• 대한수학교육학회지:학교수학
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• 제9권1호
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• pp.65-97
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• 2007

본 연구에서는 수학적 모델링에 관한 주제로 국내 학회지에 실린 총 11편의 선행 연구 및 22편의 석사학위논문을 대상으로 그 밖의 국내외 문헌을 참조하여 수학적 모델링에 관한 이해를 도모하고자 하였다. 우선, 수학적 모델링의 의미와 과정을 살펴보고, 수학적 모델링과 문제해결의 관계를 살펴보았는데, 그 결과 수학적 모델링의 중요성을 부각시키기 위한 노력 내지 의도 하에 문제해결의 진정한 의미가 다소 축소되고 간과되는 경향이 있음을 알 수 있었다. 이어서 수학적 모델링의 주요 특징을 탐색해 보고, 수학적 모델링 문제와 문제해결에서 정의되는 문제의 관계를 살펴보았는데, 이는 문제해결에서의 수학 외적 소재를 수반하는 문제의 의미 내지 범주가 보다 분명히 밝혀질 때 두 문제 사이의 범주 및 관계도 정립될 수 있을 것으로 나타났다. 결과적으로, 본 연구에서는 문제해결 문제와의 비교를 떠나 수학적 모델링 문제 자체가 지니고 있는 특징을 간추려 제시하였다. 끝으로, 수학적 모델링 과정의 전반적인 이해를 돕기 위하여 폴리아의 문제해결 과정과 연계지어 간략히 제시하였다.

• Structural Monitoring and Maintenance
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• 제4권3호
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• pp.195-220
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• 2017

Nowadays, railway system plays a significant role in transportation, conveying cargo, passengers, minerals, grains, and so forth. Railway ballasted track is a conventional railway track as can be seen all over the world. Ballast, located underneath the sleepers, is the most important elements on ballasted track, which has many functions and requires routine maintenance. Ballast needs to be maintained frequently to prevent rail buckling, settlement, misalignment so that ballast has to be modelled accurately. Continuum model was introduced to model granular material and was extended in ballast. However, ballast is a heterogeneous material with highly nonlinear behaviour. Hence, ballast could not be modelled accurately in continuum model due to the discontinuities nature and material degradation of ballast. Discrete element modelling (DEM) is proposed as an alternative approach that provides insight into constitutive model, realistic particle, and contact algorithm between each particle. DEM has been studied in many recent decades. However, there are limitations due to the high computational time and memory consumption, which cause the lack of using in high range. This paper presents a review of recent ballast modelling with benefits and drawbacks. Ballast particles are illustrated either circular, circular crump, spherical, spherical crump, super-quadric, polygonal and polyhedral. Moreover, the gaps and limitations of previous studies are also summarized. The outcome of this study will help the understanding into different ballast modelling and particle. The insight information can be used to improve ballast modelling and monitoring for condition-based track maintenance.

• Structural Engineering and Mechanics
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• 제61권1호
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• pp.125-142
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• 2017

Extensive research work has been performed on shear strengthening of reinforced concrete (RC) beams retrofitted with externally bonded carbon fiber reinforced polymer (CFRP) in form of strips. However, most of this research work is experimental and very scarce studies are available on numerical modelling of such beams due to truly challenging nature of modelling concrete shear cracking and interfacial interaction between components of such beams. This paper presents an appropriate model for RC beam and to simulate its cracking without numerical computational difficulties, convergence and solution degradation problems. Modelling of steel and CFRP and their interfacial interaction with concrete are discussed. Finally, commercially available non-linear finite element software ABAQUS is used to validate the developed finite element model with key tests performed on full scale T-beams with and without CFRP retrofitting, taken from previous extensive research work. The modelling parameters for bonding behavior of CFRP with special anchors are also proposed. The results presented in this research work illustrate that appropriate modelling of bond behavior of all the three types of interfaces is important in order to correctly simulate the shear behavior of RC beams strengthened with CFRP.

