• Journal of the Earthquake Engineering Society of Korea
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• v.19 no.1
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• pp.37-43
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• 2015

This paper presents a detailed procedure for a nonlinear soil-structure interaction of a seismically isolated NPP(Nuclear Power Plant) structure using the boundary reaction method (BRM). The BRM offers a two-step method as follows: (1) the calculation of boundary reaction forces in the frequency domain on an interface of linear and nonlinear regions, (2) solving the wave radiation problem subjected to the boundary reaction forces in the time domain. For the purpose of calculating the boundary reaction forces at the base of the isolator, the KIESSI-3D program is employed in this study to solve soil-foundation interaction problem subjected to vertically incident seismic waves. Wave radiation analysis is also employed, in which the nonlinear structure and the linear soil region are modeled by finite elements and energy absorbing elements on the outer model boundary using a general purpose nonlinear FE program. In this study, the MIDAS/Civil program is employed for modeling the wave radiation problem. In order to absorb the outgoing elastic waves to the unbounded soil region, spring and viscous-damper elements are used at the outer FE boundary. The BRM technique utilizing KIESSI-3D and MIDAS/Civil programs is verified using a linear soil-structure analysis problem. Finally the method is applied to nonlinear seismic analysis of a base-isolated NPP structure. The results show that BRM can effectively be applied to nonlinear soil-structure interaction problems.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.651-656
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• 2002

In general, the most important problem in slope stability analysis is that there is no definite way to describe the natural three-dimensional Joint network. Therefore, the many approaches were tried to anlayze the slope stability. Numerical modeling approach is one of the branch to resolve the complexity of natural system. UDEC, FLAC, and SWEDGE are widely used commercial code for the purpose on stability analysis. For the purpose on the more appropriate application of these kind of code, however, three-dimensional distribution of joint network must be identified in more explicit way. Remaining problem is to definitely describe the three dimensional network of joint and bedding, but it is almost impossible in practical sense. Three dimensional joint generation method with random number generation and the results of generation to UDEC have been applied to settle the refered problems in field site. However, this approach also has a important problem, and it is that joint network is generated only once. This problem lead to the limitation on the application to field case, in practical sense. To get rid of this limitation, Monte Carlo Simulation is proposed in this study 1) statistical analysis of input values and definition of the applied system with statistical parameter, 2) instead of the consideration of generated network as a real system, generated system is just taken as one reliable system, 3) present the design parameters, through the statistical analysis of ouput values Results of this study are not only the probability of failure, but also area of failure block, shear strength, normal strength and failure pattern, and all of these results are described in statistical parameters. The results of this study, shear strength, failure area, pattern etc, can provide the direct basement on the design, cutoff angle, support pattern, support strength and etc.

• Bulletin of the Society of Naval Architects of Korea
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• v.13 no.4
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• pp.19-24
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• 1976

Some method of analysis of rectangular plates under distributed load of various intensity with all edges built in are presented in. Analysis of many structures such as bottom, side shell, and deck plate of ship hull, and flat slab, deck systems of bridges is a problem of plate with continuous supports or clamped edges. When the four edges of rectangular plate is simply supported, the double fourier series solution developed by Navier can represent an exact result of this problem. If two opposite edges are simply supported, Levy's method is available to give an "exact" solution. When the loading condition and boundary condition of a plate does not fall into these cases, no simple analytic method seems to be feasible. Analysis of a plate under distributed loads of various intensity with all edges built in is carried out by applying Navier solution and Levy's method as well as "Principle of Superposition" In discussing this problem we start with the solution of the problem for a simply supported rectangular plate and superpose on the deflection of such a plate the deflections of the plate by slopes distributed along the all edges. These slopes we adjust in such a manner as to satisfy the condition of no rotation at the boundary of the clamped plate. This method can be applied for the cases of plates under irregularly distributed loads of various intensity with two opposite edges simply supported and the other two edges clamped and all edges simply supported and this method can also be used to solve the influence values of deflection, moment and etc. at arbitrary position of plates under the live load.

• Journal of the military operations research society of Korea
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• v.5 no.1
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• pp.7-15
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• 1979

The very fact that so many of us are here to participate in this conference on Operations Research is an indicator of the importance we attach to this relatively new and still expanding field. All of us recognize that Operations Research techniques are especially useful tools in problem solving in business, Government and the military. A discussion of the role of Operations Research and the related field of Systems Analysis in national defense policy and programming decision processes seems especially appropriate at the opening session of this conference, As you know, Operations Research as an organized form of research first found application in the review of individual military weapons systems and their effectiveness just over forty years ago. From that relatively narrow beginning has evolved a discipline whose future exploitation and utility you will explore over the next several days. I plan to review very briefly the historical development of Operations Research and Systems Analysis as tools in the defense decision-making process. Then, I will give you an overview of their application to today's military and defense problem solving by discussing the use of these techniques at the headquarters level by the United States Navy, Obviously, in such a brief period, I cannot cover all applications, specific techniques, or all of the groups involved in such a complex process. A review of the historical development of Operations Research/Systems Analysts reveals that the use of the basic concepts of Operations Research is not new; it originated with the first attempts to use the scientific approach to solve problems. We are still seeking, through modern analysis, to answer the three questions posed by John Dewey in his examination of the problem solving process in 1910.'1 - What is the problem? - What are the alternatives? - Which alternative is best? As I noted earlier, Operations Research, as an organized form of research, began in Great Britain in the late 1930s with the review of individual weapons systems.

• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1350-1364
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• 2023

2D/1D coupling method is an important neutron transport calculation method due to its high accuracy and relatively low computation cost. However, 2D/1D coupling method may diverge especially in small axial mesh size. To analyze the convergence behavior of 2D/1D coupling method, a Fourier analysis for k-eigenvalue neutron transport problems is implemented. The analysis results present the divergence problem of 2D/1D coupling method in small axial mesh size. Several common attempts are made to solve the divergence problem, which are to increase the number of inner iterations of the 2D or 1D calculation, and two times 1D calculations per outer iteration. However, these attempts only could improve the convergence rate but cannot deal with the divergence problem of 2D/1D coupling method thoroughly. Moreover, the choice of axial solvers, such as DGFEM SN and traditional SN, and its effect on the convergence behavior are also discussed. The results show that the choice of axial solver is a key point for the convergence of 2D/1D method. The DGFEM SN based 2D/1D method could converge within a wide range of optical thickness region, which is superior to that of traditional SN method.

• School Mathematics
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• v.14 no.4
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• pp.431-443
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• 2012

The purpose of the research is to offering an implication about problem posing instruction for improving problem solving ability through 5th grade elementary school students' responses on problem posing. For the purpose a survey was implemented to 281 students at Busan urban area. There was a difference between the students' completeness in terms of problem posing types. They tended to make more simple problems linguistically rather than complicated problems and made problems for the equation easily. At first for the problem posing, students need to be taught to learn for making appropriate problems about an equation.

• Journal of the Korean Home Economics Association
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• v.41 no.8
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• pp.19-31
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• 2003

This study was intended to present the plan for preventing and solving the seriousness of the consumer problem perceived in the e-commerce. For this purpose, 723 questionnaires were distributed to university As a result of analysis, the following findings were obtained: 1) It was found that e-commerce users had higher knowledge of the degree of internet un, the ability to use information on the internet, the disposition of computerization, and e-commerce related consumer than e-commerce non-users. 2) It was found that e-commerce non-users had the higher level of perceived seriousness of the consumer problem than e-commerce users. Especially, it was found that e-commerce non-users had the high level of perceived seriousness of the consumer problem related to the problem of exchange, termination and after-sale nice and the leakage of exchange, termination and after-sale service and the leakage of private information e-commerce user. 3) It was found that university consumers' perceived seriousness of the consumer problem in e-commerce over the internet showed a significant difference in the ability to use information on the internet between e-commerce users and non-users.

• Korean Journal of Human Ecology
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• v.24 no.6
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• pp.783-793
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• 2015

The purpose of this study was to investigate the effect of Parenting Attitude, Self-esteem, and Peer Attachment on Emotion Problem. The study is based on data from first wave of 'Korean Child Youth Panel Survey 2010(KCYPS)' and the subjects of this survey were 2,098 1st grade junior middle school students. To measure the variables, this study used such scales as the parenting attitude scale, self-esteem scale, and peer attachment scale and emotional problem scale. The data were analyzed using descriptive statistics, Pearson's correlation and structural equation modeling analysis. Results of structural equation modeling with data indicated that hypothesized structural equation model produced a good fit but, no direct effect between negative parenting attitude and peer attachment. The self-esteem have mediating effect between parenting attitude and peer attachment, emotion problem. The peer attachment have mediating effect between positive parenting attitude and emotion problem but, did not have mediating effect between negative parenting attitude and emotion problem. The implications for counseling and suggestions for future research are discussed.

• The Mathematical Education
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• v.47 no.2
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• pp.169-180
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• 2008

The purpose of this study was to analyze the elementary students' mathematical thinking, which is found during mathematical problem solving processes based on mathematical knowledge, heuristics, control, and mathematical disposition. The participants were 8 fifth grade elementary students in Seoul. A qualitative case study was used for investigating the students' mathematical thinking. The data were coded according to the four components of the students' mathematical thinking. The results of the analyses concerning mathematical thinking of the elementary students were as follows: First, in terms of mathematical knowledge, the elementary students frequently used conceptual knowledge, procedural knowledge and informal knowledge during problem solving processes. Second, students tended not to find new heuristics or apply new one, but they only used the heuristics acquired from the experiences of the class and prior experiences. Third, control was found while students were solving problems. Last, mathematical disposition influenced on the mathematical problem solving processes. Teachers need to in-depth observations on the problem solving processes of students, which leads to teachers'effective assistance on facilitating students' problem solving skills.

• East Asian mathematical journal
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• v.31 no.2
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• pp.145-165
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• 2015

The purpose of this study is to suggest how to go about teaching and learning secondary school algebra by analyzing problem-solving ability and problem-solving process through algebraic reasoning. In doing this, 393 students' data were thoroughly analyzed after setting up the exam questions and analytic standards. As with the test conducted with technical school students, the students scored low achievement in the algebraic reasoning test and even worse the majority tried to answer the questions by substituting arbitrary numbers. The students with high problem-solving abilities tended to utilize conceptual strategies as well as procedural strategies, whereas those with low problem-solving abilities were more keen on utilizing procedural strategies. All the subject groups mentioned above frequently utilized equations in solving the questions, and when that utilization failed they were left with the unanswered questions. When solving algebraic reasoning questions, students need to be guided to utilize both strategies based on the questions.