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        검색결과 9

        1.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The arrival of the 5G era has made electromagnetic pollution a problem that needs to be addressed, and flexible carbon-based materials have become a good choice. In this study, wet continuous papermaking technology was used to prepare carbon fiber paper (CFP) with a three-dimensional conductive skeleton network; Molybdenum disulfide ( MOS2)/ iron (Fe) @ carbon fiber paper-based shielding material was prepared by impregnating and blending molybdenum disulfide/iron ( MOS2/Fe) phenolic resin MOS2/ Fe@ CFP. The morphology, structure, electrical conductivity, mechanical properties, hydrophobicity, and electromagnetic shielding properties of the composite were characterized. The results show that the three-dimensional network structure based on a short carbon fiber paper-based conductive skeleton and the synergistic effect of the MOS2 dielectric wave absorbing agent and Fe magnetic wave absorbing agent have good electromagnetic shielding performance. Conduct electromagnetic shielding simulation using HFSS software to provide options for the structural design of CFP. The electromagnetic shielding performance of CFP reaches 70 dB, and the tensile strength reaches 34.39 MPa. Based on the mechanical properties, the compactness of carbon fiber paper is ensured. The lightning damage model test using CST software expands the direction for the use of carbon fiber paper. In summary, MOS2/ Fe @CFP with excellent shielding performance has great application prospects in thinner and lighter shielding materials, as well as high sensitivity, defense and military equipment.
        4,500원
        2.
        2024.06 구독 인증기관 무료, 개인회원 유료
        Electric-propulsion systems for ships, also known as electric propulsion devices, represent the current direction of development for maritime power. Issues concerning the environment and fuel economy have compelled the maritime transport sector to seek solutions that reduce emissions and improve fuel efficiency. In this process, power electronics technology plays a significant role in the propulsion systems of ships. Selecting an efficient battery system is of great importance for enhancing the cruising range of yachts and minimizing environmental impact. The battery model is crucial for revealing the working principles of batteries, and it is extremely critical for the application and development of battery technology. The Battery Management System (BMS) serves a crucial regulatory function, optimizing both the safety and performance of battery cells. Central to its operation is the precise estimation of the battery's State of Charge (SOC), a process dependent on an exacting battery model. This system not only enhances longevity and reliability but also ensures that energy storage solutions meet high standards of efficacy. This study focused on testing the impedance characteristics of lithium-sulfur batteries (LSB) at various SOC points and establishing first- and second-order RC equivalent circuit models. The model parameters were identified through experimental data. Subsequently, a simulation platform was constructed using MATLAB/Simulink to simulate the behavior of LSB under a constant current discharge condition. The simulation results showed that the second-order RC model had significantly lower errors than the first-order model, demonstrating higher accuracy. These achievements can provide technical support for the research of energy storage systems in the green aviation and maritime industries.
        4,800원
        3.
        2023.12 구독 인증기관 무료, 개인회원 유료
        The rack cylinder is an important part of the pile leg structure of the jack up platform. Because of its complex structure, the flow field around the rack cylinder is different from that around the ordinary cylinder, which brings difficulties to the research of the rack cylinder. In this paper, using CFD(Computational Fluid Dynamics) solved the flow field of chords with different rack height and rack width under different KC and Re, the characteristics of the flow field around the cylinder with rack are obtained. The results show that Re, KC, rack height and rack width all have different effects on the flow field. When Re and KC are constant, Cd will increase with the increase of rack height ratio, the change of Cd and Cl is not significant, while the change of Cd and Cl varies with Re when the chord structure is fixed.
        4,000원
        4.
