• Journal of Korea Multimedia Society
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• v.20 no.1
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• pp.1-9
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• 2017

Explosive deployment of smart mobile devices such as smart phones, and tablets along with expansion of wireless internet bandwidth have enabled the deployment of mobile video streaming such that video traffic becomes the most important service in wireless networks. Recently, for more efficient video streaming services, the ISO MPEG group standardized a protocol called DASH (Dynamic Adaptive Streaming over HTTP) and the standard has been quickly adopted by many service providers such as YouTube and Netflix. Despite of the convenience of mobile streaming services, users also suffer from low QoE(Quality of Experience) due to dynamic channel fluctuations and unnecessary downloading due to high churning rates. This paper proposes a noble efficient video rate selection algorithm considering user buffer level, channel condition and churning rate. Computer simulation based performance study showed that the proposed algorithm improved the QoE significantly compared to a method that determines the video rate based on current channel conditions. Especially, the proposed method reduced the rebuffering rate, one of the most important performance factors of the QoE, to a nonnegligible level.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.2
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• pp.20-28
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• 2018

In general, the choking phenomenon occurs due to the flow acceleration of a turbine under high pressure-ratio. During choking, the total pressure ratio increases without any variation in the mass flow rate. It is difficult to predict choking characteristics by using conventional meanline analysis, which utilizes mass flow inlet boundary condition. In this study, an algorithm for predicting the choking point is developed to solve this problem. In addition, a performance estimation algorithm is presented to estimate the performance after choking, based on the flow behavior of flow expansion at the choked nozzle or rotor. The analysis results are compared with 3D CFD analysis and experimental data to validate this method.

• Journal of Digital Convergence
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• v.19 no.12
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• pp.103-113
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• 2021

In this study, the Q method is used to investigate the types of perceptions of liberal arts education perceived by college students and to investigate the characteristics of each type. 33 Q samples were extracted from the Q population collected through literature research, open questionnaires, and deep interviews. Q classification was conducted for 27 students of A University located in B City. The data was analyzed using the QUANL program. In the research, the types of awareness of liberal arts education were derived as "pursuit of various experiences", "pursuit of practical studies", "pursuit of accident expansion", and "pursuit of social change". The results of this study re-establish the meaning of liberal arts education in university education and suggest that it is necessary to consider various educational contents and teaching learning methods.

• Convergence Security Journal
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• v.21 no.1
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• pp.107-113
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• 2021

Recently, large-scale research and efforts aimed at the smart world such as smart city, smart home, smart transportation, and smart care are continuing. As these smart worlds become more common, the expansion of connectivity with the Internet and the threat of cyber terrorism will be inevitable. Increasing the threat of cyber terrorism is increasing the likelihood of a massive disaster and safety accident. Therefore, in this paper, we examine smart worlds that are expanded in various forms and derive the security threat factors that smart worlds have. In addition, it is proposed to block the threat of terrorism from abroad if access from abroad is not required when constructing a smart world. Through this, we intend to present a method to eliminate cyber terror threats for the establishment and operation of a safe smart world.

• Korean Journal of Organic Agriculture
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• v.29 no.1
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• pp.1-23
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• 2021

The form of agri-food transaction has taken a rapid change from the existing method since Covid-19. In response to changes in the market environment such as Covid-19, the integrated marketing organization in Jeollabuk-do was diagnosed from the point of view of innovation, and the future direction was examined. In order to improve the distribution structure of the production area, an integrated marketing organization was fostered, and both quantitative and qualitative growth were brought about. However, some regions still lack willingness to participate and lack of expertise. In particular, there is no infrastructure and strategy to prepare for the increase in non-face-to-face transactions post Covid-19. Online transactions also require economies of scale, so non-face-to-face transaction capabilities must be reinforced by adding a separate organization and experts in charge of online transaction functions within the integrated marketing organization. In the future, online sales are highly likely to expand not only to transactions between producers and individual consumers (C to C), but also to mass consumer (B to B) transactions. It will be an opportunity. In addition, it is necessary to efficiently use production area distribution facilities such as sorting and packaging. Since the non-contact transaction method will increase after Corona 19, it is necessary to strengthen marketing capabilities such as expansion of utilization rate, order placement, settlement, and customer management, and reorganization of specialized organizations.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.3
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• pp.104-111
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• 2019

A separate type rotary engine consisting of a compressor and an expander is under development. The engine motoring, compressor pressure, and fuel combustion have been tested with the initial prototype for operability checks of the mechanism. This paper describes an engine cycle analysis method designed specifically for this new-concept engine. The unique operational mechanism of the engine and the thermodynamic properties of each step of air intake, compression, filling of combustion chamber, combustion, expansion and exhaust were analyzed. The cycle efficiencies of this engine according to various engine design parameters as well as the cooling effect of compressed air between the compressor and expander can be easily calculated with this method; further, some case studies are presented in this paper.

