• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.2
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• pp.127-135
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• 2022

Compared to the continuous increase of domestic nano-satellite development cases, the initial communication success rate is relatively low. In a situation where communication cases of LEO satellites using commercial satellite communication networks are increasing recently. In this situation, the SNIPE project developed by the KASI(Korea Astronomy and Space Science Institute), KARI(Korea Aerospace Research Institute), and Yonsei University apply an Iridium module for communication test to the SNIPE nano-satellites. Therefore, in this paper, the visibility analysis of the iridium module on the SNIPE satellite was analyzed under considering the orbital and communication environment of the iridium satellite constellation and the attitude control mode. In the case of LEO satellites, the communication possibility was limited due to the relatively small iridium communication coverage for high altitude and the high doppler shift considered in the iridium communication network. For this reason, in this paper, it could be simulated that there was a more performance difference according to the difference in relative RAAN(Right Ascension of Ascending Node) angle with the Iridium constellation. Finally, by checking the visibility of communication module under the tumbling situation that occurred during the initial deployment of the nano-satellite, the possibility of using the iridium communication technology was analyzed.

• International Journal of Knowledge Content Development & Technology
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• v.4 no.2
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• pp.97-108
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• 2014

Institutional repositories are essential research infrastructures for research-based universities. A properly dimensioned institutional repository has the potential to increase research impact and enhance the visibility of an institution through its scholarly outputs. The aim of the study reported in this paper was to design and develop a web-based digital repository for scholarly communications using NM-AIST as a case study. The system was developed using open source software. Findings obtained from system validation tests show that the system is a viable solution to the major challenges encountered in the management and sharing of scholarly information at the institution.

• ETRI Journal
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• v.26 no.2
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• pp.92-100
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• 2004

In this paper, we propose an efficient method to broadcast digital television signals using single frequency networks (SFNs) within the Advanced Television Systems Committee (ATSC) transmission systems. In implementing the SFNs of an 8-vestigial side band (8-VSB) Digital Television (DTV) system, the ambiguity problem of the trellis coder is unavoidable in a conventional ATSC transmission system. We propose a memory initialization of the trellis coder to resolve this ambiguity problem. Since the proposed scheme to synchronize multiple transmitters minimizes the changes from the conventional ATSC system, the hardware complexity for these changes is very low. Our simulation results show that the proposed scheme makes a less than 0.1 dB degradation at the threshold of visibility with a bit error rate of $3{\times}10^{-6}$ in the additive white Gaussian noise (AWGN) channel. It is possible to reduce the performance degradation by increasing the initialization period of the proposed scheme.

• Journal of the military operations research society of Korea
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• v.35 no.1
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• pp.83-93
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• 2009

The future warfare is known as an effective centric paralysis warfare where military high technologies such as pinpoint strikes are applied. In this future warfare, for supporting military operation leadership and power of concentration in the combat, a new concept of logistic support is required and the focused logistic is proposed as an alternative. To implement this focused logistic, asset visibility should be assumed for every combat units in real time. However, current logistic information systems provide only limited information. In this study, a prototype information system for class 2 and 4 supplies is proposed for overcome limitations of current information system. The developed prototype zooms in on combat units providing business process integrations and logistic function synchronization. Also, asset visibility, the essential element of focused logistics, is presented and utilized to show the speedy and effective logistic support.

• Journal of Korean Society of Rural Planning
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• v.20 no.4
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• pp.89-99
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• 2014

The purpose of this research is first, to define what measurement items in terms of subjective consideration and preference can be used to assess the landscape values of agriculture and fisheries heritage, and second, to understand the perceptive patterns particularly how landscape experts weigh up the importance of the each measurement item. In order to extract the measurement items, extensive literature review was performed including research documents as well as domestic and international policy reports. A survey targeting the experts was conducted to ask their opinions on the importance of the selected items. For the analysis, SPSS 20.0 for Windows was used to carry out reliability analysis, descriptive statistics such as arithmetic mean and frequency distribution, factor analysis, and multiple linear regression modeling. The results are: the importance value of the landscape values in agriculture and fisheries heritage was 4.1494; the ratio value that the experts perceived the importance was 87.2%; and the average of the importance value of the analyzed items was 3.71. All the items have more than 3.00. Ten factor groups were summarized and defined whose total explanation power was 67.86%. The factor groups were named as lyricism, authenticity, environmentally-friendliness, durability, recognizability, regionality, visibility, value of sightseeing, social image, and universality. The factors influencing the landscape values are, in order of importance, recognizability, authenticity, visibility, universality, durability, and nativeness. According to the analysis, however, environmentally-friendliness, regionality, value of sightseeing, and social image were not as important.

