Earticle

Lightweighting is crucial in various industries, especially for bicycles where weight and stiffness are key. Traditional materials like steel, aluminum, and carbon each have pros and cons. This study compares hybrid tubes made of aluminum and carbon composites with conventional aluminum tubes. Using structural analysis and experimental testing, the hybrid tubes showed a weight reduction of up to 17.25% and maintained acceptable deformation levels. Finite element analysis confirmed these findings, demonstrating the hybrid tubes' potential as superior bicycle frame materials. Future research should focus on long-term durability and fatigue characteristics.

The prototype of Hanhwa AUV (Autonomous Underwater Vehicle) was developed to prepare future system developments in Hanwha Corporation. This paper presents the procedure and results of the structural design and analysis for the End Cap of Hanwha AUV. Several methodologies used for structural optimization were presented and applied to the design of the End Cap structure. Both shape optimization and thickness optimization were performed simultaneously. And because the FEM analysis model was used for structural optimization, design and analysis procedures were simultaneously conducted. Several analysis methods such as static analysis, buckling analysis, and normal mode analysis were used with procedure that was similar to the MDO (Multidisciplinary Design Optimization). The objective is to design the structural weight. The constraints are maximum displacement and maximum von Mises stress in static analysis, the buckling coefficient in buckling analysis, and lowest natural frequency in normal mode analysis. The design variable concerning thickness optimization is the thickness of the End Cap shell, as well as the depth of the End Cap concerning shape optimization. In thickness optimization, the optimization for variable thicknesses at the final shape iteration was performed, and we can see that the weight was significantly reduced.

Electric motors, as the core of modern electric propulsion platforms, face increasing demands for high power density and lightweight designs. Conventional electric motors, relying on copper windings and iron cores, encounter significant limitations in meeting these requirements, particularly in applications such as aircraft and heavy-duty vehicles. High-temperature superconducting (HTS) tapes, characterized by their superior current-carrying capacity under critical conditions, offer a promising alternative. Motors incorporating HTS tapes demonstrate exceptional power-to-weight ratios, driving extensive research into replacing conventional motors. However, for mobility applications, HTS motors require optimized support structures designed to meet weight constraints. Unlike static applications of HTS coils, the support structure for a rotating superconducting rotor must ensure torque transmission and maintain cryogenic conditions while addressing both structural and thermal factors. This study focuses on the optimized design of the support structure for a superconducting rotor equipped with HTS coils. The proposed design is evaluated through finite element method (FEM) analysis, verifying its mechanical and thermal performance under operational conditions.

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.

The design variables and material properties as well as the external loads concerned with structural engineering are used to be deterministic in optimization process. These values, however, have variability from expected performance. Therefore, deterministic optimum designs that are obtained without taking these uncertainty into account could lead to unreliable designs, which necessitates the Reliability-Based Design Optimization(RBDO). RBDO involves an evaluation of probabilistic constraints which constitutes another optimization procedure. So, an expensive computational cost is required. Therefore, how to decrease the computational cost has been an important challenge in the RBDO research field. Approximation models, response surface model and Kriging model, are employed to improve an efficiency of the RBDO.

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.

This study analyzes the aerodynamic and structural characteristics of an H-Darrieus vertical-axis wind turbine (VAWT) under varying inlet velocities using transient analysis. The k-ε turbulence model and six-DOF were applied to simulate urban environments in the flow analysis, while the structural analysis considered blade momentum of inertia and RPM conditions. The numerical results showed that the drag and lift forces increased by 60% and 53% respectively from the nominal wind speed to the cut-off wind speed conditions. Structural analysis indicated that the maximum Von-Mises stress in the blade did not exceed the yield strength of 69 MPa of PC-ABS, ensuring structural stability. However, the connecting rod exceeded the yield strength of SPCC 270 MPa, suggesting potential failure due to repeated rotational loads. This study confirms that materials with a yield strength of more than 1,100 MPa required for connecting rods to ensure reliable operation at high wind speed. These findings provide important insights for the design of robust VAWTs suitable for extreme environments.

