• The Journal of the Acoustical Society of Korea
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• v.14 no.2
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• pp.80-91
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• 1995

A theoretical models has been prepared which describes the noise generated by tire/road interaction for the tire structure-borne sound analysis. The model begin with a set of thin shell equations describing the motion of the belt of a radial ply tire, as drived by Bohm('mechanisms of the belted tire', Igeniur-Archiv, XXXV, 1966). Structural quantities required for these equations are derived from material properties of the tire. The rolling shape of a tire is computed from the steady-state limit of these equations. Vibrational response of the tire is treated by the full dependent shell equations. The force input at the tire/road interface is calculated on the basis of tread geometry and distribution of contact patch pressure. Radiation of noise is calculated by a simpson integral. Using the programs, the effect on noise of various tire design variations is computed and discussed. Trends which lead to quiet tire design are identified.

• Education of Primary School Mathematics
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• v.11 no.2
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• pp.141-159
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• 2008

The purpose of this study id to delve into how elementary mathematics textbook deal with the quadrilaterals from a view of Didactic Transposition Theory. Concerning the instruction period and order, we have concluded the following: First, the instruction period and order of quadrilaterals were systemized when the system of Euclidian geometry was introduced, and have been modified a little bit since then, considering the psychological condition of students. Concerning the definition and presentation methods of quadrangles, we have concluded the following: First, starting from a mere introduction of shape, the definition have gradually formed academic system, as the requirements and systemicity were taken into consideration. Second, when presenting and introducing the definition, quadrilaterals were connected to real life. Concerning the contents and methods of instruction, we have concluded the following: First, the subject of learning has changed from textbook and teachers to students. Second, when presenting and introducing the definition, quadrilaterals were connected to real life. Third, when instructing the characteristics and inclusive relation, students could build up their knowledge by themselves, by questions and concrete operational activities. Fourth, constructions were aimed at understanding of the definition and characteristics of the figures, rather than at itself.

• Journal of Educational Research in Mathematics
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• v.27 no.4
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• pp.701-725
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• 2017

Students need to have opportunities to share their ideas with peers by taking part in the conversation voluntarily that is, by persuading others and reflecting the consequences. Recognizing the importance of this point, this study intended to examine students' argumentation occurring in the process of performing tasks in the math classroom. Also, it tried to explore the types of the argument that students used in the classroom and the reason why they employed them with a focus on 'rebuttal', which is one of the six elements of the argument scheme such as claim, data, warrent, backing, qualifiers, and rebuttal. The analysis of argumentation is based on the five argumentation schemes suggested by Verheij(2005). The experimental class was conducted twice a week with four participants who are third grade middle school students. In the argumentation class students were promoted to address two different kinds of geometrical tasks. After the second session of class, the researcher conducted the semi-structured interview. Accordingly, this study contributes to the existing research by making students to have concrete and active argumentation while obtaining the sound understanding of the argumentation.

• Archives of design research
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• v.18 no.2 s.60
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• pp.325-334
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• 2005

The purpose of this thesis is to explore the fundamental reasons and general circumstances of the introduction of geometric shape to the 20th century's design education. The modern design education was directly influenced by the German Kindergarten Movement and its educational ideal, so they began to employ geometric shapes in visual education. When Friedrich Frobel, a professional German child educator of the 19th century, invented the 'Spielgaben,' it soon became a popular educational tool. It was a turning point in the child educational system, from then they began to actively employ 'tools' in art education. The Spielgaben was created based on the geometric principle of a popular block game of the 19th century. On the other hand, a game program called 'Bechaftigungsmaterial' led early Modernists to adopt geometric shape in their works. Then, geometric shape were applied to a primary educational program designed by the Bauhaus that gave birth to the Modern design education in the 20th century. likewise, the substantial reasons why the principles of point/line/plain and geometric shapes had been taken in the 20th century design education can be explained through this historical background. This research is to investigate how Kindergarten Movement and Modern design education can be associated with each other, particularly in the light of geometric elements. Therefore, I first referred to the historic records in order to reveal their relation, and then analyzed the similarities and differences between the two activities. In result, I could explore the relationship between child educational tools and the 20th century's design education.

• Journal for History of Mathematics
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• v.24 no.4
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• pp.87-96
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• 2011

Hans Freudenthal made important contributions to algebraic topology and geometry. He also made significant contributions in history of mathematics and mathematics education. In the 1970s, his intervention prevented the Netherlands from the movement of "new math". He had a very important role as a founder of realistic mathematics education and became famous internationally by that. Because he raised the profile of ICMI strongly, Bass used the expression 'Freudenthal Era' for the period that Freudenthal was the president of ICMI. Now many mathematics educator agree to use the Freudenthal Era when they mention about the history of ICMI. In this paper, we present on the life of Freudenthal and his contributions for mathematics education, especially ICMI.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.121-131
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• 2005

For thrust motion of high speed underwater torpedo the special hydro reactive fuels that burns in vapor water and water supply from aboard is used. The main component of this hydro reactive fuel is the powder of active metal (Mg, Al) that can burn in water vapor with large heat generation in the rocket combustion chamber. The thermodynamic analysis of combustion properties of the burning of the particles of these active metal in the vapor water have been carried out. The conception for the possible content variants of the hydro reactive fuels have been discussed using the geometrical and thermodynamic combustion conditions with the basic recommendation for contents of designed hydro reactive fuels in future.

