• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.6
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• pp.815-821
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• 2021

This study addresses on the design of performance monitoring system for the time synchronization service of the enhanced long-range navigation (eLoran) system, which has a representative ground-wave radio broadcast system capable of providing positioning, navigation, timing and data (PNT&D) services. The limitations of time-synchronized systems due to the signal vulnerabilities of the global navigation satellite system (GNSS) are explained, and the performance monitoring system for the eLoran timing service as a backup to the GNSS is proposed. The time synchronization service using eLoran system as well as system configurations and the user requirements in the differential Loran (dLoran) system are described to monitor the time synchronization performance. The results of the designed system are presented for long-term operation in the eLoran testbed environment. As the results of time performance monitoring, we were able to verify the time synchronization precision within 43.71 ns without corrections, 22.52 ns with corrections. Based on these results, the eLoran system can be utilized as a precise time synchronization source for GPS timing backup.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.5
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• pp.53-60
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• 2021

The number of visually impaired and blind people is increasing, but braille translation textbooks for them are insufficient, which violates their rights to education despite their will. In order to guarantee their rights, this paper develops a learning system, HunMinJeomUm, that helps them access textbooks, documents, and photographs that are not available in braille, without the assistance of others. In our system, a smart phone app and web pages are designed to promote the accessibility of the blind, and a braille kit is produced using Arduino and braille modules. The system supports the following functions. First, users select documents or pictures that they want, and the system extracts the text using OCR. Second, the extracted text is converted into voice and braille. Third, a membership registration function is provided so that the user can view the extracted text. Experiments have confirmed that our system generates braille and audio outputs successfully, and provides high OCR recognition rates. The study has also found that even completely blind users can easily access the smart phone app.

• Journal of Digital Convergence
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• v.19 no.9
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• pp.125-133
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• 2021

This study investigated to explore the broadened concept of the subscription service market and categorize of the subscription market and its consumer behavior. We examined the satisfaction of the service users and the reasons for terminating the subscription. Survey respondents were 443 people in their 20s and 30s, who actively use subscription services. As a result of the survey it was found that users in their 20s were more satisfied with the overall subscription service than those in their 30s, and that user's residential areas were evenly distributed regardless of metropolitan area or non-metropolitan area. As a reason for the cancellation of subscription service: the lower the novelty of subscription, the less personalization tailored to consumer, the lack of feeling self-growth while using the service, and the more termination is made. Our findings have magnified the understanding of consumers behaviors in the age of 20s and 30s of using and terminating subscription service and hopefully be used for future studies of subscription services.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.31 no.5
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• pp.919-939
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• 2021

As a next-generation communication technology, 5G networks are capable of handling large amounts of traffic based on higher speeds, shorter communication delays, and higher connectivity compared to 4G networks. In this 5G network environment, base stations are installed all over the city at high density due to their characteristics, and are connected to user terminals to provide services. Therefore, if the base station is damaged by a malicious attacker, it is expected to cause great damage to users and society as a whole. So the need for secure communication equipment such as 5G base stations has emerged. Therefore, in this paper, we propose the security functional requirements derived using threat modeling, a systematic methodology for 5G base stations, and the security assurance requirements at the level that can cope with the backdoor issues. The security requirements proposed in this paper can be used for base station design and development to construct a secure network environment as a security evaluation standard for 5G base stations.

• The Journal of the Korea Contents Association
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• v.21 no.9
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• pp.176-183
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• 2021

Digital medical technology is very effective and at the same time faces the challenge of protecting privacy. However, for contact tracking and exposure notification apps in COVID-19 environment, there is always a trade-off between privacy measures and the effectiveness of the app's use. Today, many countries have developed and used contact tracking and exposure notification apps in various forms to prevent the spread of COVID-19, but the suspicion of digital surveillance (digital panopticon) is unavoidable. Therefore, this study aims to identify the factors of personal information infringement and dissatisfaction through text mining analysis by extracting user reviews of "Self-Quarantine Safety Protection" in Korea. As a result of the text mining analysis, we derived four groups, 'Address recognition error', 'Exit warning error', 'Access error', and 'App. program error'. Since 'Address recognition error' and 'Exit warning error' can give the app users a strong perception that they are keeping under surveillanc by the app, transparent management of personal information protection and consent procedures related to personal information collection are required. In addition, if the other two groups are not corrected immediately due to an error in an app function or a program bug, the complaints of users can be maximized and a protest against the monitor can be raised.

• Journal of the Korea Convergence Society
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• v.12 no.12
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• pp.93-106
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• 2021

Blenderbot 2.0 is a dialogue model representing open domain chatbots by reflecting real-time information and remembering user information for a long time through an internet search module and multi-session. Nevertheless, the model still has many improvements. Therefore, this paper analyzes the limitations and errors of BlenderBot 2.0 from three perspectives: model, data, and dialogue. From the data point of view, we point out errors that the guidelines provided to workers during the crowdsourcing process were not clear, and the process of refining hate speech in the collected data and verifying the accuracy of internet-based information was lacking. Finally, from the viewpoint of dialogue, nine types of problems found during conversation and their causes are thoroughly analyzed. Furthermore, practical improvement methods are proposed for each point of view, and we discuss several potential future research directions.

