• Tunnel and Underground Space
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• v.34 no.3
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• pp.218-230
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• 2024

Recently, many studies have been conducted for safety management in construction sites by incorporating computer vision. Anchor box parameters are used in state-of-the-art deep learning-based object detection and segmentation, and the optimized parameters are critical in the training process to ensure consistent accuracy. Those parameters are generally tuned by fixing the shape and size by the user's heuristic method, and a single parameter controls the training rate in the model. However, the anchor box parameters are sensitive depending on the type of object and the size of the object, and as the number of training data increases. There is a limit to reflecting all the characteristics of the training data with a single parameter. Therefore, this paper suggests a method of applying multiple parameters optimized through data split to solve the above-mentioned problem. Criteria for efficiently segmenting integrated training data according to object size, number of objects, and shape of objects were established, and the effectiveness of the proposed data split method was verified through a comparative study of conventional scheme and proposed methods.

• Journal of Cadastre & Land InformatiX
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• v.54 no.1
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• pp.19-32
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• 2024

This study examined the feasibility of image-based surveys by detecting objects in facilities and agricultural land using the YOLO algorithm based on drone images and comparing them with the land category by law. As a result of detecting objects through the YOLO algorithm, buildings showed a performance of detecting objects corresponding to 96.3% of the buildings provided in the existing digital map. In addition, the YOLO algorithm developed in this study detected 136 additional buildings that were not located in the digital map. Plastic greenhouses detected a total of 297 objects, but the detection rate was low for some plastic greenhouses for fruit trees. Also, agricultural land had the lowest detection rate. This result is because agricultural land has a larger area and irregular shape than buildings, so the accuracy is lower than buildings due to the inconsistency of training data. Therefore, segmentation detection, rather than box-shaped detection, is likely to be more effective for agricultural fields. Comparing the detected objects with the land category by law, it was analyzed that some buildings exist in agricultural and forest areas where it is difficult to locate buildings. It seems that it is necessary to link with administrative information to understand that these buildings are used illegally. Therefore, at the current level, it is possible to objectively determine the existence of buildings in fields where it is difficult to locate buildings.

• Journal of Korean Society of Disaster and Security
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• v.17 no.1
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• pp.1-8
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• 2024

In Korea, mountainous areas cover 60% of the land, leading to increased factors such as concentrated heavy rainfall and typhoons, which can result in debris flow and landslide. Despite the high risk of disasters like landslides and debris flow, there has been a tendency in most regions to focus more on post-damage recovery rather than preventing damage. Therefore, in this study, precise topographic data was constructed by conducting on-site surveys and drone measurements in areas where debris flow actually occurred, to analyze the risk zones for such events. The numerical analysis program RAMMS model was utilized to perform debris flow analysis on the areas prone to debris flow, and the actual distribution of debris flow was compared and analyzed to evaluate the applicability of the model. As a result, the debris flow generation area calculated by the RAMMS model was found to be 18% larger than the actual area, and the travel distance was estimated to be 10% smaller. However, the simulated shape of debris flow generation and the path of movement calculated by the model closely resembled the actual data. In the future, we aim to conduct additional research, including model verification suitable for domestic conditions and the selection of areas for damage prediction through debris flow analysis in unmeasured watersheds.

• Composites Research
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• v.37 no.3
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• pp.204-208
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• 2024

De-icing/anti-icing fluid is essential for removing ice formation on aircraft. It chemically removes ice using organic solvents, which can cause damage to the topcoat surface in the process. In this study, glycol-based deicing/anti-icing fluid was used to remove ice, and the resulting damage to the topcoat was examined. USB microscope was used to observe the formation and growth of ice, while a confocal microscope was employed to observe the surface morphology after treatment with de-icing/anti-icing fluid. Additionally, coating thickness measurements and Fourier transform infrared (FT-IR) analysis were conducted to investigate the physical and chemical changes on the surface. The repeated application of de-icing/anti-icing fluid showed a reduction in the ice formation rate and an increase in the growth rate. Damage during the pressurization process and surface damage to the polyurethane topcoat caused by ethylene glycol were observed during the de-icing process. Although no chemical changes were detected, the analysis revealed that surface uniformity decreased, with physical damage such as cracks and undulations forming on the surface. It was confirmed that while de-icing/anti-icing fluid is effective in removing ice, it also causes surface damage.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.6
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• pp.403-421
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• 2023

As the number of underground structures has increased in recent decades, it has become crucial to predict geological hazards ahead of a tunnel face during tunnel construction. Consequently, this study developed a finite element (FE) numerical model to simulate electrical resistivity surveys in tunnel boring machine (TBM) operations for predicting mixed ground conditions in front of tunnel faces. The accuracy of the developed model was verified by comparing the numerical results not only with an analytical solution but also with experimental results. Using the developed model, a series of parametric studies were carried out to estimate the effect of geological conditions and sensor geometric configurations on electrical resistivity measurements. The results of these studies showed that both the interface slope and the difference in electrical resistivity between two different ground formations affect the patterns and variations in electrical resistivity observed during TBM excavation. Furthermore, it was revealed that selecting appropriate sensor spacing and optimizing the location of the electrode array were essential for enhancing the efficiency and accuracy of predictions related to mixed ground conditions. In conclusion, the developed model can serve as a powerful and reliable tool for predicting mixed ground conditions during TBM tunneling.

