• The Journal of Korea Robotics Society
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• v.19 no.1
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• pp.71-78
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• 2024

The paper presents a hardware-in-the-loop (HIL) system designed for satellite movement testing in the microgravity environment on the ground with two industrial robots. Especially, the paper deals with the contact between satellites during rendezvous and docking simulations of satellites using a robotic HILS system. For this purpose, the admittance control method plays a core role in preventing damage to the satellite or robot from contact force between satellites. The coordinate frames are transformed into the mass center of the satellite and the admittance control at the level of exponential coordinates is adopted to actively use the properties of Lie groups related to tracking errors. These methods effectively mitigate the risk of robot damage during inter-satellite contact and ensure efficient tracking performance of satellite movements.

• Advances in aircraft and spacecraft science
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• v.10 no.6
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• pp.521-543
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• 2023

Reynolds-averaged Navier-Stokes (RANS) models are extensively employed in industrial settings for the purpose of simulating intricate fluid flows. However, these models are subject to certain limitations. Notably, disparities persist in the Reynolds stresses when comparing the RANS model with high-fidelity data obtained from Direct Numerical Simulation (DNS) or experimental measurements. In this work we propose an approach to mitigate these discrepancies while retaining the favorable attributes of the Menter Shear Stress Transport (SST) model, such as its significantly lower computational expense compared to DNS simulations. This strategy entails incorporating an explicit algebraic model and employing a neural network to correct the turbulent characteristic time. The imposition of realizability constraints is investigated through the introduction of penalization terms. The assimilated Reynolds stress model demonstrates good predictive performance in both in-sample and out-of-sample flow configurations. This suggests that the model can effectively capture the turbulent characteristics of the flow and produce physically realistic predictions.

• The Transactions of the Korea Information Processing Society
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• v.13 no.6
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• pp.278-283
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• 2024

When implementing software, there can be side effects that pose a threat to human life. Therefore, it is necessary to measure the impact of software on safety and create alternatives to mitigate and prevent threats. To conduct a software safety assessment to measure the impact of threat factors, the following components are necessary. This paper aims to classify the threat factors of software into internal and external factors and quantitatively demonstrate the impact of these threat factors.

• International Journal of Computer Science & Network Security
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• v.24 no.3
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• pp.71-82
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• 2024

This paper proposes a new communication system for e-learning applications to mitigate the negative impacts of COVID-19 where the online massive demands impact the current commu-nications systems infrastructures and capabilities. The proposed system utilizes high-altitude platforms (HAPs) for fast and efficient connectivity provision to bridge the communication in-frastructure gap in the current pandemic. The system model is investigated, and its performance is analyzed using adaptive antenna arrays to achieve high quality and high transmission data rates at the student premises. In addition, the single beam and multibeam HAP radio coverage scenarios are examined using tapered uniform concentric circular arrays to achieve feasible communication link requirements.

• International Journal of Advanced Culture Technology
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• v.12 no.2
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• pp.98-103
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• 2024

This paper revisits politeness expressions in English, exploring their linguistic characteristics and the underlying social dynamics they reflect. Grounded in pragmatic theories, politeness is examined as a phenomenon shaped by societal norms, wherein language users navigate the delicate balance between efficiency and maintaining positive social interactions. Through an analysis of various linguistic devices such as modal auxiliary verbs, progressive and past tenses, depersonalization, and the use of hedges, the study elucidates how speakers endeavor to mitigate potential burdens on listeners and foster smoother communication. By understanding and employing these linguistic strategies, English learners can better navigate the nuances of politeness expressions in the English cultural context. This exploration underscores the pivotal role of politeness in interpersonal communication and highlights its significance in facilitating effective interaction among language users.