        2023.06 구독 인증기관 무료, 개인회원 유료
        In order to solve the problem of improper thrust distribution of each thruster of underwater vehicle, the PSO optimization algorithm is used to solve the problem of thrust distribution. According to the spatial layout of the thruster, the algorithm model of the underwater vehicle propulsion system is established. The thrust input is carried out under the broken line search trajectory, and the simulation verifies the thrust allocation results of the PSO algorithm and the traditional pseudo-inverse method. The simulation results show that compared with the traditional algorithm. First of all, the PSO algorithm can set the physical threshold for each thruster to prevent the thruster from having too much thrust. Secondly, it can ensure that the thruster can turn with a reasonable torque to prevent the robot from drifting due to the large thrust gap. This paper provides a theoretical reference for thrust distribution of underwater salvage robot, and has practical engineering significance.
        4,000원
        6.
        2018.10 구독 인증기관·개인회원 무료
        RNA interference (RNAi)-based strategy has been developed to control various phytophagous chewing pests. However, only a few cases of RNAi-based control success have been reported for sucking pests, suggesting that sucking pests likely ingest less amount of transgenic subcellular hairpin RNA (or dsRNA). In this study, as the basic information for the establishment of ingestion RNAi against sucking pests, feeding amount and time course of plant subcellular fractions of the four sucking pest species (Frankliniella occidentalis, Frankliniella intonsa, Tetranychus urticae and Nilaparvata lugans) were determined by quantitative PCR (qPCR). Adults of the four species were starved for 24 h and then fed with kidney bean leaf (F. occidentalis, F. intonsa, T. urticae) or rice leaf (N. lugens) for 48 h. The leaf-fed adults were collected every 6-h interval and their genomic DNA was extracted. The ingested fractions of chloroplast and nuclear were quantified using rubisco and 50s rRNA as marker genes, respectively. The ingested amount of rubisco and 50s rRNA genes in F. occidentalis, F. intonsa and T. urticae showed rapid increasing pattern after feeding and then slightly reduced over time. In contrast, N. lugens neither ingest nuclear nor showed any distinct feeding pattern of chloroplast. These results demonstrate that F. occidentalis, F. intonsa and T. urticae ingest both chloroplasts and nucleus along with cytosol as cell-feeders but N. lugens, a phloem sap feeder, does not ingest nucleus during sucking. Our findings further suggest that ingestion RNAi-based control strategy would work better for cell-feeding sucking pests compared to phloem sap-feeding sucking pests.
        7.
        2016.07 구독 인증기관 무료, 개인회원 유료
        Level of urbanization in China has reached 53.73% in 2013, indicating a tremendous progress on the urbanization of China. On the other hand, the number of villages in China reduces by around one million from 3.6 million in 2000 to 2.7 million in 2010 (Zhang, 2014). Issues in both urban and rural areas of China appear, including the imbalance between increased population and limited resources in urban region, and more significantly, the increasing disparity between rural and urban areas. Chinese researchers interpret and analyse these matters from different perspectives. For instance, Zheng (2006) and Ma (2006) suggest the importance of the infrastructure construction and public service. Wu (2006) advises that the government should pay attention to the development of the secondary and tertiary industry. Wen (2005) proposes that the improvement of social institution and the recovery of social cultural environment are required to achieve sustainability in the urbanization process in China. Previous studies in environmental psychology put quality of life, attachment to place, and residence satisfaction at the center to understand the relationship between inhabitants and their neighborhood of residence. However, there are gaps in this research realm in both practice and theories. Firstly, very limited research studies this environmental psychology issue in China (e.g. Mao, Fornara, Manca, Bonnes, & Bonaiuto, 2015). Secondly, there are different opinions on the causal order between quality, attachment, and satisfaction. Research on the relationship between perceived residential environment quality (PREQ), place attachment, and environmental satisfaction has not reached a consensus. The debate on the direction of the causal relationship between perceived quality and satisfaction has been summarized by Bradya and Robertson (2001). They conclude that the quality to satisfaction causal order holds up well across diverse cultures. However, relevant debate is