• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.12
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• pp.1889-1894
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• 2017

Global automobile manufacturers are developing electric vehicles (EVs) to eliminate the pollutant emissions from internal combustion vehicles and to minimize fossil fuel consumptions for the future generations. However, EVs have a disadvantage of shorter traveling distance than that of conventional vehicles. To answer this shortfall, more batteries are installed in the EV to satisfy the consumer expectation for the driving range. However, as the energy capacity of the battery mounted in the EV increases, the amount of heat generated by each cell also increases. Naturally, a better battery thermal management system (BTMS) is required to control the temperature of the cells efficiently because the appropriate thermal environment of the cells greatly affects the power output from the battery pack. Typically, the BTMS is divided into an active and a passive system depending on the energy usage of the thermal management system. Heat exchange materials usually include gas and liquid, semiconductor devices and phase change material (PCM). In this study, an application of PCM for a BTMS was investigated to maintain an optimal battery operating temperature range by utilizing characteristics of a PCM, which can accumulate large amounts of latent heat. The system was modeled using Dymola from Dassault Systems, a multi-physics simulation tool. In order to compare the relative performance, the BTMS with the PCM and without the PCM were modeled and the same battery charge/discharge scenarios were simulated. Number of analysis were conducted to compare the battery cooling performance between the model with the aluminum case and PCM and the model with the aluminum case only.

• Journal of Ocean Engineering and Technology
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• v.33 no.5
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• pp.470-478
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• 2019

Because the global positioning system (GPS) is not available in underwater environments, an inertial navigation system (INS)/doppler velocity log (DVL) integrated navigation system is generally implemented. In general, an INS/DVL integrated system adopts a loosely coupled method. However, in this loosely coupled method, although the measurement equation for the filter design is simple, the velocity of the body frame cannot be accurately measured if even one of the DVL transducer signals is not received. In contrast, even if only one or two velocities are measured by the DVL transducers, the tightly coupled method can utilize them as measurements and suppress the error increase of the INS. In this paper, a filter was designed to regenerate the measurements of failed transducers by taking advantage of the tightly coupled method. The regenerated measurements were the normal DVL transducer measurements and the estimated velocity in RPM. In order to effectively estimate the velocity in RPM, a filter was designed considering the effects of the tide. The proposed filter does not switch all of the measurements to RPM if the DVL transducer fails, but only switches information from the failed transducer. In this case, the filter has the advantage of being able to be used as a measurement while continuously estimating the RPM error state. A Monte Carlo simulation was used to determine the performance of the proposed filters, and the scope of the analysis was shown by the standard deviation ($1{\sigma}$, 68%). Finally, the performance of the proposed filter was verified by comparison with the conventional tightly coupled method.

• Animal Bioscience
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• v.35 no.8
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• pp.1129-1140
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• 2022

Objective: With improvements in living standards and increase in global population, the demand for meat products has been increasing; improved meat production from livestock could effectively meet this demand. In this study, we examined the differences in the muscle traits of different male crossbred sheep and attempted to identify key genes that regulate these traits. Methods: Dubo sheep×small-tailed Han sheep (DP×STH) and Suffolk×small-tailed Han sheep (SFK×STH) were selected to determine meat quality and production performance by Masson staining. Transcriptome sequencing and bioinformatic analysis were performed to identify differentially expressed genes (DEGs) related to meat quality. The presence of DEGs was confirmed by real-time polymerase chain reaction. Results: The production performance of SFK×STH sheep was better than that of DP×STH sheep, but the meat quality of DP×STH sheep was better than that of SFK×STH sheep. The muscle fiber diameter of DP×STH sheep was smaller than that of SFK×STH sheep. Twenty-two DEGs were identified. Among them, four gene ontology terms were related to muscle traits, and three DEGs were related to muscle or muscle fibers. There were no significant differences in the number of single nucleotide mutations and mutation sites in the different male parent cross combinations. Conclusion: This study provides genetic resources for future sheep muscle development and cross-breeding research.

• Journal of Advanced Navigation Technology
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• v.27 no.1
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• pp.133-138
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• 2023

As a side effect of recent rapid climate change and global warming, the frequency and scale of flood disasters are increasing worldwide. In Korea, the water level of the Han River is a major management target for preventing flood disasters in Seoul, the capital of Korea. In this paper, to improve the water level prediction of the Han River based on machine learning, we perform a comprehensive assessment of the quality of related dataset and propose data preprocessing methods to improve it. Specifically, we improve the dataset in terms of completeness, validity, and accuracy through missing value processing and cross-correlation analysis. In addition, we conduct a performance evaluation using random forest and LightGBM to analyze the effect of the proposed data improvement method on the water level prediction performance of the Han River.

• Journal of Industrial Convergence
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• v.21 no.1
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• pp.43-53
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• 2023

In China, enterprises are increasingly shifting the focus of their reforms toward stimulating the development of organizational effectiveness under the guidance of the long-term planning system. Innovative ideas and constructive suggestions originating internally are likely to inject new vitality into their ongoing development, allowing them to better face new global opportunities and challenges. Therefore, this study verifies the impact of voice endorsement and outcomes for the workers in china and selected perceived organizational support as a mediator variable. Based on theoretical research, this study proposes and tests 6 key research hypotheses using structural equation modeling(SEM). Data were collected from employees in China by the survey method. The analysis results reveal that perceived organizational support plays a mediating role in the relationship between voice endorsement and the outcomes of job satisfaction, job commitment, and job performance except for job stress.