• Journal of Korean Society of Transportation
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• v.22 no.3 s.74
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• pp.127-135
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• 2004

교차로 안전성 진단과 관련된 기존의 연구는 교차로 상에서 발생한 사고 자료에 기초하여 교차로 기하구조 요소, 교통량 및 신호운영방법 등과 관련된 요인을 변수로 사용하여 교통사고건수 예측모형 개발에 관한 연구가 대부분이다. 그러나, 분석하고자 하는 대상 교차로의 사고건수 예측모형을 개발하기 위해 필요한 교통사고 자료의 경우 단 기일에 걸쳐 획득되지 않으며 몇 년간의 사고 자료를 요구할 수도 있다. 이러한 자료를 이용하더라도 사고 발생 기간동안 교차로 사고에 영향을 미치는 요인(교차로 운영방법, 기하구조 등)이 변화될 수도 있다는 문제점을 지닌다. 이와 같은 이유로 교차로 안전성을 진단하는데 있어 기존 교통사고 자료는 언제나 절대적인 자료가 될 수 없다. 이에 대한 보완책으로, 3일에서 5일정도의 조사 자료만으로도 안전성 진단이 가능한 상충자료를 이용하여 교차로 안전성 진단을 할 수 있다. 본 연구는 기존사고 자료를 이용하여 사고 발생에 기인하는 여러 변수들을 교통사고심각도와의 상관관계를 분석하고, 상관관계가 높은 변수를 이용하여 신경망 사고심각도 예측모형을 개발하였으며, 모형 검증을 위해 다중회귀사고심각도 예측모형을 개발하여 비교 평가한 결과 신경망 사고심각도 예측모형의 예측력이 우수한 것으로 나타났다. 현장에서 조사된 상충자료를 신경망 사고심각도 예측모형에 적용하여 상충이 사고로 연결 될 경우 사고심각도를 예측하였으며, 예측된 사고심각도에 가중치를 부여하여 대상 교차로 위험우선순위를 결정한 결과 사고비용에 기초한 위험우선순위 결정법과 같은 순위의 결과를 도출하였다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.4
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• pp.435-442
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• 2014

In this paper, radar cross section (RCS) analysis program, RACSAN has been developed to predict RCS of complex structures. RACSAN is based on the high frequency range analysis method of Kirchhoff approximation in physical optics (PO). This program can present RCS including multi-bounce effect in complex structures by combination of geometric optics (GO) and PO method. GO method has a concern in the evaluation of the effective area, and PO method is involved in the calculation of RCS for the final effective area that is evaluated by GO method. Comparisons of the predicted results and analytical solutions showed that the developed program could be an effective tool for predicting RCS in complex structures.

• Journal of Biomedical Engineering Research
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• v.23 no.3
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• pp.171-179
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• 2002

It is well known that the geometry of the articular surface plays a major role in the kinematic and kinetic analysis to understand human knee joint function during motion. The functionality of the knee joint cannot be accurately modeled without considering the effects of sliding and lolling motions. We Present a 3-D human knee joint model considering sliding and rotting motion and major ligaments. We employ more realistic articular geometry using two cam profiles obtained from the extrusion of the sagittal Plain view of the representative Computerized Tomography image of the knee joint compared to the previously reported model. Our model shows good agreement with the already reported experimental results on Prediction of the lines of force through the human joint during gait. The contact point between femur and tibia moves toward the Posterior direction as the knee undergoes flexion, reflecting the coupling of anterior and Posterior motion with flexion/extension. The anterior/posterior displacement of the contact Point on the tibia plateau during one gait cycle is about 16 mm. for the lateral condyle and 25 mm. for the medial condyle using the employed model Also. the femur motion on the tibia undergoes lateral/medial movement about 7 mm. and 10 mm. during one gait cycle for the lateral condyle and medial condyle. respectively. The developed computational model maybe Potentially employed to identify the joint degeneration.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.4
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• pp.64-69
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• 2002

Dynamic analysis of laminated beams with a embedded damping layer under tension or compression axial load is investigated. Improved Layer-Wise Zig-Zag Beam Theory and Interdependent Kinematic Relation using the governing equations of motion are incorporated to model the laminated beams with a damping layer and a corresponding beam zig-zag finite element is developed. Flexural frequencies and modal loss factors under tension or compression axial load are calculated based on Complex Eigenvalue Method. The effects of the axial tension and compression load on the frequencies and loss factors are discussed.