• The Journal of Information Systems
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• v.28 no.3
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• pp.105-121
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• 2019

Purpose One of the reasons for the expansion of information systems in the enterprise is the increased efficiency of data analysis. In particular, the rapidly increasing data types which are complex and unstructured such as video, voice, images, and conversations in and out of social networks. The purpose of this study is the customer needs analysis from customer voices, ie, text data, in the web environment.. Design/methodology/approach As previous study results, the word frequency of the sentence is extracted as a word that interprets the sentence has better affects than frequency analysis. In this study, we applied the TF-IDF method, which extracts important keywords in real sentences, not the TF method, which is a word extraction technique that expresses sentences with simple frequency only, in Korean language research. We visualized the two techniques by cluster analysis and describe the difference. Findings TF technique and TF-IDF technique are applied for Korean natural language processing, the research showed the value from frequency analysis technique to semantic analysis and it is expected to change the technique by Korean language processing researcher.

• Magazine of korean Tunnelling and Underground Space Association
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• v.21 no.1
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• pp.101-112
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• 2019

This case study presented a simplified failure mechanism approach used as a preliminary deformation prediction for the Mexico City's metro system expansion. Because of the Mexico City's difficult subsoils, Line 12 project was considered one of the most challenging projects in Mexico. Mexico City's subsurface conditions can be described as a multilayered stratigraphy changing from soft high plastic clays to dense to very dense cemented sands. The Line 12 trajectory crossed all three main geotechnical Zones in Mexico City. Starting from to west of the City, Line 12 was projected to pass through very dense cemented sands corresponding to the Foothills zone changing to the Transition zone and finalizing in the Lake zone. Due to the change in the subsurface conditions, different constructions methods were implemented including the use of TBM (Tunnel Boring Machine), the NATM (New Austrian Tunneling Method), and cut-and-cover using braced Diaphragm walls for the underground section of the project. Preliminary crown and excavation front deformations were determined using a simplified failure mechanism prior to performing finite element modeling and analysis. Results showed corresponding deformations for the crown and the excavation front to be 3.5cm (1.4in) and 6cm (2.4in), respectively. Considering the complexity of Mexico City's difficult subsoil formation, construction method selection becomes a challenge to overcome. The use of a preliminary results in order to have a notion of possible deformations prior to advanced modeling and analysis could be beneficial and helpful to select possible construction procedures.

• Asia-Pacific Journal of Business
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• v.11 no.3
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• pp.217-227
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• 2020

Purpose - Against the backdrop of the recent intense political conflict in Korea's political circles, it is to reveal from an economic point of view the hidden aspects behind the hostile conflict between the two political forces. Design/methodology/approach - This paper is not a normative study to find a solution to political conflict, but a positive study to reveal the mechanism of reciprocity that exists between the two parties of conflict in real politics. Therefore, the analysis is based on game theory methodology. Findings - It is shown that the ruling party should choose a level of preemptive response that is neither insufficient nor excessive if it aims to avoid radical anti-government struggles by opposition parties. We also find that even if the chances of success of the opposition's radical offensive struggle are low, the use of that strategy is not necessarily reduced. In addition, we have obtained comparative static results that do not deviate much from our intuition. What's interesting is that unlike our intuition that the choice of the method will be indifferent if the marginal effects of radical and normal methods of struggle are the same, the opposition party rather chooses the normal method of struggle more often. Research implications or Originality - In forming the analytical model, it reflected the support of the general public following the opposition's struggle against the ruling party in order to capture real politics well in the conflict between the two opposing parties.

• International Journal of Computer Science & Network Security
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• v.22 no.7
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• pp.75-84
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• 2022

The efficiency of the regional fiscal policy implementation is based on the achievement of target criteria in the formation and distribution of own financial resources of local budgets, reducing their deficit and reducing dependence on transfers. It is also relevant to compare the development of financial autonomy of regions in the course of decentralisation of fiscal relations. The study consists in the cluster analysis of the effectiveness of fiscal policy implementation in the context of 24 regions and the capital city of Kyiv (except for temporarily occupied territories) under conditions of fiscal decentralisation. Clustering of the regions of Ukraine by 18 indicators of fiscal policy implementation efficiency was carried out using Ward's minimum variance method and k-means clustering algorithm. As a result, the regions of Ukraine are grouped into 5 homogeneous clusters. For each cluster measures were developed to increase own revenues and minimize dependence on official transfers to increase the level of financial autonomy of the regions. It has been proved that clustering algorithms are an effective tool in assessing the effectiveness of fiscal policy implementation at the regional level and stimulating further expansion of financial decentralisation of regions.