 있기 때문에, 고온에서 분 해되면서 다양한 유해가스와 오염물질이 발생할 수 있고, 이러한 공해물질은 적극적으로 관리되지 않으면 대기오염, 수질 오염 등 다 양한 환경문제를 발생시킬 수 있다. 때문에 친환경적이고 지속적인 재활용에 대한 필요성이 대두되고 있다. 폐타이어 고무 분말을 아스팔트 혼합물의 골재 일부로 치환하여 재활용하는 접근 방식은 환경에 미치는 영향을 완화할 뿐만 아니라 천연 자원의 고갈 측면에서도 긍정적인 영향을 미치는 것으로 판단된다. 따라서 타이어분말을 아스팔트 혼합물에 적용하는 것은 환경 문제를 해결하고 자원 효율성을 높이는 두 가지 이점을 가지고 있다. 폐타이어 분말을 아스팔트 바인더와 아스팔트 혼합물에 적용할 경우 미치는 영향을 평가하기 위하여 TTI의 반사균열 저항성 시험, FN Test를 진행하였다.

In this study, the performance evaluation of steel dampers was conducted based on existing research results. The test variables are cross-sectional shape and lateral deformation prevention details. As a result of performance tests according to cross-sectional shape, the circular cross-section was evaluated to be superior than the rectangular cross-section in terms of envelope, stiffness reduction, and energy dissipation capacity. In addition, it was evaluated that the rectangular cross-section where lateral deformation occurs can be restrained by lateral deformation prevention details, thereby improving strength and deformation capacity.

The laser power has been continually increased since the laser was developed in the mid-20th century. Achieving higher laser power requires not only enhancing the cooling performance of laser systems but also addressing the potential degradation of optical characteristics due to thermal deformation induced by laser beam absorption in a mirror. This study delves into the thermal deformation characteristics of mirrors in high-power laser systems. To minimize thermal deformation by heat absorption, Zerodur, known for its low coefficient of thermal expansion, was employed as the mirror material. Various configurations including circular, rectangular, and spline shapes were implemented on a solid mirror structure. Furthermore, two different diameter of a mirror, 300mm and 400mm, were considered to investigate the size effect of the high-power laser beams. Also, three different transmitted beam power were adopted: 50W, 250W, and 500W. Based on the finite element analysis for the thermal deformation, the deformation characteristics of the different types of mirror structures were investigated and analyzed for high-power laser systems.

Steel plate shear walls (SPSWs) have been recognized as an effective seismic-force resisting systems due to their excellent strength and stiffness characteristics. The infill steel plate in a SPSW is constrained by a boundary frame consisting of vertical and horizontal structural members. The main purpose of this study was to investigate deformation modes and hysteretic characteristics of steel plate shear walls (SPSWs) to consider the effects of their aspect ratios and width-to-thicness ratios. The finite element model (FEM) was establish in order to simulate cyclic responses of SPSWs which have the two-side clamped boundary condition and made of conventional steel grade. The stress distribution obtained from the FEA results demonstrated that the principal stresses on steel plate with large thickness-to-width ratio were more uniformly distributed along its horizontal cross section due to the formation of multiple struts.

The EV electric vehicle market is growing rapidly worldwide. Magnet fixing technology is important for mass production of driving motors, a key part of electric vehicles. The magnet fixing method was carried out by the PAM (Polyamide molding) method. This study conducted the injection of rotor core magnet PA of EV traction motor and is a study on the amount of rotor core deformation. In this study, the change in the outer diameter of the product after injection and the non-molding phenomenon were tested. An injection mold was made and the results and phenomena of product deformation types are discussed.

Radiant tubes heat exchangers are critical components that facilitate the heat transfer process to steel in an annealing furnace, and it addresses several engineering problems, such as thermal stress and mechanical failure due to long-term thermal cycling, which can significantly affect the longevity of the tubes and maintenance requirements. In this study, we used commercial software (ANSYS) to simulate the thermal stress and deformation of radiant tubes subjected to extreme thermal conditions and pressure loads. We evaluated both thermally induced deformation and creep deformation, which is a time-dependent deformation under constant stress over the long term. The results showed that uneven temperature conditions and pressure loads lead to significant deformation and potential failures. To mitigate these engineering challenges, we also tested several designs that include supporting brackets. This study provides valuable insights for designing radiant tube heat exchangers in annealing furnaces to extend their lifespan and ensure system safety.