• 한국기계가공학회지
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• 제18권10호
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• pp.75-82
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• 2019

Few studies have been conducted regarding theoretical turning force modelling while considering cutting constant. In this paper, a new cutting force modelling technique was suggested which considers the specific cutting force coefficients for turning. The specific cutting force is the multiplication of the cutting force coefficient and uncut chip thickness. This parameter was used for experimental modelling and prediction of theoretical cutting force. These coefficients, which can be obtained by fitting measured average forces in several conditions, were used for the formulation of three theoretical cutting forces for turning. The cutting force mechanism was verified in this research and its results were compared with each of the experimental and theoretical forces. The deviation of force was incurred by a small amount in this model and the predicted force considering feed rate, nose radius, and radial depth shows a physical behavior in main force, normal force, and feeding force, respectively. Therefore, this modelling technique can be used to effectively predict three turning forces with different tool geometries considering cutting force coefficients.

• 제어로봇시스템학회논문지
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• 제16권2호
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• pp.151-157
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• 2010

This paper presents the modelling of an MR damper system through extensive experimental studies. The hysteresis of the MR damper is modelled by using the improved Bouc-wen model. A test bed for experimental studies of measuring parameters of the MR damper is designed and implemented. Based on the experimental data, the Bouc-Wen Model is modified for the MR damper system. To check the modelling property, a vehicle suspension system is controlled using a PID controller for the verification of the MR damper model.

• Smart Structures and Systems
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• 제10권4_5호
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• pp.485-499
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• 2012

Mode shape expansion is useful in structural dynamic studies such as vibration based structural health monitoring; however most existing expansion methods can not consider the modelling errors in the finite element model and the measurement uncertainty in the modal properties identified from vibration data. This paper presents a reliable approach for expanding mode shapes with consideration of both the errors in analytical model and noise in measured modal data. The proposed approach takes the perturbed force as an unknown vector that contains the discrepancies in structural parameters between the analytical model and tested structure. A regularisation algorithm based on the Tikhonov solution incorporating the L-curve criterion is adopted to reduce the influence of measurement uncertainties and to produce smooth and optimised expansion estimates in the least squares sense. The Canton Tower benchmark problem established by the Hong Kong Polytechnic University is then utilised to demonstrate the applicability of the proposed expansion approach to the actual structure. The results from the benchmark problem studies show that the proposed approach can provide reliable predictions of mode shape expansion using only limited information on the operational modal data identified from the recorded ambient vibration measurements.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.843-847
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• 1988

In electromagnetic transient analysis studies, complex transmission system should be modelled in detail. But in large system, modelling of complete system is a big burden in many sides such as computation time, modelling efforts. It is needed to model only a concerned part of the system in detail. The remaining parts of the system have to be reduced to equivalents. This study suggests a method of generating a simple network equivalents which has equivalent frequency charastics in wide frequency range.

• 디지털융복합연구
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• 제18권8호
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• pp.37-48
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• 2020

본 연구는 텍스트 마이닝을 활용하여 리빙랩 연구의 동향을 파악하고 연구 방향 정립에 필요한 함의를 도출하고자 하였다. 리빙랩 관련 연구가 발표되기 시작한 2011년부터 2019년 11월까지의 논문 166편의 키워드와 초록을 대상으로 네트워크 분석 및 토픽 모델링 기법을 사용하여 분석하였다. 키워드 중 혁신, 지역, 사회, 기술, 스마트시티 등의 출현빈도가 높았고, 중심도 분석결과 현재까지 리빙랩 연구가 혁신, 사회, 기술, 개발, 사용자 등의 키워드를 중심으로 이루어짐을 파악하였다. 토픽 모델링 결과 지역혁신과 사용자지원, 정부 사회정책사업, 스마트시티 플랫폼구축, 기업기술혁신모델 및 시스템전환 참여 등 5개 토픽을 추출하였으며 토픽을 이어주는 키워드는 혁신, 기술, 사용자, 참여인것으로 분석하였다. 2017년 KNoLL 출범 후 토픽별 비중은 고른 분포로 연구 주제가 다양화됨을 확인하였다. 텍스트마이닝을 이용한 리빙랩 연구동향 분석과 방향 제시는 연구와 정책방향 수립에 유용한 자료를 제공할 수 있다.

