• Communications of Mathematical Education
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• v.12
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• pp.377-386
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• 2001

역사의 시작은 어디인지 아득하지만 일반적으로 문헌을 통한 과학적인 신뢰성을 갖게 되는 실질적인 방법이 원칙이다. 하지만 이런 연구가 거의 전무한 우리 수학의 뿌리에 대한 연구는 문헌 연구가 그 기반을 이룰 것이다. 따라서 본 연구자는 우리 역사의 뿌리를 수학적 관점에서 한 분야로서 여러 기존의 문헌을 중심으로 특히 사학 연구를 활용하여 수학의 뿌리를 찾으려고 하며, 민족 신화(단군신화) 이전의 경전인 천부경(天符經)의 사상을 기초로 한 동양 사상과 철학의 배경으로 그 위상을 세우고자 한다. 결코 우리 민족의 우수성과 고난의 시절에서 많은 상황적 변화로서 와전되어 있는 부분도 있지만 이를 해석한 여러 문헌을 논리적으로 체계화하려는데 초점을 두고 있다. 주로 신라 시대의 석학인 최치원 선생에 의해 천부경 81자의 한자로 구성되어 해석한 사실에 주목해야한다. 특히 한민족의 언어가 아닌 한자로 우리의 언어와 사상이 기록되어 있고, 이 민족의 침입으로 인한 민족 문화의 말살이 걸림돌이 되고 있다. 그럼에도 불구하고 현재에 어려움을 인식하고 연구가 수행되었음을 부인할 수 없다. 따라서 본 연구는 우리 민족 수학의 뿌리를 찾아 민족의 수학사를 인식하는 계기를 주고, 자주적인 민족 정서의 수학 교육에 첫 걸음을 내딛는데 연구의 필요성과 목적이 있다.

• Proceedings of the KIEE Conference
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• 2008.10c
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• pp.83-85
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• 2008

본 논문은 변압기의 대부분 고장원인이 되는 권선 간의 단자 시 발생하는 진동을 수치적으로 계산하고 전자력 계산을 위한 방법으로 Pseudospectral Method을 적용하여 단락권선사이의 강제진동해석을 수행하였다. 나선형권선의 방정식은 Chebyshev다항식 시리즈의 확장과 Gauss-Lobatto collocation 과정을 수행되어진다. 알고리즘 검증을 위하여 22.9kV/220V, 1000kVA 용량의 케이블 타입의 변압기의 FEM 시물레이션 결과와 이론적 수치적계산과 함께 비교하였다.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.556-557
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• 2010

본 논문은 하이브리드 자동차의 구동모터용 인버터에 적용되는 수랭 히트싱크의 설계 타당을 수치해석을 통해 검증하는 방법을 제시한다. 전력변환장치의 손실 계산, 발열체 모델링, 히트싱크 형상 모델링, 수랭 조건 입력, 히트싱크상의 열적 분포 해석, 유체 거동 시뮬레이션의 과정을 거치며, 본 논문에서는 650Vdc, 150kW급의 시리즈 하이브리드 차량의 구동 모터용 인버터를 예로 그 과정을 설명하고자한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.178-179
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• 2011

해양 분야에서는 최근 e-navigation 실현을 위한 차세대 표준에 관한 연구가 진행 중이다. IHO(국제수로기구)를 중심으로 전자해도뿐만 아니라 해양의 지리 정보 및 관련 데이터의 교환, 공유, 활용을 위해 S-100기반 다양한 표준이 가능하다. IHO S-100 표준은 ISO 19100 시리즈 표준의 프로파일로, 응용 분야와 서비스에 따른 S-10x 표준의 기반이 된다. 프로파일링을 통해 S-101, S-102, S-10x 등 다양한 표준 프로파일이 만들어지면 각 표준에서 정의하는 데이터 모델의 요소를 일관성 있고 명확하게 해석하는 것이 필요하다. 본 논문에서는 S-10x 표준의 기반이 되는 S-100 표준을 일관된 의미 해석과 처리를 할 수 있도록 S-100 표준의 온톨로지로의 변환 방안을 제시한다.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.288-292
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• 2008

Plastics is commonly used in consumer electronics because of it is high strength per unit mass and good productivity. But plastic parts are usually distorted after injection molding due to the residual stress after filling, packing, cooling process, and etc. And plastic material is to be deteriorated according to various temperature conditions and operating time, which can be characterized by stress relaxation and creep. The viscoelastic behaviour of plastic materials in time domain can be expressed by the Prony series of the commercial code, ABAQUS. In the paper, the process to predict the post deformation under cyclic thermal loadings was suggested. The process was applied to the real panel, and the deformation predicted by the analysis was compared with that of real test, which showed the possibility of applying the suggested process to predict the post deformation of plastic product under thermal loadings.

