• Structural Engineering and Mechanics
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• 제14권6호
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• pp.661-677
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• 2002

The subject of this investigation is to study the buckling of cross-ply laminated orthotropic cylindrical thin shells with variable elasticity moduli and densities in the thickness direction, under external pressure, which is a power function of time. The dynamic stability and compatibility equations are obtained first. These equations are subsequently reduced to a system of time dependent differential equations with variable coefficients by using Galerkin's method. Finally, the critical dynamic and static loads, the corresponding wave numbers, the dynamic factors, critical time and critical impulse are found analytically by applying a modified form of the Ritz type variational method. The dynamic behavior of cross-ply laminated cylindrical shells is investigated with: a) lamina that present variations in the elasticity moduli and densities, b) different numbers and ordering of layers, and c) external pressures which vary with different powers of time. It is concluded that all these factors contribute to appreciable effects on the critical parameters of the problem in question.

• 아동학회지
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• 제29권1호
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• pp.103-113
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• 2008

This study examined the difference in children's performance between two types of task by the number of protagonists and children's implicit understanding of false-belief. The implicit measure by eye gaze was contrasted with children's explicit answers to the experimenter's question about where the protagonist would look for an object. Results showed there was no difference according to the task type by number of protagonists. On false-belief, 2- and 3-year-olds showed low performance compared with 4-year-olds on explicit responses. On implicit responses, 3- and 4-year-olds out-performed 2-year-olds. These results suggest that implicit understanding precedes explicit understanding.

• Kyungpook Mathematical Journal
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• 제59권4호
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• pp.821-834
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• 2019

The reductivity of a spherical curve is the minimal number of times a particular local transformation called an inverse-half-twisted splice is required to obtain a reducible spherical curve from the initial spherical curve. It is unknown if there exists a spherical curve whose reductivity is four. In this paper, an unavoidable set of configurations for a spherical curve with reductivity four is given by focusing on 5-gons. It has also been unknown if there exists a reduced spherical curve which has no 2-gons and 3-gons of type A, B and C. This paper gives the answer to this question by constructing such a spherical curve.

• 한국항만경제학회지
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• 제21권4호
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• pp.239-253
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• 2005

Although logistics service quality is considered an essential strategy for success and survival in today's internet environment, there are still a lot of question: what variables determine the extent of logistics service effect, how difficultly do the determinants affecting logistics service effect and how accomplish the decision making in the implementation of inter-organization information system. The purpose of this study is to examine a model to utilize the application and effect of logistics service through e-marketplaces. The results of empirical analysis are mentioned as follows; First, among the interorganization information system factors, four variables(top management support in organization characters, competitive degree in environment characters, relative advantage and information efficiency in innovation characters) have been shown to be primary determinant of the effect of logistics service quality. Second, the type of independent variable used results in a significant difference in the effect of logistics service quality. Third, Korean firms have to pursue the corporate strategy focused on logistics service quality.

• 대한수학회보
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• 제48권2호
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• pp.397-412
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• 2011

In this paper, the equation of the transient Stokes flow of an incompressible viscous fluid is studied. Growth and decay estimates are established associating some appropriate cross sectional line and area integral measures. The method of the proof is based on a first-order differential inequality leading to an alternative of Phragm$\'{e}$n-Lindell$\"{o} $f type in terms of an area measure of the amplitude in question. In the case of decay, we also indicate how to bound the total energy.

• 한국학교수학회논문집
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• 제13권2호
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• pp.185-203
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• 2010

학생들의 수학 학습 정도는 학교수학의 각 영역이나 내용에 따라 다양하게 나타날 수 있다. 이러한 수학 학습상황을 평가하고 활용하기 위한 통합적인 평가 틀의 구성은 유용하다. 본 논문에서는 일차방정식의 내용으로 한정하여 유형별 평가와 문항별 평가에 대한 평가표를 구성하였으며, 두 가지 평가를 기초로 종합평가를 통한 수학 학습 지도에 대하여 알아보았다. 구성한 평가표는 학생 개개인의 학습 상황에 대한 정보를 제공함으로 개별적인 수학 학습 지도에 유용하다.

