• International Journal of Fuzzy Logic and Intelligent Systems
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• 제8권2호
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• pp.116-120
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• 2008

Clustering is a method for unsupervised learning. General clustering tools have been depended on statistical methods and machine learning algorithms. One of the popular clustering algorithms based on machine learning is the self organizing map(SOM). SOM is a neural networks model for clustering. SOM and extended SOM have been used in diverse classification and clustering fields such as data mining. But, SOM has had a problem determining optimal number of clusters. In this paper, we propose an improvement of SOM using gap statistic and probability distribution. The gap statistic was introduced to estimate the number of clusters in a dataset. We use gap statistic for settling the problem of SOM. Also, in our research, weights of feature nodes are updated by probability distribution. After complete updating according to prior and posterior distributions, the weights of SOM have probability distributions for optima clustering. To verify improved performance of our work, we make experiments compared with other learning algorithms using simulation data sets.

• Asia pacific journal of information systems
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• 제19권2호
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• pp.73-94
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• 2009

The general aspects for the future warfare shows that the concept of firepower and maneuver centric warfare has been replacing with that of information and knowledge centric warfare. Thus, some developed countries are now trying to establish the information systems to perform intelligent warfare and innovate defense operations. The C4I(Command, Control, Communication, Computers and Intelligence for the Warrior) systems make it possible to do modern and systematic war operations. The basic idea of this study is to investigate how TAM(Technology Acceptance Model) can explain the acceptance behavior in military organizations. Because TAM is inadequate in explaining the acceptance processes forcomplex technologies and strict organizations, a revised research model based upon TAM was developed in order to assess the usage of the C4I system. The purpose of this study is to investigate factors affecting the usage of C4I in the Korean Army. The research model, based upon TAM, was extended through a belief construct such as self-efficacy as one of mediating variables. The self-efficacy has been used as a mediating variable for technology acceptance, and the variable was included in the research model. The external variables were selected on the basis of previous research. The external variables can be classified into following: 1) technological, 2) organizational, and 3) environmental factors on the basis of TOE(Technology-Organization-Environment) framework. The technological factor includes the information quality and the task-technology fitness. The organizational factor includes the influence of senior colleagues. The environmental factor includes the education/train data. The external variables are considered very important for explaining the behavior patterns of information technology or systems. A structured questionnaire was developed and administrated to those who were using the C4I system. Total 329 data were used for statistical data analyses. A confirmatory factor analysis and structured equation model were used as main statistical methods. Model fitness Indexes for measurement and structured models were verified before all 18 hypotheses were tested. This study shows that the perceived usefulness and the self-efficacy played their roles more than the perceived ease of use did in TAM. In military organizations, the perceived usefulness showed its mediating effects between external variables and dependent variable, but the perceived ease of use did not. These results imply that the perceived usefulness can explain the acceptance processes better than the perceived ease of use in the army. The self-efficacy was also used as one of the three mediating variables, and showed its mediating effects in explaining the acceptance processes. Such results also show that the self-efficacy can be selected as one possible belief construct in TAM. The perceived usefulness was influenced by such factors as senior colleagues, the information quality, and the task-technology fitness. The self-efficacy was affected by education/train and task-technology fitness. The actual usage of C4I was influenced not by the perceived ease of use but by the perceived usefulness and selfefficacy. This study suggests the followings: (1) An extended TAM can be applied to such strict organizations as the army; (2) Three mediation variables are included in the research model and tested at real situations; and (3) Several other implications are discussed.

• 대한지구과학교육학회지
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• 제4권3호
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• pp.267-277
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• 2011

The purpose of this study is to examine the effect of IIM-based science writhing lesson on the science process skills and self-directed learning in elementary science-gifted students. To verify research problems, the subjects of this study were forth-grade students selected from one classes of an elementary science-gifted class in Busan National Universty of education : the research group is composed of twenty students who were participated in IIM-based science writing lessons. During 12 weeks, the IIM-based science writing lessons was executed in the reasearch group. Post-test showed following results: First, the research group showed a significant improvement in the science process skill. We look into detailly this, the research group showed a significant improvement in the basis science skill. The sub-factor 'expectation' of the science process skill effects a significant improvement. Second, the research group showed a significant improvement in the self-directed learning. In conclusion, IIM-based science writing lesson was more effective on science process skill and self-directed learning. However, since the study has a limit on an object of the study and the applied program, the additional studies need to be conducted with an extended comparative group and program.

