• The Journal of Society for e-Business Studies
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• v.15 no.2
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• pp.1-18
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• 2010

Mobile Communication Companies are trying to increase data services rather than telephone communication services that already became saturated as the competition of mobile communication market gets intensified. However, it is hard and time-consuming for customers to find desired mobile phone wireless services because of the limitation of screen and speed of the mobile phone. Therefore, the market does not grow rapidly as mobile communication companies expected. In our research, we suggest a personalized wireless service recommendation system that considers each individual context by using geographic information and wireless internet usage logs to overcome the mentioned problems. In order to design and implement the system, we conducted clustering analysis on base stations and real service usage logs of each base station, and suggested a personalized recommendation system based on collaborative filtering that uses the clustering results. Moreover, we verified the performances of our system with experiments.

• Smart Media Journal
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• v.6 no.4
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• pp.94-100
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• 2017

Procurement of development funds is a very difficult process in the Korean game industry where competition is fierce. Recently, crowdfunding has been used as a convenient platform to attract potential investors to secure the development cost of the game. This study explored the factors influencing the success of crowdfunding for game development projects. We collected data on 229 game development projects in Tumblebuck, a reward-based crowdfunding site in Korea. According to the results of the logistic regression model, the factors that have a positive effect on the success of funding are the average compensation amount relative to the target amount, the number of SNS shares, the number of updates, and the originality of the proposed game. Video playback time has been found to have a negative impact. Based on the results of this study, it is expected that planning a game development project considering the variables affecting the success of crowdfunding will help financing.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.3
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• pp.322-331
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• 2013

Wireless Mesh Networks(WMNs) is generally composed of radio nodes in the mesh topology. WMNs consists of mesh client, mesh router and gateway connected to a wired network. Each client and router relay messages to the gateway for communication. WMNs is widely used recently in many areas can provide extended coverage based on multi-hop communication and ubiquitous communication at any time and any location. However the competition and collision between each node to transmit data is inevitable when the same channel is used for transmission. The transmission opportunities and the throughput of nodes located far from gateway decrease more if the communication channel is accessed based on competitive CSMA/CA scheme using DCF(Distributed Coordination Function) provided by IEEE 802.11 MAC. In this paper, we improve the performance of the TCP fairness and throughput of the nodes with more than 2 hops by applying various algorithms for controlling contention window values. Also, we evaluate the performance using ns-2 simulator, According to the results, proposed scheme can enhance the fairness characteristic of each node irrespective of data to the gateway.

• Nutrition Research and Practice
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• v.9 no.4
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• pp.343-349
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• 2015

BACKGROUND/OBJECTIVES: Fermentation of dietary fiber results in production of various short chain fatty acids in the colon. In particular, butyrate is reported to regulate the physical and functional integrity of the normal colonic mucosa by altering mucin gene expression or the number of goblet cells. The objective of this study was to investigate whether butyrate modulates mucin secretion in LS174T human colorectal cells, thereby influencing the adhesion of probiotics such as Lactobacillus and Bifidobacterium strains and subsequently inhibiting pathogenic bacteria such as E. coli. In addition, possible signaling pathways involved in mucin gene regulation induced by butyrate treatment were also investigated. MATERIALS/METHODS: Mucin protein content assay and periodic acid-Schiff (PAS) staining were performed in LS174T cells treated with butyrate at various concentrations. Effects of butyrate on the ability of probiotics to adhere to LS174T cells and their competition with E. coli strains were examined. Real time polymerase chain reaction for mucin gene expression and Taqman array 96-well fast plate-based pathway analysis were performed on butyrate-treated LS174T cells. RESULTS: Treatment with butyrate resulted in a dose-dependent increase in mucin protein contents in LS174T cells with peak effects at 6 or 9 mM, which was further confirmed by PAS staining. Increase in mucin protein contents resulted in elevated adherence of probiotics, which subsequently reduced the adherent ability of E. coli. Treatment with butyrate also increased transcriptional levels of MUC3, MUC4, and MUC12, which was accompanied by higher gene expressions of signaling kinases and transcription factors involved in mitogen-activated protein kinase (MAPK) signaling pathways. CONCLUSIONS: Based on our results, butyrate is an effective regulator of modulation of mucin protein production at the transcriptional and translational levels, resulting in changes in the adherence of gut microflora. Butyrate potentially stimulates the MAPK signaling pathway in intestinal cells, which is positively correlated with gut defense.

• Publications of The Korean Astronomical Society
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• v.26 no.3
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• pp.89-101
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• 2011

The International Olympiad on Astronomy and Astrophysics (IOAA) initiated by the Thailand Astronomical Society in 2007 is an annual competition for high school students. One of its aim is to enhance the development of international exchange in the field of school education in astronomy and astrophysics. This paper first provides the overview of the IOAA in terms of key regulations based on its statutes, history and current status. Secondly, the published syllabus of the IOAA is used for content analysis according to subject areas regarding the exam questions of the IOAA in theoretical, observational and data analysis parts from 2007 to 2010. Also, a scientific inquiry framework is applied to the same questions for assessment based on scientific inquiry in the cognitive aspect with two sub-classes of scientific knowledge and scientific reasoning. Among a dozen astronomy subject areas listed on the syllabus, the theoretical part of the IOAA makes more frequent use of the Sun, the solar system, properties of stars, and concept of time. In content knowledge, a factor of scientific knowledge, the IOAA questions, especially in the theoretical part have a lesser degree in difficulty than the IAO (International Astronomy Olympiad) exam questions for the same period whose degree in difficulty is comparable to college level. With regard to scientific reasoning, the IOAA questions tend to involve convergent rather than divergent thinking. Lastly, in light of these findings, discussions are given on the outcome of Korean participation in the previous IOAAs and ways to help better in preparing Korean students for future astronomy Olympiads.