• Journal of Advanced Technology Convergence
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• v.3 no.1
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• pp.21-31
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• 2024

The study confirmed the relationship between attractiveness and suitability in the relationship between the formativeness of creating the artistic form of a virtual influencer who acts as an advertising model, advertising attention, and advertising attitude. To confirm this, the subjects of the study were the MZ generation and X generation, which have a high rate of SNS use. The analysis method used SPSS statistics 27.0 and SPSS process macro version. The research results are as follows. First, it was confirmed that attractiveness and suitability fully mediate the relationship between formativeness and advertising attention. In the path of formativeness and advertising attention, the total effect was found to be higher than the direct effect, and it was confirmed that there was a double parallel mediation effect through attractiveness and suitability in the relationship between the formativeness of virtual influencers and advertising attention. Second, it was confirmed that formativeness affects the mediating variable, attractiveness, but attractiveness does not affect attitude toward advertising. Since formativeness affects suitability and suitability in turn influences attitude toward advertising, it was confirmed that there is a full mediating effect between these variables. According to these results, the parallel mediating effect of attractiveness and formativeness was not confirmed in the relationship between formativeness and attitude towards advertising. The above study is significant in that it presents academic implications and practical implications by examining the dual and parallel mediating effects of attractiveness and suitability in the relationship between formativeness, advertising attention, and advertising attitude variables, which are considered in the production of virtual influencers.

• Journal of the Korean GEO-environmental Society
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• v.25 no.4
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• pp.29-35
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• 2024

This is an analytical study to confirm the passive resistance effect before post-tensioning of steel bar anchors. When using a steel bar as a permanent anchor, if displacement occurs within the slope even before the head load is applied, the displacement is suppressed by the passive resistance caused by the interaction between the steel bar, grout, and surrounding soil. Accordingly, the shape of the failure surface and changes in the safety factor were examined using limit equilibrium analysis and finite element analysis targeting sites where steel bar anchors were actually applied. It was found that the safety factor of the slope reinforced with steel bar anchors is 2.02 using finite element analysis, which is about 5.9% smaller than 2.14 using limit equilibrium analysis. Also, the location of the failure surface was found to be deeper compared to the unreinforced slope. Likewise, the factor of safety has a 153% and 163% increase using finite element method and limit equilibrium analysis, respectively. In addition, the maximum displacement occurs in the lower unreinforced section within the slope, and the displacement is found to be reduced by 42 to 83% at the location where the steel bar anchors are installed.

• Journal of the Korea Organic Resources Recycling Association
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• v.32 no.1
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• pp.31-38
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• 2024

In this study, vinyl waste, which is the cause of environmental pollution, is recycled via an electrospinning method and applied as a separator that can be employed for energy storage devices. In detail, vinyl wastes are dissolved in a solution containing p-xylene and cyclohexanone, followed by electrospinning to obtain a vinyl waste-derived separator(VWS), and then the hydrophilic functional groups on the surface of VWS are introduced using a plasma treatment to improve wettability. Scanning electron microscopy analysis have verified that the shape and thickness of as-spun VWS vary depending on the concentration of vinyl waste. The surface hydrophility of VWS is modified by plasma treatment with applied powers ranging from 80 to 120W. The lowest contact angle is observed when the 100W power is applied to VWS(VWS-100W). In electrochemical analysis, the VWS-100W-based supercapacitor device shows the highest specific capacitance of 57.9 F g^-1. This is ascribed to the high porosity achieved by electrospinning as well as the introduction of hydrophilic functional groups by the oxygen plasma treatment. In conclusion, vinyl waste is successfully recycled into separators for energy storage devices, suggesting a new way to reduce environmental pollution.

• Journal of the Korea Organic Resources Recycling Association
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• v.32 no.1
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• pp.21-29
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• 2024

In this study, EMC(Epoxy molding compound) waste from the semiconductor molding process is recycled and synthesized into silica nanoparticles, which are then applied as abrasive materials contains CMP(Chemical mechanical polishing) slurry. Specifically, silanol precursor is extracted from EMC waste according to the ultra-sonication method, which provides heat and energy, using ammonia solution as an etchant. By employing as-extracted silanol via a facile sol-gel process, uniform silica nanoparticles(e-SiO₂, experimentally synthesized SiO₂) with a size of ca. 100nm are successfully synthesized. Through physical and chemical analysis, it was confirmed that e-SiO₂ has similar properties compared to commercially available SiO₂(c-SiO₂, commercially SiO₂). For practical CMP applications, CMP slurry is prepared using e-SiO₂ as an abrasive and tested by polishing a semiconductor chip. As a result, the scratches that are roughly on the surface of the chip are successfully removed and turned into a smooth surface. Hence, the results present a recycling method of EMC waste into silica nanoparticles and the application to high-quality CMP slurry for the polishing process in semiconductor packaging.

• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.3
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• pp.255-280
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• 2024

If there are concerns about the stability of segment lining due to section deficiency or large deformation in shield TBM tunnel, reinforcement can be done through ground grouting outside the tunnel or by using steel plate reinforcement, ring beam reinforcement, or inner double layer lining inside the tunnel. Traditional analyses of shield TBM tunnels have been conducted using a continuum method that does not consider the segmented nature of segment lining. This study investigates the reinforcement mechanism for double layer reinforced sections with internal steel linings. By improving the modeling of segment lining, this study applies Break-joint mode (BJM), which considers the segmented characteristics of segment lining, to analyze the deformation characteristics of double layer reinforced sections. The results indicate that the existing concrete segment lining functioned similarly to ground reinforcement around the tunnel, rather than distribution the load. In general, both the BJM model considering the segmentation of segment lining and the continuum rigid method were similar deformation shapes and stress distributions of the lining under load. However, in terms of deformation, when the load strength exceeded the threshold, the deformation patterns of the two models differed.