• Journal of Navigation and Port Research
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• v.28 no.6
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• pp.481-489
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• 2004

Ship collisions and grounding continue to occur regardless of continuous efforts to prevent such accidents. With the increasing demand for safety at sea and for protection of the environment, it is of crucial importance to be able to reduce the probability of accidents, assess their consequences and ultimately minimize or prevent potential damages to the ships and the marine environment. Numerical simulations for actual collision problem are conducted with a special attention with respect to finite element size, fracture criteria and material properties, which require a careful consideration to improve the accuracy. A parametric analysis varying colliding speed, angle, design loading condition is conducted using nonlinear finite element analysis method for 46,00 dwt Product/chemical carrier. The relationship between the absorbed energy and indentation are derived quantitatively using the insights observed from this study, and a novel design concept for assessing the anti-collision performance are proposed.

• Journal of Korean Association for Spatial Structures
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• v.4 no.1 s.11
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• pp.77-86
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• 2004

It is the buckling of the compression portions of the deckplate that govern its behaviour under wet concrete construction loading. The size and position of intermediate stiffeners in the compression flanges of thin-plate steel decks exert a strong influence on the dominant buckling mode of the flange. Test sections composed of high-strength steel were brake pressed with a variety of Flat-hat intermediate stiffeners in the compression flange forming a progression from small to large stiffeners. The ABAQUS program to determine the effectiveness of intermediate stiffeners in controlling buckling modes is undertaken. A series of specimens are loaded with simple beam. Various buckling wave forms prior to ultimate failure through a plastic collapse mechanism. The experimentally determined buckling stresses are found to be comparable with studies performed using the ABAQUS program analysis and using each country code.

• Communications of Mathematical Education
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• v.35 no.3
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• pp.257-275
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• 2021

This study investigated the prospective teacher's noticing of students' mathematical thinking from the perspective of how the prospective teacher pays attention to, interprets, and responds to the student's responses related to variables. The prospective teachers were asked to infer the students' thinking from the variables related to the tasks and suggest feedback accordingly. An analysis of the responses of 26 prospective teachers showed that it was not easy for prospective teachers to pay attention to the misconception of variables and that some of them did not make proper interpretations. Most prospective teachers who did not attend and interpret were found to have failed to provide an appropriate response due to a lack of overall understanding of variables. even though prospective teachers who did proper attend and interpret were found to have failed to respond appropriately due to a lack of empirical knowledge, even with proper attention and interpretation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.1
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• pp.126-132
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• 2018

This paper discusses about results of advanced buckling strength design for several kinds of perforated plated in the twin-hull car-ferry. For medium / small sized high speed vessels with a length of more than 50 meters and a length / width ratio of more than 12, such as car-ferries, it is highly possible that the buckling strength becomes weak due to the relatively thin thickness and the use of low strength capacity such as mild steel. Especially, it becomes big problem about weak buckling rigidity around the opening to access purpose in the perforated. As regarding safety design point of view for perforated plate, it is necessary to clarify buckling strength and ultimate strength by the distribution of in-plane load distribution around the opening. In this study, nonlinear series analysis using ANSYS was performed to clarify the influence of parameters such as aspect ratio, opening ratio and opening shape affecting the buckling and ultimate strength characteristics of the perforated plate under axial compression and we are derived the optimum design as buckling strength point of view. Based on these results, the governing factor determining the buckling strength of the perforated plate was the opening ratio, and the aspect ratio and the shape of the hole were not influenced.

• Education of Primary School Mathematics
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• v.17 no.3
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• pp.253-263
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• 2014

In this paper we review an axiomatic definition of the area of plane figures with area axioms, discuss what the area axioms mean, and analyze the contents about the area of plane figures in elementary school mathematics from the view point of area axioms. So we evaluate which aspects of the concept of area are emphasized or deemphasized in the current elementary school mathematics textbook.