A fixed-point iteration is proposed to integrate the stress and state variables in the incremental analysis of plastic deformation. The Conventional Newton–Raphson method requires a second-order derivative of the yield function to generate a complicated code, and the convergence cannot be guaranteed beforehand. The proposed fixed-point iteration does not require a second-order derivative of the yield function, and convergence is ensured for a given strain increment. The fixed-point iteration is easier to implement, and the computational time is shortened compared with the Newton–Raphson method. The plane-stress condition is considered for the biaxial loading conditions to confirm the convergence of the fixed-point iteration. 3-dimensional tensile specimen is considered to compare the computational times in the ABAQUS/explicit finite element analysis.

For a plastic diffusion lens to uniformly diffuse light, it is important to minimize deformation that may occur during injection molding and to minimize deformation. It is essential to control the injection molding condition precisely. In addition, as the number of meshes increases, there is a limitation in that the time required for analysis increases. Therefore, We applied machine learning algorithms for faster and more precise control of molding conditions. This study attempts to predict the deformation of a plastic diffusion lens using the Decision Tree regression algorithm. As the variables of injection molding, melt temperature, packing pressure, packing time, and ram speed were set as variables, and the dependent variable was set as the deformation value. A total of 256 injection molding analyses were conducted. We evaluated the prediction model's performance after learning the Decision Tree regression model based on the result data of 256 injection molding analyses. In addition, We confirmed the prediction model's reliability by comparing the injection molding analysis results.

국내의 서비스 수준 지진(SLE)과 최대 고려 지진(MCE)의 두 RC 건물 구조물의 실험 및 해석 결과에서 얻은 탄성 및 비탄성 응답은 비틀림에 대한 전단 및 비틀림 거동에서 저항 메커니즘의 특성을 연구하는데 사용될 수 있다. 불균형 구조의 특성 연구에서는 전단력 및 비틀림 모멘트에 대한 병진 변형 및 비틀림 변형의 상호 작용 효과를 나타내는 방정식이 제안하였다. 탄성과 비탄성 거동에서 힘과 변형 사이에 상관 관계 유무가 다르기 때문에 증분 전단력과 증분 비틀림 모멘트를 최대 벽 프레임 변형을 중심으로 항복, 제하 및 재 하중 단계로 구분하여 해당 증분 변형 및 증분 비틀림 변형 측면에서 해석을 수행하였다. 두 가지 주요 지배 모드의 탄성 조합에서 병 진 변형은 주로 전단력에 기여하는 반면 비틀림 변형은 전체 비틀림 모멘트에 크게 기여한다. 그러나 비탄성 응답에서는 증분 병진 변 형이 증분 전단력과 증분 비틀림 모멘트 모두에 기여하게 된다. 따라서 주어진 방정식을 이용하여 비탄성 응답에서 비틀림의 편심 감 소, 비틀림 강성 저하 및 겉보기 에너지 생성과 같은 모든 현상들을 설명하였다.

CNTs/Al-Li composite was first prepared by hot-pressed sintering from Al-Li alloy powder and CNTs solution, and then the hot compression tests were performed on MMS-100 thermal simulator at strain rate range of 0.01– 10 s− 1, deformation temperature range of 350–500 °C, and total deformation amount of 60%. True stress–strain curves were plotted, and constitutive equation as well as hot processing maps were successfully confirmed based on Arrhenius constitutive model and Prasad instability criterion. Results show that CNTs/Al-Li composite have a very poor hot deformation ability and narrow processing region, which is strain rate range of 0.1–1 s− 1 and deformation temperature range of 360–400 °C. Hot extrusion experiment was carried out and the processing parameters were selected according to the established hot processing map, and an improvement on strength and a good balance between strength and plasticity can be obtained, which is about 650 MPa for tensile strength and 9% for elongation.

The rear door of the wheeled armored vehicle is a part that provides a passage for the crew to get on and off when it is opened and plays a role in forming watertightness and airtightness when it is closed. A case where the rear door was deformed during the rear door opening/closing operation occurred. The rear door should be improved because when it has been deformed, it is impossible to form watertight and positive pressure so that damage for humans and repair cost may occur. Therefore, in this paper, the causes of deformation were analyzed, and improvement plans were derived in order to prevent the deformation of the rear door of wheeled armored vehicles. In addition, a verification test was conducted to evaluate the appropriateness of the improvement plans.