• International Journal of Contents
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• 제13권3호
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• pp.59-64
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• 2017

The purpose of this study is to identify the types of injuries and the protective behaviors of soccer club members to prevent injuries, and promote health. Data was collected from 395 soccer club members from thirteen football clubs in Seoul and Gyeonggi province using question tool developed by researchers. Data analysis was performed using SPSS 23 for descriptive analysis and Chi-square test. The results showed that sport for soccer injuries was serious and medical expenses was significant. The demographic information showed that 50-year-old and over adults were vulnerable and had a disproportionate number of injuries. Those employees who helded administrative positions, white-collar and specialized jobs also experienced the high level of injury experience. Despite this many injuries, many respondents appeared to be lacking a protective actions, such as not wearing protective gear. It was critical for the club members to improve their knowledge and awareness of safe sports activities.

• 대한수학회보
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• 제25권2호
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• pp.175-178
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• 1988

Let .SIGMA. be a smooth compact manifold without boundary having the same homotopy type as a sphere, which is called a homotopy sphere. Supose a group G acts smoothly on .SIGMA. with the fixed point set .SIGMA.$^{G}$ consists of two isolated fixed points p and q. In this case, tangent spaces $T_{p}$ .SIGMA. and $T_{q}$ .SIGMA. at isolated fixed points, as isotropy representations of G are called Smith equivalent. Moreover .SIGMA. is called a supporting homotopy sphere of Smith equivalent representations $T_{p}$ .SIGMA. and $T_{q}$ .SIGMA.. The study on Smith equivalence has rich history, and for this we refer the reader to [P] or [Su]. The following question of pp.A.Smith [S] motivates the study on Smith equivalence.e.

• Journal of Astronomy and Space Sciences
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• 제11권1호
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• pp.21-30
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• 1994

VV Cep-type long period spectroscopic-eclipsing binary AZ Cas has been observed for five years, 1985 Oct~1990 Feb, UBV at the Ilsan Station of Yonsei University Observatory. A total of 431 observations (U=129, B=142 and V=160) are made for 86 nights. Instrumental differential UBV and B-V light curves made with these observations cover phases nearly a half of one period. There is no appreciable light variation in V but in other two passbands a gradual decrease of the brightness is clearly noticed. The loss of light in B resulted in a reddening in $\Delta(B-V)$ by + 0.06 at phases between 0.4~0.5 as compared with that of at phase ~0.1. This intrinsic reddening arouses a question why at the orbital phase of the transit of a hot star in front of a cool M supergiant the heating of the facing hemisphere of M supergiant by the strong radiation from the B stat is absent. With regard to this unusual situation we propose a hypothesis that a large amount of gas stream of low temperature ejected from the surface of M supergiant component towards the B star dominates the brightness of B star and the reflection effect.

• 한국정보과학회 언어공학연구회:학술대회논문집(한글 및 한국어 정보처리)
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• 한국정보과학회언어공학연구회 2018년도 제30회 한글 및 한국어 정보처리 학술대회
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• pp.645-648
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• 2018

기계 독해는 기계가 주어진 본문을 이해하고 질문에 대한 정답을 본문 내에서 찾아내는 문제이다. 본 논문은 질문 유형을 추가하여 정답 선택에 도움을 주도록 설계하였다. 우리는 Person, Location, Date, Number, Why, How, What, Others와 같이 8개의 질문 유형을 나누고 이들이 본문의 중요 자질들과 Attention이 일어나도록 설계하였다. 제안 방법의 평가를 위해 SQuAD의 한국어 번역 데이터와 한국어 Wikipedia로 구축한 K-QuAD 데이터 셋으로 실험을 진행하였다. 제안한 모델의 실험 결과 부분 일치를 인정하여, EM 84.650%, F1 86.208%로 K-QuAD 제안 논문 실험인 BiDAF 모델보다 더 나은 성능을 얻었다.