• Journal of Positioning, Navigation, and Timing
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• v.11 no.1
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• pp.23-28
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• 2022

The eLoran system is a high-power terrestrial navigation system that is recognized as the most appropriate alternative to complement the GNSS's vulnerability to radio frequency interference. Accordingly, Korea has conducted eLoran technology development projects since 2016. The eLoran system developed in Korea provides 20 m positioning accuracy to maritime user in Incheon and Pyeongtaek harbor. To accurately calculate the position with the eLoran signal, it is necessary to apply a compensation method that mitigates the propagation delay. In this paper, we develop the compensation method to mitigate the eLoran signal propagation delay and evaluate the positioning performance in Incheon harbor. The propagation delay due to the terrain characteristics is pre-surveyed and stored in the user receiver. Real-time fluctuations in propagation delay compared to the pre-stored data are mitigated by the temporal correction generated at a nearby differential Loran station. Finally, two performance evaluation tests were performed to verify the positioning accuracy of the Korean eLoran system. The first test took place in December 2020 and the second in April 2021. As a result, the Korean eLoran service has been confirmed to provide 20 m location accuracy without GPS.

• Smart Structures and Systems
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• v.31 no.6
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• pp.573-583
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• 2023

Although unmanned aerial vehicles have been used to overcome the limited accessibility of human-based visual inspection, unresolved issues still remain. Onsite inspectors face difficulty finding previously detected damage locations and tracking their status onsite. For example, an inspector still marks the damage location on a target structure with chalk or drawings while comparing the current status of existing damages to their previous status, as documented onsite. In this study, an augmented-reality-based structural inspection system with onsite damage information marking was developed to enhance the convenience of inspectors. The developed system detects structural damage, creates a holographic marker with damage information on the actual physical damage, and displays the marker onsite via an augmented reality headset. Because inspectors can view a marker with damage information in real time on the display, they can easily identify where the previous damage has occurred and whether the size of the damage is increasing. The performance of the developed system was validated through a field test, demonstrating that the system can enhance convenience by accelerating the inspector's essential tasks such as detecting damages, measuring their size, manually recording their information, and locating previous damages.

• The Journal of the Convergence on Culture Technology
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• v.9 no.4
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• pp.617-623
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• 2023

Among the fire incidents in Korea over the past decade, building fires are the most common, and property and human casualties are the most common. However, the existing fire fighting system does not only inform the location of emergency exits and guide safe routes to help casualties evacuate smoothly. A system was proposed to help successful evacuation by distinguishing vertical and horizontal characteristics using spatial characteristics. In this study, an effective evacuation system was proposed by predicting fires using temperature detection sensors and smoke sensor values, and calculating the optimal evacuation path through the Dijkstra algorithm.

• 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 Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.374-375
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• 2022

Recently, Metaverse service has been widely used to naturally communicate with a remote location, freeing from time and spatial constraints. In order to produce such contents, it is necessary to restore and synthesize a 3D model based on real space data. In this paper, a 3D-generated reconstruction model is produced based on continuous images using multiple cameras and a technique to correct the reconstructed 3D model is presented. For this. offline multi-camera setup was performed, errors were analyzed on the 3D model created through images obtained from various angles, and correction was performed using a matching technique between image frames. It is expected that 3D reconstructed data can be utilized in various service fields such as culture, tourism, and medical care.

• Smart Media Journal
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• v.12 no.9
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• pp.38-44
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• 2023

In this paper, a blockchain-based platform of NFT(Non-Fungible Token) reports was proposed to ensure the reliable performance contents of field study trip. It is possible to identify and manage the personal multi biomeric authentication user ID of activity records for students in a mobile IP-based metaverse with the linkage of extended reality(XR). At this time, many quests and incentives of platform are provided to induce students to experience smart and fun field studying facilities by linking real trip experiences and virtual extended_reality studies in the metaverse interworking.

• Structural Monitoring and Maintenance
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• v.10 no.3
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• pp.261-281
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• 2023

Magnetic flux sensors are commonly used in monitoring the cable force, but the application of the sensors in large diameter non-closed Galfan cables, as those adopted in Yueqing Gymnasium which is located in Yueqing City, Zhejiang Province, China and is the largest span hybrid space structure in the world, is seldom done in engineering. Based on the construction of Yueqing Gymnasium, this paper studies the cable tension monitoring using the magnetic flux method across two stages, namely, the pre-calibration stage before the cable leaves the rigging factory and the field tension formation stage of the cable system. In the pre-calibration stage in the cable factory, a series of 1:1 full-scale comparative tests were carried out to study the feasibility and relability of this kind of monitoring method, and the influence on the monitoring results of charging and discharging voltage, sensor location, cable diameter and fitting method were also studied. Some meaningful conclusions were obtained. On this basis, the real-time cable tension monitoring system of the structure based on the magnetic flux method is established. During the construction process, the monitoring results of the cables are in good agreement with the data of the on-site pressure gauge.The work of this paper will provide a useful reference for cable force monitoring in the construction process of long-span spatial structures.

