• Korean Journal of Remote Sensing
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• v.39 no.4
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• pp.371-393
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• 2023

Crack detection in structures plays a vital role in ensuring their safety, durability, and reliability. Traditional crack detection methods sometimes need significant manual inspections, which are laborious, expensive, and prone to error by humans. Deep learning algorithms, which can learn intricate features from large-scale datasets, have emerged as a viable option for automated crack detection recently. This study presents an in-depth review of crack detection methods used till now, like image processing, traditional machine learning, and deep learning methods. Specifically, it will provide a comparative analysis of crack detection methods using deep learning, aiming to provide insights into the advancements, challenges, and future directions in this field. To facilitate comparative analysis, this study surveys publicly available crack detection datasets and benchmarks commonly used in deep learning research. Evaluation metrics employed to check the performance of different models are discussed, with emphasis on accuracy, precision, recall, and F1-score. Moreover, this study provides an in-depth analysis of recent studies and highlights key findings, including state-of-the-art techniques, novel architectures, and innovative approaches to address the shortcomings of the existing methods. Finally, this study provides a summary of the key insights gained from the comparative analysis, highlighting the potential of deep learning in revolutionizing methodologies for crack detection. The findings of this research will serve as a valuable resource for researchers in the field, aiding them in selecting appropriate methods for crack detection and inspiring further advancements in this domain.

• Smart Media Journal
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• v.12 no.6
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• pp.27-34
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• 2023

As Netflix usage has increased due to the COVID-19 pandemic, users' experiences with the service have also increased. Therefore, this study aims to conduct topic modeling analysis based on Netflix review data to explore the changes in Netflix user experience and service before and after the COVID-19 pandemic. We collected Netflix app review data from the Google Play Store using the Google Play Scraper library, and used topic modeling to examine keyword differences between app reviews before and after the pandemic. The analysis revealed four main topics: Netflix app features, Netflix content, Netflix service usage, and Netflix overall reviews. After the pandemic, when user experience increased, users tended to use more diverse and detailed keywords in their reviews. By using Netflix review data to analyze users' opinions, this study shows the changes in user experience of Netflix services before and after the pandemic, which can be used as a guide to strengthen competitiveness in the competitive OTT market.

• Journal of the Korea Society of Computer and Information
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• v.28 no.12
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• pp.221-229
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• 2023

Recently, Grid-forming(GFM) converter, which offers features such as virtual inertia, damping, black start capability, and islanded mode operation in power systems, has gained significant attention. However, in low-voltage microgrids(MG), it faces challenges due to the coupling phenomenon between active and reactive power caused by the low line impedance X/R ratio and a non-negligible power angle. This power coupling issue leads to stability and performance degradation, inaccurate power sharing, and control parameter design problems for GFM converters. Therefore, this paper serves as a review study on not only control methods associated with GFM converters but also power decoupling techniques. The aim is to introduce promising control methods and enhance accessibility to future research activities by providing a critical review of power decoupling methods. Consequently, by facilitating easy access for future researchers to the study of power decoupling methods, this work is expected to contribute to the expansion of distributed power generation.

• Journal of Electrochemical Science and Technology
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• v.15 no.1
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• pp.96-110
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• 2024

Polymer electrolyte membrane fuel cells (PEMFCs) are green energy conversion devices, for which commercial markets have been established, owing to their application in fuel cell vehicles (FCVs). Development of cathode electrocatalysts, replacing commercial Pt/C, plays a crucial role in factors such as cost reduction, high performance, and durability in FCVs. PtNi octahedral catalysts are promising for oxygen reduction reactions owing to their significantly higher mass activity (10-15 times) than that of Pt/C; however, their application in membrane electrode assemblies (MEAs) is challenged by their low stability. To overcome this durability issue, various approaches, such as third-metal doping, composition control, halide treatment, formation of a Pt layer, annealing treatment, and size control, have been explored and have shown promising improvements in stability in rotating disk electrode (RDE) testing. In this review, we aimed to compare the features of each strategy in terms of enhancing stability by introducing a stability improvement factor for a direct and reasonable comparison. The limitations of each strategy for enhancing stability of PtNi octahedral are also described. This review can serve as a valuable guide for the development of strategies to enhance the durability of octahedral PtNi.

