• International Journal of Control, Automation, and Systems
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• v.4 no.6
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• pp.775-781
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• 2006

An intelligent optimization method for designing Fractional Order PID(FOPID) controllers based on Particle Swarm Optimization(PSO) is presented in this paper. Fractional calculus can provide novel and higher performance extension for FOPID controllers. However, the difficulties of designing FOPID controllers increase, because FOPID controllers append derivative order and integral order in comparison with traditional PID controllers. To design the parameters of FOPID controllers, the enhanced PSO algorithms is adopted, which guarantee the particle position inside the defined search spaces with momentum factor. The optimization performance target is the weighted combination of ITAE and control input. The numerical realization of FOPID controllers uses the methods of Tustin operator and continued fraction expansion. Experimental results show the proposed design method can design effectively the parameters of FOPID controllers.

• Journal of Mechanical Science and Technology
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• v.15 no.4
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• pp.492-499
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• 2001

The characteristics of Prand시-Meyer expansion of supersonic flow with condensation along a wavy wall in a channel are investigated by means of experiments and numerical analyses. Experiments are carried out for the case of moist air flow in an intermittent indraft supersonic wind tunnel. The flow fields are visualized by a Schlieren system and the distributions of static pressure along the upper wavy wall are measured by a scanning valve system with pressure transducers. In numerical analyses, the distributions of streamlines, Mach lines, iso-pressure lines, and iso-mass fractions of liquid are obtained by the two-dimensional direct marching method of characteristics. The effects of stagnation temperature, absolute humidity, and attack angle of the upper wavy wall on the generation and the locations of generation and reflection of an oblique shock wave are clarified. Futhermore, it is confirmed that the wavy wall plays an important role in the generation of an oblique shock wave and that the effect of condensation on the flow fields is apparent.

• Communications for Statistical Applications and Methods
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• v.15 no.2
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• pp.147-159
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• 2008

We consider using ranked set sampling methods to draw inference about the three well-known measures of overlap, namely Matusita's measure $\rho$, Morisita's measure $\lambda$ and Weitzman's measure $\Delta$. Two exponential populations with different means are considered. Due to the difficulties of calculating the precision or the bias of the resulting estimators of overlap measures, because there are no closed-form exact formulas for their variances and their exact sampling distributions, Monte Carlo evaluations are used. Confidence intervals for those measures are also constructed via the bootstrap method and Taylor series approximation.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.145-152
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• 1999

In the applying of the reinforced soil method, it would be possible to obtain reinforcement effect more than before in terms of economic if high water content clayey soils could be used as embanking material. Futhermore it would be possible to expect the expansion of the applying field of reinforced soil method too. In this study, the authors describe the analysis results on the behavior of 5 meter high walls reinforced with nonwoven geotextile having the permeability and woven geotextile or geogrid having large tensile strength on the soil ground. The behavior of the walls were investigated for about 100 days after construction and the deformations of reinforcements, lateral soil pressures, vertical and horizontal displacements of the walls were examined by automatical measuring system. It was found that this kinds of reinforcing system might effectively improve the performance of the steep walls by virtue of the reciprocal action between soil and reinforcements, and it might be concluded that construction of the clayey reinforced soil walls with three kinds of geotextiles could be done successfully even on the comparative weak ground.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.1
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• pp.214-223
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• 1996

Noise effects on image profiles reconstructed by the spectral inverse scattering technique is studied based on moment method with series-expanded basis function. It is found that the Fourier series expansion to the field distribution and the averaging of the reconstructed profile in each enlarged cell provides an effective tool for the reduction of noise effects.

• Journal of Distribution Science
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• v.12 no.7
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• pp.45-51
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• 2014

Purpose - This study aims to explore the success of Lotte Mart in the global market, as well as examining the factors related to its entry methods. Research design, data, and methodology - This study analyzed the differences between Lotte Mart and E-mart in terms of their market entry methods, based on references and secondary data. This study is based on qualitative research that analyzes actual cases. Based on the results, this study analyzed and discussed actual cases based on references and secondary data, including newspaper interviews on Lotte Mart. Results - Lotte Mart succeeded in adapting to local markets it did this by ensuring the use of both mergers and acquisitions (M&As) and greenfield methods. In contrast, E-mart utilized only greenfield methods. Conclusions - The findings of this study may not be generalized to all industries, as only Lotte Mart was examined using the case analysis method. Therefore, the successful market entry modes of various companies should be explored in terms of FDI.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.10
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• pp.42-49
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• 1993

In this paper, we evaluate the quality of synthesized speech by rule using the LPC CD as a objective measure, and then compare the test result with the subjective one. Speech used for the test consists of 108 words which are selected by word construction method using Korean attribute and frequency distribution, synthesized by demi-syllable rule. By evaluating the quality of synthesized speech by reule objectively, we have tried to resolve the problems such as lots of evaluation time, expansion of test scale, and variables of analysis result arised by subjective measure. We have, also, proved the validity of the objective test using the LPC CD, by comparing intelligibility which is the index for the subjective quality evaluation of synthesized speech by rule with MOS. From this results, we can provide a guide for quality assessment that would be useful in the R&D of synthesis method and the commercial products using synthesized speech.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.7
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• pp.199-210
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• 1994

Most of clustering methods usually employ a center or predefined shape of a cluster to assign the input data into the cluster. When there is no information about data set, it is impossible to predict how many clusters are to be or what shape clusters take. (the shape of clusters could not be easily represented by the center or predefined shape of clusters) Therefore, it is difficult to assign input data into a proper cluster using previous methods. In this paper, to overcome such a difficulty a cluster is to be represented as a collection of several subclusters representing boundary of the cluster. And membership functions are used to represent how much input data bllongs to subclusters. Then the position of the nearest subcluster is adaptively corrected for expansion of cluster, which the subcluster belongs to by use of a competitive learning neural network. To show the validity of the proposed method a numerical example is illustrated where FMMC(Fuzzy Min-Max Clustering) algorithm is compared with the proposed method.

• Journal of the Korean Institute of Telematics and Electronics
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• v.19 no.3
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• pp.1-4
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• 1982

The purpose of this paper is to find and compare efficient and "statistically accurate" algorithms for linear systems with bandlimited random inputs. Using the previously investigated truncated expansions[2], a new state-transition algorithm is derived. With statistical error criteria (mean-square error), comparative study on the Performances has been done for the first and second-order linear system models. The results show that a new bandlimited state-transition algorithm works better than any commonly used algorithms (e. g., first-order state-transition method or Z-transform method).

• Journal of Distribution Science
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• v.16 no.12
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• pp.33-45
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• 2018

Purpose - This study analyzes how Hanssem, which ranks first in domestic market in the furniture industry, responds to the expansion of IKEA, a large overseas furniture maker, and investigates the recent strategic changes of Hanssem and IKEA. Research design, data, and methodology - As a research method, a general method of case studies, literature research, is carried out through academic research results, reports, articles, and statistics. In addition, methods such as field observation and interview with stakeholder were performed to collect in-depth understanding and information about the companies. Results - Along with its core competences, Hanssem has pursued strategic changes to compensate for its weaknesses. IKEA has also used a variety of strategies changes to match the situation in Korea. Conclusion - Both companies have properly balanced localization elements and standardization strategies that value the needs of local consumers. In particular, Hanssem has implemented various strategies based on its core competence in response to IKEA's strategy. In addition, Hanssem and IKEA are actively managing and have good performance not only in Korea but also in foreign markets.