경량화와 연비 개선을 위해 크루즈선 선루 구조에는 박판 보강판 구조가 널리 사용된다. 그러나 이러한 세장한 형상은 압축, 횡 방향 및 전단 하중이 복합적으로 작용할 경우 좌굴에 매우 취약하다. 따라서 좌굴 강도의 정확한 평가는 구조 설계의 핵심 요소이나, 기존 의 유한요소해석 기반 접근법은 시간이 많이 소요되어 초기 설계 단계에서 광범위한 파라미터 연구를 수행하기에는 비실용적이다. 본 연구 에서는 DNV Panel Ultimate Limit State(PULS) 방법을 이용하여 크루즈선 선루 구조를 대표하는 박판 보강판의 체계적인 좌굴 강도 평가를 수 행하였다. 다양한 판 두께와 2차 보강재 유무를 포함한 보강재 구성을 갖는 패널 모델들을 복합 면내 하중 조건에서 분석하였으며, 초기 기 하학적 결함은 선급 요구사항에 따라 명시적으로 고려하여 실제적인 좌굴 거동을 확보하였다. 결과에 따르면, 2차 보강재 설치는 판의 좌굴 길이를 효과적으로 감소시켜 좌굴 강성을 크게 향상시키지만, 그 효과는 판 두께와 보강재 강성 간의 상호작용에 크게 의존한다. 변수 분석 결과, 판 두께 증가가 항상 더 높은 좌굴 강도로 이어지는 것은 아니며, 일정 두께 임계값을 넘어서면 보강재의 국부 좌굴이 극한 강도를 지배할 수 있음이 확인되었다. 또한 다양한 구성에서 일관된 좌굴 강도 경향이 관찰되어, 개별적인 설계 조정보다는 판과 보강재 변수의 통 합 최적화가 중요함을 강조한다. 본 연구의 결과는 크루즈선 선루 구조의 박판 보강판 최적화를 위한 실용적인 설계 통찰을 제공하며, DNV-PULS 방법이 예비 및 비교 설계 단계에서 좌굴 강도를 신속하고 신뢰성 있게 평가하는 도구로서의 유효성을 확인하였다.

본 연구의 목표는 정적 탠덤 진수 조건에서 대형 선박 블록의 효율적이고 정확한 종방향 강도 평가를 위한 표준화된 유한 요소 (FE) 메쉬 크기를 확정하는 것이다. FE 해석은 높은 정확도를 제공하지만, 과도한 모델링 및 계산 비용으로 인해 조선소에서의 일상적인 사용에 제약이 있다. 반대로, 간소화된 규칙 기반 빔 이론 평가는 효율적이지만, 복잡하고 부분적으로 용접된 블록 형상을 적절하게 표현 하지 못하여 생산 단계 평가의 정확성에 대한 문제를 갖고 있다. 이러한 격차를 해소하기 위해, 국부적인 용접과 스트롱백 구속 조건을 포함한 실제 제작 단계 조건을 명시적으로 반영한 174K급 LNG 운반선(LNGC) 후미 블록의 상세한 FE 모델을 분석하였다. MSC.NASTRAN 선형 정적 해석법을 사용하여 20mm에서 1,200mm까지의 요소 크기에 걸쳐 조합 응력 응답을 평가하는 체계적인 메쉬 수렴 분석을 수행하 고, 그 결과를 ABS 규칙 기반 계산 결과와 비교 분석하였다. 조밀한 요소 크기(20~100mm)는 국부적인 응력 집중에 의한 응력 차이가 크게 발생하고, 메쉬 크기가 약 800mm 이상에서는 최대응력이 일정하게 수렴하는 결과를 나타냈다. 유한 요소법으로 계산된 조합 응력은 허용 단면 계수 및 구조적 안전성 평가를 포함한 규칙 기반 평가 결과와 높은 일치도를 보였다. 따라서 요소 크기 800mm는 전체적인 종방향 강도 평가에 있어 계산 효율성과 구조적 정확도 사이의 최적의 결과를 제공하는 것으로 확인되었다. 이러한 결과는 선급 협회의 요구 사 항을 준수하면서 신뢰할 수 있고 생산 지향적인 평가를 가능하게 하는 실용적인 유한 요소 모델링 지침을 제공하고 있다.

