• Fire Science and Engineering
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• v.33 no.1
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• pp.23-29
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• 2019

Rechargeable battery such as lithium-ion battery has been noticed as a kinds of the energy storage system in the recent energy utilization and widely used actually in various small electronic equipment and electric vehicles. However, many thermal runaway caused battery accidents occurred recently, which still is obstacle for advanced application of lithium ion battery. One of the main differences to general fires is the existence of ionized electrolyte with electron during combustion. Therefore, we simply simulated the ion addition effects of battery fires by introducing an ionized fuel in jet diffusion flames. When the ionized methane through a corona discharge was used as fuel, the overall flame stability and shape such as flame length showed no significant difference from normal methane flame, but NOx and CO emissions measured at the post flame region decreased. The ion addition effect of methane oxidation was also numerically simulated with the modeling of hydrogen addition in the mixture. It was confirmed that the hydrogen addition at a fixed temperature had a similar effects on ionization of methane and hence could be modeled successfully.

• The Journal of the Korea Contents Association
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• v.19 no.8
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• pp.194-204
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• 2019

This study aims to review previous research on the key elements of an Initial Coin Offering (ICO) and establish their priorities in order to help relevant stakeholders build and invigorate an ecosystem that integrates blockchain technology with the digital content industry. To achieve this goal, we first structured the key elements identified from previous studies into a hierarchy model. We then assigned weighted values to each element using the Analytic Hierarchy Process (AHP) methodology. Among the main elements, the priorities were identified as follows, from most important to least: Business (0.422) > Technology (0.172) > Contents (0.144) > Human Resources (0.104) > Institutions (0.099) > Token (0.059). With regard to the sub-elements, the weighted values were found to be as follows, in descending order: Probability (0.162) > Laws and Regulations (0.071) > Estimated Growth (0.063). The implications of the results are also described within the present study. The findings of this study will be of great value to ICO founders as well as investors and provide a much-needed academic basis for the burgeoning blockchain-integrated ecosystems and businesses.

• Journal of Digital Convergence
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• v.17 no.8
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• pp.149-157
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• 2019

This study analyzed the impact of various factors on the use-diffusion of smart speakers. 300 survey responses of Chinese consumers were analyzed using structured models. The results show that both autonomy and adaptability had significant impacts on perceived usefulness and perceived easy of use. Multifunctionality and ability to cooperate affected perceived usefulness, while reactivity did not affected perceived usefulness or perceived easy of use. Anthropomorphism increased perceived enjoyment. Both perceived usefulness and perceived easy of use have been identified to improve the use-diffusion of smart speakers. Perceived enjoyment enhanced the variety of use. We expect these results help understand the factors that need to be considered for the design or marketing communication of smart products.

• Journal of the Korea Computer Graphics Society
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• v.25 no.3
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• pp.1-9
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• 2019

The image obtained from systems such as autonomous driving cars or fire-fighting robots often suffer from several degradation such as noise, motion blur, and compression artifact due to multiple factor. It is difficult to apply image recognition to these degraded images, then the image restoration is essential. However, these systems cannot recognize what kind of degradation and thus there are difficulty restoring the images. In this paper, we propose the deep neural network, which restore natural images from images degraded in several ways such as noise, blur and JPEG compression in situations where the distortion applied to images is not recognized. We adopt the channel attention modules and skip connections in the proposed method, which makes the network focus on valuable information to image restoration. The proposed method is simpler to train than other methods, and experimental results show that the proposed method outperforms existing state-of-the-art methods.

• Explosives and Blasting
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• v.37 no.2
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• pp.14-21
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• 2019

Distinct element method is a powerful numerical tool for modelling the jointed rock masses. It is also a useful tool for modelling of later stage of blasting requiring large displacement. The distinct element method utilizes a rigid block idea in which the interacting force between distinct elements is calculated from contact displacement as elements penetrate slightly. The properties of joints defined as the boundaries of distinct elements are critical parameters to determine the block behavior, and affect the deformation and failure mode. However, regardless of real joint properties, joint stiffnesses have sometimes been selected without special concern just to prevent elements from penetrating too far into each other in some quasi-static problems. Depending on whether the main interest in the analysis is the prediction of the deformation with high precision, or the prediction of the block behaviour after failure, the input data such as joint stiffness may or may not have a significant effect on the results. The purpose of this study is to provide a sound understanding of the effect of the joint stiffness on the distinct element analysis results, and to help guide the selection of input data.

