Osan University

Abstract This study examines the degradation behavior of PC/GF composites with varying short glass fiber (SGF) contents (10, 20, and 30 wt%) and fiber orientations (0°, 45°, and 90°) when exposed to conditions of 85 °C/85% RH. Although the elastic modulus remained largely unchanged, both tensile strength and strain at break exhibited significant deterioration as a result of moisture ingress, which promoted interfacial debonding (after 1008 h, tensile strength decreased by up to 27.7% and strain at break by up to 45.8%). To quantify chemical degradation, a hydroxyl index (HI) was derived from ATR-FTIR spectroscopy. The temporal evolution of HI followed a power-law kinetic model that was independent of fiber content, indicating that matrix hydrolysis governs the degradation rate, with HI increasing by up to 3.57×, while the bulk-average molecular weight decreased by 5.8–8.7%. Furthermore, a phenomenological model was developed linking the HI to macroscopic mechanical properties. This model accurately captured time-dependent, anisotropic degradation based on the material’s chemical state, yielding cross-validation errors under 5%. Ultimately, these findings demonstrate that non-destructive spectroscopic techniques can reliably estimate structural integrity, providing a robust framework for durability assessment and lifetime prediction in harsh environments.

The sewage from paint is quite turbid and contains a lot of suspended and scattered particles. Achatina achatina (AA) shell’s ability to coagulate and flocculate and remove suspended particles from paint effluent was considered. The analyses included Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD). Surface area 64.6 m2/g; ash content 8.2 %; moisture content 11.964 %; bulk density 0.962 g/cm-3; tapped density 1.389 gcm-3; true density 1.667 gcm-3; porosity 42.29 %; pH 7.9; and pHzpc 6.9 are the results of the samples’ delineation. Optimum values obtained from varying the operating parameters are: 500mg/L AA, settling time 30 minutes and pH 8. FTIR result indicates that AA has some functional groups. XRD result indicates that AA consists of aragonite, and SEM shows different surface morphologies before and after coag-flocculation, suggesting effective coagulation. Suspended fragments in the paint effluent sample consistently declined with time, pursuant to time evolution of cluster size allotment. Coagulation period (τ1/2) lowest values of 0.05565 seconds and 0.01209 seconds were recorded at 500 mg/L and pH of 8 respectively. This study provided information on animal based coag-flocculation potential which is beneficial for environmental quality management and environmental disputation.

Prior research showed that observers can tolerate large speed alterations in real-world videos. The present study examined how sensitive the human visual system is to the change of kinematic information of human actions with altered playback speeds. We recorded four persons walking at various speeds and produced point-light walker stimuli (standard stimuli), from which we also created test stimuli either by speeding up or slowing down the playback speed. In the experiments, two point-light walkers were presented sequentially: one standard and the other test stimuli. Importantly, in each trial, the expected speed of translation was kept constant (e.g., a pair of one walking at 5.40 km/h and the other walking at 2.70 km/h but played with double speed), differing only in gait kinematic information. Participants reported which stimulus was played at a normal speed. We also included the manipulations of orientation (upright vs. inverted) and spatial scrambling of the point-light dots. The results showed that the unnaturalness detection was performed at above chance levels, confirming that kinematic inconsistencies provided a discernible cue. However, detection was only reliable when the speed alteration in a test stimulus was fairly large. Interestingly, we found little differences in performance among upright-intact, inverted, and scrambled conditions. The lack of the large detriments from inversion or scrambling suggests that the participants did not rely strongly on global form or orientation cues to perform the unnaturalness detection and points to greater contributions of local motion signals.

This study reports the effect of varying copper (Cu) concentrations in the aluminum-copper (AlCu) alloy used in the interdigital transducer (IDT) electrodes of surface acoustic wave (SAW) resonators on nonlinearity and power durability. Finite element method (FEM) simulations were conducted to investigate the strain distribution in the IDT electrodes, which is one of causes of nonlinearity. The strain was significant at the bottom of the electrodes, suggesting that reinforcement of the part is important. In order to investigate the effect of Cu content, two test groups were prepared. The first test group had Cu distributed uniformly in AlCu electrode, while the second test group had Cu concentrated at the bottom of the electrode. As predicted by the FEM simulation, the second test group SAW resonator demonstrated excellent power durability and better nonlinearity.

