• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.6
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• pp.489-496
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• 2021

The X-band frequencies for transmitting the data from earth observation satellites are limited, so a number of satellites share the frequency bands. In order for multiple satellites to utilize same or adjacent frequency bands, International Telecommunication Union - Radiocommunication (ITU-R) limits power flux density (PFD), which overcomes the interferences among multiple satellites. However, even under the regulation, the interference effect needs to be analyzed when multiple satellites are connected to communicate with multiple ground stations (GSs) located close to each other. In this paper, the interference effect is analyzed based on signal to interference plus noise ratio (SINR) when two low earth orbit (LEO) satellites operating in different orbits are connected to communicate with randomly located two GSs in Korean peninsula. From the analysis results, it is confirmed that there can be interferences during 365 days operation even if the satellites meet PFD requirement, but the periods under interference effects are short and the interference can be foreseen.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.4
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• pp.13-27
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• 2021

In this study, the impact of traffic flow on the market penetration rate of autonomous vehicles(AV) was analyzed using the data for the year 2020 of the Yongin IC~Yangji IC section of Yeongdong Expressway. For this analysis, a microscopic traffic simulation model VISSIM was utilized. To construct the longitudinal control of the AV, the Intelligent Driver Model(IDM) was built and applied, and the driving behavior was verified by comparison with a normal vehicle. An examination of the study results of mobility and safety according to the market penetration rate of the AV, showed that the network's mobility improves as the market penetration rate increases. However, from the point of view of safety, the network becomes unstable when normal vehicles and AVs are mixed, so there should be a focus on traffic management for ensuring safety in mixed traffic situations.

• Journal of Korean Classical Literature and Education
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• no.39
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• pp.41-66
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• 2018

This paper investigates how narrative folk songs have been transmitted and enjoyed through literature data and field research, and discusses their educational significance. Narrative folk songs have changed from songs that were enjoyed by common women to songs enjoyed by upper class men according to the times. They have ranged from tragic songs lamenting hardships to comic songs that relieve oppression, depending on the performance situation. Moreover, narrative folk songs have been enjoyed through media transmission beyond traditional custom. Narrative folk songs have not been enjoyed in one fixed way, but rather in various ways depending on the situation, so they have functioned to enable common women, who are their main singers, to share emotions, communicate, and maintain their community. Therefore, in literature education, narrative folk songs can be used as very appropriate materials for learners to reflect on themselves, communicate with others and contribute to desirable community life. By experiencing the various ways of enjoying narrative folk songs, learners will be able to grow into subjects who actively solve their own problems and those of their communities.

• International Area Studies Review
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• v.12 no.2
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• pp.79-97
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• 2008

After entering into the WTO in October, 2001, China started opening her bank industry on a full scale and her financial markets from the end of 2006. It is true that the Chinese commercial banks should make efforts to enhance their operational efficiency for adapting the rapid change of financial environments. In this paper, the efficiency of 4 Chinese state-owned commercial banks and 11 share holding commercial banks has been estimated. Our Tobit model to find out the determinants of these banks' efficiency. The results are as follows: The efficiency of these banks kept being improved from 1999 to 2003. With regard to the relationship between the determinants and the bank efficiency, their capital ratios, ownership structures and government subsidies are significant at the 5% level while the return on asset(ROA) is significant at the 10% level. The relationship between the determinants and the efficiency has showed that the size, capital ratios, ROA and ownership structure showed significantly before the entry to WTO, on the other hand, after WTO their capital ratios are the only factor to determine their efficiencies.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.4
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• pp.89-100
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• 2011

Physical memory analysis has been an issue on a field of live forensic analysis in digital forensics until now. It is very useful to make the result of analysis more reliable, because record of user behavior and data can be founded on physical memory although process is hided. But most memory analysis focuses on windows based system. Because the diversity of target system to be analyzed rises up, it is very important to analyze physical memory based on other OS, not Windows. Mac OS X, has second market share in Operating System, is operated by loading kernel image to physical memory area. In this paper, We propose a methodology for physical memory analysis on Mac OS X using symbol information in kernel image, and acquire a process information, mounted device information, kernel information, kernel extensions(eg. KEXT) and system call entry for detecting system call hooking. In additional to the methodology, we prove that physical memory analysis is very useful though experimental study.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.31 no.3
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• pp.481-496
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• 2021

