• 한국수학교육학회지시리즈A:수학교육
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• 제34권1호
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• pp.17-63
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• 1995

The exploration of Mathematics-learningmodel on the basis of Cognitive development The purpose of this paper is to sequenctialize Mathematics-learning contents, and to explore teaching-learning model for mathematics, with on the basis of the theory of cognitive development and the period of condservation formation for children. The Specific topics are as follows: (1) Systemizing those theories of cognitive development which are related to Mathematics - learning for children. (2) Organizing a sequence of Mathematics - learning, on the basis of experimental research for the period of conservation formation for children. (3) Comparing the effects of 4 types of teaching - learning model, on the basis of inference activity and operational learning principle. $\circled1$ Induction-operation(IO) $\circled2$ Induction-explanation(IE) $\circled3$ Deduction-operation(DO) $\circled4$ Deduction-explanation(DE) The results of the subjects are as follows: (1) Cognitive development theory and Mathe-matics education. $\circled1$ Congnitive development can be achieved by constant space and Mathematics know-ledge is obtained by the interaction of experience and reason. $\circled2$ The stages of congnitive development for children form a hierarchical system, its function has a continuity and acts orderly. Therefore we need to apply cognitive development for children to teach mathematics systematically and orderly. (2) Sequence of mathematical concepts. $\circled1$ The learning effect of mathematical concepts occurs when this coincides with the period of conservation formation for children. $\circled2$ Mathematics Curriculum of Elementary Schools in Korea matches with the experimental research about the period of Piaget's conservation formation. (3) Exploration of a teaching-learning model for mathematics. $\circled1$ Mathematics learning is to be centered on learning by experience such as observation, operation, experiment and actual measurement. $\circled2$ Mathematical learning has better results in from inductional inference rather than deductional inference, and from operational inference rather than explanatory inference.

• Journal of Advanced Research in Ocean Engineering
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• 제1권3호
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• pp.157-167
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• 2015

In order to provide simple and accurate wave theory in design of offshore structure, an analytical approximation is introduced in this paper. The solution is limited to flat bottom having a constant water depth. Water is considered as inviscid, incompressible and irrotational. The solution satisfies the continuity equation, bottom boundary condition and non-linear kinematic free surface boundary condition exactly. Error for dynamic condition is quite small. The solution is suitable in description of breaking waves. The solution is presented with closed form and dispersion relation is also presented with closed form. In the last century, there have been two main approaches to the nonlinear problems. One of these is perturbation method. Stokes wave and Cnoidal wave are based on the method. The other is numerical method. Dean's stream function theory is based on the method. In this paper, power series method was considered. The power series method can be applied to certain nonlinear differential equations (initial value problems). The series coefficients are specified by a nonlinear recurrence inherited from the differential equation. Because the non-linear wave problem is a boundary value problem, the power series method cannot be applied to the problem in general. But finite number of coefficients is necessary to describe the wave profile, truncated power series is enough. Therefore the power series method can be applied to the problem. In this case, the series coefficients are specified by a set of equations instead of recurrence. By using the set of equations, the nonlinear wave problem has been solved in this paper.

• 한국실내디자인학회논문집
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• 제20권3호
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• pp.135-142
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• 2011

There occurs subtle shaking in our eyes while in looking at objects and this study sets up the standard of reconciliation from the property of observation and organizes the property of data reconciliation by the observation range to secure the feasibility of reconciliation range and method of the original data obtained from observation experiment and its analysis process. The results from above study can be concluded as in the followings: First, it made clear the process to exclude eye blink and data out of image range from the original data so to set up the range of available data. Second, on the basis of existing theory, it was possible to define the minimum attention time as 0.1 second (3 times of observation) and the visual understanding time of space as 0.3 second (9 times of observation) in the study on the property of observation, and this definition of observation time of sight fixation becomes an important indicator in the analysis of observation data. Third, based on the observation theory of continuity securing and attention, it was able to arrange the standard of reconciliation by carrying out reconciliation works only when fixed data with more than three times of observation showed consecutively before and behind the data with intermittent movements. Fourth, In the sector whether visual understanding occurred (more than 9 times), it increased by 12% for the frequency of observation and by 7.8% for the times of observation compared with the ones before the reconciliation. These results showed to have a constant change by subjects so that it was able to arrange a foundation to secure objective data in the analysis of the observation range and its extent.