• International Journal of Fluid Machinery and Systems
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• v.5 no.3
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• pp.134-142
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• 2012

The competition to deliver ultra-low emitting vehicles at a reasonable cost is driving the automotive industry to invest significant manpower and test laboratory resources in the design optimization of increasingly complex exhaust after-treatment systems. Optimization can no longer be based on traditional approaches, which are intensive in hardware use and laboratory testing. The CFD is in high demand for the analysis and design in order to reduce developing cost and time consuming in experiments. This paper describes the development of a comprehensive practical model based on experiments for simulating the performance of automotive three-way catalytic converters, which are employed to reduce engine exhaust emissions. An experiment is conducted to measure species concentrations before and after catalytic converter for different loads on engine. The model simulates the emission system behavior by using an exhaust system heat conservation and catalyst chemical kinetic sub-model. CFD simulation is used to study the performance of automotive catalytic converter. The substrate is modeled as a porous media in FLUENT and the standard k-e model is used for turbulence. The flow pattern is changed from axial to radial by changing the substrate model inside the catalytic converter and the flow distribution and the conversion efficiency of CO, HC and NOx are achieved first, and the predictions are in good agreement with the experimental measurements. It is found that the conversion from axial to radial flow makes the catalytic converter more efficient. These studies help to understand better the performance of the catalytic converter in order to optimize the converter design.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4B
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• pp.620-629
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• 2010

The analogue radio broadcasting was proven to be a successful and efficient media of delivering information because of free content and wide availability of cheap receivers. But the competition was more dropped than any other media due to the limited amount of radio spectrum that is available. The risk of doing nothing is to miss the opportunity and to loss existing audiences in the long term, or to be locked into inefficient proprietary systems. That is the reason why it is important to act now. It is time for regulators and market participants to hone their strategies, by clearly establishing factors to adopt the digital radio and to facilitate its diffusion. The purpose of this study is to find adoption factors that affected to potential users of digital radio broadcasting. Former research based on diffusion of innovation theory showed that adoption of innovation is affected by demographic variables, media usage and consumer's attitude of innovation. In this study based on a consumer survey, we examined those factors and characteristics of each steps that suggested in diffusion of innovation theory. The findings of this study have implications to explore the suitable technologies and services of digital radio broadcasting.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.1
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• pp.134-139
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• 2022

Recently, interest in programming and artificial intelligence is continuously increasing, and software education is being implemented as a mandatory education from elementary school. For efficient programming education, it is basically necessary to build a lab environment suitable for students and teachers, but there are performance problems due to the inadequacy of old computers and network equipment. Therefore, in this paper, we propose a web page-based online practice environment and algorithm competition scoring system using React and Spring boot to solve the problem of the programming practice environment. Through this, it is thought that programming learning can be carried out using only a web browser even on low-spec computers. In addition, since various programming languages can be learned irrespective of the language to be learned, it is considered that the time cost for establishing a practice environment can be reduced.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.5
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• pp.807-816
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• 2022

See-In-The-Middle (SITM) is an analysis technique that uses Side-Channel information for differential cryptanalysis. This attack collects unmasked middle-round power traces when implementing block ciphers to select plaintext pairs that satisfy the attacker's differential pattern and utilize them for differential cryptanalysis to recover the key. Romulus, one of the final candidates for the NIST Lightweight Cryptography standardization competition, is based on Tweakable block cipher Skinny-128-384+. In this paper, the SITM attack is applied to Skinny-128-384 implemented with 14-round partial masking. This attack not only increased depth by one round, but also significantly reduced the time/data complexity to 2^14.93/2^14.93. Depth refers to the round position of the block cipher that collects the power trace, and it is possible to measure the appropriate number of masking rounds required when applying the masking technique to counter this attack. Furthermore, we extend the attack to Romulus's Nonce-based AE mode Romulus-N, and Tweakey's structural features show that it can attack with less complexity than Skinny-128-384.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.31 no.3
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• pp.119-132
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• 2023

In recent years, the competition for employment among college students has become more intense. It is also the time when strong personal beliefs and will to develop careers are required for successful employment through stable major study. Therefore, in this study, we tried to find out the effect on major attitude and employment efficacy according to the level of aviation safety perception, which is an important issue in the aviation industry. For analysis, survey is conducted targeting college students majoring in aviation service who are enrolled in universities in the metropolitan area and Chungcheong area. To verify the hypotheses of the study, demographic characteristics are identified based on questionnaires, reliability and validity of measurement items are verified, and structural equation model analysis is performed to verify the hypotheses. The analysis results are as follows. First, it is found that safety knowledge and safety consciousness, which are sub-factors of aviation safety perception of college students majoring in aviation service, have a positive (+) effect on subject recognition, learning process recognition, and career recognition of major recognition. Second, subject recognition, learning process recognition, and career recognition, which are sub-factors of major recognition, are found to have a positive effect on major commitment. Third, it is found that major commitment have a positive (+) effect on employment efficacy. Based on the research results, practical support plans and strategies for effective major study and successful employment are presented.