This study investigates the repeated impact behavior and compression-after-impact (CAI) performance of triaxially braided carbon/glass fiber-reinforced polymer (C/GFRP) composite tubes. A two-stage experimental strategy was proposed to evaluate the synergistic effect of interlayer hybridization and axial yarn reinforcement on damage evolution and mechanical performance. In Stage I, six hybrid braided tubes with different carbon/glass stacking configurations—including pure carbon, pure glass, layered, and reversed-layered structures—were subjected to repeated low-velocity impacts at 31 J. Micro-CT was employed to reconstruct the internal damage morphology and assess damage accumulation. The optimal interlayer configuration was selected based on impact force, displacement, energy absorption, and internal failure characteristics. In Stage II, the selected structure was further reinforced with four types of axial yarns (none, carbon, glass, and carbon/glass alternating), and their axial compressive and CAI performance after 10 J impact was tested. Results revealed that reversed interlayer design effectively suppressed crack propagation and improved damage tolerance under cyclic impacts. Moreover, the inclusion of hybrid axial yarns significantly enhanced residual compressive strength without compromising energy absorption. This study establishes a lightweight, high-performance braided tube design strategy suitable for aerospace and transportation applications.

Carbon fibers (CFs) are notable for their lightweight, high strength, and excellent electrical conductivity, making them promising for applications like electrical wiring. However, integrating CFs into copper-based wiring systems faces challenges, particularly regarding conductivity loss in fractured CFs. This article discusses a two-step experiment to enhance electrical and mechanical connection. Electrothermal-induced solvent evaporation (EISE) and meniscus-confined electrochemical deposition (MECD) were identified as effective methods for welding fractured CFs and were successfully implemented in open-air environment. Deposition of carbon nanotubes (CNTs) around the fiber improved conductivity by reducing fiber-tofiber contact resistance and creating a metal-like surface. Microstructural analysis and EDS analysis revealed that the CNT cladding exhibited high density and fewer irregularities and bulges in the joint area. Furthermore, the CNTs were tangled, forming a less organized structure compared to the original CF. In contrast, the Cu cladding exhibited paint-like coverage, significant irregularities, bulges, and cracks but maintained a small thickness. Electrical testing revealed that the average resistance of a single joined fiber decreased to resistance of 11.45 Ω and an electrical resistivity of 2.27 Ω/m, demonstrating improved electrical conductivity. Under optimal conditions, the joined fibers exhibited plastic fracture, and all joints showed improved performance except joint 1.e-g enhanced mechanical strength and stress tolerance.

Thermal property represents a critical metric when evaluating the performance of next generation nuclear graphite. Despite the extensive measurement data available, a detailed investigation into the influence of microstructure on graphite’s thermal conductivity remains underexplored. In this work, taking advantage of the distinct microstructures between different graphite grades, a comparative study of four graphite grades was conducted to elucidate the structure–property relationship. The microstructures of graphite were characterized by Raman spectroscopy and X-ray diffraction techniques, demonstrating specimen preparation induced damage and annealing induced restoration. Thermal properties were investigated across multiple scales using laser flash analysis and photothermal radiometry. The results indicate that despite similar densities, thermal conductivity varies significantly between different grades and correlates positively with crystallite sizes. By interpolating an infinitely large crystallite and removing the impact of macroscale porosity, an upper bound for the thermal conductivity of isotropic defect-free nuclear graphite has been established.

