• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.12
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• pp.5860-5876
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• 2018

A single snapshot data can only provide limited amount of information so that the rank of covariance matrix is not full, which is not adopted to complete the parameter estimation directly using the traditional super-resolution method. Aiming at solving the problem, a joint time delay and angle estimation using matrix pencil method based on information reconstruction vector for orthogonal frequency division multiplexing (OFDM) signal is proposed. Firstly, according to the channel frequency response vector of each array element, the algorithm reconstructs the vector data with delay and angle parameter information from both frequency and space dimensions. Then the enhanced data matrix for the extended array element is constructed, and the parameter vector of time delay and angle is estimated by the two-dimensional matrix pencil (2D MP) algorithm. Finally, the joint estimation of two-dimensional parameters is accomplished by the parameter pairing. The algorithm does not need a pseudo-spectral peak search, and the location of the target can be determined only by a single receiver, which can reduce the overhead of the positioning system. The theoretical analysis and simulation results show that the estimation accuracy of the proposed method in a single snapshot and low signal-to-noise ratio environment is much higher than that of Root Multiple Signal Classification algorithm (Root-MUSIC), and this method also achieves the higher estimation performance and efficiency with lower complexity cost compared to the one-dimensional matrix pencil algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.2
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• pp.139-148
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• 2019

The paper proposes an analytical framework for the impact of technical change on business model innovation. Based upon the examination of the relationship between the mission of business and technology, it introduces classification of technology-based business models such as problem-solving model, production model and network model, respectively employing intensive technology, interlinked technology and mediating technology as a key technology. The discussion of various cases of business model innovation shows that the impact of digital technology is first translated into the value generation in terms of efficiency or effectiveness. These new values then enable a new business model which is based on a different key technology through business model shift, expansion, unbundling, or platform. Quite often those business model changes involves system-wide innovation. The framework for the analysis of the impact of technical change on business model innovation is presented with directions for future research.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.1
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• pp.37-49
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• 2019

Recently, most companies are using information technology and its importance is emphasized daily. In an environment where technology is changing rapidly, organizations focus on making good use of reasonable information technology. However, having excellent human resources and reducing turnover is a problem for most organizations. Accordingly, job satisfaction is a factor that can reduce negative factors and enhance positive factors. Therefore, this study explored the factors that can improve job satisfaction. In this regard, this study conducted an empirical analysis on employees who work in small and medium-sized Korean enterprises. We focused on mobile instruction and mobile information sharing as reasonable factors that improve employee job satisfaction. In addition, we examined the effects of employee self-efficacy to increase the influence of reasonable mobile task instruction and mobile information sharing on job satisfaction. Through the results, this research suggests ways to improve employee job satisfaction in the field of small and medium-sized Korean enterprises. It also provides practical implications and discusses future research directions.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.1
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• pp.97-102
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• 2019

There are many difficulties to define because there is no systematic classification and analysis method using accurate criteria or numerical values for creative people. In order to solve this problem, this study attempts to analyze how to distinguish creative people and what kind of personality they have when distinguishing creative people. In this study, I first survey the Big 5 personality trait, classify and analyze the data set using the data mining tool WEKA, and then analyze the data set related to the creativity The goal is to analyze the features using various machine learning techniques. I use seven feature selection algorithms, select feature groups classified by feature selection algorithms, apply them to machine learning algorithms to find out the accuracy, and derive the results.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.2
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• pp.65-72
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• 2019

In long freight trains, there is a brake time delay in neighboring freight cars, which causes damage and fractures in the couplers, especially at their knuckle. A problem in the couplers of the cars can cause derailment and damages of human life and property. In this study, maximum forces on the couplers are studied when a long freight car brakes with the brake delay time and coupler gap. We make a dynamic model of 50 freight cars and couplers, applying contact between the couplers and a characteristic curve to express the force and displacement of the buffers using SIMPACK, which is a multi-body dynamics program. We use EN 14531-2, which is a standard of freight car brakes, to verify the dynamic model. Then, we compare the analyzed impact force with the coupler knuckle standard after applying the two carriages of a locomotive in the model based on the dispersed double head control system. The result shows that all coupler gap conditions satisfy the infinite lifetime of the material when the brake delay time is 0.1 second.

