• 대한수학회보
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• 제36권2호
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• pp.363-370
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• 1999

A new and simple estimate using a convex function for convergence factors of Schwarz algorithms orthogonal spline collocation method is presented. The estimated convergence factors in this context depend only on a way to split a given domain.

• 대한수학회보
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• 제50권5호
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• pp.1737-1751
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• 2013

An efficient and stable point collocation scheme based on a meshfree method is studied for the stationary incompressible Navier-Stokes equations. We describe the diffuse derivatives associated with the moving least square method. Using these diffuse derivatives, we propose a point collocation method to fit in solving the Navier-Stokes equations which improves the stability of the direct point collocation scheme. The convergence of the numerical solution is investigated from numerical examples. The driven cavity ow and the backward facing step ow are implemented for the reliability of the scheme. Also, the viscous ow on complicated geometry is successfully calculated such as the ow past a circular cylinder in duct.

• Journal of applied mathematics & informatics
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• 제30권5_6호
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• pp.951-969
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• 2012

In this paper, we propose a class of meshless collocation approaches for the solution of time dependent partial differential algebraic equations (PDAEs) in terms of a radial basis function interpolation numerical scheme. Kansa's method and the Hermite collocation method (HCM) for PDAEs are given. A sensitivity analysis of the solutions from different shape parameter c is obtained by numerical experiments. With use of the random collocation points, we have obtain the more accurate solution by the methods than those by the finite difference method for the PDAEs with index-2, i.e, we avoid the influence from an index jump of PDAEs in some degree. Several numerical experiments show that the methods are efficient.

• 호남수학학술지
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• 제43권3호
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• pp.373-383
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• 2021

In this study, a numerical method deals with the Chebyshev wavelet collocation and Adomian decomposition methods are proposed for solving Korteweg-de Vries equation. Integration of the Chebyshev wavelets operational matrices is derived. This problem is reduced to a system of non-linear algebraic equations by using their operational matrix. Thus, it becomes easier to solve KdV problem. The error estimation for the Chebyshev wavelet collocation method and ADM is investigated. The proposed method's validity and accuracy are demonstrated by numerical results. When the exact and approximate solutions are compared, for non-linear or linear partial differential equations, the Chebyshev wavelet collocation method is shown to be acceptable, efficient and accurate.

• 영어어문교육
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• 제17권3호
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• pp.141-159
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• 2011

This study examined the effects of collocation-based instruction on L2 vocabulary acquisition and learners' interests in it. Fifty one students were randomly assigned to the experimental group (collocation-based instruction group) and to the control group. The participants' English vocabulary capacity was checked through pre and post tests, and two surveys were used to probe the learners' vocabulary learning behaviors and their interests in English vocabulary learning respectively. To better understand the participants' opinions and feelings on the collocation-based learning, follow-up interviews were also carried out. The results showed that second language (L2) learners' vocabulary capacity was significantly improved through collocation-based instruction. However, the participants' degree of interest in vocabulary learning did not reach our expectation partly because of external factors such as the Test for the College Scholastic Ability Test (CSAT) and lack of familiarity of collocations. Such results indicate that the high school students' rooted perception of putting importance on test-based language learning could not be easily changed since it is closely related to their immediate needs. Based on the results, this study suggested how to implement collocations into L2 classrooms effectively.

• 영어어문교육
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• 제13권3호
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• pp.157-176
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• 2007

Based on the consensus that vocabulary plays an essential role in improving reading ability, the present study investigates the effects of two different methods of English vocabulary instruction - the traditional wordlist-based vocabulary instruction (G1) and the collocation-based vocabulary instruction (G2) - on improving English reading ability for high school learners. First, the results of the collocation test revealed that G1 and G2 groups attained similar mean scores on the pretests; however, G2 significantly outperformed G1 on the post-test administered at the end of the learning activity. The results proved that students who learned vocabulary in a collocation-oriented setting had better retention through the lexical-chunking achieved by the collection method. Second, in terms of reading comprehension achieved on nationwide academic trial tests, the result was, after considering more tests, that G2 gained a significantly higher mean score on the third and fourth than G1 did, although the two groups yielded a similar mean score on the first and second test. The implication of these results is that collocation-based vocabulary activities had a more significant influence on reading skills than wordlist-oriented ones.