• Fashion & Textile Research Journal
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• v.24 no.3
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• pp.303-314
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• 2022

This study examined the impact of the social features (identification, interaction, information value) and technical features (visibility affordance, metavoicing affordance, social connecting affordance) in live commerce on consumers' attachment, which in turn affects consumers' continued intent to watch live commerce and intent to purchase from the platform. Consumers' attachment was represented by emotional attachment to the live shopping streamer and functional dependence on live commerce. Furthermore, this study investigated the effect of attachment on continuous watching intention and purchase intention. Using a web-based survey and consumers in their 20s and 30s (average age: 30.32) as a sample, this study collected 274 usable responses. The results showed that among the live commerce social system constructs, identification and interaction positively affected emotional attachment to the live commerce streamer. Among the live commerce technical system constructs, visibility affordance and social connecting affordance positively influenced functional dependence on live commerce. Both emotional attachment to the live streamer and functional dependence on live commerce were positively related to a continued intent to watch, which influenced the intent to purchase. This study empirically investigated live commerce based on the socio-technical systems framework and confirmed that both social and technical factors have a significant effect on consumers. This study also identified the impact of live commerce on consumers' attitudes through attachment theory. In addition, it has proved the antecedents and effect of continuous watching of live commerce on purchase behavior by focusing on continuous watching intention where less attention was paid in live commerce research.

• International conference on construction engineering and project management
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• 2024.07a
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• pp.516-523
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• 2024

This study introduces a comprehensive framework for 4D safety analysis in construction site layout planning (CSLP), using a Site Information Model (SIM) environment to enhance spatial hazard identification and effectively integrate it with activity-based safety management. The framework, grounded in a continuous-space layout approach, accurately positions objects to mirror temporary facilities' actual boundaries, incorporating spatial relationships and inherent safety hazards. It also features rasterization to translate layouts into a grid system. Central to this framework are three modules for spatial hazard identification: Visibility Analysis, Spatial Hazard Mapping, and Travel Path Analysis, designed to identify less visible spaces, assess spatial hazards, and simulate optimal travel paths considering safety aspects. By applying this framework to case studies of a residential complex and a commercial office project, the research demonstrates its practical utility in improving visibility and spatial hazard assessment, despite the inherently complex dynamics of construction sites. The study acknowledges challenges, such as the reliance on safety managers' experiential knowledge for setting hazard parameters and the need for further development in integrating these insights with activity-based safety management. It underscores the framework's significant potential to advance construction safety management by offering a method to preemptively recognize and mitigate spatial hazards. The approach promises not only to contribute to accident prevention but also to enhance overall project performance by incorporating spatial and temporal dimensions of safety into CSLP. This research marks a significant step toward a more holistic and integrated approach to construction safety, highlighting the importance of continuous improvement and adaptation in safety practices.

• International conference on construction engineering and project management
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• 2024.07a
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• pp.152-159
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• 2024

Cracks in structural materials present a critical challenge to infrastructure safety and long-term durability. Timely and precise crack detection is essential for proactive maintenance and the prevention of catastrophic structural failures. This study introduces an innovative approach to tackle this issue using U-Net deep learning architecture. The primary objective of the intended research is to explore the potential of U-Net in enhancing the precision and efficiency of crack detection across various concrete crack detection under various environmental conditions. Commencing with the assembling by a comprehensive dataset featuring diverse images of concrete cracks, optimizing crack visibility and facilitating feature extraction through advanced image processing techniques. A wide range of concrete crack images were collected and used advanced techniques to enhance their visibility. The U-Net model, well recognized for its proficiency in image segmentation tasks, is implemented to achieve precise segmentation and localization of concrete cracks. In terms of accuracy, our research attests to a substantial advancement in automated of 95% across all tested concrete materials, surpassing traditional manual inspection methods. The accuracy extends to detecting cracks of varying sizes, orientations, and challenging lighting conditions, underlining the systems robustness and reliability. The reliability of the proposed model is measured using performance metrics such as, precision(93%), Recall(96%), and F1-score(94%). For validation, the model was tested on a different set of data and confirmed an accuracy of 94%. The results shows that the system consistently performs well, even with different concrete types and lighting conditions. With real-time monitoring capabilities, the system ensures the prompt detection of cracks as they emerge, holding significant potential for reducing risks associated with structural damage and achieving substantial cost savings.

• Journal of Positioning, Navigation, and Timing
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• v.8 no.4
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• pp.215-223
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• 2019

This paper analyzes navigation performances of the Korean Positioning System (KPS) constellation with respect to the orbit parameters which fulfills the specification requirements. Specifically, the satellite configuration and navigation requirements of KPS are explained, and the daily mean horizontal dilution of precision (HDOP) and satellite visibility on KPS coverage are analyzed to confirm the adequate orbit parameters. However, due to orbital slot saturation, geostationary-orbit (GEO) satellites may not be allocated in the original orbit as specified in the KPS requirements. Therefore, in a spanned window of 4 degrees from the reference longitude the navigation performance of each GEO satellite orbit is investigated.

• ETRI Journal
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• v.37 no.5
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• pp.1012-1022
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• 2015

Conventional cryptographic algorithms are not sufficient to protect secret keys and data in white-box environments, where an attacker has full visibility and control over an executing software code. For this reason, cryptographic algorithms have been redesigned to be resistant to white-box attacks. The first white-box AES (WB-AES) implementation was thought to provide reliable security in that all brute force attacks are infeasible even in white-box environments; however, this proved not to be the case. In particular, Billet and others presented a cryptanalysis of WB-AES with 230 time complexity, and Michiels and others generalized it for all substitution-linear transformation ciphers. Recently, a collision-based cryptanalysis was also reported. In this paper, we revisit Chow and others's first WB-AES implementation and present a conditional re-encoding method for cryptanalysis protection. The experimental results show that there is approximately a 57% increase in the memory requirement and a 20% increase in execution speed.