This study proposed TACT based optimization model for improving work continuity in apartment structural work. The model was developed by focusing on three key as follows; First, the proposed model allows work crews to effectively rotate tasks to maximize the labor productivity. Second, the proposed model makes a plan for an efficient way to repeatedly carry out the same tasks by standardizing smaller TACT processes. Third, The proposed model suggests a multi-dimensional way to look at a frame construction process to comprehensively reflect characteristics of the construction site such as the combination of work crew and labor productivity, the calculation of the number of workers and equipments that are suitable to carry repetitive works. Through case study, the proposed model showed productivity increase of 25%, non-working days and half-working days decrease of 5 and 4 days, respectively, compared to 6 day cycle. The proposed model would help contractors to achieve successful completion of projects by establishing practical plans with improved work continuity and productivity.

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.

본고는 한국 사설 헤드라인의 기계번역 품질 저하가 번역 엔진의 성능이 아니라 한일 양국 헤드라인의 구조적 비대칭에 기인한다는 인식에서 출발한다. 일본 사설 헤드라인은 ‘키워드＋공백＋클레임’이라는 이분 구조를 신문사에 관계없이 일관되게 유지하는 반면, 한국 사설 헤드라인은 이에 필적할 형식적 규칙성을 보이지 않는다. 본고는 본 연구자가 한일 사설 헤드라인 대조에 관한 일련의 연구를 통해 규명한 키워드–클레임 이분 구조, 기호 사용의 제한, 문말표현 유형 분포, 헤드라인–본문 간 응집성을 통합하여 일본식 헤드라인 구조 모델을 도출하고, 이를 Claude API의 프롬프트로 형식화하였다. 한국 사설 본문을 입력하여 구조 모델에 따른 한국어 헤드라인을 생성한 뒤 DeepL API로 번역하는 파이프라인을 구축하고, 적용 결과에 대해 (a) 구조 모델 적용, (b) 일반 지시, (c) 원제목 직접 번역의 세 조건을 비교 검증하였다. 그 결과, 구조 모델을 적용해 생성한 헤드라인(a)이 이분 구조 준수율 100%, 번역 후 평균 자수 20.6자, 기호 사용률 10%, 문말표현 분포에서 실제 일본 사설에 가장 근접하였으며, 사례 분석에서도 관용 표현의 의미 소실 차단, 과잉 정보의 억제, 담화 기능의 재현이 확인되었다. 종래의 사전 편집이 어휘･통사 수준에 머물렀던 한계를 넘어, 목표 언어의 장르적 관습을 구조 모델로 형식화하여 기계번역 입력을 재구성하는 전략의 유효성을 실증한 점에서 의의가 있다.

In this study, I argue that the deterioration in the quality of machine translated Korean editorial headlines to Japanese stems from the structural asymmetry between the headline conventions of the two countries. Japanese editorial headlines maintain a 100% binary “keyword + space + claim” structure across all newspapers, which is missing in Korean headlines. When I integrated findings from five previous studies on keyword-claim structure, punctuation restrictions, sentence-final expressions, and headline-body cohesion, our study derived a Japanese-style structural model and formalized it as a Claude API prompt. An automated pipeline generated structurally-converted Korean headlines from editorial texts and translated them through DeepL API. I verified 60 editorials across three conditions—(a) structural model application, (b) general instruction only, and (c) direct translation. I showed that condition (a) most closely approximated Japanese norms: 100% binary structure compliance, a post-translation mean of 20.6 characters, 10% punctuation rate, and sentence-final expression distributions that match Japanese patterns. This study extends conventional pre-editing beyond lexical-syntactic modification to demonstrate the effectiveness of formalizing target-language genre conventions as a structural model.

In this study, Proline pentamer model was used to investigate change in the dihedral angle, intramolecular hydrogen bonding and formation energies during structural optimization. L-Proline (LP, as an imino acid residue) pentamers having four conformation types [β: φ/ψ=t−/t+, α: φ/ψ=g−/g−, PPII: φ/ψ=g−/t+ and P-like: φ/ψ= g−/g+] were carried out by QCC [B3LYP/6-31G(d,p)]. The optimized structure and formation energy were examined for designated structure. In LP, P-like and PPII types did not change by optimization, and β types were transformed into PPII having no H-bond independently of the designated ψ values. PPII was more stable than P-like by about 2.2 kcal/mol/mu. The hydrogen bond distances of d2(4-6) type H-bonds were 1.94 - 2.00Å. In order to understand the processes of the transformations, the changes of φ/ψ, distances of NH-OC (dNH/CO) and formation energies (ΔE, kcal/mol/mu) were examined.

