Earticle

본 연구에는 다 지지조건을 가지는 슬래브 구조물의 자유진동 문제에 대하여 SIMP방법에 의한 재료 위상 최적설계 MATLAB 프로그램을 개발하고 동적 위상 최적화의 수학적 모델링에 필요한 집중질량과 분포질량의 등가조합 질량행렬을 유도하였다. 또한 강성행렬과 질량행렬에 벌칙 인자가 도입된 관계식과 경사도 기반 최적화방법인 MMA 알고리즘, MATLAB 고유치해석(명령어 Eigs) 박스7)를 이 용하여, 여러 가지 예제를 해석함으로써 다음과 같은 결론을 얻을 수 있었다. (1) 본 연구에서 개발한 동적 위상 최적설계 MATLAB 프로그램은 기존의 정적 위상 최적설계 MATLAB 프로그램 알고리즘 안에 구조해석을 위한 고유치해석 Eigs 함수를 적용함으로써 간편하게 구현 가능하였다. (2) 보-기둥 시스템을 연결하는 슬래브 구조물은 자유진동 위상 최적설계 문제에 대하여 보강재로서 구현되는 최적위상이 지지조건에 민감함을 알 수 있다. (3) 위상 최적설계 문제에 대하여 부피 제약조건이 클수록 수렴하는 최대 고유진동수가 감소한다. (4) 위상 최적설계 문제에 대하여 지지조건이 많을수록, 즉, 켄틸레버형(1변지지), 2변지지, 4변지지 슬래브 일수록 보강재가 보유하는 최대 고유진동수가 점점 감소한다.

The goal of this study is to present conceptual information of optimal design of slab structures often used for main building frames by using topology optimization method. Topology optimization method is well-known as an optimal material distribution tool to extract both optimal shape and topology, i.e. connectivity of members deposited by a given material quantity, which has been mainly evaluated in engineering fields such as mechanics, electronics, ship, and aero industries. This study targets design of mega structures like as structures for civil or building industries, not above-mentioned vitalized engineering fields. Design results of this study may have a limit of only producing basic conceptual information for practical design due to inexact design conditions and a lot assumptions. Therefore note that there are many supplementary and insufficient components for practice in this study, which have to be improved in the future. Topology optimization problem presented in this study is to determine the layout of material of specified volume in a domain that maximizes the first natural Eigenfrequency for dynamic responses under a given set of boundary conditions. Numerical applications showing appropriate optimal shapes of slabs with varied supports verifies the present topology optimization method is practically an alternative to produce a conceptual information of material distribution for practical designs of building frames.

Recently, P.E.B systems with tapered section shape are usually used in steel factory and warehouse. The tapered shape provides the effective cross-section performance considering the difference in the stress distribution of member. Therefore, this study presents the initial topology decision method of steel structure considering tapered shape. The optimal topology of tapered shape structure is obtained by performing topology optimization according to design constraints and load conditions. Through the application results, we can find out the reasonable initial shape of steel structure with tapered shape.

미세 위치제어를 위한 미세 산업용 로봇의 작업물의 정도 보정을 위해 마이크로 조정기가 고안되었다. 피에조전기 엑추에이터를 이용한 능동 메커니즘을 증폭시키기 위한 메커니즘 설계는 위상 최적설계와 형상 최적설계의 진일보를 위해서 기하학적으로 구조적으로 둘 다 필요하다. 메커니즘의 총괄적인 기하학적 장점과 기계적 효율이 객관적성능으로서 고려되었으며, 이는 입력의 힘분에 출력의 변위, 지지발의 수직 운동과 조정기의 구조 강성의 각각의 비이다. 이들 목적함수를 최대화하기 위하여, 순차 선형 프로그램최적 기준법이 위상 재료 분포, 능동 구조물과 굽힘힌지의 기하학적 차원을 위해 사용되었다. 이 연구는 메커니즘의 능동성을 최대화 할 뿐 아니라, 위치도의 정확도와 충분한 작업공간을 보장하는 종합적 설계 공정을 보여준다. 실험은 역학적, 구조적 성능의 비교를 통해 설계공정을 유효화하기 위해 시행되었다

This paper provides the results of the investigation on the optimum topology of the deep beam structures subjected to the self-weight. As the objective function in the optimization process, the strain energy to be minimized is employed and the initial volume of structures is adopted as the constraint function. The resizing algorithm devised from the optimality criteria method is used to update the hole size of the cell existing in each finite element. Several important topology optimization parameters are throughly tested for case of distributed load such as the self-weight. Various essential boundary conditions are also employed to provide the information on the effect of the essential boundary condition to the final optimum topology of deep beam structures. The filtering process for avoiding the checker boarding phenomenon is also consistently used. From numerical tests, the optimum topology of the deep beam structures subjected to the self-weight is closely related with the values of optimization parameters and the filtering process play important role in order to find the proper optimum topology of the deep beam structures.

