• 한국추진공학회지
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• 제26권2호
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• pp.1-11
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• 2022

일반적인 축소 확대형 초음속 노즐에 대한 열해석에서 경계조건으로 사용되는 벽면의 열전달 계수는 노즐 전체의 열해석 정확도에 영향을 미친다. 이에 많은 열전달계수 도출 방법이 제안되어 왔으며, 본 연구에서는 각각의 기법들을 실제 실험 조건에서 열전달 계수를 계산하고 비교하고자 하였다. 이를 위해 기 수행된 벽면 등온 노즐의 열전달실험에 대해 이론 기반의 analogy 기법과 반경험식, 유체전산해석을 통해 열전달 계수를 도출하고 실험결과와 비교하였다. 해석 결과는 반경험식들은 전반적으로 다른 방법에 비해 대류 열전달 계수를 과도하게 예측하고, Prandtl-Taylor analogy 기법과 k-ω SST 모델을 적용한 전산해석 결과가 실험결과와 비교적 잘 일치하는 경향성을 보였다.

• 한국농공학회지
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• 제45권4호
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• pp.115-125
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• 2003

Shell structures are widely used in a variety of engineering application, and mathematical solution of shell structures are available only for a few special cases. The solution of shell structure is more complicated when it has such condition as winkler foundation, other problems. In this study many simplified methods (analogy of beam on elastic foudation, finite element method and transfer matrix method) are applied to analyze a hemisphere-cylindrical shell structures on elastic foundation. And the transfer matrix method is extensively used for the structural analysis because of its merit in the theoretical backgroud and applicability. Therefore, this paper presents the analysis of hemisphere-cylindrical shell structure base on the transfer matrix method. The technique is attractive for implementation on a numerical solution by means of a computer program coded in FORTRAN language with a few elements. To demonstrate this fact, it gives good results which compare well with finite element method.

• 산업경영시스템학회지
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• 제19권40호
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• pp.329-339
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• 1996

This study presents the eigen ethnic function and mathematical processing method of human information. Human information can be definded as the overlap area taking the superposition property composed of intuition and sensory in stimulus/response (S/R) model, In S/R model, the intuition and sensory eigen ethnic function acts on the forming of perception. Perception process by the superposition property of intuition and sensory analogy to the basic neural network model. This analogy model extends to the analysis method. As an analysis method, optimal ratio number induced to the golden section ratio. Golden section ratio drived out by diverse source and implicated to the sensory and intuitive context such as beauty, harmony, optimality etc. This numerical orders can be applied to analysing the Perception process and extended to pursue the Potential human behavior, On the basic of proposed applying method, an illustrative mathematical examples are presented.

• 소음진동
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• 제6권6호
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• pp.755-762
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• 1996

An acoustic transmission loss analysis method for mufflers with complex geometry is developed using MSC/NASTRAN on the basis of acoustic-structural analogy and two-microphone method. In this study, mufflers with simple and complex shapes are analyzed using this method and compared with theoretical and experimental results to verify it. Applying this method to design of discharge muffler in a rotary compressor, we obtained 2dB(A) of noise reduction in the range of lower than 1300Hz. Futhermore, adopting this technique for a suction muffler in reciprocal compressor, more than 10dB(A) noise reduction at 500Hz, and in total, 3dB(A) noise reduction is achieved.

• Journal of Information Processing Systems
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• 제8권4호
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• pp.621-652
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• 2012

Software Estimations provide an inclusive set of directives for software project developers, project managers, and the management in order to produce more realistic estimates based on deficient, uncertain, and noisy data. A range of estimation models are being explored in the industry, as well as in academia, for research purposes but choosing the best model is quite intricate. Estimation by Analogy (EbA) is a form of case based reasoning, which uses fuzzy logic, grey system theory or machine-learning techniques, etc. for optimization. This research compares the estimation accuracy of some conventional data mining models with a hybrid model. Different data mining models are under consideration, including linear regression models like the ordinary least square and ridge regression, and nonlinear models like neural networks, support vector machines, and multivariate adaptive regression splines, etc. A precise and comprehensible predictive model based on the integration of GRA and regression has been introduced and compared. Empirical results have shown that regression when used with GRA gives outstanding results; indicating that the methodology has great potential and can be used as a candidate approach for software effort estimation.