This study investigates the Dunhuang medallion patterns of the Tang Dynasty as its primary focus, conducting a systematic analysis of their morphological structures and color characteristics across four distinct historical phases, from the Early to the Late Tang periods. It also elucidates the evolution of patterns, tracing their transformation from the Early Tang's “cross” structure to the Middle-Late Tang's “six-partition” structure. Additionally, it interprets the sociological and cultural significance embedded within this progression. The study integrates shape grammar theory to create a layered deconstruction framework for pattern analysis based on split grammar principles and proposes an innovative design methodology that includes four deduction rules: generative, modifying, inherited, and derivative. New patterns are generated through vectorized extraction and regularized deduction, preserving traditional elements while aligning with modern aesthetics. The method's feasibility and utility were validated through a practical case using the design on a silk scarf, completing a research cycle of “analysis-extraction-derivation-validation.” Research shows that shape grammar provides a systematic method for innovating traditional patterns, while the resulting framework opens new avenues for reinterpreting cultural heritage.

Plant-derived natural products, recognized for their bioactive properties and minimal side effects, have been widely explored for their potential in obesity management. Identifying plant-based agents that can modulate adipocyte function with low cytotoxicity is essential for developing safe and effective anti-obesity interventions. In this study, Philadelphus schrenkii (Korean mock orange) was identified as a promising candidate following an initial screening for agents that exhibit minimal cytotoxicity and reduced adipocyte differentiation, as assessed by Oil Red O staining. The anti-obesity effects of P. schrenkii methanol extract (PSE) were evaluated by using in vitro and in vivo models. PSE treatment significantly reduced C3H10T1/2 preadipocyte differentiation and upregulated thermogenic markers, including Ucp1 and Dio2, in differentiated cells. Although PSE did not induce weight loss, alter food intake, or improve the serum metabolic profiles in a diet-induced obesity mouse model, it notably enhanced the thermogenic Ucp1 expression in inguinal white adipose tissue (iWAT) and brown adipose tissue. It also mitigated high-fat diet-induced adiposity in iWAT, accompanied by Protein Kinase A signaling activation. These findings suggest that PSE modulates adipose tissue function by suppressing adipogenesis and promoting thermogenic gene expression without weight reduction or metabolic improvement. Based on these effects, PSE may contribute as a supportive agent to plant-based therapeutic strategies against obesity

The present study evaluated the antibacterial efficacy of Maclura tricuspidata root (MTroot) extracts against the cariogenic bacterium Streptococcus mutans. The chloroform (CHCl3) fraction obtained from organic solvent partitioning of the MTroot ethanol extract was subfractionated using open-column chromatography on silica gel. Among the subfractions obtained, subfraction 3 (Fra-3) obtained in 1:1 (v/v) n-hexan:ethyl acetate solvent system exhibited the most potent antibacterial activity. Accordingly, the chemical composition was analyzed using ultraperformance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry in positive electrospray ionization mode. In addition, the antibacterial activity of Fra-3 against S. mutans was assessed at each stage of extraction. While the minimum inhibitory concentrations (MICs) of the CHCl3, EtOAc, n-butanol, and aqueous fractions against S. mutans were above 15, 120, 120, and 120 μg/mL, respectively, the MICs of the subfractions obtained from silica gel open-column chromatography using different n-hexane:ethyl acetate ratios (3:1, 1:1, and 1:3) were 3.0, 1.5, and 25.0 μg/mL, respectively. Fra-3 was tentatively found to contain 38 major compounds, including kuwanon C, kuwanon E, cudratricusxanthone L, morusin C, cycloartocarpesin, kuwanon A, mulberrofuranol, and moracin U, which accounted for 66.7% of the total ion response. Collectively, these findings suggest that kuwanon C, kuwanon E, and cudratricusxanthone L present in MTroots may serve as novel therapeutic targets to prevent dental caries caused by S. mutans.