This study explores the enhancement of magnetic field homogeneity in Nuclear Magnetic Resonance (NMR) magnets through optimized ferromagnetic shimming design. Traditional shimming techniques, which involve attaching ferromagnetic materials to the magnet bore, often lack manufacturability considerations, limiting their effectiveness in real-world applications. To address this, we employ a topology optimization (TO) approach using the Solid Isotropic Material with Penalization (SIMP) scheme for design parametrization. The proposed optimization framework includes volume and perimeter constraints to improve the practical manufacturability of the shim. Numerical analysis demonstrates that the TO-based design method achieves superior magnetic field homogeneity, achieving 0.45 ppm with integer thickness shims, compared to conventional designs. This approach also effectively reduces manufacturing complexity by minimizing design sensitivity to the thickness and placement of individual shimming elements. The proposed design framework is broadly applicable to superconducting magnets in NMR and MRI systems, where high magnetic field homogeneity is essential. This study presents a significant advancement in ferromagnetic shimming technology, offering a viable solution for enhancing the performance and manufacturability of high-precision magnetic field devices.

신체영역무선통신망(WBAN)에서 클러스터 헤드(CH) 선출 및 최적경로의 라우팅은 에너지 효율 향상과 네트워크 노드 운영수명 연장을 위해 해결해야 할 이슈이다. 이러한 연구를 위해 본 논문에서는 BKOA알고리즘과 그리드 기반 멀티홉 라우팅 프레임워크를 결합한 하이브리드 BKOA-GRID를 제안한다. 시뮬레이션 수행결과 제안된 BKOA-GRID는 PSO, LEACH, EEUC 등 기존 알고리즘보다 노드생존율 90%, 잔류에너지 지속성은 총 에너지의 약 60%를 유지하여 높은 에너지 효율을 보였다.

Cluster head(CH) election and optimal path routing in a Wireless Body Area Network(WBAN) are issues that must be addressed to improve energy efficiency and extend the operating life of network nodes. To address these issues, this paper proposes a hybrid BKOA-GRID (Black Kite Optimization Algorithm-GRID) framework, which integrates the Black Kite Optimization Algorithm with a grid-based multi-hop routing structure. Simulation results demonstrate that the proposed BKOA-GRID exhibits superior energy efficiency compared to existing algorithms such as PSO, LEACH, and EEUC, maintaining a node survival rate of 90% and preserving approximately 60% of the total residual energy.

본 연구에서는 위상최적화의 수렴성을 개선하기 위한 새로운 방법으로서 초기 설계영역 안에 구멍의 적용과 설계변수의 가속법을 제시한다. 설계변수의 가속법은 “이동과 정규화된 Heaviside 함수”를 이용하여 설계변수의 변화 속도를 개선한다. 이 함수는 밀도값이 존재하는 0과 1사이의 정의역내에서 오목함수와 볼록함수의 조합으로서 정의되기 때문에, 설계변수 값은 밀도값이 0.5미만일 때 0으로 향해 가속이 되며, 0.5를 초과하는 경우 1로 빠르게 이동된다. 초기 설계영역에 초기구멍의 도입은 설계변수의 유한적인 변화에 의한 구조물의 위상변화를 강화시켜 최적화의 수렴성을 개선한다. 본 논문에서는 위상최적화의 밀도분포법을 이용하여 선형 탄성 구조물의 수치 예제를 가지고 초기구멍과 설계변수의 가속효과를 검증하였다.

This Study proposes the introduction of the hole in initial design and an accelerating method of design variable as new methods for the optimization of convergence of topology. The accelerating method of design variable implements a "moved and regularized Heaviside function" and improves the movement velocity of design variable. Since this function is defined as the combination of concave and convex function in domain between 0 and 1, design variables under 0.5 move fast toward value of 0 and those over 0.5 are rapidly transferred to value of 1. Introduction of initial hole enforces changes of topology by finite changes of design variable and therefore improves the convergence of optimization. In this study, the effects of the introduction of the initial hole and the accelerating method of design variables in the density distribution method of topology optimization are verified with numerical examples of linear elastostatic structures.

