• Journal of The Korean Association For Science Education
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• v.25 no.6
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• pp.698-709
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• 2005

When modeling students' conceptual understanding, there are several different frameworks, among which are the alternative conception framework and the mental model framework, which converge to suggest a form of knowledge representation. However, little research has explained how they are different from each other and from memory. The purpose of this study was to develop a new mental model theory that integrates the different terminologies and their background theories, which refer to students' ideas not only in science education, but also in other research areas. For this purpose, at first, we compared different terminologies including alternative conception, p-prim, and mental models, and the underlying theories used for representing students' ideas in learning science. Through such comparison, we tried to find the relationship among them. We reviewed related literature and synthesized the results from both cognitive science (related research areas) and science education approaches, especially, Vosniadou's mental model theory. Based on reviewing previous studies, we have developed a preliminary mental model theory 'an integrated theoretical structure of mental models'. We applied the new mental model theory to interpret data on students' ideas about circular motion from our previous research. We expect our new mental model theory will help us understand how students form their own ideas in science from an integrated perspective.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.3
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• pp.91-98
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• 2007

This paper presents the induced mathematical modeling equations for evaluating the operation stability with automatic transmission of heavy duty vehicle. This theoretical approach indicates that linearized governing equations of system can be converted into eigen-value problems. if the eigen-value has positive number, we can predict the engine operating point locates an unstable operating region. To be a stable state, the unstable operating point diverges toward a stable point which is able to maintain uniform velocity. Based on the previous theoretical analysis, we carry out dynamic simulation to show the behavior of engine operating point and torque converter in transient state. As a result of the dynamic simulation, the suggested theoretical method is found to be reasonable for evaluating the operation stability of a torque converter. In addition, the numerical results explain the engine stops and fluctuating phenomenon in reality.

• Journal of Power System Engineering
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• v.12 no.1
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• pp.41-46
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• 2008

The primary objective of this study is to truly understand exciting forces of the in-line 4 cylinders engine. Exciting forces of the engine apply a source of the vehicle NVH(Noise, Vibration, Harshness). To understand exciting forces, first was governed theoretical equations for single cylinder engine. And this theoretical equations was programming using MATLAB software. To compare theoretical analysis value, was applied MSC.ADAMS software. To determined the specification of engine(2,000cc, in-line 4) was applied ADAMS/Engine module. And this specification for engine was applied ADAMS/View and MATLAB software. The geometry model for ADAMS/View analysis was produced by the 3-D design modeling software. After imported 3-D model, each rigid body was jointed suitable. Under idle speed for engine, was analysed. The results of analysis are fairly well agreed with those of three analysis method. Using MATLAB software proposed in this study, engine exciting fores can be predicted. Also using ADAMS/Engine module and ADAMS/View software, engine exciting forces can be predicted.

• Smart Structures and Systems
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• v.14 no.2
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• pp.247-266
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• 2014

Conventional cantilevered piezoelectric energy harvesters (PEHs) are usually fabricated with continuous electrode configuration (CEC), which suffers from the electrical cancellation at higher vibration modes. Though previous research pointed out that the segmented electrode configuration (SEC) can address this issue, a comprehensive evaluation of the PEH with SEC has yet been reported. With the consideration of delivering power to a common load, the AC outputs from all segmented electrode pairs should be rectified to DC outputs separately. In such case, theoretical formulation for power estimation becomes challenging. This paper proposes a method based on equivalent circuit model (ECM) and circuit simulation to evaluate the performance of the PEH with SEC. First, the parameters of the multi-mode ECM are identified from theoretical analysis. The ECM is then established in SPICE software and validated by the theoretical model and finite element method (FEM) with resistive loads. Subsequently, the optimal performances with SEC and CEC are compared considering the practical DC interface circuit. A comprehensive evaluation of the advantageous performance with SEC is provided for the first time. The results demonstrate the feasibility of using SEC as a simple and effective means to improve the performance of a cantilevered PEH at a higher mode.

• Korean Journal of Remote Sensing
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• v.10 no.2
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• pp.17-35
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• 1994

A semi-empirical model for microwave polarimetric radar backscattering from bare soil surfaces was developed using polarmetric radar measurements and the knowledge based on the theoretical and numerical solutions. The microwave polarimetric backscatter measurements were conducted for bare soil surfaces under a variety of roughness and moisture conditions at L-, C-, and X-band frequencies at incidence angles ranging from 10` to 70`. Since the accrate target parameters as well as the radar parameters are necessary for radar scattering modeling, a complete and accurate set of ground truth data were also collected using a laser profile meter and dielectric probes for each surface condition, from which accurate measurements were made of the rms height, correlation length, and dielectric constant. At first, the angular and spectral dependencies of the measured radar backscatter for a wide range of roughnesses and moisture conditions are examined. Then, the measured scattering behavior was tested using theoretical and numerical solutions. Based on the experimental observations and the theoretical and numerical solutions, a semi-empirical model was developed for backscattering coeffients in terms of the surface roughness parameters and the relative dielectric constant of the soil surface. The model was found to yield very good agreement with the backscattering measurements of this study as well as with independent measurements.