• Journal of Korean Foot and Ankle Society
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• v.16 no.2
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• pp.94-100
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• 2012

Purpose: The purpose of this study is to analyze the clinical features of distal tibia fractures and to evaluate the treatment outcomes of minimally invasive plate osteosynthesis (MIPO). Materials and Methods: From January 2004 to December 2009, 84 cases of 81 patients treated with plate fixation for distal tibia fracture were enrolled in this retrospective review. We investigated age, sex, injury mechanism, fracture patterns, and complications, and the clinical features were analyzed. To evaluate the treatment outcomes of MIPO, we divided into two groups. MIPO group consisted of 55 patients were treated with MIPO technique and conventional group consisted of 18 patients were treated with open reduction and internal fixation with conventional anterolateral plating. The results were compared between two groups by assessing bony union time, operation time, amount of blood loss, range of ankle motion, clinical score by American Orthopaedic Foot and Ankle Society (AOFAS) score, and post-operative complications. Results: The mean age of 81 patients with distal tibia fracture was 54.8 years. According to AO classification, A1:2:3 were 16, 20, 16 patients, B1:2:3 were 2, 8, 7, C1:2:3 were 1, 3, 11 patients. According to injury mechanism, slip down injury was patients, traffic accident was 26, fall from height injury was 14 patients respectively. The type A fractures were lower energy trauma and more older patients. The type C fractures were higher energy trauma and younger patients. MIPO group was better than conventional group in operative time, blood loss, bony union time, and ankle joint motion. In complications, MIPO group showed no nonunion and infection, one malunion, one skin necrosis, nine skin irritations, and one screw breakage. Conventional group showed two nonunion, four infections, two skin necrosis, and one metal failure. Conclusion: Distal tibial fractures caused by low energy trauma were on the increase. Minimal invasive plate osteosynthesis was shorter bony union time and operation time, less blood loss, and larger ankle motions than conventional open reduction and plate fixation.

• Journal of Korean Elementary Science Education
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• v.25 no.2
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• pp.126-140
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• 2006

The purpose of this study was to design a 'Form of Abduction' which is the 'guide form used in generating hypothesis through abduction', and to analyze the features of the hypotheses generated with the 'Form of Abduction' compared with those generated without any special guide form. Through a review of Peirce's literature regarding the meaning and frame of abduction, a 'Form of Abduction' was designed as a three step format as follows: (i) writing down what is doubted, (ii) wiling tentative explanations which replace what is doubted with what is believed, (iii) writing the tentative explanations as hypotheses. The thirty four pre-service elementary teachers were asked to generate hypotheses without a 'Form of Abduction' at first, and then were asked to do so again using the form. The results of analysing the features of the hypotheses were as follows: in the case of using a 'Form of Abduction', firstly, the types of misunderstanding or mis-adapting the meaning of hypothesis were found to be rare, and secondly, the types of 'giving explanation about the cause of problematic situations through analogical inferencing from the existing knowledge' were found to be double the rate of when no special guide form was used. In conclusion, the hypotheses generated with the 'Form of Abduction' had the features of satisfying the original meaning of hypothesis, i.e. 'explaining the cause of phenomenon and leading to knowledge expansion'. These results also showed that using a 'Form of Abduction', although its form was simple, could be a way of helping students generate hypothesis properly in science classes.

