• Proceedings of the Korean Geotechical Society Conference
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• 1991.10a
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• pp.195-215
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• 1991

This report deals with the process of the finite element computation and the design of the particular example tunnel (the double track section tunnel for Line 5, 7, 8 of Seoul Subway). The finite element calculations are performed with the program MISES 3 was developed from Austria which have been used in Eroupe. The principles of mechanic and mathematic analysis for the program MISES 3 are based on "The Finite Element Method -3rd Edition" by O.C zienkiewicz. The calculations are approximate analysis method divide continuum into quadrilateral element and calculate deformation and stress, according to the force equations at the node of the element. On the calculation of under excavation, this is a very convenient method and able to calculate compounded structure with tunnel lining and surrounding materials. Although calculated under the same factor and conditions, the result is not same solution, according to the shape of mesh. Therefore , it is important that we collect the construction results of NATM on the spot and by comparing the results of the finite element method with the surveying results review the validity of analysis model.sis model.

• Korean Management Science Review
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• v.27 no.3
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• pp.137-147
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• 2010

Real-time supply chain environments based on RFID will be an important topic in future society; Nevertheless, adopting RFID in real industry SCM is still in its infancy. The aim of this paper is to develop the physical framework of a fully adopting RFID system from manufacturing to recycle phase and measure the effect. So, we built a simulation station with fully appling RFID and analyzed benefits with mathematic model. Then, specifying the advantages and improvement scheme for real industry limitations were suggested. This work concluded that fully appling RFID in SCM gives improvement of quality and service to both production and consumer.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.268-270
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• 2008

Bearingless switched reluctance motors (SRM) have combined advantages of conventional SRM and magnetic bearings. Therefore in this paper based on novel structure of Bearingless SRM, an accurate mathematic model of radial force is deduced. Meanwhile in order to realize steady suspending, a novel radial force control method- Direct Instantaneous Radial Force Control (DIRFC) is presented. The effectiveness of new model and DIRFC is proved by the simulation results.

• Research in Mathematical Education
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• v.20 no.1
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• pp.1-9
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• 2016

An accurate evaluation of educational process is a promise for the progress of education, because evaluation provides a meticulous idea of what has actually been achieved as a result of education. However, for all its significance in the educational fields, there are not many discussions about evaluation in South Korea. We believe that in order to overcome this discrepancy, diverse evaluation theories along with a discussion about the merits or demerits or each theory should be introduced in South Korea. We propose that Eisner's educational evaluation model may suggest alternative ways of perceiving evaluation. Eisner's educational evaluation model, named educational connoisseurship and criticism, emerged as an approach to educational evaluation from the methods used in art and literary criticism.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.379-392
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• 1996

A mathematic model was developed for the simulation of sideways overturning of agricultural tractors on slopes. The overturning motion was described as a combination of the rotational motions with respect to the first and second tipping axes using the principle of conservation of angular mementum. A stability criterion was also established in terms of angular acceleration of tractor about the second tipping axis. Verification of the proposed model was provided by comparing the stability boundaries predicted by computer simulation with those observed experimentally for an equivalent 1/6 scaled mode tractor. A good agreement was shown between the simulation and experimental results.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.2
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• pp.32-37
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• 2011

This study developed Gear Automatic Design Program that users with the basic knowledge about mechanical engineering can easily model spur gears and helical gears. The Gear Automatic Design Program used Visual LISP which is an user program based on Auto CAD and made it model the gears with involute tooth by the exact mathematic definition. Also, to verify these, the reliability was secured by comparing it with a gear generated in commercial software. And we will develop nitrocarburising process and solve problems which had been caused of SCM440's dimensional changing.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.5 s.143
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• pp.534-541
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• 2005

Until now, Korean shipyards have accumulated a great amount of data. But they do not have appropriate tools to utilize the data in practical works. Engineering data contains experts' experience and know-how in its own. It is very useful to extract knowledge or information from the accumulated existing data by using data mining technique This paper treats an evolutionary computation based on genetic programming (GP), which can be one of the components to realize data mining. The paper deals with linear models of GP for the regression or approximation problem when given learning samples are not sufficient. The linear model, which is a function of unknown parameters, is built through extracting all possible base functions from the standard GP tree by utilizing the symbolic processing algorithm. In addition to a standard linear model consisting of mathematic functions, one variant form of a linear model, which can be built using low order Taylor series and can be converted into the standard form of a polynomial, is considered in this paper. The suggested model can be utilized as a designing tool to predict design parameters with small accumulated data.

• Journal of Power Electronics
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• v.16 no.6
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• pp.2119-2128
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• 2016

Due to detection and control errors, some high-frequency harmonics with voltage-source characteristics cause circulating currents in modular inverters. Moreover, the circulating currents are usually affected by the output filters (OF) of each module due to their filter and resonance properties. The interaction among the circulating currents in the modules increase the power loss and reduce system stability and control precision. Therefore, this paper reports the results of a study on the SPWM high-frequency harmonics circulating currents for a double-module VSI. In the paper, an analysis of the circulating-current circuits is briefly described. Next, a mathematic model of the single-module output voltage based on the carrier frequency of SPWM is built. On this basis, through mathematic modeling of high-frequency harmonic circulating currents, the formation mechanism and distribution characteristics of circular currents and their influences are studied in detail. Finally, the influences of the OF on the circulating currents are studied by mainly taking an LC-type filter as an example. A theoretical analysis and experimental results demonstrate some important characteristics. First, the carrier phase shifting of the SPWM for each module is the major cause of the SPWM harmonic circulating currents, and the circulating currents are in an odd distribution around n-times the carrier frequency $n{\omega}_s$, where n = 1, 2, 3, ${\ldots}$. Second, the harmonic circular currents do not flow into the parallel system. Third, the OF can effectively suppress the non-circulating part of the high-frequency harmonic currents but is ineffective for the circulation part, and actually reduces system stability.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1307-1317
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• 2010

The various models that estimate the reliability of application software system had been made. But most of the existing models are inconvenient to industrial fields because so complicated mathematic methods as method of estimation parameter have been used. The two purposes of this paper are to develop the reliability estimation model which was easily applied to industrial fields, and to prove no differences between the existing models and the developed model. Therefore the reliability of software system and handled informations are upgraded by far.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.4
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• pp.71-77
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• 2008

This paper presents a methodology for recovering the industrial radiographic images from the effects of nonlinear distortion. Analytical approach based on the inverse square law and Beer's law is developed in order to improve a mathematic model of nonlinear type. The geometric effect due to dimensions of the radioactive source appeals on the digitized images. The relation that expresses parameters values(angle, position, absorption coefficient, length, width and pixel account) is defined in this model, matching with the sample image. To perform the search for image recovery most similar to the model, a correction procedure is designed. The application of this method on the radiographic images of steel tubes is shown and recovered results are discussed.