• 한국전산유체공학회:학술대회논문집
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• 2007.10a
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• pp.56-59
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• 2007

The screech tone of an underexpanded jet is numerically calculated without any specific modeling for the screech tone itself. A fourth-order optimized compact scheme and fourth-order Runge-Kutta method are used to solve the 2D axisymmetric Euler equation. The Fourier transform of pressure signal at upstream shows the directivity pattern of the screech tone very clearly. Pressure signal is shown to observe the generation of the screech tone. Most importantly, we can simulate the axisymmetric mode change of the screech tone very precisely with the proposed method. It can be concluded that the basic phenomenon of the screech tone including its frequency can be calculated and its mode change can be simulated with inviscid Euler equations.

• Nuclear Engineering and Technology
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• v.51 no.2
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• pp.546-555
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• 2019

Since the first nuclear reactor first critical, nuclear systems has gone through four generations of history, and the fourth generation nuclear system will be truly realized in the near future. The notions of SVBR and lead-bismuth eutectic alloy coolant put forward by Russia were well received by the international nuclear science community. Lead-bismuth eutectic alloy with the ability of the better neutron economy, the low melting point, the high boiling point, the chemical inertness to water and air and other features, which was considered the most promising coolant for the 4th generation nuclear reactors. This study mainly focuses on the structural design optimization of the 4th-generation reactor coolant pump, including analysis of external characteristics, inner flow, and transient characteristic. It was found that: the reactor coolant pump with a central symmetrical dual-outlet volute structure has better radial-direction balance, the pump without guide vane has better hydraulic performance, and the pump with guide vanes has worse torsional vibration and pressure pulsation. This study serves as experience accumulation and technical support for the development of the 4th generation nuclear energy system.

• Journal of Fashion Business
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• v.21 no.1
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• pp.12-31
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• 2017

Korean commercial-organized girl groups were remarkable in the late 1990's. However, by the late 2000's, girl groups had an even more profound effect on Korean popular music compare to past influences. This study aimed to analyze the social-cultural meaning of the changing appearance of girl group between the first and second-generations. For this purpose, this study analyzed media image and text, based on a social-cultural context, about 13 girl groups. The results are as follows. First, while the first -generation girl group tended to maintain girlish/sexy images trying to the male desire, the second -generation girl group strategically showed various sexual identities such as femininity, masculinity, masculinity and androgyny along with contextual sexual images. The reason why girl groups increased the number of strategic images featuring various sexual identities was in order to appeal to a wide, diverse audience. Second, the second generation girl groups had - slim bodies with great athleticism, basically due to trainee system. Because of this, their semiotic body images have been commercially used to promote the consumption. Third, the second generation girl groups - were the bigger stars than first generation girl groups - because the members worked in many different fields. Therefore, the group members' images were successful consumed directly and then reproduced symbolically. Fourth, each member of the second -generation girl groups characterized by appearing in diverse, yet familiar images, through various media sources. Although the intention of this was to have recognition and popularity, it became difficult for them to change their image once one particular image was deemed popular.

• The Research Journal of the Costume Culture
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• v.28 no.6
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• pp.830-844
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• 2020

The fourth Industrial Revolution, known as digital transformation, has made MZ generation to be the focus of the new consumer market, brought about the use of technological platforms a new consumption method. Currently, as various types of content collaboration are emerging that specifically targeting at the MZ generation. Content collaboration are considered an integration of content to create new values through co-existence and co-prosperity. This study identified the characteristics of collaboration of fashion brands from 2018 using literature and online news articles, and identified and classified through case studies of it determined movie content, game and virtual characters. By this research, it shown that collaboration with movie contents have increased the collaborative synergy by using the story in global media content. Collaboration with mobile games was generally used by young casual and sportswear brands. These brands which utilized characters from mobile games popular with to attract more teen consumers and strengthen brand awareness by adding values of high-technology and scarcity to the familiar images. In addition, collaboration with virtual characters has expanded value of the collaborative approach on expanding the range of advanced digital technology, from a promotional strategy during the distribution process through to the use of virtual models. As such, collaboration using the various types of content has developed beyond simple integration of identities among various areas, integrated products or brands that as a new value.

• Journal of Korea Society of Digital Industry and Information Management
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• v.19 no.3
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• pp.89-103
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• 2023

The purpose of this study is to investigate the mediating effect of news literacy in the relationship between sense of community and political efficacy. This study conducted a survey targeting the MZ generation. The survey was conducted online, and data from 309 cases were used for analysis. The research results are as follows. As a result of correlation analysis between sense of community, political efficacy, and news literacy, it was found that there was a statistically significant correlation between sense of community and news literacy sub factors. Second, the relationship between sense of community and political efficacy was found to have a significant positive effect on political efficacy as sense of community increased. Third, the relationship between sense of community and news literacy was confirmed to have a significant positive effect on news literacy as sense of community increased. Fourth, regarding the relationship between news literacy and political efficacy, it was confirmed that news literacy has a significant effect on political efficacy. Fifth, in the relationship between sense of community and political efficacy, news literacy was found to mediate the relationship between sense of community and political efficacy of the MZ generation. Based on the research results, news literacy education is required from the perspective of civic education, and differentiated educational contents by age are proposed.