• Korean Journal of Clinical Pharmacy
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• v.18 no.2
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• pp.84-96
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• 2008

In the recent, pharmacokinetic (PK)/pharmacodynamic (PD) modeling has appeared as a critical path tools in new drug development to optimize drug efficacy and safety. PK/PD modeling is the mathematical approaches of the relationships between PK and PD. This approach in new drug development can be estimated inaccessible PK and PD parameters, evaluated competing hypothesis, and predicted the response under new conditions. Additionally, PK/PD modeling provides the information about systemic conditions for understanding the pharmacology and biology. These advantages of PK/PD model development are to provide the early decision-making information in new drug development process, and to improve the prediction power for the success of clinical trials. The purpose of this review article is to summarize the PK/PD modeling process, and to provide the theoretical and practical information about widely used PK/PD models. This review also provides model schemes and the differential equations for the development of PK/PD model.

• Journal of Educational Research in Mathematics
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• v.11 no.1
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• pp.157-177
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• 2001

Modern society's technological and economical changes require high-level education that involve critical thinking, problem solving, and communication with others. Thus, today's perspective of mathematics and mathematics learning recognizes a potential symbolic relationship between concrete and abstract mathematics. If the problems engage students' interests and aspiration, mathematical problems can serve as a source of their motivation. In addition, if the problems stimulate students'thinking, mathematical problems can also serve as a source of meaning and understanding. From these perspectives, the purpose of my study is to prove that mathematical modeling tasks can provide opportunities for students to attach meanings to mathematical calculations and procedures, and to manipulate symbols so that they may draw out the meanings out of the conclusion to which the symbolic manipulations lead. The review of related literature regarding mathematical modeling and model are performed as a theoretical study. I especially concentrated on the study results of Freudenthal, Fischbein, Lesh, Disessea, Blum, and Niss's model systems. We also investigate the emphasis of mathematising, the classified method of mathematical modeling, and the cognitive nature of mathematical model. And We investigate the purposes of model construction and the instructive meaning of mathematical modeling. In conclusion, we have presented the methods that promote students' effective model construction ability. First, the teaching and the learning begins with problems that reflect reality. Second, if students face problems that have too much or not enough information, they will construct useful models in the process of justifying important conjecture by attempting diverse models. Lastly, the teachers must understand the modeling cycle of the students and evaluate the effectiveness of the models that the students have constructed from their classroom observations, case study, and interaction between the learner and the teacher.

• Journal of Korea Multimedia Society
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• v.15 no.8
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• pp.1059-1066
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• 2012

With the development of Smartphone, Smartphone contains diverse functions including many sensors that can describe users' state. So there has been increased studies rapidly about activity recognition and life pattern recognition with Smartphone sensors. This research suggest modeling of the activity data to classify extracted data in existing activity recognition study. Activity data is divided into two parts: Physical activity and Logical Activity. In this paper, activity data modeling is theoretical analysis. We classified the basic activity(walking, standing, sitting, lying) as physical activity and the other activities including object, target and place as logical activity. After that we suggested a method of visualizing modeling data for users. Our approach will contribute to generalize human's life by modeling activity data. Also it can contribute to visualize user's activity data for existing activity recognition study.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.2
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• pp.263-269
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• 2012

In order to present that the electromagnetic compatibility standards following the frequency goes up which is based automotive electronics, in this paper, a hybrid/electric vehicle battery which reflects the frequency of the equivalent circuit model is introduced. By using this circuit modeling, the impedance characteristics can be analysed and an analyze of battery one cell is finished. Using this model, each different from the discharging situation, the discharge characteristic curve could be led. Basic theoretical approaches and measuring results through MATLAB and experimental validation of the EIS measurement equipment was used.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.12
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• pp.1181-1188
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• 2004

This paper reviews the main aspects of cardiovascular system dynamics with emphasis on modeling hemodynamic characteristics using a lumped parameter approach. Methodological and physiological aspects of the circulation dynamics are summarized with the help of existing mathematical models: The main characteristics of the hemodynamic elements, such as the heart and arterial and venous systems, are first described. Lumped models of micro-circulation and pulmonary circulation are introduced. We also discuss the feedback control of cardiovascular system. The control pathways that participate in feedback mechanisms (baroreceptors and cardiopulmonary receptors) are described to explain the interaction between hemodynamics and autonomic nerve control in the circulation. Based on a set-point model, the computational aspects of reflex control are explained. In final chapter we present the present research trend in this field and discuss the future studies of cardiovascular system modeling.