• Asian Journal of Business Environment
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• 제4권4호
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• pp.39-49
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• 2014

Purpose - This study classified consumers' value inclination to find out ways to enhance consumers' eco-friendly product purchase intention. Further, it verified the differences among eco-friendly product purchase intentions depending upon value inclination. Research design, data, and methodology - The structured model and hypotheses were established, and 202 copies of effective questionnaires were used. In order to verify the hypotheses, we used single regression analysis, multiple regression, 3-step mediating regression, and path analysis. Results - Individualism had a positive influence upon materialism, need for uniqueness, and face wants, and collectivism had a positive influence upon materialism only. Factors of self-expressive consumption inclination had a positive influence upon eco-friendly product purchase intention, and factors of value inclination also had a positive influence. Finally, self-expressive consumption inclination mediated between value inclination and eco-friendly product purchase intention. Conclusion - Consumers with individualism inclination felt the need to connect the ownership of an eco-friendly product with their extended self and, further, it was clear that not only the government but also enterprises should build up their public image regarding eco-friendly products.

• 대기
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• 제21권3호
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• pp.221-228
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• 2011

The nonlinear characteristics of summer monsoon intraseasonal oscillation (ISO) in precipitation, which is manifested as fluctuations in convection and circulation, is one of the major difficulty on the prediction of East Asian summer monsoon (EASM). The present study aims to identify the spatial distribution and time evolution of nonlinear phases of monsoon ISO. In order to classify the different phases of monsoon ISO, Self-Organizing Map(SOM) known as a nonlinear pattern recognition technique is used. SOM has a great attractiveness detecting self-similarity among data elements by grouping and clustering such self-similar components. The four important patterns are demonstrated as Meiyu-Baiu, Changma, post-Changma, and dry-spell modes. It is found that SOM well captured the formation of East Asian monsoon trough during early summer and its northward migration together with enhanced convection over subtropical western Pacific and regionally intensive precipitation including Meiyu, Changma and Baiu. The classification of fundamental large scale spatial pattern and evolutionary history of nonlinear phases of monsoon ISO provides the source of predictability for extended-range forecast of summer precipitation.

• 한국정보시스템학회지:정보시스템연구
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• 제15권2호
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• pp.49-75
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• 2006

The main purpose of this study is to identify the factors affecting personnel e-Learning acceptance. We used self-efficacy and perceived playfulness as independent variables to extended Technology Acceptance Model in an e-Learning contort. Perceived playfulness is the one of the important personal intrinsic motivational factors which could enlarge the understanding process of technology acceptance in the personal perspective. Questionnaires were collected from 94 respondents who experienced e-Learning systems that L Corporation provided. This study developed and empirically tested a model representing the relationship by using Structural Equation Model among factors which are: perceived usefulness, perceived ease of use, perceived playfulness, self-efficacy and attitudes. Also we measured affective and cognitive attitude because, most psychometric literature explain attitude has two different dimensions which are affective and cognitive. The major findings of the study are summarized as follows. Firstly, the higher the perceived usefulness the more affected the behavioral intention was to use as well as attitude to be positive. Secondly, as much as perceived playfulness more affected the perceived ease of use as well as self-efficacy. Finally, the perceived ease of use and self-efficacy are not significantly affected attitude while they are affected perceived usefulness and perceived playfulness.

