• Applied Chemistry for Engineering
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• v.35 no.3
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• pp.214-221
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• 2024

Polyether ketone (PEEK) has been widely used in membranes because of its excellent thermal stability, chemical resistance, and significant mechanical strength. However, the melting temperature is very high, making it difficult to find suitable solvents. Therefore, in this study, PEEK and benzophenone (DPK) were used as diluents to prepare a membrane with excellent mechanical strength and chemical stability using the thermally induced phase separation (TIPS) method to compensate for the shortcomings of PEEK membrane preparation and achieving the highest performances. The optimal membrane manufacturing conditions were confirmed through the crystallization temperature and cloud point according to the polymer content through the phase diagram. Subsequently, the morphological changes of the membrane, influenced by the polymer and diluent content, were confirmed through scanning electron microscopy (SEM). Additionally, the membrane thickness tended to increase with higher polymer content. Tensile strength and DI-water permeability tests were conducted to confirm the mechanical strength and permeability of the membrane. Through the previous characteristic evaluation, it was confirmed that the membrane using PEEK had excellent mechanical strength and permeability.

• Journal of Service Research and Studies
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• v.14 no.3
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• pp.60-78
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• 2024

Social Network Service(SNS) has fundamentally changed the scope, boundaries, and dynamics of social interactions, becoming an integral part of everyday social communication for individuals and significantly altering the decision-making processes of individuals and organizations. Although prior studies have agreed that individual motivations significantly affect travel experience sharing behavior on SNS, different motivations need to be further examined. Also, there is little empirical study that examines the relationships between social capital and motivations. To address these gaps, this study developed a research model to investigate how two types of social capital (i.e., bridging and bonding) influence individual motivations (i.e., self-enhancement and altruism motivations), which in turn contributes to travel experience sharing behavior on SNS. The online survey was conducted from March 3 to March 17, 2021, and 516 responses were included in the data analysis. Structural Equation Modeling was applied to test the hypotheses in a research model. This research provided a comprehensive exploration of the relationship between motivations and social capital, contributing to a better understanding of why tourists share their travel experiences on SNS.

• Journal of the Society of Disaster Information
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• v.20 no.3
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• pp.484-499
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• 2024

Purpose: Recently, due to the aging of safety facilities in national industrial complexes, there has been an increase in the frequency and scale of safety accidents, highlighting the need for a shift toward a prevention-centered disaster management paradigm and the establishment of a digital safety network. In response, this study aims to provide an information system that supports more rapid and precise decision-making during disasters by utilizing digital twin-based integrated control technology to predict the spread of hazardous substances, trace the origin of accidents, and offer safe evacuation routes. Method: We considered various simulation results, such as surface diffusion, upper-level diffusion, and combined diffusion, based on the actual characteristics of hazardous substances and weather conditions, addressing the limitations of previous studies. Additionally, we designed an integrated management system to minimize the limitations of spatiotemporal monitoring by utilizing an IoT sensor-based backtracking model to predict leakage points of hazardous substances in spatiotemporal blind spots. Results: We selected two pilot companies in the Gumi Industrial Complex and installed IoT sensors. Then, we operated a living lab by establishing an integrated management system that provides services such as prediction of hazardous substance dispersion, traceback, AI-based leakage prediction, and evacuation information guidance, all based on digital twin technology within the industrial complex. Conclusion: Taking into account the limitations of previous research, we used digital twin-based AI analysis to predict hazardous chemical leaks, detect leakage accidents, and forecast three-dimensional compound dispersion and traceback diffusion.

• Journal of Internet of Things and Convergence
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• v.10 no.4
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• pp.1-8
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• 2024

As technology advances, Internet of Things (IoT) technology is rapidly evolving as well. Various protocols, including Message Queuing Telemetry Transport (MQTT), are being used in IoT technology. MQTT, a lightweight messaging protocol, is considered a de-facto standard in the IoT field due to its efficiency in transmitting data even in environments with limited bandwidth and power. In this paper, we propose a method to improve the message transmission method in MQTT 5.0, specifically focusing on the shared subscription feature. The widely used round-robin method in shared subscriptions has the drawback of not considering the current state of the clients. To address this limitation, we propose a method to select the optimal transmission method by considering the current state. We model this problem based on Markov decision process (MDP) and utilize Q-Learning to select the optimal transmission method. Through simulation results, we compare our proposed method with existing methods in various environments and conduct performance analysis. We confirm that our proposed method outperforms existing methods in terms of performance and conclude by suggesting future research directions.