• 한국실내디자인학회논문집
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• 제19권6호
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• pp.100-111
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• 2010

'Pattern' is the term that is frequently used in the aspects of history, society, and science. It always appears in the remains or relics of the age of civilization when recording was started, and its evaluation and value differ by time. Patterns in the ancient civilization were symbolic, social, and spatially crucial. However, after the modernization, they were considered to be immoral and unnecessary, so the range of their significance came to reduce. Due to the development of science, ornament patterns lost the limitation of its range of use along with new interpretation of them. Especially with the advent of new scientific theories such as the evolution theory from the biological aspect, quantum mechanics, and super string theory, morphological possibilities more than the human scale perceived by men came to be discovered. Living organisms maintain their lives through patterns, structures, and processes in order to produce a system alive. Among them, patterns are the organization of relations determining the characteristics of the system. The present patterns may correspond to this meaning. The pattern in a space is the matter of how to relate the components after all. In a space, however, there are numerous components mingled with one another. If these tasks are conducted as analogue work, it will take a lot of time and effort. However, if digital media are utilized to perform the tasks like analysis, generation, or fabrication, it will produce a result with higher precision and efficiency. In this sense, parametric modeling is quite useful media. Opening morphological variation, it realizes more possibilities, connects conveniently the relations between complex components composing a space, and helps produce creative patterns.

• Journal of Preventive Medicine and Public Health
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• 제32권2호
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• pp.215-227
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• 1999

Objectives: To investigate compliance of hypertension patients using modified Theory of Reasoned Action(TRA). Methods: The data were collected for 7-12 April 1997, by interviewing 190 Hypertension patients in Hwachon, Kangwon-do. The analytical techniques employed include contingency table analysis and logit analysis. Results: 15.1% of patients were unaware of the fact that he/she has hypertension and 11.2% did not know that he/she should take drug. 20.8% of patients took drug continuously, 20.1% had drug intermittently, and 53.1% had never have treatment. In the contingency table analysis, several variables were found to be significantly related to patient compliance. They included variables for attitude towards the consequences of taking drugs, normative beliefs, systolic BP at the enrollment, knowledge of how to take hypertensive drugs, variables for general health behavior and experience with having health worker's home visit. The logit analysis was performed by two steps. first step uses experience with drug treatment of hypertension as the dependent variable, and second step uses continuity of treatment. Included in the predictors that are significantly related to the former analysis are subjected norms produced by combining normative beliefs and motivation to comply, knowledge of how to take hypertensive drugs, and opinion about natural recovery of diseases. The only significant determinant of continuous treatment was knowledge of how to take hypertensive drugs. Conclusions: The results of analysis suggest the usefulness of TRA as a framework for the study of compliance of hypertensive patients. The findings have some practical implication as well. One is that efforts for enhancing compliance should be directed not only patients but also to other persons influencing patient's attitude and behavior. It also suggest that correct understanding of hypertension treatment is essential to perform the appropriate patient role.

• Geomechanics and Engineering
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• 제12권1호
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• pp.161-183
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• 2017

This paper investigates the damage identification of the concrete pile element through axial wave propagation technique using computational and experimental studies. Now-a-days, concrete pile foundations are often common in all engineering structures and their safety is significant for preventing the failure. Damage detection and estimation in a sub-structure is challenging as the visual picture of the sub-structure and its condition is not well known and the state of the structure or foundation can be inferred only through its static and dynamic response. The concept of wave propagation involves dynamic impedance and whenever a wave encounters a changing impedance (due to loss of stiffness), a reflecting wave is generated with the total strain energy forked as reflected as well as refracted portions. Among many frequency domain methods, the Spectral Finite Element method (SFEM) has been found suitable for analysis of wave propagation in real engineering structures as the formulation is based on dynamic equilibrium under harmonic steady state excitation. The feasibility of the axial wave propagation technique is studied through numerical simulations using Elementary rod theory and higher order Love rod theory under SFEM and ABAQUS dynamic explicit analysis with experimental validation exercise. Towards simulating the damage scenario in a pile element, dis-continuity (impedance mismatch) is induced by varying its cross-sectional area along its length. Both experimental and computational investigations are performed under pulse-echo and pitch-catch configuration methods. Analytical and experimental results are in good agreement.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.395-406
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• 2011

In this research a numerical simulation method is developed for moving body in free surface flows using fixed staggered rectangular grid system. The non-linear free surface near the body is defined by marker-density method. The body boundary is defined by line segment connecting the points where the body surface and grid line meet. Continuity equation and Navier-Stokes equations are used as governing equations and the equations are coupled with two-step projection method. The velocities and pressures of body boundary and free surface cells are calculated with simultaneous iterative method. To treat a body movement in a fixed grid system, the volume displaced by moving body is added to the divergence of the body boundary cell. For the verification of the present numerical method. vortex shedding period of advancing cylinder is calculated and the period is compared with existing experiment results. Moreover, added mass and damping coefficients of a vertically excited box are calculated and the computed results are compared with published experiment results. Impulsive pressure and water level variation due to sloshing phenomenon are simulated and the results are compared with published experiment results. Varying the plunger shape, the waves generated by plunging type wave maker are compared with the 2nd order Stokes wave theory The plunger shape generating the wave that shows the best agreement with the theory is represented.

