• Journal of the Korean Society of Visualization
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• v.21 no.3
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• pp.49-56
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• 2023

The Polymer electrolyte membrane fuel cell (PEMFC) operates at ambient temperature as a low-temperature fuel cell. During its operation, voltage losses arise due to factors such as operating conditions and material properties, effecting its performance. Computational simulations of fuel cells can be categorized into 1D simulation and CFD, chosen based on their specific application purposes. In this study, we carried out an analysis validation using 1D geometry and compared its performance with the results from 2D geometry analysis. CFD allows for the representation of pressure, velocity distribution, and fuel mass fraction according to the geometry, enabling the analysis of current density. However, the 1D simulation, simplifying governing equations to reduce time cost, failed to accurately account for fuel distribution and changes in fuel concentration due to fuel cell operations. As a result, it showed unrealistic results in the cell voltage region dominated by concentration loss compared to CFD.

• Advances in aircraft and spacecraft science
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• v.10 no.5
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• pp.419-437
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• 2023

This paper presents the study of the effects of rigid-body motion simultaneously with the presence of the effects of temporal variation due to the existence of morphing speed on the aeroelastic stability of the two-stage telescopic wings, and hence this is the main novelty of this study. To this aim, Euler-Bernoulli beam theory is used to model the bending-torsional dynamics of the wing. The aerodynamic loads on the wing in an incompressible flow regime are determined by using Peters' unsteady aerodynamic model. The governing aeroelastic equations are discretized employing a finite element method based on the beam-rod model. The effects of rigid-body motion on the length-based stability of the wing are determined by checking the eigenvalues of system. The obtained results are compared with those available in the literature, and a good agreement is observed. Furthermore, the effects of different parameters of rigid-body such as the mass, radius of gyration, fuselage center of gravity distance from wing elastic axis on the aeroelastic stability are discussed. It is found that some parameters can cause unpredictable changes in the critical length and frequency. Also, paying attention to the fuselage parameters and how they affect stability is very important and will play a significant role in the design.

• The Journal of the Acoustical Society of Korea
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• v.27 no.7
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• pp.365-371
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• 2008

In this study, beat control method using an equivalent ring model is proposed to control beat period of a slightly asymmetric ring. Slight asymmetry in a ring generates mode pair and the interaction of the mode pair makes beat in vibration and sound. In a ring, as a simplified bell type structure, mode data are measured and an equivalent ring is determined so that the measured mode condition is satisfied. By the finite element analysis on the equivalent ring, changes of mode pair condition are predicted when local mass is attached or the local thickness is decreased. The predicted results are compared with the experimental result and the validity of the proposed method is verified.

• KIPS Transactions on Computer and Communication Systems
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• v.13 no.1
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• pp.1-9
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• 2024

In the development and mass production of polymers, there are many uncontrollable variables. Even small changes in chemical composition, structure, and processing conditions can lead to large variations in properties. Therefore, Traditional linear modeling techniques that assume a general environment often produce significant errors when applied to field data. In this study, we propose a new modeling method (GPR-SEM) that combines Structural Equation Modeling (SEM) and Gaussian Process Regression (GPR) to study the Friction-Coefficient and Flexural-Strength properties of Polyacetal resin, an engineering plastic, in order to meet the recent trend of using plastics in industrial drive components. And we also consider the possibility of using it for materials modeling with nonlinearity.

• Journal of East Asia Management
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• v.5 no.1
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• pp.75-90
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• 2024

About 100 years after the start of mass production by American car maker Ford in 1913, the automobile industry has come to a major transformation in 100 years. In this transformation period, automakers are facing the biggest challenge of converting power sources, the basis of automobiles, from existing internal combustion engines to electric vehicles. Hybrid vehicles have been released in Japan since the late 1990s, and changes in automobile power sources have occurred early. In order to gain global leadership in hybrid vehicles, Japanese automakers and the Japanese government joined forces to promote the growth of the domestic hybrid vehicle market. The government has implemented a policy to substantially subsidize the high price of hybrid cars compared to internal combustion engine cars by providing purchase subsidies and tax benefits to buyers. Toyota has increased its line-up of hybrid cars around the Prius and has further strengthened communication with customers for the sale of hybrid vehicles. As a result of continuing these efforts for about 20 years, the percentage of Japan's hybrid vehicle market in 2022 reached 51% for passenger cars. Recently, each country has been setting and promoting aggressive goals for electric vehicles that require a wider range of physical and institutional infrastructure than hybrid vehicles. This study aims to assess the growth of electric vehicles by looking at the trend of hybrid vehicles and how they've been distributed in the Japanese market.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.32 no.2
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• pp.151-158
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• 2024

Microalgae are aquatic microorganisms capable of photosynthetic growth using water, carbon dioxide and sunlight, and can replace petroleum for transportation. It is receiving great attention as a potential next-generation biological resource. The microalgae biodiesel production process is largely based on the development of highly efficient strains and mass production. It consists of cultivation, harvesting, oil extraction, fuel conversion and by-product utilization. Currently, microalgae diesel is 3-5 times more expensive than petroleum diesel. However, with the optimization of each element technology and the development of integrated systems, not only biofuels, but also industrial materials, wastewater treatment, and greenhouse gases As application expands to various fields such as abatement, the timing of commercialization may be brought forward. Oil prices have recently fallen due to the influence of sail gas. Although there has been a significant drop, global warming is an urgent challenge for current and future generations. In particular, Korea, which does not have oil resources, We must always prepare for political environmental changes, high oil prices, and energy crises. In this paper, the need for eco-friendly biofuel for carbon dioxide conversion. In addition to research trends, domestic and international research trends, and economic prospects, the concept of microalgae and the element technologies of the biodiesel production process are briefly discussed introduced.