• Culinary science and hospitality research
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• v.21 no.3
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• pp.168-180
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• 2015

This study set out to make sponge cake a product of confectionery and bakery to expand the uses of rice bran and conducted a preliminary experiment to revise and supplement the addition of rice bran. The study sought to determine the level of added rice bran, 0~20%, by taking into account the taste, color, and marketability of rice bran in order to provide basic data for the possibilities of new product development and increase the usage of rice bran. As for the general composition, moisture, protein, fat, carbohydrate, and ash content comprised 9.50%, 15.51%, 18.12%, 48.17%, and 8.70% of the rice bran powder respectively. The pH of the dough decreased significantly with increased levels of rice bran. The specific gravity of the dough tended to rise significantly with the addition of rice bran. The group of 0% rice bran powder recorded the highest score of brightness, whereas the group of 20% rice bran powder scored lowest in terms of brightness. While there were significant differences between the control and experiment groups, no significant differences were found among the addition groups. Hardness also showed a tendency to significantly increase. The sensory evaluation results indicate that the group of 0% rice bran powder recorded the highest overall preference score at 5.00 and that the group of 20% rice bran powder had the lowest overall preference score at 2.87. The results also suggest that 10% rice bran powder sponge cake could be helpful in improving physical quality.

• The Journal of Engineering Geology
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• v.15 no.3
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• pp.337-348
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• 2005

Jurassic granite from Pocheon area were tested to investigate the effect of microcracks on mechanical properties of the granite. Three oriented core specimens were used for uniaxial compressive tests and each core specimen are perpendicular to the axes'R'(rift plane),'c'(grain plane) and'H'(hardway plane), respectively Among vacious elastic constants, the variation of Poisson's ratio as function of the directions was examined. From the related chart between ratio of failure strength and Poisson's ratio, H-specimen shows the highest range in Poisson's ratio and Poisson's ratio decreases in the order of C-specimen and R-specimen. The curve pattern is nearly linear in stage $I\simIII$ but the slope increases abruptly in stage H-3. As shown in the related chart, diverging point of a curve is formed when ratio of failure strength is $0.92\sim0.96$ Stage IV -3 is out of elastic region. The behaviour of rock in the four fracturing stages was analyzed in term of the stress-volumetric strain me. From the stress increment-volumetric strain equations governing the behaviour of rock, characteristic material constants, a, n, Q, m and $\varepsilon_v^{mcf}$, were determined. Among these, inherent microcrack porosity$(a, 10^{-3})$ and compaction exponent(n) in the microcrack closure region(stage I ) show an order of $a^R(3.82)>a^G(3.38)>a^H(2.32)\;and\;n^R(3.69)>n^G(2.79)>n^H(1.99)4, respectively. Especially, critical volumetric microcrack strain($\varepsilon_v^{mcf}$) in the stage W is highest in the H-specimen, normal to the hardway plane. These results indicate a strong correlation between two major sets of microcracks and mechanical properties such as Poisson's ratio and material constants. Correlation of strength anisotropy with microcrack orientation can have important application in rock fracture studies.

• Cartoon and Animation Studies
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• s.50
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• pp.75-99
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• 2018

Makoto Shinkai, an animated film maker in Japan, has been featured as a one-person production system and as a 'writer of light', but his 2016 release of "Your Name" was a departure from the elements that characterize his existing works. At the same time, by the combination of the traditional musubi(むすび) story, ending these, it was a big hit due to its rich narratives and attraction of open interpretation possibility. As it can be guessed from the title of this work, this work shows the encounter between the Japanese ancient language and the modern language in relation to the 'name', and presents the image that the role of the name(language) is repeatedly emphasized with various variations in events for the perfect 'encounter'. In this work, the interpretations of $Signifi\acute{e}$ for characters and objects are extended and reserved as a metaphorical role of the similarity, depending on the meaning of the subject which they touch. The relationship between words and objects analyzed through the structure of Signifiant and $Signifi\acute{e}$ is an epoch-making ideological discovery of modern times revealed through F. Saussure. Focusing on "the difference" between being this and that from the notion of Saussure, Derrida dismissed logocentrism, rationalism that fully obeyed the order of Logos. Likewise, dismissing the center, or dismissing the owner had emerged after the exclusive and closed principle of metaphysics in the west was dismissed. Derrida's definition of 'deconstruction' is a philosophical strategy that starts with the insight on the nature of language. 'Dissemination,' a metaphor that he used as a methodological concept to read texts acts as interpretation and practice (or play), but does not pursue an ultimate interpretation. His 'undecidability' does not start with infinity, but ends with infinity. The researcher testifies himself and identifies that we can't be an interpreter of the world because we, as a human are not the subject of language but a user. Derrida also interpreted the world of things composed of Signifiant and $Signifi\acute{e}$ as open texts. In this respect, this study aimed to read Makoto's works telling about the meeting of a thing and a thing with name as a guide, based on Derrida's frame of 'deconstruction' and 'dissemination.' This study intends to re-consider which relationship the Signifiant and $Signifi\acute{e}$ have with human beings who live in modern times, examine the relationship between words and objects presented in this work through Jacques Derrida's destruction and dissemination concepts, and recognize that we are merely a part of Signifiant and $Signifi\acute{e}$. Just as Taki and Mitsuha confirm the existence by asking each other, we are in the world of things, expecting musubi that a world of names calls me.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.596-607
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• 2017