• 한국군사과학기술학회지
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• 제14권3호
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• pp.364-371
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• 2011

This paper presents experimental results and derived experimental equations to investigate the turbulent wake characteristics generated by the self-propelled SUBOFF submarine model. A self-propelled SUBOFF model which was assumed as an axial-symmetric body was used to create wake, and a thin strut was mounted on the topside of the model. The experiments were conducted in a circulating water channel(CWC), and the hot-film was used to measure the turbulence in wake cross-section at the distance range of 0.0~2.0L from the model. The hot film anemometer measured turbulent velocity fluctuations, and the time-averaged mean velocity and turbulent intensity are obtained from the acquired time-series data. Measured results show well the general characteristics of turbulent intensity, kinetic energy and mean velocity distribution. Also, this paper presents derived experimental equations, which is extended result to the reference [1]. These experimental equations show well the general characteristics of the turbulent wake behind the self-propelled submerged body.

• 디지털융복합연구
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• 제16권6호
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• pp.117-126
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• 2018

본 연구는 VR기기를 중심으로 VR기기 수용을 결정하는 다양한 요인들을 제출하고 이러한 요인들과 소비자들의 수용의도와의 관계를 분석하고자 하였다. 본 연구의 목적을 위해 VR기기를 사용해 본 중국 소비자 238명의 설문조사 데이터를 수집하여 AMOS 23.O를 이용하여 분석하였다. 연구결과, 콘텐츠 다양성과 자기효능감이 지각된 용이성, 지각된 유희성과 지각된 유용성에 유의한 영향을 미치는 것으로 나타났다. 지각된 용이성은 지각된 유희성을 경유하여 지각된 유용성에 간접적인 영향을 미치는 것으로 나타났다. 마케팅커뮤니케이션은 수용의도에 유의한 영향을 미쳤지만 지각된 가격은 수용의도에 유의하게 나타나지 않았다. 지각된 유용성, 지각된 용이성, 지각된 유희성은 모두 VR기기의 수용의도에 영향을 미치는 것으로 확인되었다. 본 연구의 결과는 VR기기에 주목하고 있는 기업이 타겟으로 하는 소비자들을 위해 고려해야 하는 요소들을 이해할 수 있는 유용한 마케팅 전략을 제공할 수 있을 것으로 기대한다.

• Journal of Biosystems Engineering
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• 제33권6호
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• pp.423-429
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• 2008

This study was performed to investigate the effects of inertial navigation system (INS) / global positioning system (GPS) sensor fusion for agricultural vehicle navigation. An extended Kalman filter algorithm was adopted for INS/GPS sensor fusion in an integrated mode, and the vehicle dynamic model was used instead of the navigation state error model. The INS/GPS system was consisted of a low-cost gyroscope, an odometer and a GPS receiver, and its performance was tested through computer simulations. When measurement noises of GPS receiver were 10, 1.0, 0.5, and 0.2 m ($1{\sigma}$), RMS position and heading errors of INS/GPS system at 5 m/s straight path were remarkably reduced with 10%, 35%, 40%, and 60% of those obtained from the GPS receiver, respectively. The decrease of position and heading errors by using INS/GPS rather than stand-alone GPS can provide more stable steering of agricultural equipments. Therefore, the low-cost INS/GPS system using the extended Kalman filter algorithm may enable the self-autonomous navigation to meet required performance like stable steering or more less position errors even in slow-speed operation.

• Journal of Power Electronics
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• 제17권1호
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• pp.149-160
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• 2017

To improve the performance of sensorless induction motor (IM) drives, an adaptive speed estimation method based on a strong tracking extended Kalman filter with a least-square algorithm (LS-STEKF) for induction motors is proposed in this paper. With this method, a fading factor is introduced into the covariance matrix of the predicted state, which forces the innovation sequence orthogonal to each other and tunes the gain matrix online. In addition, the estimation error is adjusted adaptively and the mutational state is tracked fast. Simultaneously, the fading factor can be continuously self-tuned with the least-square algorithm according to the innovation sequence. The application of the least-square algorithm guarantees that the information in the innovation sequence is extracted as much as possible and as quickly as possible. Therefore, the proposed method improves the model adaptability in terms of actual systems and environmental variations, and reduces the speed estimation error. The correctness and the effectiveness of the proposed method are verified by experimental results.