Continual exercise has become an important concept for mental as well as physical health, with sporting industries and communities interested in promoting exercise adherence. This study examined the causal relationship among sports ability-beliefs, achievement goal orientation, and exercise adherence among Korean recreational golfers. Data from 806 golfers were collected after Institutional Review Board deliberation and approval. To reflect the characteristics of frequent participation, golfers were limited to those who had been registered members of a golf practice facility for more than three months. The measurements included the sports ability-belief scale, the achievement goal orientation scale, and the exercise adherence scale, with evidence of construct validity based on confirmatory factor analysis. The research questions were verified through a measurement model and structural model validation. The results showed that the learning factor under incremental beliefs explained task orientation (β = 0.417, p < 0.001). Conversely, the gift factor under entity beliefs explained ego orientation (β = 0.169, p < 0.001). Thus, the significant relationship between learning and task orientation implied that consistent practice and effort in golf could enhance the positive meaning of golf participation and the perception of achievement in golfers. Conversely, the static explanation of ego orientation of gift suggested that individuals with strong beliefs in their innate golf abilities or the influence of their motor skills on golf performance experienced a sense of achievement by comparing themselves with others. Secondly, when the sub factors of sports ability-beliefs were controlled, both task orientation (β = 0.420, p < 0.001) and ego orientation (β = 0.159, p < 0.001) were statistically significant in terms of exercise adherence. Thirdly, in the relationship between sports ability-beliefs and exercise adherence, both task orientation (indirect effect: 0.074, p < 0.001) and ego orientation (indirect effect: 0.012, p < 0.05) had complete mediation effects. Ultimately, the study confirmed that the relevance of sports ability-beliefs and achievement goal orientation for exercise adherence in elite sports could also be applicable in the realm of recreational sports.

Abstract. Climatic feedbacks associated with orbitally driven Sea Surface Temperature (SST) lead to a profound impact on the Southern Hemisphere (SH) vegetation cover during the Mid-Holocene, MIS5e, MIS11c, and MIS31 interglacials. Results are based on a suite of coupled climate simulations conducted with the ICTP-CGCM (Speed-Nemo), which provides the boundary conditions for the CCM3/IBIS vegetation model. The CCM3/IBIS model was run from the Speed-Nemo output of the global ocean and individualized Atlantic, Pacific and Indian ocean basins forcing, in addition to orbital parameters and greenhouse gases. For interglacials, MH, MIS 5e, and 11c, areas have been found to be significantly reduced in tropical evergreen forests, but more extensive savanna and grasslands, over parts of the southern and central African region and into northern South America (Amazon region). In another important period, the results showed that there have been changes in vegetation cover due to insolation forcing during MIS31 compared to other interglacials, but the impact was greater in Australia and central South America. However, the southern tropical climate became drier due to negative SST anomalies, induced by the Atlantic and Tropical Pacific basins, and thus reduced continental precipitation. This study demonstrates that vegetation responses across tropical regions of the Southern Hemisphere are not solely driven by orbital variations but are also significantly modulated by internal changes in Atlantic and Pacific SST patterns. In the study regions, in particular, during the MH, MIS5e and MIS11c, the seasonality of insolation was reduced in the SH, leading to the cooling of the southern tropical ocean basins, resulting in the migration of the summer precipitation zone to boreal latitudes. Therefore, combined with increased low-latitude summer temperatures and a prolonged dryer period, the forcing led to a slow retraction, but steady in the rainforests of Congo and Amazonia, causing an effect of extreme aridity.

This paper proposes a sigmoid-based particle swarm optimization (PSO) for a complete ensemble empirical mode decomposition (SPSO-CEEMD) applied to the energy management system (EMS) of a hybrid electric vehicle (HEV). The low-frequency power demand, to be supplied by the lithium-ion battery (LIB) and internal combustion engine (ICE), is calculated by the CEEMD, while sigmoid functions define the ICE reference, avoiding discontinuities in the control strategy and limiting the response frequency in the implementation of power, velocity and angle control loops for the ICE butterfly valve actuator. High-frequency demand is handled by the ultracapacitor (UC), which controls the dc-link voltage. The sigmoid functions are optimized to reduce the ICE fuel consumption and the LIB aging, considering ICE emissions as constraints in the PSO. To make the UC available in next peak demands, its terminal voltage restoration is relaxed by a phase-lag compensator (PLC) tuned to actuate only after power delivers, which reduces the influence in the LIB dynamic. Experimental and numerical results under the HWYCOL, SC03 and a Brazilian real-world drive cycles show that SPSO-CEEMD reduces the total operational cost, LIB stress and aging compared to state-of-the-art strategies. Despite larger UC voltage restoration error with the PLC, LIB power dynamic is not significantly affected, increasing its lifetime by 2.74% and 10.96% compared to traditional PI and lowpass filter strategies, respectively. Moreover, the total operational cost is reduced by 18.28% and 47.54% in relation to the exclusive operation strategy (XOS) and interval type-2 fuzzy logic control (IT2-FLC) adapted from the literature.

BackgroundA few studies suggest that Taekwondo is an effective intervention in increasing physical functions among older adults. This study is intended to focus on a multitude of health benefits of participation in a modified Taekwondo activity for nursing home residents in the U.S.MethodsThis qualitative study used semi-structured, in-depth interviews with seven participants consisting of 2 males and 5 females older adults from a community nursing home. The interview protocol included content mapping and content mining interview questions. The study followed the five steps of constant comparative analysis.ResultsFour main themes were identified as health benefits resulting from a modified Taekwondo participation: (a) promoting mental health, (b) increasing physical functions, (c) stimulating cognitive abilities, and (d) facilitating positive social interaction.DiscussionThis study indicates modified Taekwondo can be instrumental in promoting their physical functioning, cognitive functioning, social interactions, and mental health. Practical implications and further discussion are addressed in this paper.