• 한국기계가공학회지
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• 제15권5호
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• pp.57-65
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• 2016

The power flow of an 8-speed automatic transmission was analyzed using a lever analogy for the manufacturing of planetary gears. From the analysis, we found that the engine power was split between the first and second double-pinion planetary gears (DPPG1 and DPPG2), and was then passed to the DPPG3 for the fourth speed. For the fifth speed, the engine power was split between the DPPG1 and DPPG3. For the speeds 6-8, the engine power was passed only to SPPG2, while the seventh speed contained the power circulation.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.711-716
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• 2011

Today, high-speed trains enjoy wide acceptance as fast, convenient and environment-friendly means of transportation. However, increase in the speed of the train entails a concomitant increase in the aerodynamic noise, adversely affecting the passenger comfort. At the train speed exceeding 300 km/h, the effects of turbulent flows and vortex sheddding are greatly amplified, contributing to a significant increase in the aerodynamic noise. Drawing a biomimetic analogy from low-noise flight of owl, a method to reduce aerodynamic noise at inter-coach space of high-speed trains is investigated. The proposed method attempts to achieve the noise reduction by modifying the turbulent flow and vortex shedding characteristics at the inter-coach space. To determine the aerodynamic noise at various train speeds, wind tunnel testing and numerical CFD (Computational Fluid Dynamics) simulation for the basic inter-coach spacing model are carried out, and their results compared. The simulation and experimental results reveal that there are discrete frequency components associated with turbulent air flow at constant intervals in the frequency domain

• 한국초등과학교육학회지:초등과학교육
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• 제25권2호
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• pp.149-158
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• 2006

The purpose of this study was to analyze the analogies used in elementary science textbooks. For this, the analogies were classified into the following criteria : analogy-related contents included in elementary science text-books, types of representation style, and the role of analogy. The results of this study were as follows : the total of analogies was 154 in the 6th and 166 in the 7th curriculum. Most of them were expressed in textbooks and experimental texts. More structural/functional, verbal/pictorial, concrete/concrete, concrete/abstract, simple and enriched analogies were included in the science textbooks of the 7th than those of the 6th. Most of them took the role as an aid to understanding. According to the domain of science content, energy, material, life domains were increased in the 7th than the 6th, with the exception of the earth science domain. The ratio of used analogies in the life domain was higher than the others, and in the material domain it was the lowest. From these results, it can be said that, in order to help students' understanding, further research into the application of analogies is needed.

• 한국학교수학회논문집
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• 제16권4호
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• pp.927-941
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• 2013

본 연구에서는 고등학교 학생들이 삼각형에 대한 코사인 법칙으로부터 사각형과 n각형에 대한 코사인 법칙을 유추적 사고를 통하여 발견하는 과정을 조사하였으며 삼각형에 대한 코사인 법칙에 대한 충분한 이해가 일반화된 법칙을 발견하고 증명하는데 어느 정도 영향을 미치는지를 분석하였다. 이와 같이 귀납적 추론이나 유추적 사고 활동을 통해 학생 스스로 지식을 발견하고, 스스로 발견한 수학적 지식을 논리적 추론이나 연역적 증명을 통해 정당화하는 경험을 쌓을 수 있을 때, 학생들은 이 지식을 자신의 것으로 내면화할 수 있게 되고, 다양한 상황에 자유롭게 활용할 수 있는 능력을 가질 수 있을 것이다.

• 한국과학교육학회지
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• 제23권3호
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• pp.246-253
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• 2003

이 연구에서는 역할놀이 비유 활동의 효과를 학생들의 개념 이해도, 개념 응용력, 학습 동기 측면에서 조사하였다. 서울시의 남녀공학 중학교에서 1학년 4학급을 선정하여 처치 집단과 통제 집단에 무선배치하고 '분자의 운동'에 대하여 4차시 동안 수업을 시시하였다. 처치 집단은 역할놀이 비유 수업을 실시하고 통제 집단은 전통적 수업을 실시하였다. 분석 결과, 개념 이해, 개념 응용의 파지, 그리고 학습 동기 중 자신감에서 처치 집단의 점수가 통제 집단에 비해 유의미하게 높았다. 또한, 개념 응용과 학습 동기 중 주의집중 및 관련성 영역에서 수업 처치와 성의 상호작용 효과가 있었다. 개념 응용력 검사의 경우 처치 집단의 남학생과 여학생 모두 통계 집단의 학생들보다 유의미하게 높은 점수를 받았다. 주의집중 및 관련성 검사에서는 처치 집단의 남학생들이 통제 집단의 남학생들 보다 유의미하게 높은 점수를 받았다. 이에 대한 교육학적 함의를 논의 하였다.