• 한국수학교육학회지시리즈A:수학교육
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• 제30권1호
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• pp.1-19
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• 1991

This study intends to provide some desirable suggestions for the development of application oriented mathematics curriculum. More specific objects of this study is: 1. To identify the meaning of application and modelling in mathematics curriculm. 2. To illuminate the historical background of and trends in application and modelling in the mathematics curricula. 3. To consider the reasons for including application and modelling in the mathematics curriculum. 4. To find out some implication for developing application oriented mathematics curriculum. The meaning of application and modelling is clarified as follows: If an arbitrary area of extra-mathematical reality is submitted to any kind of treatment which invovles mathematical concepts, methods, results, topics, we shall speak of the process of applying mathemtaics to that area. For the result of the process we shall use the term an application of mathematics. Certain objects, relations between them, and structures belonging to the area under consideration are selected and translated into mathemtaical objects, relation and structures, which are said to represent the original ones. Now, the concept of mathematical model is defined as the collection of mathematical objcets, . relations, structures, and so on, irrespective of what area is being represented by the model and how. And the full process of constructing a mathematical model of a given area is called as modelling, or model-building. During the last few decades an enormous extension of the use of mathemtaics in other disciplines has occurred. Nowadays the concept of a mathematical model is often used and interest has turned to the dynamic interaction between the real world and mathematics, to the process translating a real situation into a mathematical model and vice versa. The continued growing importance of mathematics in everyday practice has not been reflected to the same extent in the teaching and learning of mathematics in school. In particular the world-wide 'New Maths Movement' of the 19608 actually caused a reduction of the importance of application and modelling in mathematics teaching. Eventually, in the 1970s, there was a reaction to the excessive formallism of 'New Maths', and a return in many countries to the importance of application and connections to the reality in mathematics teaching. However, the main emphasis was put on mathematical models. Applicaton and modelling should be part of the mathematics curriculum in order to: 1. Convince students, who lacks visible relevance to their present and future lives, that mathematical activities are worthwhile, and motivate their studies. 2. Assist the acqusition and understanding of mathematical ideas, concepts, methods, theories and provide illustrations and interpretations of them. 3. Prepare students for being able to practice application and modelling as private individuals or as citizens, at present or in the future. 4. Foster in students the ability to utilise mathematics in complex situations. Of these four reasons the first is rather defensive, serving to protect or strengthen the position of mathematics, whereas the last three imply a positive interest in application and modelling for their own sake or for their capacity to improve mathematics teaching. Suggestions, recomendations and implications for developing application oriented mathematics curriculum were made as follows: 1. Many applications and modelling case studies suitable for various levels should be investigated and published for the teacher. 2. Mathematics education both for general and vocational students should encompass application and modelling activities, of a constructive as well as analytical and critical nature. 3. Application and modelling activities should. be introduced in mathematics curriculum through the interdisciplinary integrated approach. 4. What are the central ideas of, and what are less-important topics of application-oriented curriculum should be studied and selected. 5. For any mathematics teacher, application and modelling should form part of pre- and in-service education.

• Composites Research
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• 제18권5호
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• pp.27-33
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• 2005

본 연구에서는 펄스-CVI (Chemical Vapor Infiltration)에 의해 탄화규소/탄소 복합재료를 제조하는 공정에 대한 수치모사가 행해졌다. 각 펄스가 가스 주입시간, 반응시간, 배출시간으로 구성될 때, 반응시간과 배출시간의 영향이 관찰되었다. 또한 반응가스 농도와 압력의 영향이 연구되었다. 탄소프리폼에의 탄화규소의 균일한 침착과 반응시간 단축을 위한 펄스-CVI공정의 이점이 확인되었다.