• The KSFM Journal of Fluid Machinery
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• v.19 no.6
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• pp.5-13
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• 2016

Three-dimensional unsteady numerical analysis has been performed to observe aerodynamic characteristics of a H-rotor. Generally, the structure of the H-rotor is simple but the aerodynamic characteristics are exceptionably complicated since the angle of attacks and incident velocities to a blade are considerably varied according to the azimuth angles and solidities. The blade in the upwind revolution between 0 to 180 degree obtains aerodynamic energy from the free stream but the blade in the downwind revolution between 180 to 360 degree does not. When the rotating speed increases, the blade in the downwind revolution accelerates the air around the blade like a fan and it consumes the energy and shows negative torque in the area. On the other hand, the direction of the free stream is bent because of the interaction between blade the free stream. Therefore, the operation point (highest power coefficient) appears at a lower tip-speed-ratio what it is expected.

• Journal of Korea Society of Digital Industry and Information Management
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• v.15 no.3
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• pp.225-239
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• 2019

Together with the emergence of Information and Communications Technology(ICT) and 4th Industrial Revolution, digital content is arising as a front-runner in the knowledge society. 21 century opened up an era of digital and cultural content, which is the industry to generating added values from future industries. This study aims to empirically examine the casual relation between three factors from Organizational Justice Theory Distributive, Procedural, Interactional Justices, and turnover intention through Organizational Immersion. A sample group for the analysis was employees at small/medium-sized digital content businesses with less than 60 workers. 200 questionnaires were distributed to the group for a week from July 22 to 28, 2019. 154 responses were collected and analyzed in this study, after eliminating 4 poor responses. The result of the study on Organizational Justice at digital content businesses showed that, first, Distributive Justice of the employees showed a positive influence on Organizational Immersion. Second, the employees' Procedural Justice showed a positive influence on Organizational Immersion. Third, the employee' Interactional Justice showed a positive influence on Organizational Immersion. Fourth, the employees' Organizational Immersion showed a positive influence on their turnover intention.

• Journal of Korea Port Economic Association
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• v.34 no.3
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• pp.159-182
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• 2018

The purpose of this study is to increase the competitiveness of big data in the maritime port organization, by understanding the expected performance and the intention to accept and use big data. In the empirical analysis of factors affecting the intention to use the big data technology for maritime port organizations, the variables employed are based on the Technology Organization Environment(TOE) and Diffusion of Innovations(DOI) theories, which are related to the acceptance of information and communication technologies. To achieve the objective of this study, an empirical analysis was conducted; this analysis targeted the personnel involved in the department of strategic planning and information technology in the related field. We set up eight hypotheses to examine the relevance between variables having three characteristics-technology, organization, and environmental characteristics. The empirical results are summarized as follows. First, it was seen that the technology characteristic, including relative advantage, complexity, and compatibility, has a significant effect on the expected performance. Second, the top management support of the organization characteristic has a significant effect, but the firm size of this characteristic has no significant effect on the expected performance. Third, the competitive pressure of the environment characteristic has a positive effect on the expected performance, while the regulatory support has no significant effect. Finally, the expected performance has a significant effect on the intention to use big data.

• Journal of Information Technology Services
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• v.19 no.2
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• pp.23-35
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• 2020

The development of digital technology is changing the paradigm of the healthcare industry to preventive and consumer-oriented. The combination of the ICT industry and the bio-healthcare industry is emerging as a core industry in the era of the Fourth Industrial Revolution. The Korean government has also selected the bio-healthcare industry as one of the three key future development industries. In May, the government announced its bio-health industry innovation strategy and set a goal of 300,000 employees. Therefore, analyzing the effects of employment on the related industries of the digital bio-healthcare industry is very important for the establishment of future industrial and technology development policies. The research method restructures the integrated classification of 32 industries into 34, including the digital bio-healthcare industry, using the classification criteria of the government and professional institutions, and then reorganizes the digital bio-healthcare industry into eight industries classified as one industry group. The analysis data was taken from the Bank of Korea's 2019 data. Various trigger coefficients and ripple effects coefficients were rewritten using the analysis method of the Input-output Statistics. The analysis of the results compares the employment-induced effects of the digital bio-healthcare industry and the ripple effects of related industries in production, investment and value-added. In addition, in terms of investment effect, the effects of in-house and related industries were compared. It is hoped that the results of this study will be used to establish employment and industrial policies.

• Journal of Convergence for Information Technology
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• v.9 no.8
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• pp.134-139
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• 2019

This paper describes the effect of multiple signal regeneration in quadrature digital radio frequency memory(DRFM). Single channel DRFM have good reproducibility after storing a single signal. However, when reproduced after storing multiple signals, the spurious signal is large. The quadrature DRFM consists of I and Q channels, which can greatly reduce the spurious signal. The amplitude of the spurious signal depends on the number of bits of data stored in the DRFM. In this paper, we have obtained the number of bits of signal regeneration according to the application of radio frequency memory by obtaining the size of the spurious signal according to the number of bits of the stored data of the DRFM for multiple signals. As a result of this study, 4 bits quadrature DRFM can achieve a spurious output of less than -20dB, which is used for 4 signals. Those are expected to greatly contribute to the signal analysis of electronic warfare equipment and the development of jamming device.