still ongoing. A number of research articles place satisfaction as an antecedent to attachment, e.g. Chen, Dwyer, and Firth (2014); Lee, Kyle, and Scott (2012); Ramkissoon and Mavondo (2015); etc. Some argue that place attachment is an indicator of satisfaction. Kyle et al. (2004) investigate the effect of place attachment on the perceived values of tourists and find that place attachment is an important factor explaining the variance of perceived values. This is supported by research e.g. Hwang, Lee, and Chen (2005); Prayag and Ryan (2012); Yuksel, Yuksel, Biljm (2010); etc. As to the relationship between perceived quality and attachment, the debate has not stopped. Through comparisons, Mesch and Manor (1996) conclude that the residents who give a higher evaluation of the social and natural environment may have greater place attachment. Brown, Perkins, and Brown (2003) also suggest that the residents who agree that the street environment is better would attach to this place. Sam, Bayram, and Bilgel (2012) have certified the relationship between residential environment quality and place attachment. Furthermore, Borrie and Roggenbuck (2001) and Walker and Ryan (2008) find that the connection between human beings and the nature environment would affect their affection toward the environment. It means that the closer the relationship with the nature environment is, the stronger the attachment would be, which in turn, enhances the intentions to protect the environment. This quality to satisfaction relationship is supported by other research such as Bonaiuto, Aiello, Perugini, Bonnes, and Ercolani (1999); Grisaffe and Nguyen (2011); Yu, Chen, and Chen (2015); etc. Nevertheless, a different opinion arguing that attachment to a place may affect one’s perception on the quality related to a place is emerging in tourism research (e.g. Neuvonen, Pouta, & Sievänen, 2010). This paper takes the credit of quality → attachment → satisfaction causal order as the initial model and proposes three hypotheses as follows. H1a: One’s PREQ has a positive impact on his/her attachment to this place; H2a: One’s attachment to a place has a positive impact on his/her satisfaction to the environmental settings in this place; H3a: Place attachment in addition performs as a mediating role between PREQ and environment satisfaction.To be noted, the initial model has its theoretical basis as discussed above but is not necessarily the absolute optimal model. Relatively, this model provides more theoretical interpretation and practical implications in the specific research context: residential psychology in urban and rural areas of China. On this basis, this article further examines a competing model illustrating an alternative theoretical framework on the relationships between these three constructs (satisfaction → attachment → quality). Relatively, another group of hypotheses in this competing model is listed as follows. H1b: One’s attachment to a place has a positive impact on his/her PREQ; H2b: One’s satisfaction to the environmental settings in this place has a positive impact on his/her attachment to this place; H3b: Place attachment in addition performs as a mediating role between environment satisfaction and PREQ. A survey approach is employed and data are collected from several backgrounds. Dataset A (rural) is collected from three villages from Heilongjiang Province and two villages from Shandong Province in China from July to August 2014. The choices of the provinces, rural areas, and the sampling process are random. 490 valid questionnaires are included in the data analysis. Dataset B (urban) is collected via an online survey portal, which allows a nationwide sampling reach. In total 1368 online survey entries are recorded and 420 valid questionnaires are included, resulting in a valid rate of 30.7%. The measures for each construct are based on an extensive literature review. The measurement of perceived residential environment quality is from Sam, Bayram, & Bilgel’s (2012) development on the perception of residential environment. The measurement of place attachment in this study is adopted from Kyle, Graefe, and Manning’s (2005) and Chen, Dwyer, and Firth’s (2014) evaluation based place attachment dimensionality and scales. As for the scale of environmental satisfaction, Pelletier, Legault, and Tuson’s (1996) measure was applied. All the entire variables adopted multiple-item, 5-point Likert scales were adopted, where “1” indicated “strongly disagree” and “5” indicated “strongly agree”. After pre-testing the preliminary version of the survey instrument, a revised version was developed. This study adopts structural equation modeling (SEM) based on partial least squares (PLS) modeling given the small sample size and the explorative purpose of this study (Dijkstra & Henseler, 