• Journal of the Korean Statistical Society
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• v.23 no.1
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• pp.13-32
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• 1994

Let A(n) and B(n) be sequences of $m \times m$ random matrices with a joint asymptotic distribution as $n \to \infty$. The asymptotic distribution of the ordered roots of $$\mid$A(n) - f B(n)$\mid$ = 0$ depends on the multiplicity of the roots of a determinatal equation involving parameter roots. This paper treats the asymptotic distribution of the roots of the above determinantal equation in the case where some of parameter roots are zero. Furthermore, we apply our results to deriving the asymptotic distributions of the eigenvalues of the MANOVA matrix in the noncentral case when the underlying distribution is not multivariate normal and some parameter roots are zero.

• Journal of applied mathematics & informatics
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• v.28 no.1_2
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• pp.515-521
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• 2010

In multivariate analysis, the inversion formula of the Stieltjes transform is used to find the density of a spectral distribution of random matrices of sample covariance type. Let $B_n\;=\;\frac{1}{N}Y_nY_n^TT_n$ where $Y_n\;=\;[Y_{ij}]_{n\;{\times}\;N}$ is with independent, identically distributed entries and $T_n$ is an $n\;{\times}\;n$ symmetric non-negative definite random matrix independent of the $Y_{ij}$'s. In the present paper, using the inversion formula of the Stieltjes transform, we will find that the limiting distribution of $B_n$ has a continuous density function away from zero.

• Journal of the Korean Society of Industry Convergence
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• v.3 no.1
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• pp.29-36
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• 2000

In order to reduce a aerodynamic drag of the rear, body, effects of rear lower end configuration of a vehicles were investigated by measuring the pressure distribution, visual flow phenomena by the use of digital image processing technique. The use of flow visualization in recent years has improved the general understanding of structure of complex flow and has yielded valuable information for analyzing fluid flow. As the results, it was found that the shape of rear lower part vehicles not only effected on the pressure distribution of the rear part of the vehicle but also difference of the flow phenomena.

• Journal of Electrical Engineering and Technology
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• v.3 no.1
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• pp.20-28
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• 2008

This paper proposes a method for solving distribution system planning problems taking into account demand uncertainty and geographical information. The proposed method can automatically select appropriate location and size of a substation, routing of feeders, and appropriate sizes of conductors while satisfying constraints, e.g. voltage drop and thermal limit. The demand uncertainty representing load growth is modeled by fuzzy numbers. Feeder routing is determined with consideration of existing infrastructure, e.g. streets and canals. The method integrates planner's experience and process optimization to achieve an appropriate practical solution. The proposed method has been tested with an actual distribution system, from which the results indicate that it can provide satisfactory plans.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.2099-2104
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• 2015

The paper presents a monitoring system for the cooling of distribution transformers. The suggested system is controlled by a microcontroller scheme. The system is designed to control the oil temperature. It gives a solution to improve the cooling system by adding a number of fans especially for indoor transformers that are placed in badly-ventilated rooms. Also, the paper includes an alarm system with the possibility of tripping the transformer if it is necessary. The monitoring system consists of acquisition temperature sensor, and on-site unit. The hardware and software of the on-site unit are demonstrated with sufficient illustrations. Small prototype is constructed in the laboratory. Some laboratory experiments are carried out for examining the designed circuit by using Proteus Virtual System Modeling as well as for testing the prototype monitoring system. Concerning this research point, a study is carried out to evaluate the economic feasibility. The results are recorded and associated with many recommendations that may be valuable to electrical distribution (utility) companies.

• Journal of the Korean Society of Safety
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• v.13 no.4
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• pp.155-161
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• 1998

Recently, there are widely needs of small scale electrostatic precipitator(ESP) in machine shop and other factories. Since the space of such factories is limited, the improvement of collection efficiency is predominant subject. In this study, we examine the influence of distribution of wind velocity and oil mist concentration inside the ESP in order to improve the performance of the ESP. The distribution of wind velocity and mist concentration is measured respectively in a cross-sectional plane of the ESP. The former is controlled by using a louver which is placed in front of an ionizer and the latter is controlled by lengthening the pipe of entrance of the ESP in order to have plenty of time that mist is dispersed evenly. It is shown that the uniformity of distribution of wind velocity and mist concentration inside the ESP can be getting by adopting a louver with proper shape and lengthening the pipe of entrance and is also contributed to collection efficiency considerably.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.1
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• pp.9-17
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• 2011

Development of high efficiency and eco-friendly LED source has been progressed continuously. Also, by nation's regulations, public institutions have changed existing luminaires to LED luminaires. However, there are several differences between existing luminaires and the intensity distribution of general planar LED luminaires. In case of changing existing luminaires to LED luminaires, by such differences, there are inefficiencies both quality aspect and energy aspect in luminous environment. Therefore, this study aims to conduct a study on the changes of intensity distribution and luminous environment by reflector shapes in indirect reflected LED luminaires with software for optical design of a luminaire (Photopia 2.0) and lighting design of a space (ReluxPro). This study shows the changes of intensity distribution and luminous environment of indirect reflected LED luminaires and indirect fluorescent lamp luminaires by reflector shapes.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.12 no.2
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• pp.119-131
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• 2008

The paper considers the computation method in the performance evaluation of cellular network in the phase-type distribution assumptions that the channel holding times induced from mobility are modeled by well-fitted distributions to reflect an actual situation. When ww consider a phase-type distribution model instead of exponential distribution, the complexity of the computation increase exponential even though the accuracy is improved. We consider an efficient numerical algorithm to compute the performance evaluations in cellular networks such as a handoff call dropping probability, new call blocking probability, and handoff arrival rate. Numerical experiment shows that numerical analysis results are well approximated to the results of simulation.

• Journal of Distribution Science
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• v.14 no.5
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• pp.17-26
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• 2016

Purpose - The E-convergence economy is requested with the economic change of the diverse energy supplies, according to the exploits of Shale gas. By analyzing the electric energy supply and demand in accordance with the various cases, it has proved indirectly to create a convergence economy. Research design, data, and methodology - The research design would make realize its potential change with which government or companies have focused on the energy objection between Shale gas and Electric vehicles. Results - The paper suggests that Shale gas has expanded with the emphasis on the Electrical convergence economy or EVs. Due to these results, they also show why it should not be delayed in the development of shale gas and electric vehicles at the same time. Conclusions - All this is from the reason of opening the E-convergence economy over time. It is required that Korea should prepare E-convergence economy. Public regional energy should be present through the consistent selection of development for energy linking E-economy and E-trans distribution.

• Journal of Distribution Science
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• v.3 no.2
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• pp.77-99
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• 2005

In the business environment which enclosed the domestic small and d medium distribution industry, and a business sign of recovery, reduction of income, job insecurity, and a national pension an aging society - positive exhibition of the large-sized store in comparison with the low personal consumption depended uneasy and deregulation, and consumer needs progress of individualization diversification it is ultimately faced with a difficult situation. Therefore the seen research examine the various range of a circulation policy through precedence research. It is going to consider and see the influence which the circulation regulation means of the purpose of large-sized store regulation and a major power is compared, and regulation.