• 한국가스학회지
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• 제20권4호
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• pp.44-49
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• 2016

본 연구는 연소실 형상 변화에 따른 디젤연소와 배출가스의 특성에 대해 살펴보았다. 발전용 커먼레일 디젤엔진의 최적화 설계를 위한 연소실형상을 제시하기 위해 5가지 타입형상을 연비 측면에서 계산하였다. 연소실 형상은 연소 시 분무면적을 변화시킴으로서 연소특성에 영향을 주었으며 이러한 주요요소는 연소실 형상 비였다. 이러한 수치해석의 결과는 연소실 형상의 변화는 발전기의 연비 개선을 가능하도록 한다고 판단되었다.

• 한국초등수학교육학회지
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• 제20권2호
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• pp.239-257
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• 2016

미국의 새 수학과 규준인 Common Core State Standards for Mathematics는 잘 알려진 것처럼 모든 학생이 대학에 진학하거나 직업에 종사하기위한 준비를 위해 명료하고 일관된 틀을 제공하는 것을 목표로 개발되어, 현재 40개의 주가 이 새로운 규준을 채택하고 있다. 이 규준에 관한 최근 우리나라의 선행연구들은 규준을 Cluster Heading 수준에서 소개하고 있고, 규준의 수준에서 우리나라의 교육과정과 비교하고 있다. 그러니 실제로 각 세부 규준의 내용을 상세하게 해석한 내용은 수면 아래의 모습을 보여 준다. 캘리포니아 주의 수학과 규준의 내용을 상세하게 해석한 책이 Mathematics Framework for California Public Schools이다. 이 연구는 미국 캘리포니아 주의 수학과 규준인 California Common Core State Standards(CA CCSSM)와 이 규준의 해설서라고 부르기에 적당한 Mathematics Framework for California Public Schools에서 제시한 초등학교 도형영역을 상세하게 살펴보는 것이 목적이다.

• 한국수학사학회지
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• 제30권5호
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• pp.261-287
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• 2017

De Zolt's axiom which is a precise formulation of Euclid's Common Notion 5, "the whole is greater than the part", for the notion of 'content' holds in any Hilbert plane. In this article, we study the history of de Zolt's axiom which has its origin in Euclid's Common Notions, and introduce an example of a plane geometry in which de Zolt's axiom does not hold. We show that there is no area function in this geometry and every square is equidecomposable with a square which is properly contained in the first one. From this we also show that there are two equidecomposable rectangles which have the same base and do not have the same altitude, and there is a rectangle which is equicomplementable with an emptyset.

• 한국정보과학회논문지:시스템및이론
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• 제31권1_2호
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• pp.135-143
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• 2004

3차원 그래픽 가속기는 지오메트리 처리(geometry processing)와 레스터라이져(rasterizer)로 구성된다. 본 논문에서는 지오메트리 처리를 고속으로 수행할 수 있는 벡터 형태의 처리 구조(VGE)를 제안하였다. 특히 기존의 부동소수점을 계산할 수 있는 구조에 4개의 FADD, FMUL, 128개의 벡터 레지스터를 추가하여 지오메트리 연산을 가속했으며 VGE와 비슷한 H/W 비용을 갖는 Hitachi의 SH4와 비교했을 때 평균 4.7배의 성능향상을 보였다. 또한 성능 평가를 위해 범용프로세서 시뮬레이터인 Simplescalar 를 수정하여 시뮬레이터를 제작했으며 Viewperf Benchmark를 입력으로 사용하였다.

• East Asian mathematical journal
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• 제27권4호
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• pp.471-483
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• 2011

The purpose of this study is to introduce the Common Core State Standards (CCSS) for mathematics which is released on June 2, 2010 in the U.S.A. The common core state standards are aligned with college and work expectations, and include rigorous content and application of knowledge through high-order skills. The most distinguishable differences between the CCSS standards and the NCTM standards are that the CCSS standards considers the mathematical modeling as one of the mathematical content domains such as algebra, geometry, ets, and the standards are designed by working together with school leaders of all states.