• Structural Engineering and Mechanics
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• 제45권5호
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• pp.595-611
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• 2013

This paper aims to compare three collocation point methods associated with the odd order stochastic response surface method (SRSM) in a systematical and quantitative way. The SRSM with the Hermite polynomial chaos is briefly introduced first. Then, three collocation point methods, namely the point method, the root method and the without origin method underlying the odd order SRSMs are highlighted. Three examples are presented to demonstrate the accuracy and efficiency of the three methods. The results indicate that the condition that the Hermite polynomial information matrix evaluated at the collocation points has a full rank should be satisfied to yield reliability results with a sufficient accuracy. The point method and the without origin method are much more efficient than the root method, especially for the reliability problems involving a large number of random variables or requiring complex finite element analysis. The without origin method can also produce sufficiently accurate reliability results in comparison with the point and root methods. Therefore, the origin often used as a collocation point is not absolutely necessary. The odd order SRSMs with the point method and the without origin method are recommended for the reliability analysis due to their computational accuracy and efficiency. The order of SRSM has a significant influence on the results associated with the three collocation point methods. For normal random variables, the SRSM with an order equaling or exceeding the order of a performance function can produce reliability results with a sufficient accuracy. The order of SRSM should significantly exceed the order of the performance function involving strongly non-normal random variables.

• 영어어문교육
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• 제11권4호
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• pp.189-208
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• 2005

The purpose of this study is to investigate knowledge and use of English collocations in their relation to Korean college students' general English proficiency and writing abilities. Participants in the present study were 203 Korean college students. Their knowledge and use of English collocations were measured by a self-designed collocation test and an essay writing test. The findings were as follows: First, there was a significant difference in students' knowledge of collocations according to their general English proficiency. Students' performance in the collocation test increased as their level of proficiency increased. Second, there was a significant difference in students' knowledge of collocations according to their writing abilities. Students showed better performance in the collocation test as their level of writing abilities increased. Third, there was a significant difference in students' use of collocations according to their writing abilities. Students' collocation use in the writing test increased as their level of writing abilities increased. Fourth, there was a strong relationship between the students' knowledge of collocations and their general English proficiency and between the students' use of collocations and their writing abilities. Pedagogical implications of the study and suggestions for further research were discussed on the basis of the research findings.

• 한국항공우주학회지
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• 제34권5호
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• pp.56-64
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• 2006

정지궤도 위성의 상대위치보정은 제한된 위지보정 박스내에 다수의 위성을 운용함으로서 발생하는 위성간 충돌, 전파간섭, 가림현상 등을 해결하기 위해 반드시 필요한 기술이다. 본 논문에서는 정지궤도 위성의 상대 궤도 운동 분석과 최적화 기법에 근거한 문제의 정립으로 상대위치보정을 수행하였다. 이상적인 정지궤도에 대한 상대운동을 다수의 멱함수와 주기함수로 표현하고, 상대위치보정에 필요한 조건들을 이들 함수로 표현한다. 이러한 구속 조건식과 더불어 연료 최소화 같은 가격 함수를 최소화하는 과정에서 궤도 수정에 필요한 절차를 수립하게 된다. 비선형 시뮬레이션을 통하여 본 논문에서 제시하고 있는 절차의 타당성을 검증하였고 또한 기존의 고전적인 방법과 비교하였다.

• 영어어문교육
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• 제10권3호
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• pp.41-66
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• 2004

Under the textbook-driven approach to English education in the Korean selling, the importance of the English textbook can not be overemphasized as the main source of learning materials. Recently, with the development of computer-based language corpora, the recognition of the importance of collocations and the availability of computerized databases of words have caused a resurgence and facilitation in the instruction of collocation. The primary purpose of the present study is to identify the characteristics of lexical collocation and the extent of its use in high school 10th-grade textbooks. From all the analyses, it is revealed that the language materials reflect various constructed collocation in the case of adjective+noun and noun+noun collocations in a natural context. However, verb+noun and adverb+verb collocations are not fully reflected. This is true for delexicalized verbs, and verb and adjective intensifiers. Also the language materials do not provide sufficient support for the lexical syllabus, even though all textbooks may be somewhat adequate in terms of vocabulary size. Finally, based on the analyses of the texts, the suggestions for English collocation instruction are made in the lexical approach.