• The Journal of the Korea Contents Association
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• v.9 no.2
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• pp.142-151
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• 2009

Previous document clustering method, NSTC measures similarities between two document pairs using TF-IDF during web document clustering. In this paper, we propose new similarity measure using common phrase-based relational graph, not TF-IDF. This method suggests that weighting common phrases by relational graph presenting relationship among common phrases in document collection. And experimental results indicate that proposed method is more effective in clustering document collection than NSTC.

• Communications for Statistical Applications and Methods
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• v.20 no.3
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• pp.217-223
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• 2013

Two influence diagnostic methods for the common mean model are proposed. First, an investigation of the influence of observations according to minor perturbations of the common mean model is made by adapting the local influence method which is based on the likelihood displacement. It is well known that the maximum likelihood estimates are in general sensitive to influential observations. Case-deletions can be a candidate for detecting influential observations. However, the maximum likelihood estimators are iteratively computed and therefore case-deletions involve an enormous amount of computations. An approximation by Newton's method to the maximum likelihood estimator obtained after a single observation was deleted can reduce much of computational burden, which will be treated in this work. A numerical example is given for illustration and it shows that the proposed diagnostic methods can be useful tools.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.324-327
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• 2001

This paper shows an example of the Design Review and Common-Cause Failure (CCF) Modeling of mechanical Parts. Reliability should be continuously monitored during the entire period of design. Design Review is the procedure to improve the reliability for the product. We proposed the reliability assessment and design review method. CCF Model is the general dependent model considering the failure mode effects several component simultaneously. This study considers the computation of the network with dependent components. It is important that CCF model is applied for mechanical pars.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.209-210
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• 2015

This paper presents a new model predictive control method without the effect of a weighting factor in order to reduce common-mode voltage (CMV) for a three-phase voltage source inverter (VSI). By utilizing two active states with same dwell time during a sampling period instead of one state used in conventional method, the proposed method can reduce the CMV of VSI without the weighting factor. Simulation is carried out to verify the effectiveness of the proposed predictive control method with the aid of PSIM software.

• Journal of Power Electronics
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• v.19 no.6
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• pp.1477-1485
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• 2019

This paper proposes an effective model predictive current control (MPCC) that involves using 10 virtual voltage vectors to reduce the current harmonics and common-mode voltage (CMV) for a two-level five-phase voltage source inverter (VSI). In the proposed scheme, 10 virtual voltage vectors are included to reduce the CMV and low-order current harmonics. These virtual voltage vectors are employed as the input control set for the MPCC. Among the 10 virtual voltage vectors, two are applied throughout the whole sampling period to reduce current ripples. The two selected virtual voltage vectors are based on location information of the reference voltage vector, and their duration times are calculated using a simple algorithm. This significantly reduces the computational burden. Simulation and experimental results are provided to verify the effectiveness of the proposed scheme.

• Environmental and Resource Economics Review
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• v.20 no.2
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• pp.335-356
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• 2011

In this paper, we attempted to suggest a way to evaluate appropriateness and efficiency for the energy consumption structure. For this, based on Markowitz (1952)' mean-variance portfolio model, we constructed an optimal fossil fuel mix. In constructing the optimal mix, we first defined returns on fossil fuels (oil, coal and natural gas) as TOE (Ton of Oil Equivalent) per $1. Then, by using the dynamic latent common factor model, we decomposed the growth rates of the returns on each fossil fuel into two parts : the common part and the idiosyncratic part. Finally, based on the results from the dynamic latent common factor model, we constructed the optimal fossil fuel mix implied by the mean-variance portfolio model. Our results indicate that for the fossil fuel mix to be on the efficient frontier, it is crucial to reduce oil consumption as low as possible. Moreover, our results imply that it is more efficient to increase natural gas consumption rather than coal consumption in reducing oil consumption. These results are in line with the strategies for the future energy consumption structure pursued by Korea and indicate that reduction in oil use can improve overall efficiency in energy consumption.

• KEPCO Journal on Electric Power and Energy
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• v.8 no.2
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• pp.127-135
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• 2022

With the advent of high technologies such as the 4th Industrial Revolution and artificial intelligence and big data, efforts are being made to solve urban problems and improve the quality of life by applying new technologies in the smart city field. In addition, as carbon neutrality has emerged as an important issue due to global warming, smart city energy platform technologies such as urban energy management, efficiency improvement, and carbon reduction are in the spotlight. In order to effectively manage urban energy, energy resource information such as electricity, water, gas, hot water, heating, etc. must be collected from the management system of various energy utilities and managed on the central platform. The centrally integrated data is delivered to external city management systems that require city energy information through an energy platform. This study developed a CIM profile for smart city energy monitoring required to provide energy data to external systems. Electric data model were designed using the CIM class of IEC 61970, and water, gas, and heat data model were designed in compliance with the UML-based design ideas of IEC 61970.

• Journal of Korean Library and Information Science Society
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• v.38 no.3
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• pp.201-221
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• 2007

According to the changing of information environment and user's need, discussion of changing role is increasing gradually in the library, in consequence, interests about the concept of Information Commons, which are integrated IT, education, learning, and cultural functions, are becoming larger. However, in order to adopt the Information Commons in the University library, the model about the consideration and application of basic element is essential. So that, the purpose of this study is to suggest the ways which are adopting the elements and process of the applying Information Commons. In addition, based on Information Commons of Arizona university Library & Indiana University Library which is well organized with model, researcher tried to attempt the virtual renovation to the 'S 'University library'. Through presenting the applicable model of Information Commons, it aims to provide the example of discussion with actively about Information Commons.

• Korean Management Science Review
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• v.31 no.4
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• pp.43-53
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• 2014

There is no generally accepted single stylized methodology for the impact assessment of standardization programs even though some scholars in the United States or Europe have been trying to set up a common methodology during past decades. It is because the economic outcome indicators that analysts seek to quantify vary significantly with the diversity and complexity of the affected industry and the analytic approach, as well as the nature of STANDARDIZATION programs. This paper builds up the model to establish common methodology which is designed to enable the comparable economic assessment analysis between various STANDARDIZATION programs. The model thus serves to enable a comparable impact assessment because it enables both universally valid and stylized analysis, while traditional impact assessment analysis can vary depending on the kinds of analytic approaches. In other words, this paper developed the common methodology which is designed to stylize the universally valid impact assessment of STANDARDIZATION programs. In addition, this paper shows that it should be accompanied by empirical research for some items in the model, to enable the realization of the both comparable and sophisticated analysis of impact assessments, thereby outputting in the range of those values which depend on the industry and/or STANDARDIZATION type.

• Journal of the Korean Society for Library and Information Science
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• v.41 no.4
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• pp.347-363
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• 2007

According to alternation of Digital Information Environment. users require more complicated and variable services. This study refined theoretically definition, concept, and materiality of Information Commons which is introduced and diffused throughout U.S. Universities' libraries. Information Commons is not simple facilities and spaces of library, but it is a united service model that is designed to fulfill variable information requirements of users with offering cooperative services, coalition of human resources, physical spaces, and facilities of redefinitions. In order to successful introduction and construction of Information Commons, it should be preceded that approaching digital information resources, offering continual services, and integration of resources that focus on the users.