• Journal of the Korean Institute of Gas
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• v.20 no.4
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• pp.44-49
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• 2016

This paper presents characteristics of diesel combustion and emissions according to adoption of various combustion chamber geometry. In order to suggest suitable combustion chamber geometry of the common rail diesel engine for electric generative use, 5 type of geometry chamber was found performance for combustion chamber to respond fuel efficiency. Combustion chamber geometry affects combustion characteristics due to change target area of spray in the combustion chamber and the main factor was the bowl aspect ratio of combustion chamber. Using the results of simulation, the effects of the variable combustion chamber can be improved the fuel efficiency for electric generation.

• Journal of Elementary Mathematics Education in Korea
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• v.20 no.2
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• pp.239-257
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• 2016

The Common Core States Standards was developed by building on the best state standards in the U.S.; examining the expectations of other highperforming countries around world; and carefully studying the research and literature available on what students need to know. The Common Core States Standards for Mathematics are reshaping the teaching and learning of mathematics in California classroom using the California Common Core States Standards for Mathematics(CA CCSSM). The aim of this study is to observe CA CCSSM. The CA CCSSM were established to address the problem of having a curriculum that is 'a mile wide and an inch deep'. And it have two types of standards. One is standards for mathematical practice which are the same at each grade level, the other is standards for mathematical content which are different at each grade level. This study focused on standards for mathematical content, in particular, on Geometry domain in elementary level, using Mathematics Framework for California Public Schools.

• Journal for History of Mathematics
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• v.30 no.5
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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.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.1_2
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• pp.135-143
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• 2004

3D Graphics accelerator is usually composed of two parts, geometry engine and rasterizer. In this paper, VGE(Vector Geometry Engine) which exploits vertex-level parallelism is proposed. In VGE, Common Floating-Point Unit by adding four-FADD, four-FMUL unit and 128-vector register accelerates geometry calculation. In comparison with SH4, Performance result show that the VGE can achieve performance gain over 4.7 times. To evaluate VGE performance, we make simulator to rebuild Simple-Scalar, general purpose processor simulator. In simulator model, we use Viewperf-benchmark.

• East Asian mathematical journal
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• v.27 no.4
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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.

• Journal of Educational Research in Mathematics
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• v.12 no.1
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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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• v.16 no.3
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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.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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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.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.2
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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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• v.6 no.1
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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.