This paper analyzed the correlation between injection molding factors through correlation analysis. In addition, the decision-tree model, which is a white box model with excellent explanatory power, was used to obtain optimal molding conditions that satisfy multiple constraint conditions. First, 243 data to be used in the experiment were created through a full factorial design. Second, a correlation analysis was conducted to understand the correlation. Third, to verify the decision-tree model, the prediction performance was evaluated using RMSE. As a result, good prediction performance was confirmed. A decision-tree experiment analysis was conducted. As a result of the progress, the same results as the correlation analysis were derived. Based on the previous analysis results, optimal molding conditions were applied to CAE. As a result, the amount of deformation in the multi-cavity could be improved by about 1.1% and 2.72% while satisfying the constraint.

The design of the corner joints in furniture structures is very important to firmly support the loaded structure and to sufficiently maintain the durability and stability. Therefore, the strength of the corner joints and the rigidity of the connected panels play a very important role in the structural performance of the assembled furniture. The structural properties can be measured or calculated experimentally or numerically, and compared by representing the applyed forces or bending moments as a function of deformed value. This paper shows the numerical models to determine the strength and stiffness of the 3-types of corner joints for simple designed furniture. Based on the finite element results, the maximum stresses are concentrated on the corner joints designed with MDF panels. And the deformation resistances and maximum applied loads are calculated for furniture corner joints under tensile and compressive moment.

This study proposes a low-cycle fatigue life derived from measurement points on pipe elbows, which are components that are vulnerable to seismic load in the interface piping systems of nuclear power plants that use seismic isolation systems. In order to quantitatively define limit states regarding leakage, i.e., actual failure caused by low-cycle fatigue, in-plane cyclic loading tests were performed using a sine wave of constant amplitude. The test specimens consisted of SCH40 6-inch carbon steel pipe elbows and straight pipes, and an image processing method was used to measure the nonlinear behavior of the test specimens. The leakage lines caused by low-cycle fatigue and the low-cycle fatigue curves were compared and analyzed using the relationship between the relative deformation angles, which were measured based on each of the measurement points on the straight pipe, and the moment, which was measured at the center of the pipe elbow. Damage indices based on the combination of ductility and dissipation energy at each measurement point were used to quantitatively express the time at which leakage occurs due to through-wall cracking in the pipe elbow.

In this study, controlling pattern gap was induced by deformation of the stretchable substrate. The pre-fabricated pattern was made by depositing an Au(gold) on the Si substrate, and PDMS(Polydimethylsiloxane) was used for the stretchable substrate in consideration of surface energy, formability, and viscoelastic characteristics. For uniform deformation of PDMS, it is manufactured in the form of a tensile specimen using a molding method. An external force is applied to the deformable substrate in the uni-axial direction using a self-manufactured JIG, and the Au thin film pattern is transferred to the substrate under tensile state. After that, the external force is removed, and the PDMS specimen is recovered to its initial state. At this time, it can be seen that the pre-fabricated pattern gap is shortened from the initial size due to the viscoelastic properties of the PDMS. As a result, it was characterized to deformation rate of the pattern gap according to elongation rate of PDMS.

본 논문에서는 CAD 시스템에서 사용하는 NURBS 기저함수를 사용하는 아이소-지오메트릭 해석(Isogeometric analysis) 방법과 기 하학적으로 엄밀한 빔 모델링(geometrically exact beam model)을 활용하여 회전과 병진 운동이 결합된 새로운 형태의 메타물질 (metamaterial)에 대한 해석을 진행하였다. 이차원 셀 구조는 자유형상변환(Free-form deformation) 법과 적절한 내삽법(Interpolation) 을 통해 원통 위에 입혀졌다. 원통의 치수와 셀 개수가 비틀림 각도에 미치는 영향이 매개변수 연구(parametric study)를 통해 확인되었 다. 비틀림과 병진 운동이 결합된 구조의 메커니즘에 대해 수치 예제를 통해 알아보았다.

Combat vehicles were developed in two types depending on the purpose of operation. The body of the vehicle is relatively large welded structure, and there is a quality problem in that welding deformation occurs in a certain area. Welding deformation is a problem that is inevitably generated during the welding process, and additional corrective work is performed. However, due to the structural characteristics of the welded structure of combat vehicl, there are many limitations in the correction method, which lowered the productivity. To improve this problem, we intend to establish improvement measures through analysis of the areas where welding deformation occurs and apply corrective measures suitable for welding structures of combat vehicles. For the design improvement plans, the finite element analysis were used and the correction method were applied to simulated structure to confirm the possibility. Finally, the improvement effect was confirmed by manufacturing the actual welded structure. Based on the results of this study, it is expected that the productivity of related similar welding structures as well as structures of wheeled armored vehicles, can be improved.