Glutamate decarboxylase (GAD, EC 4.1.1.15) is a pyridoxal 5'-phosphate (PLP) dependent enzyme, which catalyses the α-decarboxylation of L-glutamate to produce γ-aminobutyrate (GABA). Glutamate decarboxylase B (GadB) from E. coli shows multimeric structure (hexamer) and its N-terminal residues 1-15 form the triple helix bundle at acidic pH. In this study, we showed that the thermostability of GadB is considerably affected by the N-terminal structure, which is changed dramatically at different pH conditions. And the thermostability of GadB was improved through structural optimization of the N-terminal helical bundle interdomains. The amino acid residues (Gln5, Val6, Thr7, Ser11) located at N-terminal helical bundle of GadB were redesigned considering the electrostatic interaction (Gln5-Lys4, Thr7-Lys3, Ser11-Lys341) and hydrophobic interaction (Val6-Val6) between the N-terminal α-helix residues. The GadB-WT and its N-terminal mutants were expressed successfully in E. coli expression host. The T50 10 (the temperature at which 50% of initial enzymatic activity remains after 10 min heat treatment) and Tm of mutants were increased compared to that of GadB-WT. The T50 10 value of GadB TM7 [Q5D:V6I:T7E] was especially 8.5oC higher than that of GadB-WT and the Tm value was also 7.9oC higher than that of GadB-WT.

Sensitivity field distribution of the sensor in ECT system is affected by the distribution of the mixture, The "soft field" property of sensitive field bring great difficulty in image reconstruction, on the basis of analyzing capacitance tomography sensitive mechanism, by analyzing that sensor structure parameters in ECT system have influence on the uniformity of the sensitive field, this paper proposed a structural parameters optimization algorithm based on the ant colony algorithm. The algorithm first determines the parameter optimization design evaluation function, and then rapidly identifies several suboptimal paths by using particle swarm optimization and initializes the pheromones in the path, Ant colony algorithm finds the optimal solution according to the initialization pheromones and using the characteristics of rapid convergence. The experimental results show that, compared with the orthogonal algorithm, the performance of the sensor designed by using the structure parameters obtained by ant colony optimization algorithm is obviously improved, Alleviate the difficulty of data acquisition circuit design and improve the accuracy and uniformity of the sensitive field, the quality of image reconstruction is improved, the relative error of image reconstruction is reduced.

This paper presents a reliability-based topology optimization (RBTO) based on bidirectional evolutionary structural optimization (BESO). In design of a structure, uncertain conditions such as material property, operational load and dimensional variation should be considered. Deterministic topology optimization (DTO) is performed without considering the uncertainties related to the design variables. However, the RBTO can consider the uncertainty variables because it can deal with the probabilistic constraints. The reliability index approach (RIA) and the performance measure approach (PMA) are adopted to evaluate the probabilistic constraints in this study. In order to apply the BESO to the RBTO, sensitivity number for each element is defined as the change in the reliability index of the structure due to removal of each element. Smoothing scheme is also used to eliminate checkerboard patterns in topology optimization. The limit state indicates the margin of safety between the resistance (constraints) and the load of structures. The limit State function expresses to evaluate reliability index from finite element analysis. Numerical examples are presented to compare each optimal topology obtained from RBTO and DTO each other. It is verified that the RBTO based on BESO can be effectively performed from the results.

In this paper, an analytical model of a cantilever beam having a midpoint load is considered for structural optimization and design. This involves creation of the geometry through a parametric study of all design variables. For this purpose, the optimization of the cantilever beam was elaborated in order to find the optimum geometry which minimizes its volume eventually for minimum weight by FEM (finite element method) analysis. Such geometry can be obtained by different combinations of width and height, so that the beam may have the same cross-sectional area, yet different dynamic behavior. So for optimum safe design, besides minimum volume it should have minimum vibration as well. In order to predict vibration, different dynamic analyses were performed simultaneously to identify the resonant frequencies and mode shapes belonging to the lowest three modes of vibration. Next, by introducing damping effects, the tip displacement and bending stress at the fixed end was evaluated under dynamic loads of varying frequency. Investigation of the results clearly shows that only structural analysis is not enough to predict the optimum values of dimension for safe design it must be aided by dynamic analysis as well.