• The Journal of the Convergence on Culture Technology
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• v.5 no.1
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• pp.377-384
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• 2019

To cope with severe global warming and environmental pollution problem regulations on automobile emissions and fuel efficiency has been tightened around the world. Therefore zero emission vehicles which do not use fossil fuels such as electric vehicles have attracted attention by government and both industry and academia at developed countries. In the market, electric vehicles are being selected from more and more consumers because of technological advances and policy support. Recently another zero emission vehicle, hydrogen fuel cell vehicle, is drawing attention and is expected to become deployed widely. This paper reviews technology, current status and global trends of zero emission vehicle. The economical analysis of zero emission vehicles are also presented.

• Journal of Advanced Navigation Technology
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• v.23 no.1
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• pp.44-54
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• 2019

In many countries, there are needs of new transportations to replace ground congestions due to growing number of cars. In addition, the increase in the number of cars held by economic growth will further increase traffic congestion in the future. To overcome this problem, many researches have been performed for personal air vehicle (PAV). In this study, the wing loading and the power-to-weight ratio that are major design parameters for the sizing of roadable PAVs were calculated for different kinds of airfoil and engine types. I.e., in the sizing process, the study was conducted to determine the design point using the graphs of wing loading, power-to-weight ratio, brake horse power, and fuel efficiency for the given mission profiles considering domestic environments and the FAR PART 23 which is the GA class aircraft certification standard. As a result of sizing, using diesel engine require high maximum take-off weight, wing area, and power compared to gasoline engine due to more engine weight.

• The Mathematical Education
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• v.58 no.2
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• pp.225-237
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• 2019

The picture of the mathematics curriculum should carry the complex role of relieving the difficulties of mathematics while conveying the core of the mathematics contents well. This study examined the precedence of picture and text harmony and the importance of emotional expression. The discussion of children's picture books became an important reference in this process. The understanding of the child's psychology and cognitive characteristics in the long history of picture books and the insight into the relationship between text and pictures will be important guidelines for elementary school textbooks. Based on these previous studies, this study found some impressive examples of Chinese, Japanese, Indian, and American textbooks on the two complementary relationships between paintings and texts and emotional expressions of paintings. If necessary, we compared these textbooks with Korean textbooks. Through this analysis, this study draws some implications for Korean textbook drawing and textbook production process. That is, the process of reading the picture and interpreting its meaning should be treated as part of the study of mathematics. The mathematical concepts to be dealt with or the sentence description of the problem should be concurrent with the design of the picture. The monotonous expressions and dialogues of characters in textbooks should be avoided, and the personality and emotions of characters should be more abundant and freely expressive.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.448-466
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• 2019

Today, companies are increasingly focused on SCM (Supply Chain Management) as a means for cost-cutting and efficient operation. The company's ultimate objective is to win and maintain a sustained dominant position in the uncertainties of the global environment and future competitiveness. In this respect, this study examined the effects of management strategy, collaboration process and SCM integration on corporate performance in small and midsize parts manufacturers. The results of empirical analysis are summarized as follows. Management strategy, collaboration process and SCM integration had positive effects on corporate performance in domestic small and midsize parts manufacturers, and all hypotheses were supported. Consequently, it can be confirmed that quality, cost and flexibility for management strategy, and strategic objective perception, support policy, problem solution and knowledge information sharing for delivery and collaboration as small and midsize parts manufacturers are mechanisms for improving quality reliability, decreasing cost, delivery obedience and information system operation of SCM integration, and boosting corporate quantitative and qualitative performance.

• Journal of the Korea Convergence Society
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• v.10 no.4
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• pp.277-284
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• 2019

Purpose: The purpose of this study is to examine the relationships among job stress, resilience and turn over intention of new graduate nurses in general hospital. Methods: A descriptive regression design was used and the participants were 90 new graduate nurses from one general hospital in S city. Data analysis included t-test, ANOVA, pearson's correlation and multiple regression. Results: There were significant correlations between conflict with physicians(r=.17, p=.049), problem relating to supervisors(r=.18, p=.040), discrimination(r=.18, p=.041), resilience(r=-.21, p=.023) and turnover intention. The regression model explained approximately 24.5 % of turnover intention. Conclusion: The findings suggest that nursing leaders have to reduce job stress and to improve resilience of new graduate nurses.