This paper investigates the problem of ship course control in the presence of model uncertainties, external disturbances, and actuator saturation. A high-performance autopilot is developed based on a direct neural network adaptive dynamic surface control (DSC) framework integrated with deep reinforcement learning. To compensate for lumped uncertainties arising from unmodeled dynamics and disturbances, a radial basis function (RBF) neural network is employed to provide online approximation within the control design. Moreover, the actuator saturation constraint is explicitly incorporated into the controller, avoiding performance degradation commonly encountered in conventional DSC schemes.To alleviate the reliance on manual parameter tuning, the controller parameter adaptation is formulated as a continuous-action optimization problem and solved using a deep deterministic policy gradient (DDPG) algorithm. The DDPG agent learns an optimal tuning policy by maximizing a reward function that penalizes course tracking errors, excessive control variations, and energy consumption. Simulation results demonstrate that the proposed method achieves improved tracking accuracy, smoother control inputs, and enhanced robustness under complex operating conditions, thereby validating the effectiveness of the DDPG-based adaptive tuning strategy for autonomous ship navigation.

청소년에게 있어 주관적 안녕감은 단순한 행복감의 의미를 넘어 미래에 대한 희망을 밝히는 중요한 요소 이기에, 주관적 안녕감의 인과관계를 규명하는 연구는 필요한 과제라 할 수 있다. 이에 청소년이 지각한 의견존중 경험이 주관적 안녕감에 영향을 미치는지를 분석하고, 의견존중 경험이 주관적 안녕감에 미치는 영향에서 자아존중감의 매개효과를 검증하는 것을 연구 목적으로 하였다. 2024년 9월부터 10월까지 경기 도 K시 소재 청소년 대상으로 온라인 및 지면 설문지를 배포하였고, 응답자 898명의 데이터를 활용하여 분석하였다. 주요한 연구 결과는 다음과 같다. 첫째, 청소년의 의견존중 경험은 주관적 안녕감에 정적인 영향을 미치는 것으로 확인되었다. 둘째, 자아존중감은 청소년의 의견존중 경험과 주관적 안녕감의 관계에 서 매개효과를 가지는 것으로 나타났다. 이상의 연구결과를 토대로 청소년의 의견존중 경험과 자아존중감, 그리고 주관적 안녕감을 향상시키는 실천적, 정책적 방안을 제안하였다.

The adsorption of a single pollutant can no longer meet the increasingly strict requirements of environmental governance. The easy loss and secondary pollution of powdered adsorbents further hinder the industrialization of adsorption technology. Through in-situ oxidative polymerization and hydrothermal deposition, polyaniline (PANI) and magnetic Fe3O4 nanoparticles were loaded onto a polyurethane (PU) matrix to prepare polyurethane-polyaniline /Fe3O4 (PU-P/F) porous composite loading materials, aiming to simultaneously remove multiple pollutants in wastewater and solve the problem of effective solid– liquid separation at the same time. The synthesized composite material exhibited a high specific surface area (30.08 m2/ g) and a hierarchical pore structure. Within a wide pH range (5–7), it showed a synchronous adsorption and removal effect on typical pollutants (ARG, Cr (VI), NO3 −-N, TP, MB, NH4 +-N) in printing and dyeing wastewater. Equilibrium can be reached within 0.5–2 h, following pseudo-second-order kinetics and Langmuir isotherm model, indicating mainly monolayer chemical adsorption. The continuous column adsorption regeneration test showed that for the simulated mixed wastewater, the continuous adsorption reached saturation after 660 min (53 chromatographic columns), while for the actual wastewater, the continuous column adsorption reached saturation after 535 min (43 chromatographic columns), and the efficiency remains after 8 regenerations. FT-IR and XPS confirmed the REDOX reaction between the –NH—group in polyaniline and Fe in Fe3O4, facilitating the adsorption and transformation of pollutants, while DFT calculations confirmed the strong interaction between polyaniline and anionic pollutants. This research provides ideas for solving the engineering bottleneck of adsorption technology.