• The Journal of the Korea Contents Association
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• v.18 no.12
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• pp.372-382
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• 2018

Understanding is the foundation of music appreciation, the ultimate goal of music learning. The purpose of this research was to create a model for the integration and implementation of Gordon's music learning theory principles into Suzuki violin instruction. This research shows how audiation can be taught within the framework of the Suzuki philosophy and curriculum. It is expected that Gordon's music learning theory can provide Suzuki teachers with unique capabilities for teaching musical understanding, specifically through the development of audiation. Through an audiation-based approach to Suzuki instruction, thus, young violinists will be able to learn to comprehend the tonal and rhythmic aspects of the music they perform. Future researchers may wish to assemble a more complete guide to the tonal and rhythm patterns used in the Suzuki repertoire. Furthermore, additional lesson plans and activities can and should be developed that represent the application of music learning theory to Suzuki violin instruction.

• Journal of Korean Library and Information Science Society
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• v.50 no.1
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• pp.157-176
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• 2019

Recently, as the number of closed schools continues to increase due to the super aging society, low fertility rate, declining school age population, There are cases in which a new facility or space is being reborn by utilizing idle facilities and sites of a closed school. The use of closed schools can be largely understood in the context of urban regeneration, the purpose of this study is to analyze the characteristics of the area where closed school occurred and to analyze the closure type using the evaluation standard of the decline area in urban regeneration projects. In this paper, we propose that the system and model of utilizing closed school in the library should be considered based on the characteristics, type, form, and implications of the are in which closed schools occurred which derived from research results.

• Journal of Korea Society of Industrial Information Systems
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• v.24 no.2
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• pp.1-14
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• 2019

Since most documents used in web, XML, office applications are tree-structured, diff, merge, and version control for tree-structured documents in multi-user environments are crucial tasks. However research on edit scripts which is a basis for them is in primitive stage. In this paper, we present a document model for understanding the change of tree-structured documents as edit scripts are executed, and propose a method of switching adjacent edit operations on tree-structured documents based on the analysis of the effects of edit operations. Mostly, edit scripts which are produced as the results of diff on tree-structured documents only consist of basic operations such as update, insert, delete. However, when move and copy are included in edit scripts, because of the characteristics of their complex operation, it is often that edit scripts are generated to execute in two passes. In this paper, using the proposed method of switching edit operations, we present an algorithm of transforming the edit scripts of X-treeESgen, which are designed to execute in two passes, into the ones that can be executed in one pass.

• Journal of Elementary Mathematics Education in Korea
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• v.22 no.3
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• pp.283-308
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• 2018

'Divisor and multiple' is the topic included both in the elementary and in the secondary mathematics curriculum, but there has been lack of research on it. It has been reported that students have a difficulty in understanding the meaning of the greatest common divisor (GCD) and the least common multiple (LCM), while they can find out GCD and LCM. Against the lack of research on how to overcome this difficulty, this study designed teaching methods with a model for visualization to emphasize the meanings of divisor and multiple in finding out GCD and LCM, and implemented the methods in one fourth grade classroom. A questionnaire was developed to explore students' solution methods and interviews with focused students were implemented. In addition, fourth-grade students' thinking was compared and contrasted with fifth-grade students who studied divisor and multiple with the current textbook. The results of this study showed that the teaching methods with a specific model for visualization had a positive impact on students' conceptual understanding of the process to find out GCD and LCM. As such, this study provides instructional implications on how to foster the meanings of finding out GCD and LCM at the elementary school.

• Journal of Digital Convergence
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• v.17 no.9
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• pp.39-46
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• 2019

This study started with the question of whether the percentage of non-aeronautical revenues at Incheon airport was extremely high when compared with other international airports. Although aeronautical revenues for the airport based on the traditional business model have the limits to grow due to various regulations, stakeholders concerned about improving the competitiveness recently have been interested in increasing non-aeronautical revenues. This study deals with the effect of non-aeronautical revenues at international airports on airport charges as the extent of airport privatization get stronger. To examine hypotheses, we collected international data from trustful sources. Finally, we conducted an empirical analysis of 178 airports worldwide. As a result, the higher the percentage of non-aeronautical revenues at international airports, the lower the airport charges were. Besides, the private equity ratio positively moderated the relationship between the percentage of non-aeronautical revenues and airport charges. Privatization of airports may offset the effects of reduced airport charges through increased commercial activity. Graphical display for moderation effect is offered to facilitate comprehension.