• The Mathematical Education
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• v.57 no.4
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• pp.371-391
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• 2018

The purpose of this study is to analyze manifestation examples and effects of group creativity in mathematical modeling and to discuss teaching and learning methods for group creativity. The following two points were examined from the theoretical background. First, we examined the possibility of group activity in mathematical modeling. Second, we examined the meaning and characteristics of group creativity. Six students in the second grade of high school participated in this study in two groups of three each. Mathematical modeling task was "What are your own strategies to prevent or cope with blackouts?". Unit of analysis was the observed types of interaction at each stage of mathematical modeling. Especially, it was confirmed that group creativity can be developed through repetitive occurrences of mutually complementary, conflict-based, metacognitive interactions. The conclusion is as follows. First, examples of mutually complementary interaction, conflict-based interaction, and metacognitive interaction were observed in the real-world inquiry and the factor-finding stage, the simplification stage, and the mathematical model derivation stage, respectively. And the positive effect of group creativity on mathematical modeling were confirmed. Second, example of non interaction was observed, and it was confirmed that there were limitations on students' interaction object and interaction participation, and teacher's failure on appropriate intervention. Third, as teaching learning methods for group creativity, we proposed students' role play and teachers' questioning in the direction of promoting interaction.

• The Journal of the Korea Contents Association
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• v.20 no.7
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• pp.212-222
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• 2020

The purpose of this study is to understand the current status and trends of the research studies published by the Society for Industrial and Applied Mathematics which is a leader in the field of industrial mathematics around the world. To perform this purpose, titles and abstracts were collected from 6,255 research articles between 2016 and 2019, and the R program was used to analyze the topic modeling model with LDA techniques and a regression model. As the results of analyses, first, a variety of studies have been studied in the fields of industrial mathematics, such as algebra, discrete mathematics, geometry, topological mathematics, probability and statistics. Second, it was found that the ascending research subjects were fluid mechanics, graph theory, and stochastic differential equations, and the descending research subjects were computational theory and classical geometry. The results of the study, based on the understanding of the overall flows and changes of the intellectual structure in the fields of industrial mathematics, are expected to provide researchers in the field with implications of the future direction of research and how to build an industrial mathematics curriculum that reflects the zeitgeist in the field of education.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.11
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• pp.939-950
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• 2017

In this work, mathematical models are newly presented for three types of double-acting oleo-pneumatic shock absorbers as the first part of a comparative study on the several types of double-acting oleo-pneumatic shock absorbers. After a typical single-acting shock absorber model is presented for the sake of completeness, mathematical models of three types of double-acting shock absorbers are proposed. To derive the models, Bernoulli equation and orifice discharge coefficient are utilized along with the assumptions of incompressibility and poly-tropic process. The proposed models are expected to be used for investigation of the salient features of several types of double-acting oleo-pneumatic shock absorbers.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.148-149
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• 2012

본 논문은 HEV용 고출력 리튬 폴리머 배터리(LI-PB)의 수학적 모델링 기법을 제안한다. 비선형 시스템인 리튬 폴리머 배터리의 전기화학적 특성을 수학적인 상태 방정식으로 표현하고, 배터리 셀의 직접적인 충/방전, 온도 실험을 통하여 셀 모델의 파라미터를 추출하고 표현된 상태 방정식으로 최소의 오차를 가지는 파라미터를 구한다. 대용량 충방전기를 사용한 실험으로 본 연구의 적합성을 입증하였다.

• Journal of the Korean Society of Propulsion Engineers
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• v.6 no.4
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• pp.7-13
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• 2002

In this study, the mathematical model on the various complicated levels of the viscous liquid flows in the symmetric channel with the complicated shape was introduced and the assumptions applied to the simplified model was proposed. To analyse the steady cavitation flow, axis transform of physical region to non-dimensional region was performed, and multigrid were generated. Using this model, the steady cavitation flow was calculated, and good coincidence between experiment and calculation was achieved.