• (The)Study of the Eastern Classic
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• no.68
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• pp.209-235
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• 2017

This study was conducted for a review of Park Se-chae's Theory of Rituals and eclectic features. He was in agreement with Song Si-yeol's allegation and Seoin's theory of rituals(西人禮論) in the 1659 controversy over propriety(己亥禮訟) and the 1674 controversy over propriety(甲寅禮訟). After that, he was cautious and criticized for Song's claims in 1683 discussion of Hyojong's sacrifices and Taejo's posthumous name. This tendency can be seen in his paper of rituals. He wrote "服制私議"(Private opinion of mourning clothes) etc. in his early life and wrote "關西昏喪契約束"(Covenant on wedding ceremonies and mourning ceremonies in the Gwanse province), "喪祭値疫痘說"(Mourning ceremonies and sacrifice when there is an epidemic) etc. in his later life. By comparing the books, we can identify changes in Park Se-chae's eclectic features. Early in life, he reviewed Gorye(古禮, Rituals of the old such as Liji) and the timely institutions(時制) on the "朱子家禮"(A book written by Zhuzi about family rituals). However, later in life, he reviewed Gorye and the Zhuzi Jiali on the timely institutions. The following is a summary of the above. His theory of rituals can be said that the eclectic features have changed from 'on Zhuzi Jiali' to 'on the timely institution'.

• Journal of Intelligence and Information Systems
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• v.29 no.4
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• pp.325-345
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• 2023

In the rapidly evolving domain of e-commerce, our study presents a cohesive approach to enhance customer satisfaction prediction from online reviews, aligning methodological innovation with practical insights. We integrate the RFE-SHAP feature selection with LDA topic modeling to streamline predictive analytics in e-commerce. This integration facilitates the identification of key features-specifically, narrowing down from an initial set of 28 to an optimal subset of 14 features for the Random Forest algorithm. Our approach strategically mitigates the common issue of overfitting in models with an excess of features, leading to an improved accuracy rate of 84% in our Random Forest model. Central to our analysis is the understanding that certain aspects in review content, such as quality, fit, and durability, play a pivotal role in influencing customer satisfaction, especially in the clothing sector. We delve into explaining how each of these selected features impacts customer satisfaction, providing a comprehensive view of the elements most appreciated by customers. Our research makes significant contributions in two key areas. First, it enhances predictive modeling within the realm of e-commerce analytics by introducing a streamlined, feature-centric approach. This refinement in methodology not only bolsters the accuracy of customer satisfaction predictions but also sets a new standard for handling feature selection in predictive models. Second, the study provides actionable insights for e-commerce platforms, especially those in the clothing sector. By highlighting which aspects of customer reviews-like quality, fit, and durability-most influence satisfaction, we offer a strategic direction for businesses to tailor their products and services.

• Journal of Communications and Networks
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• v.5 no.4
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• pp.386-393
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• 2003

Future wireless networks are expected to achieve high bit rates at low cost, enabling multimedia and QoS-based services over the wireless medium. The impulse radio ultra-wide band (IR-UWB) technique is a promising candidate in the deployment of such networks, thanks to its potential robustness and capacity. In the past, most of the UWB research focused on hardware and physical layer aspects in order to solve the technological challenges posed by IR-UWB. UWB peculiar characteristics may, however, also stimulate innovative higher layers’ design. This work addresses MAC issues for UWB communication systems. Key areas such as medium sharing, MAC organization, packet scheduling and power control are reviewed. The impact of UWB on the above functions is discussed, and areas which require UWB specific design are identified. Finally, novel MAC functions enabled by UWB specific features, i.e., precise ranging and positioning, are presented.

• Journal of the Korean Society for information Management
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• v.9 no.2
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• pp.97-117
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• 1992

The lastest stagc of I, AN can bc characterized as easy of -use, peer - to -peer, and end - user trans parency connectlvlt) I, ~brar~e\ concernmg I A N for ~ntergratcd onhe ~nformation system need to un dcrstand the swer.il important features of the installation. Th~s paper descr~bes some of ttwse feature\ and how the) arc ~rnplc mentcd.