• Land and Housing Review
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• v.12 no.4
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• pp.61-79
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• 2021

Despite the rapid economic growth, people's quality of life has not been improved and the regional and hierarchical disparities of it have deepened. We analysed regional differences in quality of life and it was found that non-capital regions, provinces and rural areas compared to Seoul and capital region, metropolitan cities, and urban areas respectively, show a relatively lower level of satisfaction in the quality of life. An in-depth analysis of Chungcheongnam-do province shows that the trend was similar to that of the national analysis. The quality of life satisfaction of the elderly was lower than that of the young and middle-aged, and this trend was similar regardless of region. Young people living in the Dong area showed high satisfaction with the quality of life than the middle-aged and elderly living in the Myeon area. It was observed the level of Life SOC services in urban areas have been better than the one in rural areas. However, there is no clear relationship between quality of life satisfaction and the expansion of Life SOC, therefore, it is difficult to argue that the government intervention to expand Life SOC will improve the citizen's quality of life satisfaction. The implication of the study is that the future supply policy of the Life SOC should be based on the detailed analysis of the impact on the environment, and linking with the development of various programs in progress rather than supplying a Life SOC that provides a single service. Furthermore, in rural areas it is essential to enhance user demand by combining several services in supply and to improve the efficiency of managing the services.

• The Journal of the Korea Contents Association
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• v.19 no.9
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• pp.658-665
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• 2019

In the era of the rapid development of a tremendous number of new technologies and products, the emotional communication between products and users has become an important research topic. However, the user's emotional measurement methods have not been widely used in the field of product design. Besides, as an important space that can improve people's life quality and urban entertainment at the emotional level, seaside space also creates an atmosphere of frequent emotional communication among tourists, landscape and environmental facilities. To deduce the applicability and advantages and disadvantages of the experiential emotional measurement method in product design, this paper took the seaside seat users of Haeundae as the object and carried out the Self-report of the experiential emotional measurement method. Specifically, the experiment of Self-report was divided into two stages: prior survey and subsequent main investigation. Then the hypothesis was verified by using Bivariate Regression and Multiple Regression through SPSS. Furthermore, through the experiment of the Self-report, the applicability and advantages and disadvantages of experiential emotional measurement method in product design were derived. In the future, based on the applicability, advantages and disadvantages of the experiential emotional measurement method derived in this study, it is expected to become the fundamental and reliable data for the development of emotional measurement methods that can be suitable for product design.

• KIPS Transactions on Software and Data Engineering
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• v.8 no.6
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• pp.243-250
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• 2019

Because of a moving UAV has a lot of potential/kinetic energy, if the UAV falls to the ground, it may have a lot of impact. Because this can lead to human casualities, in this paper, the population density area on the UAV flight path is defined as a dangerous area. The conventional UAV path flight was a passive form in which a UAV moved in accordance with a path preset by a user before the flight. Some UAVs include safety features such as a obstacle avoidance system during flight. Still, it is difficult to respond to changes in the real-time flight environment. Using public Big Data for UAV path flight can improve response to real-time flight environment changes by enabling detection of dangerous areas and avoidance of the areas. Therefore, in this paper, we propose a method to detect and avoid dangerous areas for UAVs by utilizing the Big Data collected in real-time. If the routh is designated according to the destination by the proposed method, the dangerous area is determined in real-time and the flight is made to the optimal bypass path. In further research, we will study ways to increase the quality satisfaction of the images acquired by flying under the avoidance flight plan.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.622-631
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• 2019

The purpose of this study is to establish and apply a public transport valuation system to form required policy for institutionalization. Over the past six years, Jeju has seen a steady increase in the number of cars owned by its population. Also, as the number of tourists has changed from group to individual tourists, the rate of rental car use has increased rapidly. As a result, road congestion in Jeju city is becoming as crowded as Seoul., Jeju Island is said to have created a foundation for faster, more convenient, and cheaper use of transportation through the reorganization of the public transportation system in August 2017. This is also reflected in the Public Transportation Value Assessment. Jeju residents were in favor of strengthening public transportation priority policy. In addition, public transport valuations are highly valued in the order of public transportation fares, public transportation stability, public transportation policies for the common people, public transportation policies for the vulnerable, public transportation policies for residents, environmentally-friendly policies, and public transportation to help ease traffic congestion. This is because public transportation has a wide range of values and should refine the factors that local governments use to evaluate policy. These methods need to be institutionalized and actively utilized through the establishment of a value assessment system for public transport.