• Corrosion Science and Technology
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• v.23 no.3
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• pp.228-234
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• 2024

Zinc wiping is a phenomenon used to control zinc-coating thickness on steel substrate during hot dip galvanizing by equipment called air knife. Uniformity of zinc coating weight in length and width profile along with surface quality are most critical quality parameters of galvanized steel. Deviation from tolerance level of coating thickness causes issues like overcoating (excess consumption of costly zinc) or undercoating leading to rejections due to non-compliance of customer requirement. Main contributor of deviation from target coating weight is dynamic change in air knives equipment setup when thickness, width, and type of substrate changes. Additionally, cold coating measurement gauge measure coating weight after solidification but are installed down the line from air knife resulting in delayed feedback. This study presents a coating weight control model (Galvantage) predicting critical air knife parameters air pressure, knife distance from strip and line speed for coating control. A reverse engineering approach is adopted to design a predictive, prescriptive, and descriptive model recommending air knife setups that estimate air knife distance and expected coating weight in real time. Implementation of this model eliminates feedback lag experienced due to location of coating gauge and achieving setup without trial-error by operator.

• Nuclear Engineering and Technology
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• v.56 no.8
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• pp.3180-3187
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• 2024

Rupture disk corrosion test (RDCT) method has been recently developed for real-time measurement of initiation of stress corrosion cracking (SCC) in a high-temperature water. This work presents a parametric study on the stress distribution of a thin disk specimen of RDCT to consider the fixture shape and friction using finite element analysis (FEA). The FEA results showed a dome-shaped deformation of the specimen. From the stress analysis as a function of friction coefficient, it was suggested that the maximum stress was applied around the dome-edge, which was invariant with change to the friction coefficient. This indicates that friction between the fixture and the specimen has little effect on stress distribution. On the other hand, the stress analysis as a function of a rounded-corner radius (Rc) revealed the location at which the maximum stress was applied shifted from the dome edge to the dome center as Rc increased. From SCC initiation tests using the RDCT apparatus in a primary water environment, it was found that SCC initiates at the dome edge when Rc is 0.5 mm, while SCC initiates near the disk center when Rc is 2.0 mm. This experimental result is in good agreement with the results of FEA.

• Cross-Cultural Studies
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• v.34
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• pp.93-114
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• 2014

Gaston Bachelard had a revolutionary progress in the field of human understanding by proposing his theory of image and imagination. His theory of the new image was so powerful, almost all areas of human science, particularly that of literary criticism, were strongly influenced and this influence continues until today. Today almost everyone accepts his theory of the image without much objection, but not rarely asked where began his transfer from the philosophy of science to the images. We propose a hypothesis that the beginning of the new concept of Bachelard's image was inspired by studies of contemporary science, especially quantum mechanics. The Heisenberg's uncertainty principle was the core of quantum mechanics, and opens new perspectives on the material world. We could summarize the message of the uncertainty principle : the material world is made up of various layers, and the material can not be measured by the location and movement at the same time. So we must have a new point of view of another dimension to know this material world. Bachelard had accepted this view of Heisenberg and developed his own theory of epistemological rupture. What is revolutionary in the theory of Bachelard's image is the fact that he looked at the images with the new perspective. The human psyche is another world compared to the rational world that dominates our daily lives. Bachelard insists that the image can not be explained by the concept. The fantasy world is a totally different world to that of rationality. That is why it can not be explained by the language of rationality as the concept. The imaginary world exists independently of the real world, but it is superimposed on the real world. These two worlds are influencing each other, and it is between these two world where our daily lives continues. The declaration of Bachelard 'image is a specific reality' is never a metaphor or rhetorical expression. This is an ontological expression that must truthfully. The imaginary world is a world built on the image and it works according to its own law. It is not a representation or copy of the real world. But the world of imagination are not alone. It exists in the same time and space with the world of science. It is superimposed with the world of science. Both two world influence each other. Bachelard has made a revolutionary change by studying the images. He gave them their own place. It has changed the views on the images that were treated as mere representations of reality. Thanks to him, the image can have its own value, that of a factor that creates reality. Bachelard shows how we can go deep into the source of being and the universe if we look at the pictures with the eyes of other dimensions.