• Journal of IKEEE
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• v.18 no.2
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• pp.272-281
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• 2014

In electrical impedance tomography (EIT), modified Newton Raphson (mNR) method is widely used inverse algorithm for static image reconstruction due to its convergence speed and estimation accuracy. The unknown conductivity distribution is estimated iteratively by minimizing a cost functional such that the residual error namely the difference in measured and calculated voltages is reduced. Although, mNR method has good estimation performance, EIT inverse problem still suffers from ill-conditioned and ill-posedness nature. To mitigate the ill-posedness, generally, regularization methods are adopted. The inverse solution is highly dependent on the choice of regularization parameter. In most cases, the regularization parameter has a constant value and is chosen based on experience or trail and error approach. In situations, when the internal distribution changes or with high measurement noise, the solution does not get converged with the use of constant regularization parameter. Therefore, in this paper, in order to improve the image reconstruction performance, we propose a new scheme to determine the regularization parameter. The regularization parameter is computed based on residual error and updated every iteration. The proposed scheme is tested with numerical simulations and laboratory phantom experiments. The results show an improved reconstruction performance when using the proposed regularization scheme as compared to constant regularization scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.6
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• pp.1283-1293
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• 2014

In ubiquitous environment, data are changing rapidly and new data is coming as times passes. And sometimes all of the past data will be lost if there is not sufficient space in memory. Therefore, there is a need to make rules and combine it with new data not to lose all the past data or to deal with large amounts of data. In making decision trees and extracting rules, the weight of each of rules is generally determined by the total number of the class at leaf. The computational problem of finding a minimum finite state acceptor compatible with given data is NP-hard. We assume that rules extracted are not correct and may have the loss of some information. Because of this precondition. this paper presents a new approach for refining rules. It controls their weight of rules of previous knowledge or data. In solving rule refinement, this paper tries to make a variety of rules with pruning method with majority and minority properties, control weight of each of rules and observe the change of performances. In this paper, the decision tree classifier with extended data expression having static weight is used for this proposed study. Experiments show that performances conducted with a new policy of refining rules may get better.

• 대한공업교육학회지
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• v.41 no.2
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• pp.89-118
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• 2016

In this study, the model of Turtle Ship, which is evaluated as one of the world's first ironclad ship in battle as well as the traditional scientific and technological heritage in Korea, was combined with the Physical Computing Platform(Arduino and App Inventor) that enables students to learn the basic concepts of IT in an easy and fun way. Thus, this study contrived the Physical Computing Platform-based Turtle Ship model which will make the students of Industrial Specialized High School develop the technological literacy and humanities-based knowledge through flexible education out of stereotype and single subject as well as enhance the potential of creative convergence education. The following is a summary of the main results obtained through this study: First, Arduino-based Main-controller design and making is helpful to learn of the hardware and software knowledge about EEC(Electron Electronics Control) and to confirm the basic characteristics and performance of interaction of Arduino and actuators. Second, The fundamental Instructional environments of abilities such as implementing EEC systems, thinking logically, and problem-solving skills were provided by designing of pattern diagram, designing an actuator circuit and making, the creation of sketches as technical programming and developing of mobile app. Thirdly, This is physical computing platform based Turtle ship model that will enable students to bring up their technological literacy and interest in the cultural heritage.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.4
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• pp.419-429
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• 2003

A three-dimensional (3-D) method of analysis is presented for determining the free vibration frequencies of thick, hyperboloidal shells of revolution. Unlike conventional shell theories, which are mathematically two-dimensional (2-D), the present method is based upon the 3-D dynamic equations of elasticity. Displacement components u/sub r/, u/sub θ/, u/sub z/ in the radial, circumferential, and axial directions, respectively, we taken to be sinusoidal in time, periodic in θ, and algebraic polynomials in the r and z directions. Potential(strain) and kinetic energies of the hyperboloidal shells are formulated, and the Ritz method is used to solve the eigenvalue problem, thus yielding upper bound values of the frequencies by minimizing the frequencies. As the degree of the polynomials is increased, frequencies converge to the exact values. Convergence to four digit exactitude is demonstrated for the first five frequencies of the hyperboloidal shells of revolution. Numerical results are tabulated for eighteen configurations of completely free hyperboloidal shells of revolution having two different shell thickness ratios, three variant axis ratios, and three types of shell height ratios. Poisson's ratio (ν) is fixed at 0.3. Comparisons we made among the frequencies for these hyperboloidal shells and ones which ate cylindrical or nearly cylindrical( small meridional curvature. ) The method is applicable to thin hyperboloidal shells, as well as thick and very thick ones.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.2
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• pp.129-136
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• 2020

In this study, we develop a sampling-based seismic probabilistic risk assessment (SPRA) quantification technique that can accurately consider a partially dependent condition of component seismic fragility information. Specifically, the SPRA quantification method is proposed by combining the advantages of two representative methodologies: EPRI seismic fragility and JAERI seismic fragility input-based quantification. The most important feature of the proposed method is that it performs a SPRA using a sampling technique by transforming the EPRI seismic fragility input into JAERI seismic fragility input. When the proposed sampling-based approach was applied to an example of simple system and to a SPRA problem of a nuclear power plant, it was observed that the proposed method yields approximately similar system seismic fragility and seismic risk results as those of the exact solution. Therefore, it is believed that the approach proposed in this study can be used as a useful tool for accurately assessing seismic risks, considering the partial seismic dependence among the components; the existing SPRA method cannot handle such partial dependencies.

