• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2004.11a
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• pp.188-193
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• 2004

3D spatial-modeling can be used in various safety-enhancement applications and for as-built data acquisition in project-control systems. The objective of the research reported herein was to provide spatial-modeling methods that represent construction sites in an efficient manner and to validate the proposed methods by testing them in an actual construction environment. Algorithms to construct construction-site scenes and to carry out coordinate transformations in order to merge data from different acquisition locations are presented. Field experiments were conducted to establish performance parameters and validation for the proposed methods and models. Initial experimental work has demonstrated the feasibility of this approach.

• Journal of the Korean Chemical Society
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• v.63 no.6
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• pp.459-472
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• 2019

The purpose of this study was to investigate the effect of science writing for different audiences on preservice chemistry teachers' chemistry concept understanding and modeling ability in general chemistry experiment activities using Argument-based Modeling (AbM) strategy. And we also examined preservice chemistry teachers' perceptions of modeling in different audience groups. The participants of the study were 18 university students in the first grade of preservice chemistry teachers taking a general chemistry experiment course. They completed eleven topics of general chemistry experiment using argument-based modeling strategy. The understanding of chemistry concept was compared with the effect size of pre- and post-chemistry concept test scores. To find out modeling ability, we analyzed level of model by each preservice chemistry teacher. Analytical framework for the modeling ability was composed of three elements, explanation, representation, and communication. The questionnaire was conducted to check up on preservice chemistry teacher's recognition of modeling. The result of analyzing the effect of modeling for different audience on the understanding of chemistry concept and modeling ability, the preservice chemistry teachers' were found to be more effective when the level of audience was low. There was no difference in the recognition of modeling between the groups for audience. However, we could confirm that the responses of preservice chemistry teachers are changed in concrete when they have an experience in succession on modeling.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2819-2822
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• 2003

본 논문에서는 압전소자 구동기를 모델링하고 이를 이용하여 제어기를 설계하였다. 지금까지 많이 쓰이고 있는 방법이 압전소자 구동기의 히스테리시스 특성에 대한 대략적인 모델링을 구하고 이의 역함수를 적용한 방법이었으나 오차가 많고 다른 시스템에 대한 적용이 어려운 단점이 있었다. 이에 정확한 예측이 가능한 모델링 방법을 사용하여 제어기 설계의 정확성을 기하였다. 압전소자 구동기의 히스테리시스 특성을 제거하기 위한 방법으로는 Signal Preshaping 과 PI-제어기를 사용한 피드백 제어를 사용하였다. 이에 따른 모델링 시스템에서의 모사와 이를 실제 시스템에 적용하여 얻어낸 실험치와 그 결과에 대해서 논하였다.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.11a
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• pp.579-584
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• 2001

컴퓨터 그래픽스 기술을 이용한 응용분야가 증가함에 따라 물체의 사실적인 모델에 대한 요구가 증가되고 있다. 모델링 시간이 많이 필요한 기존의 3차원 모델링 툴 외에 최근에 사용자의 스케치에 기반한 모델링 방법과 영상기반 모델링, 3차원 스캐너가 발표되었지만, 정확성이 떨어지거나 고가의 장비를 필요로 하는 단점이 있다. 본 논문에서는 정육면체 프레임과 광평면(light plane) 프로젝터, 카메라를 이용한 물체의 3차원 구조 복원 시스템을 제안하고, 실험을 통하여 모델링의 정확도를 분석한다.

• Journal of KSNVE
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• v.8 no.1
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• pp.57-74
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• 1998

This paper is concerned with a combination of experimental and analytical investigation aimed at identifying modeling errors, accounted for the lack of correlation between experimental measurements and analytical predictions of the modal parameters for lap joint panels. A nonlinearity vibration test methodology, initiated from the theoretical analysis, is suggested for measurements of dynamic stiffnesses in a lap joint using the rivet fastener. Based on the experimental evidence on discrepancies between measured and predicted frequencies, improved finite element models of the joint are developed using PATRAN and ABAQUS, in which the beam element size is evaluated from the joint stiffnesses readily determined in the test. The beam element diameter as a principal design parameter is tuned to match experimental results within the evaluated bound value. Frequencies predicted by the proposed numerical model are compared with frequencies measured by the test. Improved predictions based on this new model are observed when compared with those based on conventional modeling practices.

