• Wind and Structures
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• 제11권2호
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• pp.121-135
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• 2008

The paper is concerned with a comparative study of both the along and cross-wind responses of a tall industrial chimney with and without flexibility of soil. The along-wind response has been estimated by means of approaches presented in three Standards: the Polish, the ISO and the Eurocode and by random vibration approach which is outlined below. The cross-wind response has been estimated by means of the three models developed by Vickery and Basu, Ruscheweyh and Flaga and methods presented in Standards: the Polish, the ISO and the Eurocode (Approach 1 and 2). Computer programmes were developed to obtain estimates of responses of a six-flue, 250 m-tall chimney. The analytical results computed according to the methods presented in different standards and random vibration approaches have been compared. Some unexpected conclusions have been observed.

• 한국의류학회지
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• 제29권1호
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• pp.46-57
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• 2005

This empirical research aims to identify and compare key success factors in Computer Aided Design (CAD) education in Korea, Japan, Germany and USA. Employing a couple of statistical methods (multiple regression and factor analysis) on survey data, it was found that the decisive factors in the CAD education differed among four countries. Generally speaking, however, educational methods are less important than educational conditions, of which professors and educational environment are dominant factors. This implies that the so called constructivistic way of teaching/learning is not so effective as expected. In order to improve educational performance in Korea, as far as CAD education is concerned, professors need to enhance relationship with industry and universities to support more hardware and software.

• Journal of Electrical Engineering and Technology
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• 제8권1호
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• pp.70-79
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• 2013

In this paper, a comparative study on the frequency estimation methods using IRDWT (Improved Recursive Discrete Wavelet Transform), FRDWT(Fast Recursive Discrete Wavelet Transform), and GCDFT(Gain Compensator Discrete Fourier Transform) is presented. The 345[kV] power system modeling data of the Republic of Korea by EMTP-RV is used to evaluate the performance of the proposed two kinds of RDWT(IRDWT and FRDWT) and GCDFT. The simulation results show that the frequency estimation technique based on FRDWT could be the optimal frequency measurement method, and thus can be applied to FDR(Fault Disturbance Recorder) for wide-area blackout protection or frequency measurement apparatus.

• 한국해양공학회지
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• 제21권3호
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• pp.16-25
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• 2007

A comparative study on the turbulent flaw simulation and the potential flaw analysis has been performed. A law Mach number preconditioned Navier-Stokes solver, using the multi-block grid method and a panel method based on the velocity potential, have been developed and validated by comparison to the experimental data. The present numerical analysis methods are applied to the ground effect problem around the NACA 4412 airfoil. It has been confirmed that the potential flaw analysis on the ground effect, using the image method, is consistent, to some degree, with the viscous calculations for high Reynolds number flows.

• Journal of Ubiquitous Convergence Technology
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• 제2권1호
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• pp.40-50
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• 2008

The problem of assigning customers to satellite channels is a difficult combinatorial optimization problem and is NP-complete. For this combinatorial optimization problem, standard optimization methods take a large computation time and so genetic algorithms (GA) and ant colony optimization (ACO) can be used to obtain the best and/or optimal assignment of customers to satellite channels. In this paper, we present a comparative study of GA and ACO to this problem. Various issues related to genetic algorithms approach to this problem, such as solution representation, selection methods, genetic operators and repair of invalid solutions are presented. We also discuss an ACO for this problem. In ACO methodology, three strategies, ACO with only ranking, ACO with only max-min ant system (MMAS), and ACO with both ranking and MMAS, are considered. A comparison of these two approaches (i,e., GA and ACO) with the standard optimization method is presented to show the advantages of these approaches in terms of computation time.

• Communications for Statistical Applications and Methods
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• 제7권2호
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• pp.465-473
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• 2000

There is no progress in interpreting the correlation between the high school record and the scholastic aptitude test. This study gives the degree of the linearity between the high school record and the scholastic aptitude test by using the method of the individual scholastic evaluation which was proposed by Chung(1999). The limits of the individual scholastic evaluation are pointed out additionally in inferring the promising individuals having the high scores in the scholastic aptitude test so that the individual scholastic evaluation be used as reference materials when the colleges applying the comparative school record in the entrance exams.

• Communications for Statistical Applications and Methods
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• 제6권2호
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• pp.635-644
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• 1999

This study aims at solving the problem in the application method of the comparative school record which is currently being discussed in depth among colleges. The application method of Kay O. Lee and Yeon Soo Cung(1997) which was appied in the 1999 Korean air force Academy Admission Process was found to be problematic in the following respects. First the setting of the standard which divides all the high schools in kora into five groups relative to their scholastic level is somewhat vague and subjective secondly the difference among those levels which resulted from the five grouping could greatly influence on the admission of the applicants and thirdly there is no standard in choosing those few promising individuals with high scholastic aptitude test results from the low level groups such as level four and five,. Therefore this study suggests and introduces a nationwide individual scholastic evaluation that would complement the limits and problems in the application method of the comparative school record.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제3권1호
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• pp.127-132
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• 2003

This paper proposes a wrapper generation method for collecting comparative shopping information from various Internet shopping malls. The proposed method is a kind of supervised learning method to learn wrappers from sample web pages along with information locations designated by the administrators. It generates wrappers expressed in the form of generalized tags sequences and frame filling procedures for semi-structured web pages. The paper also presents how to use the learned wrappers and describes a prototype system which implemented the proposed ideas and methods.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.159-162
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• 2007

Comparative study on a low cost sustaining driver with single and dual path energy recovery circuits for plasma display panels (PDPs) is shown in this paper. The cost of PDPs has been still high and about half of the cost has been occupied by driving circuit. A simple sustaining driver is proposed to reduce the cost and size of driving circuit. The proposed driver has small number of devices and reactive components and there are two methods for charging and discharging PDPs such as single and dual path energy recovery circuits. A comparative research on two-types of energy recovery path is practiced to evaluate performance. As a result, the dual energy recovery path circuit has low power consumption, low surge current and high performance. To verify those results, experiment will be shown with 42-inch HD panel.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.333-335
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• 2006

Position of surface objects can be fixed in many ways. The most popular radionavigational systems, including satellite systems, make possible obtaining nearly continuous and very precise ship's position. However, under the water application of radionavigational systems is impossible. Underwater navigation requires other tools and solutions then these encountered in surface and air navigation. In underwater environment vehicles and submarines, operate that have to possess alternative navigational systems. Underwater vehicles, in order to perform their tasks require accurate information about their own, current position. At present, they are equipped with inertial navigational systems (INS). Accuracy of INS is very high but in relatively short periods. Position error is directly proportional to time of working of the system. The basic feature of INS is its autonomy and passivity. This characteristic mainly decides that INS is broadly used on submarines and other underwater vehicles. However, due to previously mentioned shortcoming i.e. gradually increasing position error, periodical calibration of the system is necessary. The simplest calibration method is surface or nearly surface application of GPS system. Another solution, which does not require interruption of performed task and emergence on the surface, is application of comparative navigation technique. Information about surrounding environment of the ship, obtained e.g. by means sonic depth finder or board sonar, and comparing it with accessible pattern can be used in order to fix ship's position. The article presents a structure and a description of working of underwater vehicle navigation system simulator. The simulator works on the basis of comparative navigation methods which exploit in turn digital images of echograms and sonograms. The additional option of the simulator is ability to robust estimation of measurements. One can do it in order to increase accuracy of position fixed with comparative navigation methods application. The simulator can be a basis to build future underwater navigation system.