• 대한수학교육학회지:수학교육학연구
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• 제12권1호
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• pp.95-108
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• 2002

In this article we drew out five definition-methods in school geometry. They are called synonymous method, denotative method, analytic method. And we analyzed them theoretically. On our analysis we tried to identify the level of common sense and the level of science in definition of those two levels on the definition-methods of circle. While the definition-method in elementary school could be regarded as the level of common sense, that in middle school could be considered as the level of science. Finally, we made the following didactical comments. Definitions in school mathematics might have the levels as regard to their roles. Thus, Mathematics teachers, curriculum developers, and text authors all need to recognize the subtle differences in the level of definition-methods.

• KIEAE Journal
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• 제16권3호
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• pp.35-46
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• 2016

Purpose: This paper aims to analyse the composition system of architectural elements including shape, kinetic and material elements of kinetic facades and establish the design parameter system as a common conceptual and practical knowledge sharing platform with mechanical and electrical experts. Method: This research has been conducted in a three steps. At first, 120 cases of external shading devices are analyzed and their classification criteria have been established. Secondly geometric, kinetic and material elements are categorized in a common kinetic facade coordinates system considering environmental effects and operation method, and the applicability of combination of each element are tested. Lastly core design parameters for each element have been established in a common office building installation coordinate. Result: Geometry elements are categorized into seven geometric shapes and kinetic elements is categorized into basic linear and rotational motion and combinational folding and rolling motion. The combined set of parameters for three elements composes the whole design parameters for architectural elements of kinetic façade. Design parameters of shape elements are composed of shape, installation and arrangement parameters; design parameters for kinetic elements are composed of axis and range parameters; and design parameters of material elements are composed of thermal, lighting and color parameters.

• 한국자동차공학회논문집
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• 제14권6호
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• pp.179-183
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• 2006

Whiplash injuries of the neck are one of the most common injuries reported from automotive rear impacts. Whiplash injuries can be reduced by changing geometry of head restraint. Therefore, geometries of head restraint were evaluated according to the test procedures of the Korea New Car Assessment Program(KNCAP) to improve safety of head restraint. In this study, nine vehicle's head restraints were tested. As the test results, one head restraints is rated at "Marginal", three head restraints are rated at "Acceptable" level, and the last five head restraints are rated at "Good" level.

• 한국자동차공학회논문집
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• 제9권2호
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• pp.28-34
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• 2001

Great attentions are paid to HSDI diesel engine for passenger cars because of its high thermal efficiency. The most interesting research in HSDI diesel engine developments is focused on applying common rail system as a fuel injection equipment. In this study, a series of tests are carried out to investigate the effect of injection pressure variation on the smoke and fuel concluded in a small HSDI diesel engine with common rail system. As a result of this study it is concluded that there is an optimum rail pressure dependent on combustion system such as nozzle type, combustion chamber geometry.

• International Journal of Precision Engineering and Manufacturing
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• 제6권1호
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• pp.65-72
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• 2005

Drilling process is one of the most common, yet complex operations among manufacturing processes. The performance of a drill is largely dependent upon drilling forces, Many researches focused on the effects of drill parameters on drilling forces. In this paper, an effective theoretical model to predict thrust and torque in drilling is presented. Also, with the predicted forces, the stress analysis of the drill tool is performed by the finite element method. The model uses the oblique cutting model for the cutting lips and the orthogonal cutting model for the chisel edge. Thrust and torque are calculated analytically without resorting to any drilling experiment, only by tool geometry, cutting conditions and material properties. The stress analysis is performed by the commercial FEM program ANSYS. The geometric modeling and the mesh generation of a twist drill are performed automatically. From the study, the effects of the variation of the geometric features of the drill and of the cutting conditions of the drilling on the drilling forces and the stress distributions in the tool are calculated analytically, which can be applicable for designing optimal drill geometry and for improving the drilling process.