• Physical Therapy Rehabilitation Science
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• v.6 no.3
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• pp.127-133
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• 2017

Objective: The purpose of this study was to explore the effect of repetitive wrist extension task training with electromyography (EMG)-triggered neuromuscular electrical stimulation (NMES) for wrist extensor muscle recovery in patients with stroke. Design: Randomized controlled trial. Methods: Fifteen subjects who had suffered a stroke were randomly assigned to an EMG-triggered NMES group (n=8) or control group (n=7); subjects in both groups received conventional therapy as usual. Subjects in the experimental group received application of EMG-triggered NMES to the wrist extensor muscles for 20 minutes, twice per day, five days per week, for a period of four weeks, and were given a task to make a touch alarm go off by activity involving extension of their wrist. In the control group, subjects performed wrist self-exercises for the same duration and frequency as those in the experimental group. Outcome measures included muscle reaction time and spectrum analysis. Assessments were performed during the pre- and post-treatment periods. Results: In the EMG-triggered NMES group, faster muscle reaction time was observed, and median frequency also showed improvement, from 68.2 to 75.3 Hz, after training (p<0.05). Muscle reaction time was significantly faster, and median frequency was significantly higher in the experimental group than in the experimental group after training. Conclusions: EMG-triggered NMES is beneficial for patients with hemiparetic stroke in recovery of upper extremity function.

• Journal of the Korean Solar Energy Society
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• v.33 no.4
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• pp.39-45
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• 2013

This paper presents the estimation of minimum BESS capacity for regulating the output of wind farms considering power grid operating condition in Jeju Island. To analyze the characteristics of wind farm outputs with a BESS, the real data of wind farms, Sung-San, Sam-dal and Hang-Won wind farm, located in the eastern part of Jeju island is considered. The wind farms are connected to Sung-san substation to transfer the electric power to Jeju power grid. Consequently, at PCC (Point of Common Coupling), it can see a huge wind farm connected to the substation and thus it can be expected that the smoothing effect is affected by not only the different wind speeds for each area but also the different mechanical inertia of wind turbines. In this paper, two kinds of simulation have been carried out. One is to analyze the real data of wind farm outputs during a winter season, and the other is to connect a virtual BESS to eliminate the unintended generating power changes by the uncontrolled wind farm outputs as shown in the former data. In the conclusion, two kinds of simulation results show that BESS installed in the substation is more efficient than each wind farms with BESS, respectively.

• Journal of Internet of Things and Convergence
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• v.7 no.1
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• pp.55-62
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• 2021

The world is changing rapidly as the Internet spreads and various smart devices appear. High-performance PCs and high-speed communication networks are rapidly spreading in every home, and all kinds of the internet sites are emerging. In particular, the high education enthusiasm of Korean parents adds to this, and the ratio of the internet users among teenagers is exploding every day. In the case of adolescents, most of them use the Internet for online games, indicating that online games are the main cause of the internet addiction. This study was conducted using a questionnaire for male and female high school students using the Internet, and demographic and sociological characteristics were used only as basic data. In this study, as much as parents, students and teachers think, the results of the internet addiction type analysis according to academic achievement in humanities high school students are to be investigated to determine whether internet use has an effect on academic achievement.

• Journal of Information Technology Applications and Management
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• v.26 no.6
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• pp.29-46
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• 2019

This study analyzed the factors influencing the technology acceptance of the general public in the drones and ARs, one of the key technologies of the industry 4.0. The theoretical basis was the extended unified theory of acceptance and use of technology model(UTAUT2), which uses performance expectancy, effort expectancy, social influence, facilitating conditions, and hedonic motivation as factors common to both services. The price value factor was excluded considering that most ARs were free, and the perceived risk factors, including privacy, which were not in UTAUT2, were included because they are important factors for ICT technology acceptance. The hypothesis was tested by structure equation model. Social influence and hedonic motivation had a positive(+) effect on intention to use technology. On the other hand, in the case of effort expectancy, neither the AR nor the drone had a significant influence on intention to use technology. Furthermore, performance expectancy had a positive(+) effect on intention to use in AR, but no significant influence was found out in drones. On the contrary, in the case of the facilitating conditions, the influence of the drones was positive (+), but the relation of AR was not investigated. The perceived risk was tested for the negative (-) influence of use intention of AR, but no significant relationship was found out for the drones. Among the significant influencing factors, hedonic motivation was the most powerful factor in AR and drones. Theoretical and practical implications are presented based on these results.

• The Journal of Information Systems
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• v.20 no.4
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• pp.181-204
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• 2011

Recently, the development of ICT(information & communications technology) with the advent of new media paradigm shift in learning has brought a dramatic impact on the competitiveness of universities. The previous studies on the academic performance of e-learning mainly targeted on e-learning users, studying additional synchronization and system quality factors to measure academic performance. This study empirically analyzed the learning flow and academic performance considering both DeLone & McLean model system quality and synchronizing factors based on ARCS model. Relating to quality and synchronization factors, the academic performance of e-learning system was tested, and the difference between learning flow and academic performance was also analyzed based on time-series data, by the test difference(in the beginning, during, and final of the semester). The results of the study are as follows. First, the study shows that both system quality and synchronization directly affected the learning performance. Thus, when designing e-learning system, it is necessary to consider these two factors at the same time. Second, the indirectly mediating effect on the system quality and synchronization factors turned out to be significant in learning flow. Third, the result of regression analysis on the contents of utilizing dummy variable presents that the teacher's explanation has greater influence than multimedia has to the academic performance, and furthermore, the test difference showed no significance. Further research should be undertaken to consider the learner's degree of acceptance which reflects various aspects for building m-learning or u-learning.