2015a). The software used was Smart PLS 3.0. The reliability and validity of the constructs were assessed. Cronbach’s alpha and the value of CR of each construct were found to exceed the cut-off value of 0.70 (Fornell & Larcker, 1981), except for adequacy of education which is close to 0.70 (only for Cronbach’s alpha but not for CR). Furthermore, the AVE of each construct exceeded the variance attributable to its measurement error cut-off value of 0.50 (Chin, 1998; Fornell & Larcker, 1981). In addition, heterotrait-monotrait ratio (HTMT) is recommended as a better method to test discriminant validity (Henseler, Dijkstra, Sarstedt, Ringle, Diamantopoulos, Straub, Ketchen, Hair, Hult, & Calantone, 2014). The result shows that there is neither value of the HTMT higher than the threshold of 0.85 nor confidence interval containing the value one, indicating that all the constructs exhibit satisfactory discriminant validity. The hypothesized effects in the theoretical model were tested by structural equation modeling (SEM). The first group of models tested the effect of perceived environmental quality on environmental satisfaction through place attachment i.e. initial model (Model A, Model B, Model C), while the second group of models tested the reverse effect of environmental satisfaction on perceived environmental quality through place attachment (Model D, Model E, Model F). Both the full model and the multi-group model were tested. The value of SRMR of the full model that tests either the effect of perceived environmental quality on environmental satisfaction (SRMR = 0.104, t = 41.826, p < 0.001) or the reversed effect (SRMR = 0.106, t = 37.736, p < 0.001) shows that the models fit the data quite well (Dijkstra & Henseler, 2015b). However, the former is little bit more significant. In this study, PREQI is found different impacts on place attachment and environmental satisfaction. This provides evidence to support a similar mechanism of studying residents’ psychology with SERVEQUAL model. However, the model testing is found significantly different between rural and urban samples, indicating a systematic difference in the psychology of rural and urban populations. Quality  attachment  satisfaction causal order is found significant and supported by both samples in this study. However, a reversed causal order model (satisfaction  attachment  quality) is also supported by the samples. Although the results may not be able to end the debate on alternative models between PREQ, place attachment, and environmental satisfaction, this paper provides empirical evidence from a specific context (urban and rural China) for further research. Specifically, PREQ has a significant impact on place attachment in both urban and rural areas in China. As for the impact of place attachment on environmental satisfaction as well as the indirect impact of PREQ on environmental satisfaction, the influence is more significant in cities of China compared to rural areas. This suggests in the urban areas in China, affective and emotional responses to their lives play an important role to residents. Local government in cities should balance between improving and maintaining quality of the environment and strengthening local residents’ psychological attachment to the place. Governments in rural areas, on the other hand, should lay great focus on the physical aspects of the environment including nature, health, education, commerce, and venture of the rural areas, to enhance residents’ living experience and satisfaction. Further, there are some limitations. Although this study attempts to clarify the framework of “perception-affection-attitude” in the field of environment management, considering the practical implications, the future study could bring the individuals’ behaviors or intentions into this model such as willingness-to-pay for environment-friendly products. It will also benefit from reviewing more literature on community-based social marketing.
        4,000원
        9.
        2023.11 서비스 종료(열람 제한)
        In recent years, safety recalls have occurred frequently in the biopharmaceutical industry, which affects the health of consumers. This article attempts to use the fsQCA method to draw a conclusion through the study of ESG and its quantification system, as well as the study of data samples related to MES and GMP processes, that is, MES-DPT has a positive impact on process safety management, and GMP-DPT has a positive impact on process safety. Management has a positive and positive impact, and ESG-DPT has a positive and positive impact on process safety management. Finally, this article puts forward suggestions for improving ESG-DPT, MES-DPT, GMP-DPT and the biomedical ESG-DPT model. Future research hopes to further study ESG -DPT model and ESG biomedical industry indicators.