• The Korean Journal of Archival Studies
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• no.54
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• pp.151-178
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• 2017

The purpose of this study is to identify the problems of electronic records management in the records management field and to develop a new electronic records management system that can cope with the rapidly changing records production and management environment, which is rapidly changing because of the introduction of new IT. It is time to design the next-generation records management system in all areas of process, system, and infrastructure to meet the new government record management innovation. In this point of view, the right value and direction of the next-generation records management system are determined, and the problems of the process, system, and infrastructure are identified and settled.

• Journal of Veterinary Science
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• v.25 no.3
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• pp.47.1-47.12
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• 2024

Importance: Staphylococcus aureus and Escherichia coli contribute to global health challenges by forming biofilms, a key virulence element implicated in the pathogenesis of several infections. Objective: The study examined the efficacy of various generations of cephalosporins against biofilms developed by pathogenic S. aureus and E. coli. Methods: The development of biofilms by both bacteria was assessed using petri-plate and microplate methods. Biofilm hydrolysis and inhibition were tested using first to fourth generations of cephalosporins, and the effects were analyzed by crystal violet staining and phase contrast microscopy. Results: Both bacterial strains exhibited well-developed biofilms in petri-plate and microplate assays. Cefradine (first generation) showed 76.78% hydrolysis of S. aureus biofilm, while significant hydrolysis (59.86%) of E. coli biofilm was observed by cefipime (fourth generation). Similarly, cefuroxime, cefadroxil, cefepime, and cefradine caused 78.8%, 71.63%, 70.63%, and 70.51% inhibition of the S. aureus biofilms, respectively. In the case of E. coli, maximum biofilm inhibition (66.47%) was again shown by cefepime. All generations of cephalosporins were more effective against S. aureus than E. coli, which was confirmed by phase contrast microscopy. Conclusions and Relevance: Cephalosporins exhibit dual capabilities of hydrolyzing and inhibiting S. aureus and E. coli biofilms. First-generation cephalosporins exhibited the highest inhibitory activity against S. aureus, while the third and fourth generations significantly inhibited E. coli biofilms. This study highlights the importance of tailored antibiotic strategies based on the biofilm characteristics of specific bacterial strains.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.2
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• pp.149-154
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• 2023

In the Fourth Industrial Revolution, hydrogen energy is in the spotlight. There is a difficulty in commercialization due to the lack of hydrogen infrastructure. Therefore, a lot of hydrogen should be imported and a method using ammonia is the most useful. In this study, using the mixed gas of hydrogen and nitrogen generated when ammonia is decomposed, the hydrogen separation performance is to be tested. Hydrogen was separated using an electrochemical hydrogen compressor based on a fuel cell and the experiment was conducted by changing the ratio of hydrogen and nitrogen. In addition, the performance was also compared by the difference both the pressure and the membrane.

• Korea and Global Affairs
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• v.1 no.2
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• pp.129-148
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• 2017

The political system of Xi Jinping which was launched in 2013, faced many difficulties both domestically and internationally. Xi Jinping must integrate and stabilize society through political reforms, such as sustained economic growth and Resolved corruption. In addition, he should seek new relations with the United States on the denuclearization of the Korean peninsula. Therefore, this study analyzed political leadership of Chinese political leaders including Xi Jinping using Max Weber 's political domination type. From the first generation political leaders to the fourth generation political leaders in China, the types of political domination of the first and second generation political leaders tend to be charismatic rather than legitimate domination. But the third generation political leaders tend to have a tendency of traditional domination rather than legitimate domination, and the fourth generation political leaders have a tendency to dominate more than traditional domination. On the other hand, the type of political domination of Xi Jinping shows traditional domination and legitimate domination tendency in the process of political growth and emergence, but shows tendency of charismatic domination after domination of political power.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.597-600
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• 2003

Wireless Internet access shows an early-stage market that is entering a period of strong and sustained growth., reaching almost $40 billion in combined related equipment services by 2008 with equipment and services of nearly equal proportion. This explosive development is possible due to the continued growth of two of the most successful markets in history, the internet and mobile telephony. The number of global wireless internet users will incense from approximately 1.9million in 2001 to 1.3billion by 2006. Technological changes are the main factor in the emergence of what is being called the fourth generation of mobile communications.