• Journal of the Korea Computer Graphics Society
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• v.1 no.2
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• pp.248-253
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• 1995

Mandelbrot에 의하여 제안된 Random Fractal은 현실감 있는 지형의 모델링을 가능하게 하였으며. Fournier등은 수학적으로 매우 복잡한 Fractal이론을 단순화한 중간점 분할 알고리즘(Midpoint Subdivision Algorithm)을 고안하여 다양한 형태의 지형 모델링에 매우 성공적인 결과를 얻게 되었다. 그러나, Random Fractal을 응용한 여러 종류의 알고리즘들은 이것의 특성으로 인하여, 생성되는 지형의 형태를 예측하기 어려운 단점이 있다. 따라서, 본 논문에서는 중간점 분할 알고리즘을 이용하여 사용자가 원하는 형태의 지형을 모델링할 수 있는 방법에 대하여 논하였다. 전체적인 지형의 모델링 과정을 크게 전역 제어와 지역 제어의 두 단계로 구분하여, 전역 제어 단계에서 전체 지형의 개략적인 형태를 제어하여 모델링한 후 지역 제어 단계에서의 세부적인 형태제어를 통하여 최종적으로 사용자가 원하는 형태의 지형을 모델링할 수 있는 방법을 제안하였다. 또한, GUI(Graphical User Interface)를 이용하여 전역 제어와 지역 제어에서 생성되는 전체 지형의 형태를 wire frame을 이용하여 실시간에 회전시키며 점검할 수 있도록 하여 세부적인 수정을 용이하게 하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.516-522
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• 2020

Water trees can cause considerable damage to the performance of underground cables. Theymay formwithin the dielectric used in buried or water-immersed high voltage cables. They grow in a bush-like or tree-like form, often taking decades before causing damage to a cable's performance. They are usually found on very old underground cables, often in an inaccessible place. It is costly and time-consuming to detect watertrees in underground cables. Tree detection technology, including mathematical modeling,can reduce the maintenance cost and time necessary for detecting these trees.To simulate detection of water trees in this study, a mathematical model ofan XLPE cable and a water tree were developed. The complex water tree structure was simplified, based on two identified patterns of aventedtree. A Matlab simulation was performed to calculate and analyze the capacitance and resistance of a cable insulation layer,based on growth of a watertree. Capacitance size increased about 0.025×10^-13[Farads/mm] compared to normal when the tree area of the cable was advanced to 95% of the insulation layer. The resistance value decreased by about 0.5×10¹⁶[ohm/m]. These changesand changesshowninaBurkes paper physical modeling simulation are similar.The value of mathematical modeling for detecting water trees and damage to underground cables has been demonstrated.

• Korean Chemical Engineering Research
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• v.53 no.5
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• pp.545-552
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• 2015

Process modeling and simulation is a powerful methodology to quantitatively predict the change of process variables when operating and design conditions are changed. In this study, considering drawbacks of currently used process simulator for combined cycle plants, we developed process modeling system equipped with an ease of use and flexibility for model development. For this purpose, the analysis of combined cycle processes was carried out and consequently, mathematical models and libraries were developed. Furthermore, in view of the fact that the level of the abstraction of process models depends on the purpose of simulation as well as the available data, simple and rigorous models were also developed for some important units. In use of reference combined plant, we executed process simulation using the developed modeling system and the comparison was made between the results of simulation and the reference data. Less than 1% marginal error was identified and we concluded that the modeling system can be applied for commercial combined cycle processes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.7
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• pp.71-78
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• 2006

Sun sensors are frequently implemented by satellites for attitude sensing, due to its simple manufacturability and light weight. A modeling of sun sensors has an important effect on the accuracy of satellite attitude determination. This paper addresses a new modeling of a 2-axis miniature fine sun sensor with improved accuracy. Unlike other previous algebraic modeling methods, the newly suggested physical modeling method takes into account the shadowing effect of the slit thickness. It was shown that a newly proposed sun sensor modeling provides a substantial accuracy improvement of 29% compared to the generic algebraic modeling. The proposed sensor modeling was validated using 2-axis fine sun sensors with FOV(Field of View) of ${\pm}60^{\circ}$ mounted on HAUSAT-2 small satellite, currently under development by SSRL(Space System Research Lab.) at Hankuk Aviation University, Korea.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.4
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• pp.12-22
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• 1999

본 논문에서는 PCS의 확장개념으로 최근 관심이 높아지고 있는 In-Building PCS에서 가입자 이동성향과 이동 트래픽 특성을 이용해서 시스템의 트래픽 성능을 분석하였다. 이를 위해 빌딩내 적절한 셀 모양을 설정하고 가입자 이동성을 수학적으로 모델링하였으며 모델링된 셀에서의 가입자 이동률을 다양한 이동 파라메터로서 정의하고 이로부터 2차원 Morkov 생성-소멸 상태도를 유도하였다. 마지막으로 모델링된 가입자 이동성과 트랙픽 상태도를 통해 셀 내에서의 트래픽 성능을 분석하고 평가하였다.