• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1439-1450
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• 2013

This paper investigates a robust neuro-fuzzy control (NFC) method which can accurately follow the speed reference of an interior permanent magnet synchronous motor (IPMSM) in the existence of nonlinearities and system uncertainties. A neuro-fuzzy control term is proposed to estimate these nonlinear and uncertain factors, therefore, this difficulty is completely solved. To make the global stability analysis simple and systematic, the time derivative of the quadratic Lyapunov function is selected as the cost function to be minimized. Moreover, the design procedure of the online self-tuning algorithm is comparatively simplified to reduce a computational burden of the NFC. Next, a rotor angular acceleration is obtained through the disturbance observer. The proposed observer-based NFC strategy can achieve better control performance (i.e., less steady-state error, less sensitivity) than the feedback linearization control method even when there exist some uncertainties in the electrical and mechanical parameters. Finally, the validity of the proposed neuro-fuzzy speed controller is confirmed through simulation and experimental studies on a prototype IPMSM drive system with a TMS320F28335 DSP.

• Structural Monitoring and Maintenance
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• v.5 no.2
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• pp.273-295
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• 2018

In this study, an investigation of a damage detection methodology for global condition assessment is presented. A particular emphasis is put on the utilization of wireless sensors for more practical, less time consuming, less expensive and safer monitoring and eventually maintenance purposes. Wireless sensors are deployed with a sensor roving technique to maintain a dense sensor field yet requiring fewer sensors. The time series analysis method called ARX models (Auto-Regressive models with eXogeneous input) for different sensor clusters is implemented for the exploration of artificially induced damage and their locations. The performance of the technique is verified by making use of the data sets acquired from a 4-span bridge-type steel structure in a controlled laboratory environment. In that, the free response vibration data of the structure for a specific sensor cluster is measured by both wired and wireless sensors and the acceleration output of each sensor is used as an input to ARX model to estimate the response of the reference channel of that cluster. Using both data types, the ARX based time series analysis method is shown to be effective for damage detection and localization along with the interpretations and conclusions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.4
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• pp.398-414
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• 1992

For designing the radar integrated data network, we construct the network structure with a spatial hierarchy decomposition scheme. The RIDN can be decomposed into several subnet classes, those of which are composed of the several group classes of radar sits, In a group class, the communication nodes of a radar site are modeled by the software modules formulated with the statistical attributes of discrete events. And we get the analysis over the network through the separately constructed infra group level models which were coded with the C language. After constructing the local area network with these infra models through the proper data links. We got the analysis of the communication performance of inner models and the global network.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.2
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• pp.182-191
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• 2001

The paper describes the improvement on concurrent subspace optimization(CSSO) via automatic differentiation. CSSO is an efficient strategy to coupled multidisciplinary design optimization(MDO), wherein the original design problem is non-hierarchically decomposed into a set of smaller, more tractable subspaces. Key elements in CSSO are consisted of global sensitivity equation, subspace optimization, optimum sensitivity analysis, and coordination optimization problem that require frequent use of 1st order derivatives to obtain design sensitivity information. The current version of CSSO adopts automatic differentiation scheme to provide a robust sensitivity solution. Automatic differentiation has numerical effectiveness over finite difference schemes tat require the perturbed finite step size in design variable. ADIFOR(Automatic Differentiation In FORtran) is employed to evaluate sensitivities in the present work. The use of exact function derivatives facilitates to enhance the numerical accuracy during the iterative design process. The paper discusses how much the automatic differentiation based approach contributes design performance, compared with traditional all-in-one(non-decomposed) and finite difference based approaches.

• Journal of the Korean Society for information Management
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• v.23 no.4 s.62
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• pp.215-231
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• 2006

Recently there are many bibliometric studies attempting to utilize Pathfinder networks(PFNets) for examining and analyzing the intellectual structure of a scholarly field. Pathfinder network scaling has many advantages over traditional multidimensional scaling, including its ability to represent local details as well as global intellectual structure. However there are some limitations in PFNets including very high time complexity. And Pathfinder network scaling cannot be combined with cluster analysis, which has been combined well with traditional multidimensional scaling method. In this paper, a new method named as Parallel Nearest Neighbor Clustering (PNNC) are proposed for complementing those weak points of PFNets. Comparing the clustering performance with traditional hierarchical agglomerative clustering methods shows that PNNC is not only a complement to PFNets but also a fast and powerful clustering method for organizing informations.