Carbon neutrality by 2050 was declared and are focusing on developing innovative energy technologies aimed at reducing greenhouse gas emissions. Active investment and research are underway in the full-cycle development of hydrogen energy technologies, including hydrogen production, storage, transportation, and utilization, which is gaining attention as a promising future eco-friendly energy source. The storage density of liquid hydrogen is 70.79kg/m3, which is higher than the 41kg/m3 of compressed hydrogen at 700bar, making it more suitable for large-scale storage. To store hydrogen at 20K, insulation technologies such as vacuum insulation, powder insulation, or multi-layer insulation (MLI) are typically required. Consequently, there is active research being conducted on the design of insulation systems and materials. However, research on the design for improving the structural integrity of the supports between the inner and outer tanks remains insufficient. n this study, topology optimization was performed for the support design of a liquid hydrogen storage tank using commercial finite element analysis (FEA) software. The structural safety was validated through structural analysis of a simplified self-designed model.

Weight-based exercise equipment is unreasonable because of its large weight or volume and has limitations in use at home. On top of that, it is not easy to control the weight of domestic muscular exercise devices such as dumbbells and latex bands. This study proposes a new type of exercise equipment that can be used at home by modifying the exercise equipment used in fitness centers. Home training exercise equipment has been optimized by replacing the weight of strength training equipment, which is the core of weight control, with electric motors. For optimal design, process integration and design optimization (PIANO), a commercial PIDO tool, was analyzed in conjunction with DAFUL, a multi-body dynamics analysis program. When formulating the optimal design, the objective function was to minimize the weight, and the shape of the pinwheel and pulley used in exercise equipment was proposed considering the stress of cables as design constraints. As a result of optimization, design proposals were derived while meeting the design requirements and reduced by 5% compared to the initial model. In this work, we have miniaturized the shape of exercise equipment compared to conventional exercise equipment by optimizing its shape.

This study shows a variance regularization method in order to obtain the stable optimal solutions, when a numerical method accelerating design variables is used for material topology optimization algorithm. Since a moved and regularized Heaviside function used in the accelerated method is composed of nonlinear concave and convex functions in a given design domain between 0 and 1, design variables below 0.5 can move fast toward the value of 0 and those over 0.5 are rapidly located to the value of 1. However optimal solutions may be not stable due to singularity of element stiffness, while the accelerated design variables are too closed to value 0. In particular this instability may occur to the accelerated method-based material topology optimization algorithms much repeating the moved and regularized Heaviside function. In order to resolve the problem, in this study, a variance regularization is formulated within a linear governing equation for structural analyses of optimization procedures. Numerical examples for topologically optimally modeling a linear elastostatic MBB-beam verify that the accelerated method of design variables take numerical stability of topological optimal solutions by being associated with the variance regularization method.

In this paper, a method of reducing the weight of vehicle wheels through topology optimization by finite element method is proposed. Recently, various environmental pollution caused by the operation of vehicles is gradually increasing, and this has a great correlation with the fuel efficiency of the vehicle. Therefore, it is required to reduce the weight of the vehicle to increase fuel efficiency. Among them, the vehicle's wheels are a key part of vehicle acceleration and braking, and passenger safety. Because the shape of the wheels is different, various effects such as reduced fuel economy and reduced airpower occur as well as aesthetic factors. The stiffness of the wheels plays an important role in transmitting the vehicle's power to the tires and braking. In this study, to reduce weight while satisfying the stiffness value, we propose to use topology optimization to design an arbitrary shape according to the number of spokes on the wheel.

This study investigates the effect of different objective functions on the topology optimization of a loudspeaker basket for structural resonance avoidance. Three objective functions were considered: maximization of the first natural frequency, minimization of static strain energy, and minimization of dynamic strain energy. The results show that, for all objective functions, the first natural frequency increased significantly compared to the initial design, while both static and dynamic strain energies were reduced, indicating effective suppression of structural resonance. Although the performance differences among the objective functions were not substantial, minimization of static and dynamic strain energy exhibited higher computational efficiency compared to natural frequency maximization. In particular, minimization of static strain energy demonstrated advantages in computational efficiency and ease of implementation, suggesting it as a practical alternative for resonance-avoidance design of loudspeaker baskets. This study highlights the importance of objective function selection by quantitatively comparing optimization outcomes under different formulations.

In the automobile manufacturing industry, lightweight design is one of the essential challenges to be solved fundamentally. The vehicle wheels are classified as safety related components as the main substructure of the vehicle. In this study, we illustrate a technique for selecting the appropriate number of spokes. Based on the basic model of the selected number of spokes, we propose a method to maintain stiffness and design lightweight using topology optimization software. Based on the basic model of the selected number of spokes, it was redesigned to be lightweight while maintaining stiffness by utilizing topology optimization software. By comparing and reviewing the structural analysis results of the basic model and the redesigned model, a design technique that can maintain structural safety and reduce wheel mass was proposed.