• Steel and Composite Structures
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• 제26권6호
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• pp.771-791
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• 2018

This paper deals with the low velocity impact response and dynamic stresses of composite sandwich truncated conical shells (STCS) with compressible or incompressible core. Impacts are assumed to occur normally over the top face-sheet and the interaction between the impactor and the structure is simulated using a new equivalent three-degree-of-freedom (TDOF) spring-mass-damper (SMD) model. The displacement fields of core and face sheets are considered by higher order and first order shear deformation theory (FSDT), respectively. Considering continuity boundary conditions between the layers, the motion equations are derived based on Hamilton's principal incorporating the curvature, in-plane stress of the core and the structural damping effects based on Kelvin-Voigt model. In order to obtain the contact force, the displacement histories and the dynamic stresses, the differential quadrature method (DQM) is used. The effects of different parameters such as number of the layers of the face sheets, boundary conditions, semi vertex angle of the cone, impact velocity of impactor, trapezoidal shape and in-plane stresses of the core are examined on the low velocity impact response of STCS. Comparison of the present results with those reported by other researchers, confirms the accuracy of the present method. Numerical results show that increasing the impact velocity of the impactor yields to increases in the maximum contact force and deflection, while the contact duration is decreased. In addition, the normal stresses induced in top layer are higher than bottom layer since the top layer is subjected to impact load. Furthermore, with considering structural damping, the contact force and dynamic deflection decrees.

• 한국콘텐츠학회논문지
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• 제19권3호
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• pp.475-484
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• 2019

현재 디자인 연구 분야에서는 후카사와 나오토가 제시한 "Without Thought" 디자인에 대한 체계적인 연구가 부족한 실정이며 어포던스(Affordance)의 개념과 혼동되어 사용하는 경우도 많이 볼 수 있다. 따라서 본 연구는 후카사와 나오토의 Without Thought 디자인 이념 및 이와 관련 있는 무의식 이론을 바탕으로 Without Thought의 개념을 정의하고자 한다. Without Thought는 사용자와 물건 간의 무의식적인 인터렉션을 완성시키며 사용자에게 "적절하다"는 느낌을 받도록 하는 디자인 이념이라고 할 수 있다. 또한, 후카사와 나오토의 저서, 논문, 연설, 작품 및 관련 문헌을 고찰하고 분석하여 "행위의 연속성, 의미의 명확성, 인지의 공통성, 생활상황을 위한 디자인, 자연적인 수요를 위한 디자인" 5개의 Without Thought 디자인 원칙을 도출하였다. 본 논문은 Without Thought의 개념을 체계적으로 정의하는데 도움을 줄 것으로 기대된다. 또한, Without Thought 개념을 활용하는 디자인 프로세스 개발의 기초 연구 자료가 될 것으로도 기대가 된다.

• Structural Engineering and Mechanics
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• 제90권3호
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• pp.233-252
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• 2024

This research explores a new finite element model for the free vibration analysis of bi-directional functionally graded (BDFG) beams. The model is based on an efficient higher-order shear deformation beam theory that incorporates a trigonometric warping function for both transverse shear deformation and stress to guarantee traction-free boundary conditions without the necessity of shear correction factors. The proposed two-node beam element has three degrees of freedom per node, and the inter-element continuity is retained using both C1 and C0 continuities for kinematics variables. In addition, the mechanical properties of the (BDFG) beam vary gradually and smoothly in both the in-plane and out-of-plane beam's directions according to an exponential power-law distribution. The highly elevated performance of the developed model is shown by comparing it to conceptual frameworks and solution procedures. Detailed numerical investigations are also conducted to examine the impact of boundary conditions, the bi-directional gradient indices, and the slenderness ratio on the free vibration response of BDFG beams. The suggested finite element beam model is an excellent potential tool for the design and the mechanical behavior estimation of BDFG structures.