• International journal of advanced smart convergence
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• v.13 no.2
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• pp.25-34
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• 2024

The paper investigates how the semiconductor and electric vehicle industries are addressing safety and security concerns in the era of autonomous driving, emphasizing the prioritization of safety over security for market competitiveness. Collaboration between these sectors is deemed essential for maintaining competitiveness and value. The research suggests solutions such as advanced autonomous driving technologies and enhanced battery safety measures, with the integration of AI chips playing a pivotal role. However, challenges persist, including the limitations of big data and potential errors in semiconductor-related issues. Legacy automotive manufacturers are transitioning towards software-driven cars, leveraging artificial intelligence to mitigate risks associated with safety and security. Conflicting safety expectations and security concerns can lead to accidents, underscoring the continuous need for safety improvements. We analyzed the expansion of electric vehicles as a means to enhance safety within a framework of converging security concerns, with AI chips being instrumental in this process. Ultimately, the paper advocates for informed safety and security decisions to drive technological advancements in electric vehicles, ensuring significant strides in safety innovation.

• Korean Journal of Artificial Intelligence
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• v.12 no.2
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• pp.25-33
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• 2024

This study examines the relationship between customer satisfaction and management response in the hotel industry amid the COVID-19 pandemic. By applying regression analysis and topic modeling to consumer reviews on online platforms, we assess how consumer perceptions and management behaviors have shifted since the onset of the pandemic. The findings reveal a significant decline in customer satisfaction linked to COVID-19. Significantly, while the pandemic has reduced overall customer satisfaction levels, high response rates and high review-response content similarity mitigate the impact of the crises. These results highlight the critical need for hotel managers to continuously monitor online reviews and adapt their engagement strategies to maintain and enhance customer satisfaction during ongoing and future crises. This research not only corroborates existing theories on customer satisfaction but also exposes novel dynamics introduced by the pandemic, offering new insights for effective customer relationship management in turbulent times.

• Current Optics and Photonics
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• v.8 no.3
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• pp.239-245
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• 2024

This paper proposes single logarithmic amplification (single-LA) and deep learning (DL)-based fixed-threshold on-off keying (OOK) detection for free-space optical (FSO) communication. Multilevel LAs (MLAs) can be used to mitigate intensity fluctuations in the received OOK signal by their nonlinear gain characteristics; however, it is ineffective in the case of high scintillation, owing to degradation of the OOK signal's extinction ratio. Therefore, a DL technique is applied to realize effective scintillation compensation in single-LA applications. Fully connected (FC) networks and fully connected neural networks (FCNN), which have nonlinear modeling characteristics, are deployed in this work. The performance of the proposed method is evaluated through simulations under various scintillation effects. Simulation results show that the proposed method outperforms the conventional adaptive-threshold-decision, single-LA-based, MLA-based, FC-based, and FCNN-based OOK detection techniques.

• Nuclear Engineering and Technology
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• v.56 no.1
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• pp.180-188
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• 2024

This research examined consumption-based carbon emission reduction by nuclear energy consumption and environmental tax while considering the context of trade globalization in the highest five emitter nations from 1990 to 2020. This study used various empirical methodologies, including preliminary analysis to check the stationarity and cointegration, the CS-ARDL for long-run analysis, CCEMG, AMG for robustness, and the D-H causality test for short-term pairwise causation. The results indicated that nuclear energy consumption, environmental tax, and trade globalization help to mitigate consumption-based carbon emissions while economic growth and population density boost carbon emissions. Furthermore, the results also found two-way casual connection exists between nuclear energy consumption, population density, and consumption-based carbon emissions. Thus, the results emphasize the need for government policies that encourage nuclear energy and environmental tax as a strategy to reduce carbon emissions and achieve and maintain environmental development.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.119-120
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• 2023

Corrosion of the steel rebar in coastal environment caused huge economical loss of the globe. Therefore, coating on the steel rebar being used to mitigate the corrosion. In the present study, we have applied epoxy coating on arc thermal sprayed Al coating (a dual metal/polymeric coating) vis-à-vis compared with as coated one (Al coating). The corrosion studies were performed in simulated concrete pore solution with 3.5 wt. % NaCl solution. The morphology of the dual epoxy/Al coating is smooth while Al coating shows rankle and defects. Due to defects, Al coating is susceptible to corrosion while dual epoxy/Al coating has performed excellent compared to as coated one at extended period of immersion.