• Atmosphere
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• v.28 no.3
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• pp.273-289
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• 2018

This paper evaluates daily precipitation products from Integrated Multisatellite Retrievals for Global Precipitation Measurement (IMERG), Tropical Rainfall Measuring Mission Multisatellite (TRMM) Precipitation Analysis (TMPA), and the Climate Prediction Center Morphing Method (CMORPH), validated against gauge observation over South Korea and gauge-based analysis data East Asia during one year from June 2014 to May 2015. It is found that the three products effectively capture the seasonal variation of mean precipitation with relatively good correlation from spring to fall. Among them, IMERG and TMPA show quite similar precipitation characteristics but overall underestimation is found from all precipitation products during winter compared with observation. IMERG shows reliably high performance in precipitation for all seasons, showing the most unbiased and accurate precipitation estimation. However, it is also noticed that IMERG reveals overestimated precipitation for heavier precipitation thresholds. This assessment work suggests the validity of the IMERG product for not only seasonal precipitation but also daily precipitation, which has the potential to be used as reference precipitation data.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.3
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• pp.204-215
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• 2020

Efforts on the continued increase of local government's fiscal spending related to improving the residential environment are desirable to counter the declining phenomenon of urban decline. At the same time, however, it is also important to know how to operate limited finances more efficiently to improve the residential environment. This study aims to contribute to the rational allocation of fiscal expenditure and the creation of productive results for the improvement of the settlement environment. To this end, this study analyzed the efficiency of financial expenditure related to the improvement of the residential environment in 225 local governments nationwide. The relationship between financial expenditure and residential environmental performance was also measured and the CCR, BCC and SBM models were used to measure efficiency. The analysis showed that most local governments need to scale back their fiscal spending related to improving the government environment. In addition, it was required to prepare feasible spending plans by bench-marking the processes of residential environment improvement projects in areas such as Haman-gun, Jongno-gu, Seoul, and Seocho-gu, which are considered to be under efficient operation.

• Journal of the Korean Data and Information Science Society
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• v.22 no.4
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• pp.735-740
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• 2011

In recent, electronic devices were able to develop and focus for ultra-compact size, intelligence, multifunction and broadband. Their SMPS is realized to ultra-compact size, light weight, high efficiency, high reliability, low noises. The power module which can be used to supply DC output from a commercial power supply (85 to 265 VAC). A switching power supply can be made easily by adding simply external circuit, such as microcontroller, a relay, etc. It would be apply to mostly electronic devices, and fit the global project "Saving energy". But we need to statistical analysis for a quality and performance about a load and an output voltage in product.

• Journal of the Korean Home Economics Association
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• v.50 no.8
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• pp.97-112
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• 2012

The purpose of this study is to develop the concept of manner leadership for adolescents based on the manner of the East and leadership of the West. Also, it is to investigate the influence of manner leadership on happiness of adolescents. For this, manner leadership was developed through literature review, focus group interview, empirical study, in-depth interview, exploratory factor analysis, and confirmatory factor analysis. The sub-dimensions of manner leadership consisted of time management, academic performance, goal attainment and citizenship behavior, communication, family relationship, social relationship, image management and conflict resolution. The data were obtained by administering a self-reported questionnaire to high school students residing in Seoul. Statistical analyses were carried out using SPSS and AMOS. The main results of the study can be summarized as follows. First, the level of the adolescents' manner leadership tended to be more than average. In addition, they were good at image management but time management was absolutely lacking among the sub-dimension of manner leadership. On the other hand, it appeared that the adolescents' happiness level was lower than the manner leadership. Second, the result of the study was that the manner leadership was positively correlated with happiness of adolescents. Finally, happiness of adolescents was affected on these variables, such as grade, self-efficacy, emotional intimacy between mother and adolescent, time management, goal attainment, communication, and family relationship. Based on this study, it is expected that the manner leadership programs for enhancing happiness for adolescents would be developed.

• Journal of Environmental Science International
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• v.29 no.3
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• pp.283-297
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• 2020

Technology used by human beings has developed drastically over the years. Although people enjoy affluent lives as a result of this development, the depletion of resources has brought about a variety of environmental problems such as emission of fine dust, treatment of waste water, and global warming. Although studies on environmental pollution are being conducted continuously, there are a limited number of studies that analyze research trends from quantitative and qualitative perspectives. In order to examine the current research landscape, we employed Scopus to combine research interest in environmental science with bibliographic analysis. Among 74,089 papers published in 57 journals of environmental science, 3,212 papers were published by Korean authors and citations per publications and Field-Weighted Citation Impact (FWCI) of those papers were 7.3 and 1.0, respectively. By assessing the bibliometric indicators in the field of environmental science, this study provides insight into research trends and related data to aid researchers in developing research strategies.