• Structural Engineering and Mechanics
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• v.91 no.1
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• pp.87-102
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• 2024

In recent years, the focus on vibration analysis of multilayer smart structures has attracted considerable attention in many engineering applications. In this work, vibration analysis of a three-layer microporous beam with a core amplified by a composite material reinforced with graphene platelets and two piezoelectric thin films is discussed. It is assumed that piezoelectric layers with a thickness of 0.01 core are very thin and the properties of the matrix and reinforcement vary in the thickness directions. The governing equations of motion are obtained using an energy approach and the method of numerical differential quadrature to solve them. The results of this work are compared to other research and there is good agreement between them. The influences of the volumetric weight fraction of graphene wafers, different graphene platelets distributions, porosity distribution, mass scale parameters and thin ratio of graphene platelets take into account the natural dimensionless frequencies of the micro-beam. The results of this study show that the symmetric distribution of graphene platelets based on the symmetric porosity distribution has a great influence on the natural frequencies without basic dimension of the micro-beam, while the shape ratios of graphene platelets do not have a significant influence on natural frequency changes.

• Journal of Veterinary Science
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• v.25 no.4
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• pp.54.1-54.16
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• 2024

Importance: As one of the main etiologic agents of infectious diseases in pigs, pseudorabies virus (PRV) infections have caused enormous economic losses worldwide. EP0, one of the PRV early proteins (EP) plays a vital role in PRV infections, but the mechanisms are unclear. Objective: This study examined the function of EP0 to provide a direction for its in-depth analysis. Methods: In this study, the EP0-deleted PRV mutant was obtained, and Tandem Mass Tag-based proteomic analysis was used to screen the differentially expressed proteins (DEPs) quantitatively in EP0-deleted PRV- or wild-type PRV-infected porcine kidney 15 cells. Results: This study identified 7,391 DEPs, including 120 and 21 up-regulated and down-regulated DEPs, respectively. Western blot analysis confirmed the changes in the expression of the selected proteins, such as speckled protein 100. Comprehensive analysis revealed 141 DEPs involved in various biological processes and molecular functions, such as transcription regulator activity, biological regulation, and localization. Conclusions and Relevance: These results holistically outlined the functions of EP0 during a PRV infection and might provide a direction for more detailed function studies of EP0 and the stimulation of lytic PRV infections.

• Journal of Web Engineering
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• v.14 no.4
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• pp.741-755
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• 2022

In this study, odor components were analyzed using gas chromatography/mass spectrometry (GC/MS) and solid-phase microextraction (SPME), and odor-active compounds (OACs) were identified using GC-olfactometry (GC-O). Among the volatile compounds identified through GC-O, p-anisaldehyde, limonene, estragole, anethole, and trans-anethole elicit the fennel odor. In particular, trans-anethole showed the highest odor intensity and content. Changes in body weight during the experimental period showed decreasing values of fennel essential oil (FEO)-inhaled groups, with both body fat and visceral fat showing decreased levels. An improvement in the body's lipid metabolism was observed, as indicated by the increased levels of cholesterol and triglycerides and decreased levels of insulin in the FEO-inhaled groups compared to group H. Furthermore, the reduction in systolic blood pressure and pulse through the inhalation of FEO was confirmed. Our results indicated that FEO inhalation affected certain lipid metabolisms and cardiovascular health, which are obesity-related dysfunction indicators. Accordingly, this study can provide basic research data for further research as to protective applications of FEO, as well as their volatile profiles.

• Clinical Nutrition Research
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• v.13 no.3
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• pp.149-155
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• 2024

Estimating the nutritional requirements for pediatric patients requires a comprehensive approach with various factors including age, gender, body mass index, and physical activity level, due to the significant growth and developmental changes observed in this population. This complexity renders the use of a simplistic generalization or a standard formula impractical. A number of methodologies have been established to calculate nutritional needs for the pediatric population. However, the application of these methodologies is challenging due to the variability in the aforementioned factors. Determining nutritional requirements for pediatric patients with underlying medical conditions is complicate, influenced by variables such as the nature of the illness, treatment modalities, and the patient's overall condition. Nutritional support in severely traumatically brain-injured pediatric patients is directly correlated with prognosis and growth outcomes. Therefore, this case study aims to validate existing methodologies for estimating nutritional requirements in pediatric patients with severe traumatic brain injury and to provide primary data for the development of effective nutritional support strategies. A case of a 5-year-old male patient admitted to the intensive care unit due to severe traumatic brain injury is examined. Future case studies and ongoing research are imperative to ensure the safe and effective nutritional support of pediatric patients with severe traumatic brain injury.