• Journal of the Korean Geotechnical Society
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• v.34 no.8
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• pp.15-26
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• 2018

Recently, as the seismic performance based design methods have been introduced, dynamic numerical analyses need to be performed to evaluate the actual performance of structures under earthquakes. The verification of the numerical modeling is the most important for the performance based design. Therefore, 2-dimensional numerical analyses were performed to simulate the seismic behavior of a pile-supported structure, to provide the proper numerical modeling and to determine of input parameters. A dynamic centrifuge test of a pile group in dry loose sand was simulated to verify the applicability of the numerical model. The numerical modeling was carefully made to reflect the actual condition of the centrifuge test including dynamic soil properties, soil-pile interaction, boundary condition, the modeling of the group pile and structure and so on. The predicted behavior of the numerical analyses successfully simulated the acceleration variation in ground, the moment and displacement of the pile, and the displacement and acceleration of the structure. Therefore, the adopted numerical modeling and the input parameters can be used to evaluate the seismic performance of pile groups.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.6
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• pp.143-154
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• 2020

The mathematical modeling applying experimental coefficients to a conventional model was validated through the hydraulic test for the components and the full system of a small-sized liquid rocket engine's propellant supply system. According to the simulations, pressures difference for the fluid resistance components and the pump were mainly predicted. In order to improve the modeling accuracy, the loss coefficients obtained by the empirical method were applied to the modeling. Based on the governing equation of the flow or the well known empirical equation, the method of deriving the empirical coefficients was summarized and the coefficients were presented for the commercial products used in this study. The prediction results by modeling were in good agreement with the experimental data. Through the comparison with the experimental data, the factors affecting the accuracy of the simulation were analyzed and improving methods of the accuracy was proposed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.6
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• pp.537-543
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• 2016

A new approach to systematically model aerodynamic coefficients using an adaptive sampling based wind tunnel testing considering cost is proposed. The Latin Hypercube design is used for selecting initial test points. The Gaussian Process (GP) is iteratively used during the experiment to determine additional experimental points that minimizes the uncertainty reduction per incremental cost. A numerical simulation based experiment was conducted using the static aerodynamic coefficient database a fighter aircraft, which demonstrated the validity of the proposed method.

• Journal of The Korean Association For Science Education
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• v.32 no.1
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• pp.1-14
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• 2012

The purpose of this study is to analyze the student's modeling patterns of modeling experiments. The 1st year students who were taking the general chemistry laboratory course performed three modeling inquiry experiments and submitted laboratory reports. Students expressed the model in a formula form and/or a written form. Student's modeling patterns could be classified by five types; 'Refining tentative modeling', 'Accepting alternative modeling', 'Discarding tentative modeling', 'Failing to find causes', 'Disbelieving results'. This modeling experiment provides for students the opportunity for understanding how a scientific model is created and what the nature of scientific modeling is.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.1
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• pp.33-41
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• 2011

This study presents modeling technologies applicable to an unbonded post-tension system using a finite element software package. In this study, both direct modeling method and multiple spring method were used. The direct modeling method adopts tube-to-tube contact elements to represent the physical feature of a post-tension system. The multiple spring method uses virtual tendons attached to the real tendons using a number of rigid axial springs that freely rotate at the ends. Both modeling technologies provide accurate predictions. However, only the multiple spring method provides numerically stable and reliable responses with a consideration of concrete tension stiffening effects. Therefore, the multiple spring method turned out to be a generally applicable modeling technology for the unbonded post-tension system. Comparisons were made for the analytical and experimental results for the verification of the selected method, and parameter studies were carried out to confirm the appropriateness of the modeling assumptions and parameters adopted in the analysis.