• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.17 no.2
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• pp.1-10
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• 2021

Lithium-ion batteries with high energy density, long cycle life and other advantages, have been widely used to energy storage systems(ESS). But as ESS fires frequently occur, the safety concern has become the main obstacle that hinders the large-scale applications of lithium-ion batteries. Especially, thermal runaway is the key scientific problem in battery safety research. Therefore, in this study, we performed a numerical analysis on the thermal runaway phenomenon of NCM111, NCM523 and NCM622 batteries using a two-dimensional analysis model. The results show that the two-dimensional simulation results are generally matched with three-dimensional simulation. Also, In the case of NCM111 with a low Ni content in the temperature range used in this study, thermal runaway phenomenon does occurred very slowly, but as the Ni content is increased, the thermal runaway phenomenon occurs rapidly and the thermal stability tends to be decreased. And, in NCM523 and NCM622 batteries, chain reactions occur almost simultaneously, but in the case of NCM111 battery, it is found that after the SEI(Solid Electrolyte Interface) layer decomposition reaction, the cathode-electrolyte reaction is appeared sequentially. After that, the anodic decomposition reaction is increased and leads to the thermal runaway reaction.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.4
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• pp.408-417
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• 2021

This paper describes the quality attributes of an integrated simulation software for weapon systems named Advanced distributed simulation environment(AddSIM). AddSIM is developed as a key enabler for Defense Modeling & Simulation(M&S) systems which simulate battlefields and used for battle experiments, analyses, military exercises, training, etc. AddSIM shall provide a standard simulation framework of the next Defense M&S systems. Therefore AddSIM shall satisfy not only functional but also quality requirements such as availability, modifiability, performance, testability, usability, and others. AddSIM consists of operating softwares of hierarchical components including graphical user interface, simulation engines, and support services(natural environment model, math utility, etc.), and separated weapon system models executable on the operating softwares. The relation between software architectures and their quality attributes are summarized from previous works. And the AddSIM architecture and its achievements in the aspect of quality attributes are reviewed.

• Journal of Information Processing Systems
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• v.16 no.6
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• pp.1372-1390
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• 2020

An attractive user interface (UI) design with a clear user experience (UX) is the key for the success of applications. Therefore software development projects require very close collaboration between SI developers and front-end service developers. However, methodologies for software development only exist with inadequate development processes or work standards for collaboration. This survey derived 13 risk factors in developing UI/UX from 113 risk factors of IT projects through a questionnaire and factor analysis and proposed a collaboration-based UI/UX development model that can eliminate or mitigate six risks with high weights and reliability. To extract risk factors with high reliability, factor and reliability were analyzed to extract 13 major risks, and based on the expert opinions and the results of correlation analysis, UI/UX development stages were classified into planning, design, and implementation. The causal relationships between risks were verified through regression analysis. This study is the first to expertly analyze major risks based on collaboration in UI/UX development and derive a theoretical basis that can be used in project risk management. These findings are expected to provide a basis for research on development methodologies for higher levels of front-end services and to construct rational collaboration systems between SI practitioners and front-end service providers.

• Steel and Composite Structures
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• v.37 no.6
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• pp.741-759
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• 2020

Steel plate-concrete composite slabs provide attractive features, such as more effective loading transfer, and more cost-effective stay-in-place forms, thereby enabling engineers to design more high-performance light structures. Although significant studies in the literatures have been directed toward designing and implementing the steel plate-concrete composite beams, there are limited data available for understanding of the composite slabs. To fill this gap, nine the composite slabs with different variables in this study were tested to unveil the impacts of the critical factors on the ultimate strength behavior. The key information of the findings included sample failure modes, crack pattern, and ultimate strength behavior of the composite slabs under either four-point or three-point loading. Test results showed that the failure modes varied from delamination to shear failures under different design factors. Particularly, the shear stud spacing and thicknesses of the concrete slabs significantly affected their ultimate load-carrying capacities. Moreover, an analytical model of the composite slabs was derived for determining their ultimate load-carrying capacity and was well verified by the experimental data. Further extensive parametric study using the proposed analytical methods was conducted for a more comprehensive investigation of those critical factors in their performance. These findings are expected to help engineers to better understand the structural behavior of the steel plate-concrete composite slabs and to ensure reliability of design and performance throughout their service life.