It is imperative to migrate the current public key cryptosystem to a quantum-resistance system ahead of the realization of large-scale quantum computing technology. The National Institute of Standards and Technology, NIST, is promoting a public standardization project for Post-Quantum Cryptography(PQC) and also many research efforts have been conducted to apply PQC to TLS(Transport Layer Security) protocols, which are used for Internet communication security. In this paper, we propose a scenario in which a server and multi-clients share session keys on TLS by using the parallelized NTRU which is PQC in the key exchange process. In addition, we propose a method of accelerating NTRU using GPU and analyze its efficiency in an environment where a server needs to process large-scale data simultaneously.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.31 no.3
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• pp.353-363
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• 2021

As the Untact era is rapidly changing, collaboration tools are increasing their utilization and value as digital technologies for non-face-to-face work. While instant messenger-based collaboration tools support a variety of functions, crime and accident concerns are also increasing in proportion to their convenience, such as information leakage and security incidents. Meanwhile, the digital forensics perspective on collaborative tools is not enough, so forensics research is needed. This study analyzes significant artifacts in the two operating environments through Windows and Android forensics research on Microsoft Teams, the collaboration tool with the highest share in the world. Also, based on differences in artifacts and data attributes according to the operating environment, by applying 'differential forensic', we proved that the usefulness of evidence can be improved by presenting a complementary analysis method and timeline configuration through information linkage.

• Journal of Distribution Science
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• v.19 no.1
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• pp.61-73
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• 2021

Purpose: The transition from a traditional to a modern food distribution system induces several adjustments on the supply side since supermarkets must collect food on a larger scale and with higher quality standards. This situation becomes a real challenge for small scale farmers to access supply in a modern distribution channel. This gives rise to an original solution: supplying supermarkets through farmer associations or cooperatives. Based on this context of Vietnam linking to the case of distribution science, the paper proposes an industrial organization model of the food processing system in developing countries. The model presents the competitive relationship between two competing distribution systems: a traditional and a modern one. The former is composed of several retailers that sell their products on the traditional market while the latter is based on cooperatives that collect food and negotiate with supermarkets. The current study is to discuss the conditions under which the evolution of the food distribution system occurs by using the proposed model. Research design, data, and methodology: Based on the proposed model, the study explored the quantity flow from small producers to consumers through a Nash equilibrium and address the question of farmer repartition by a free-entry equilibrium. Results: The result shows that there is a unique positive equilibrium in the food market with participation of cooperative associations; Since farmers serve cooperative associations, they not only receive quantity incentive prices but also share profits within their organization. Conclusions: This study shows a unique distribution equilibrium where the profits of farmers working for middlemen and cooperatives are maximized. Further insights were discussed.

• The Journal of the Convergence on Culture Technology
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• v.7 no.1
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• pp.595-607
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• 2021

In response to increasing demand of contactless services, the overall usage of "task-oriented chatbots" in the industry is on the rise. The purpose of a task-oriented chatbot is to raise the efficiency of data sharing and workflow; in order to establish a guideline, there must be a discussion on "what" and "how" to share information. We investigate the effects of personalization and different types of the interface on 'performance expectancy', 'effort expectancy', 'intention to use', and 'satisfaction' in the context of a task-oriented chatbot. Results show that 'intention to use' and 'satisfaction' were higher when the level of personalization was higher. Within the closed-discourse interface, 'intention to use' and 'satisfaction' were higher when personalization was lower. We highlight the practical insights in the use of personalization and types of chatbot interface based on 'perceived personalization', 'expectation disconfirmation theory', 'privacy concern' and 'privacy paradox'.

• Journal of the Korea Society of Computer and Information
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• v.26 no.2
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• pp.125-132
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• 2021

In this paper, We propose a study on the construction of an environment for collaboration in mixed reality and a method for working with wearable IoT devices. Mixed reality is a mixed form of virtual reality and augmented reality. We can view objects in the real and virtual world at the same time. And unlike VR, MR HMD does not occur the motion sickness. It is using a wireless and attracting attention as a technology to be applied in industrial fields. Myo wearable device is a device that enables arm rotation tracking and hand gesture recognition by using a triaxial sensor, an EMG sensor, and an acceleration sensor. Although various studies related to MR are being progressed, discussions on developing an environment in which multiple people can participate in mixed reality and manipulating virtual objects with their own hands are insufficient. In this paper, We propose a method of constructing an environment where collaboration is possible and an interaction method for smooth interaction in order to apply mixed reality in real industrial fields. As a result, two people could participate in the mixed reality environment at the same time to share a unified object for the object, and created an environment where each person could interact with the Myo wearable interface equipment.