• Journal of Korean Dental Hygiene Science
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• v.5 no.1
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• pp.39-45
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• 2022

Background: Dental hygienists undergo 3 or 4 years of college education, and dental hygienist education must receive continuous feedback through evaluation. The purpose of this study was to compare the educational performance of students from the Department of Dental Hygiene in 2018 with those from other departments in the healthcare field. Methods: We used data from the National Assessment of Student Engagement in Learning, conducted by the Korean Educational Development Institute in 2018. The survey data of 55 dental hygiene students and 60 healthcare students at K University were provided after excluding all identifying information. An independent t-test was used for comparisons between the Department of Dental Hygiene and other healthcare departments. Results: Regarding class-related activities, dental hygiene students were passive in presentations, discussions, and projects and had significantly lower grades in cooperative learning and challenging learning. Regarding extra-class activities, dental hygiene students had significantly lower global learning and external experiences, domestic experiences, club activities, and interactions with professors. Regarding learning outcomes, students had significantly lower grades in writing, speaking, critical and analytical thinking, data evaluation, understanding of data meaning, problem-solving ability, goal setting and execution, core content extraction, human and material resource utilization, creative convergence thinking, statistical understanding and analysis, information technology use, collaboration, sense of community, stress management, time management, and foreign language proficiency. Conclusions: Dental hygiene education requires innovation in educational methods and efforts of instructors to improve poor learning activities and outcomes.

• Journal of Korea Trade
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• v.26 no.7
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• pp.59-76
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• 2022

Purpose - As ahigher-order ability, improvisational capability is often employed to help a firm cope with unexpected or unanticipated issues. In light of the severe global business challenges and turbulent environmental changes, this study aimed to explore whether home-based network ties could shape the influence of improvisational capability on international entrepreneurship, alongside investigating the boundary conditions of competitive turbulence in their moderating effects. Design/methodology - The sample for the international entrepreneurship sector was obtained from the Industry and Information Technology Department of Jiangsu. In September 2021, the questionnaires were sent to the targeted ventures and required the top managers to complete the survey by email or telephone. The final research sample comprised 113 international new ventures. To test the hypotheses, moderated hierarchical regression analysis was conducted. Findings - Our empirical results suggested that (1) unlike some previous literature, a positive effect of improvisational capability on the performance of international new ventures was not found; (2) home country-based networks (both political ties and business ties) are contingent factors that may partially stimulate the value creation of improvisational capability; and (3) in a highly competitive environment, the moderating role of business ties at home may become much stronger, however, the contingent role of political ties at home was not found. Originality/value - This study mainly concentrates on the two important types of home country-based networks, political and business ties at home, that may help international new ventures access strategic resources necessary for supporting the performance implications of improvisational capability. Thus, it extends the existing improvisational theory to encompass international entrepreneurship.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.310-323
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• 2023

The k-eigenvalue neutronics/thermal-hydraulics coupling calculation is a key issue for reactor design and analysis. Jacobian-free Newton-Krylov (JFNK) method, featured with super-linear convergence rate and high efficiency, has been attracting more and more attention to solve the multi-physics coupling problem. However, it may converge to the high-order eigenmode because of the multiple solutions nature of the k-eigenvalue form of multi-physics coupling issue. Based on our previous work, a modified JFNK with a line search method is proposed in this work, which can find the fundamental eigenmode together with thermal-hydraulics feedback in a wide range of initial values. In detail, the existing modified JFNK method is combined with the line search strategy, so that the intermediate iterative solution can avoid a sudden divergence and be adjusted into a convergence basin smoothly. Two simplified 2-D homogeneous reactor models, a PWR model, and an HTR model, are utilized to evaluate the performance of the newly proposed JFNK method. The results show that the performance of this proposed JFNK is more robust than the existing JFNK-based methods.

• Information Systems Review
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• v.19 no.1
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• pp.169-183
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• 2017

As global competition is heating up and product life cycle has been rapidly shortened, each company pursues a variety of competitive technology innovations through different means of innovation. In this study, we assume that open innovation can be a shift motive of the technology innovation paradigm of small and medium enterprises (SMEs) being beyond the limitations of R&D within a company. We analyze the process and content of open innovation and performance. In addition, we identify the problems generated in the open innovation process and analyze the ways to strengthen open innovation. This study is based on the investigations into the technological competitiveness of local SMEs. The innovation ecosystem is analyzed from the perspective of product/service innovation, organizational innovation, and marketing innovation. Situational analysis is presented on the relationship between the innovation capabilities of information and communication technology SMEs and innovation performance.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.1
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• pp.143-156
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• 2024

Federated Learning (FL) has emerged as a potent methodology for decentralized model training across multiple collaborators, eliminating the need for data sharing. Although FL is lauded for its capacity to preserve data privacy, it is not impervious to various types of privacy attacks. Differential Privacy (DP), recognized as the golden standard in privacy-preservation techniques, is widely employed to counteract these vulnerabilities. This paper makes a specific contribution by applying an existing, task-specific adaptive DP mechanism to the FL environment. Our comprehensive analysis evaluates the impact of this mechanism on the performance of a shared global model, with particular attention to varying data distribution and partitioning schemes. This study deepens the understanding of the complex interplay between privacy and utility in FL, providing a validated methodology for securing data without compromising performance.