• Steel and Composite Structures
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• v.42 no.2
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• pp.191-207
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• 2022

Undoubtedly, the employment of direct bond interaction between steel and concrete is preceding the other mechanisms because of its ease of construction. However, the large scatter in the experimental data about the issue has hindered the efforts to characterize bond strength. In the following research, the direct bond interaction and bond-slip behavior of CFTs with circular cross-section were examined through repeated load-reversed push-out tests until four cycles of loading. The influence of different parameters including the diameter of the tube and the use of shear tabs were assessed. Moreover, the utilization of expansive concrete and external spirals was proposed and tested as ways of improving bond strength. According to the results section dimensions, tube slenderness, shrinkage potential of concrete, interface roughness and confinement are key factors in a natural bond. Larger diameters will lead to a considerable drop in bond strength. The use of shear tabs by their associated bending moments increases the bond stress up to eight times. Furthermore, employment of external spirals and expansive concrete have a sensible effect on enhancing bonds. Macro-locking was also found to be the main component in achieving bond strength.

• Advances in materials Research
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• v.12 no.1
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• pp.43-65
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• 2023

Free vibration analysis of power law and sigmoidal sandwich plates made up of functionally graded materials (FGMs) has been carried out using finite element based higher-order zigzag theory. The present model satisfies all-important conditions such as transverse shear stress-free conditions at the plate's top and bottom surface along with continuity condition for transverse stresses at the interface. A Nine-noded C0 finite element having eleven degrees of freedom per node is used during the study. The present model is free from the requirement of any penalty function or post-processing technique and hence is computationally efficient. The present model's effectiveness is demonstrated by comparing the present results with available results in the literature. Several new results have been proposed in the present work, which will serve as a benchmark for future works. It has been observed that the material variation law, power-law exponent, skew angle, and boundary condition of the plate widely determines the free vibration behavior of sandwich functionally graded (FG) plate.

• Journal of Platform Technology
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• v.10 no.4
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• pp.56-61
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• 2022

Various convergence technologies discovered through the 4th industrial revolution are permeating the industry. Drones are being used in industries such as construction, transportation, and national defense based on convergence technology. Quart-copter drone control is being used in a wide range of fields from the visual field of operation with the naked eye to the remote field of view using GCS. If we classify those who operate industrial drones, there are general pilots who directly use drones, instructors who train drone pilots, and mechanics who check the status of drones and use them for a long time. Depending on the shape of the screen of the drone GCS, a user's quick response or key data can be acquired. Accordingly, in this study, GUI characteristics were analyzed for the mission planner GCS and a screen composition method according to the user was proposed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.5
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• pp.1489-1515
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• 2022

The number of interconnected real-world devices such as sensors, actuators, and physical devices has increased with the advancement of technology. Due to this advancement, users face difficulties searching for the location of these devices, and the central issue is the findability of Things. In the WoT environment, keyword-based and geospatial searching approaches are used to locate these devices anywhere and on the web interface. A few static methods of indexing and ranking are discussed in the literature, but they are not suitable for finding devices dynamically. The authors have proposed a mechanism for dynamic and efficient searching of the devices in this paper. Indexing and ranking approaches can improve dynamic searching in different ways. The present paper has focused on indexing for improving dynamic searching and has indexed the Things Description in Solr. This paper presents the Things Description according to the model of W3C JSON-LD along with the open-access APIs. Search efficiency can be analyzed with query response timings, and the accuracy of response timings is critical for search results. Therefore, in this paper, the authors have evaluated their approach by analyzing the search query response timings and the accuracy of their search results. This study utilized different indexing approaches such as key-words-based, spatial, and hybrid. Results indicate that response time and accuracy are better with the hybrid approach than with keyword-based and spatial indexing approaches.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.05a
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• pp.339-341
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• 2023

This paper presents a multithread and efficient cryptographic hardware access (MECHA) for efficient and fast cryptographic operations that eliminates the need for context switching. Utilizing a UNIX domain socket, MECHA manages multiple requests from multiple applications simultaneously, resulting in faster processing and improved efficiency. We comprise several key components, including the Server thread, Client thread, Transceiver thread, and a pair of Sender and Receiver queues. MECHA design is portable and can be used with any communication protocol, with experimental results demonstrating a 83% increase in the speed of concurrent cryptographic requests compared to conventional interface design. MECHA architecture has significant potential in the field of secure communication applications ranging from cloud computing to the IoT, offering a faster and more efficient solution for managing multiple cryptographic operation requests concurrently.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.1
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• pp.43-47
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• 2024

The size of semiconductor devices has been scaled down to improve packing density and output performance. However, there is uncontrollable spreading of the dopants that comprise the well, punch-stop, and channel-stop when using high-temperature annealing processes, such as rapid thermal annealing (RTA). In this context, low-temperature deuterium annealing (LTDA) performed at a low temperature of 300℃ is proposed to reduce the thermal budget during CMOS fabrication. The LTDA effectively eliminates the interface trap in the gate dielectric layer, thereby improving the electrical characteristics of devices, such as threshold voltage (V_TH), subthreshold swing (SS), on-state current (I_ON), and off-state current (I_OFF). Moreover, the LTDA is perfectly compatible with CMOS processes.