• Journal of Digital Convergence
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• v.18 no.10
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• pp.59-80
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• 2020

The purpose of this study is to analyze the current problems with the recovery methods and support systems for harm caused by digital sexual assault, based on cases in the U.S., U.K., and Australia. The significance of this study is the implications on problem solving related to digital sexual assault based on the legislation and systems of advanced foreign nations. The analytical method behind this study is the investigation of research literature. The reference materials are from judicial precedents, comparative analysis on media data, experts' advisory conferences, study forums, foreign theses, and documents on law and policy. As shown by the results of this study, we need to examine digital sexual exploitation and seek countermeasures from the victim's perspective after comparing foreign cases to determine the best protections and support systems. As digital sexual content can spread indefinitely, we certainly recognize the inherent difference between digital sexual crimes and offline sexual crimes. Thus, each case needs to be professionally categorized and an appropriate punishment must be suggested that satisfies the victims' needs. Ultimately, this study is meaningful for suggesting preventive measures against digital sexual crimes.

• Journal of Digital Convergence
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• v.18 no.10
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• pp.325-334
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• 2020

This study was done to examine parents, peer, teacher attachment, depression, and self-conception in adolescents. A survey using a structured questionnaire was conducted with 2,3 grade students of middle school located in 137 subjects. Data were analyzed using an independent t-test, one-way ANOVA, Pearson's correlation, and multiple stepwise regression analysis with the SPSS WIN 22.0 program. There was a significant difference in parents attachment(F=13.878, p<.001), peer attachment(F=7.431, p<.001), teacher attachment(F=7.425, p<.001), depression(F=13.241, p<.001), and self-conception(F=13.136, p<.001) according to participants' school grades. In the correlations of study variables, self-conception showed statistically significant correlations with parents, peer and teacher attachment in aspects of positive, and depression in aspect of negative. Participants' depression explained 61% of variance in self-conception. Findings from this study should be useful in the development of programs to promote participants' self-concept through their depression as a major problem in adolescent mental health.

• Journal of Digital Convergence
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• v.11 no.10
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• pp.331-340
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• 2013

The recent economic downturn has created new challenges for today's company workers such as increased job instability; layoffs; the need to maintain dual income households and the associated childcare requirements; and other job stresses. These stresses give rise to serious problems for workers and ultimately to organizations. Companies therefore need to pay attention to solving the problem of stress. These days, many companies seek a solution from EAP. EAP aims to support workers through counseling, consulting and coaching services to help them overcome issues which may adversely affect job satisfaction and performance. EAP was introduced in this country ten years ago. Formerly, many companies viewed stress primarily as a personal issue. But now more companies are in a hurry to adopt EAP as a means for individuals to resolve stress. This study draws on the example of EAP use in LG Hausys. The company has adopted EAP under the CEO's strong support. The company has effectively managed EAP services which include professional counseling and the training of internal counselors. This study derives implications for the further implementation of EAP services.

• Journal of Digital Convergence
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• v.11 no.1
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• pp.413-421
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• 2013

We, currently settled on the peninsula, have a long history and our ancestors lived over the vast land further to the central Asia and northern China. Normally, our ancestors traded with many countries, but they fought battles when they were on bad terms and many countries emerged and disappeared. In this history, a variety of cultures have been established and the traditional martial arts is a part of those cultures. Our martial arts has been almost severed because of the development of fire weapons in the late Chosun Dynasty, Japan's colonial rule, and 1950-53 Korean War. Fortunately, we can study the traditional martial arts from history books, the records on the martial art books and relics. Muyeadobotongji, the martial art book published in the late Chosun Dynasty, regrets the negligence of martial arts Giyae(arts) after Japanese Invasion of Korea in 1592 and the Manchu war of 1636 and accommodated the martial art skills from Chosun, China and Japan. It is useful for studying martial arts, because it contains detailed description and drawings, clothes and accessories, and the specification of the weapons. However, the problem is the level of Giyae of the martial arts organization and individuals based on Muyeadobotongji vary and some organizations are arguing about the numbers.

• Journal of Digital Convergence
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• v.11 no.10
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• pp.59-69
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• 2013

20s country employment rate to 57% in the last four years, is staying low. College graduates in the 25-29 year old crowd real unemployment rate is over 20% youth unemployment, the analysis problem is serious enough. Accordingly, activation of Cooperation, which addresses the issues of these countries now being recognized as the primary means, and in the future, government policy and national indicators to be given more attention and support seems clear. Government from 2012 'Cooperation Development Project leading universities' (LINC: Leaders in INdustry-university Cooperation) by promoting companies that require manpower, actual research and development and technology transfer to enable the University - Industry - between research institutions based on organic correlated with local universities and industrial growth model for the creation of a variety of leading industry cooperation. has to diffuse. This background, the aim of this study at the University of excavation site close-type talent. Fostering curriculum development are essential to the field on the form will close. In this study, major department (Department) conducted by major research based on the results of the curriculum needs to spread the field for Cooperation closely analyze the curriculum and Annual type, domain-specific promotion measures proposed.