This study examined the method for adding related to "stomach neoplasms" as filters to the Medical Subject Headings (MeSH) for search as well as a method for improving the search efficiency through a word-proximity search by measuring the distance of co-occurring terms. A total of 8,625 articles published between 2007 and 2016 with the major topic terms "stomach neoplasms" were downloaded from PubMed article titles. The vocabulary to be added to the MeSH for search were analyzed. The search efficiency was verified by 277 articles that had "Stomach Neoplasms" indexed as MEDLINE MeSH in KoreaMed. As a result, 973 terms were selected as the candidate vocabulary. "Gastric Cancer" (2,780 appearances) was the most frequent term and 7,376 compound words (88.51%) combined the histological terms of "stomach" and "neoplasm", such as "gastric adenocarcinoma" and "gastric MALT lymphoma". A total of 5,234 compounds words (70.95%), in which the co-occurring distance was two words, were found. The matching rate through the MEDLINE MeSH and KoreaMed MeSH Indexer was 209 articles (75.5%). The search efficiency improved to 263 articles (94.9%) when the search filters were added, and to 268 articles (96.7%) when the 13 word-proximity search technique of the co-occurring terms was applied. This study showed that the use of a thesaurus as a means of improving the search efficiency in a natural language search could maintain the advantages of controlled vocabulary. The search accuracy can be improved using the word-proximity search instead of a Boolean search.

• Korean Chemical Engineering Research
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• v.53 no.1
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• pp.31-38
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• 2015

At present, carbon dioxide ($CO_2$) emission, which causes global warming, is a major issue all over the world. To reduce $CO_2$ emission directly, commercial deployment of $CO_2$ separation processes has been attempted in industrial plants, such as power plant, oil refinery and steelmaking plant. Besides, several studies have been done on indirect reduction of $CO_2$ emission from recycle of reducing gas (carbon monoxide or hydrogen containing gas) in the plants. Unlike many competing gas separation technologies, pressure swing adsorption (PSA) and membrane filtration are commercially used together or individually to separate a single component from the gas mixture. However, there are few studies on operation of sequential separation process of multi-component gas which has more than two target gas products. In this paper, process simulation model is first developed for two available configurations: $CO_2$ PSA-CO PSA-$H_2$ PSA and $CO_2$ PSA-CO PSA-$H_2$ membrane. Operation optimization and economic evaluation of the processes are also performed. As a result, feed gas contains about 14% of $H_2$ should be used as fuel than separating $H_2$, and $CO_2$ separation should be separated earlier than CO separation when feed gas contains about 30% of $CO_2$ and CO. The simulation results can help us to find an optimal process configuration and operation condition for separation of multicomponent gas with $CO_2$, CO, $H_2$ and other gases.

• Progress in Medical Physics
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• v.26 no.4
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• pp.286-293
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• 2015

The purpose of this study was to evaluate the set up accuracy using stereotactic body frame and frameless immobilizer for lung stereotactic body radiation therapy (SBRT). For total 40 lung cancer patients treated by SBRT, 20 patients using stereotactic body frame and other 20 patients using frameless immobilizer were separately enrolled in each group. The setup errors of each group depending on the immobilization methods were compared and analyzed. All patients received the dose of 48~60 Gy for 4 or 5 fractions. Before each treatment, a patient was first localized to the treatment isocenter using room lasers, and further aligned with a series of image guidance procedures; orthogonal kV radiographs, cone-beam CT, orthogonal fluoroscopy. The couch shifts during these procedures were recorded and analyzed for systematic and random errors of each group. Student t-test was performed to evaluate significant difference depending on the immobilization methods. The setup reproducibility was further analyzed using F-test with the random errors excluding the systematic setup errors. In addition, the ITV-PTV margin for each group was calculated. The setup errors for SBF were $0.05{\pm}0.25cm$ in vertical direction, $0.20{\pm}0.38cm$ in longitudinal direction, and $0.02{\pm}0.30cm$ in lateral direction, respectively. However the setup errors for frameless immobilizer showed a significant increase of $-0.24{\pm}0.25cm$ in vertical direction while similar results of $0.06{\pm}0.34cm$, $-0.02{\pm}0.25cm$ in longitudinal and lateral directions. ITV-PTV margins for SBF were 0.67 cm (vertical), 0.99 cm (longitudinal), and 0.83 cm (lateral), respectively. On the other hand, ITV-PTV margins for Frameless immobilizer were 0.75 cm (vertical), 0.96 cm (longitudinal), and 0.72 cm (lateral), indicating less than 1 mm difference for all directions. In conclusion, stereotactic body frame improves reproducibility of patient setup, resulted in 0.1~0.2 cm in both vertical and longitudinal directions. However the improvements are not substantial in clinic considering the effort and time consumption required for SBF setup.