• 한국자동차공학회논문집
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• 제5권6호
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• pp.141-147
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• 1997

For the effective finite element analysis of the structures including material interfaces or contact surfaces, interface elements are proposed. Most of early works in this problem require not only iterative computation but also complex formulation because of the kinematic nonlinearities caused from the discontinuous behavior and the stress concentration phenomena. The proposed elements, however, are consistently formulated using relative displacements and tractions between top and bottom regular finite elements. The effectiveness of these elements are shown by solving various numerical sample problems including an leaf spring and comparing with results of general finite element analysis. As a result, more stable solutions are conveniently obtaines using interface elements than regular finite elements.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2004년도 추계학술대회
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• pp.96-98
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• 2004

At the previous papers, we showed that K2O-CaO-P2O5 glasses had a solubility in air so that they could be used for glass fertilizer. In this work, we fabricated the Eco-glass fertilizer containing trace elements such as B, Mg, Zn, Fe, Cu, Co, and Mo by a melt-quenching process and the dissolution properties of these glasses were investigated with pH meter and ICP analyzer. In case of the glasses containing the trace elements, effect of trace elements on the dissolutions is not obvious and ignorant the stability of mother glass. Also, the dissolution amounts of each trace elements depend on the mother glass composition and the quantity of each trace element, and mother glasses determined the dissolving velocity of chemical elements.

• 대한인간공학회지
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• 제26권4호
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• pp.143-146
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• 2007

Due to the expansion of cities and the increasing number of large-scale and complex public spaces, there is an increase in public signage. Moreover, the information described on these signs tends to be diverse and complicated. Complex signs that contain multiple destinations or other information must be considered to determine not only the proper size, color, etc. but also the most effective arrangement of design elements. In the previous research, the cognitive utility of complex public signs was estimated using computer simulation software. In the current research, we focused on the objective estimation of the effectiveness of the results obtained in the previous research utilizing an eye mark recording system. Two cognitive engineering experiments clarified five points for improvement in the usability of complex signs, as follows: 1) Parallel construction of characters and pictograms is more efficient. 2) Grouping elements result in rapid recognition of information chunks. 3) Visual characters and pictograms are effective, along with proper density of information. 4) Specific arrangement of sign arrows is effective. 5) Figures on signs influence the sequence of information searches.

• 대한전기학회논문지
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• 제38권11호
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• pp.870-876
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• 1989

A systematic procedure for the elements of system matrix is suggested for the multimachine systems with constant impedance loads. Synchronous machines are represented by either a two-axis model or a classical model. The interrelationship of submatrices of system matrix has been investigated. Once elements of one submatrix are determined, they can be used to calculate the elements of the other submatrix. This algorithm is more effective as the number of generators modeled by a two-axis model increases. It is illustrated for 9-Bus multimachine system.

• 한국학교수학회논문집
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• 제3권1호
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• pp.131-148
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• 2000

Above all, the ability to solve problems must be emphasized as a basic skill of mathematics, but it is neglected when we teach. In this study, learning task means ［same meaning］ ［same form］ ［same technique］, so I tried to extend mathematical scholastic ability of the students as an extensional problem solving that is a basic element of mathematics. The purpose of this study is the investigation of level type learning, using the basic learning elements to extend thinking ability. From the constructed hypothesis as follows and then implement it. I selected basic learning elements from an analyzed textbook and then task learning material was created for each level type learning. The problem solving ability will be extended through the level type learning of the small group, using the level type learning task material. The conclusions this study are as follows. The level type learning in small group learning, using and making level type learning material, having basic learning elements in analysed text are. Basic learning content is understood clearly and deeply, so, fundamentally, it is effective in achieving the problem solving in mathematics. It is an effective method to achieve the meta-cognitive faculty because achieved the expected method of solving problems and resulted in the true learning of content.

• 한국주거학회논문집
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• 제20권2호
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• pp.101-108
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• 2009

The purpose of this study is to develop basic data for the design of the housing space for unit that factors in the sentiment of the residents by using aesthetic elements and expression method to search for the ways to design housing space for differentiated unit. The results are as follows: First, aesthetic elements in the aesthetic element in the unit housing space for unit can be classified into basic elements and detailed elements. Second, it is possible to classify into distortion, mixing, superposition and juxtaposition methods. Third, use of the 'material' for 'wall' is recommended when designing differentiated housing space by using basic elements. At this time, expression using the method of 'mixing' is effective for inducing differentiation. In particular, elements that can perceive the difference in time are mixed, to add on slight differentiation. Fourth, 'illumination' and 'material' are used when designing differentiated housing space by using detailed elements. Fifth, preference degree of the expression method is manifested differently depending on the selected elements. Lastly, this study conducted a study on the preference level of the aesthetic elements and expression method targeting the experts alone to differentiate the design of the residential space for unit.

• Journal of Power Electronics
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• 제7권3호
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• pp.257-264
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• 2007

Active power filters can be cost-effective for use in practical systems with the insertion of a few passive elements in shunt or series configuration. The resulting hybrid filters can be designed to provide dominant lower order harmonic elimination and reactive power support by the passive elements so that the burden on the active filter counterpart is reduced. In this paper, the rate reduction in the shunt active filter is estimated when it is connected in parallel with suitable passive tuned harmonic filters. The active filtering system is based on an appropriate control scheme. The simulation and the experimental results of the shunt active filter, along with the estimated value of reduction in rating, show that the hybrid shunt filtering system is quite effective in compensating for the harmonics and reactive power, in addition to being cost-effective.

• Coupled systems mechanics
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• 제6권1호
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• pp.1-15
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• 2017

Despite the exceptional mechanical properties of individual carbon nanotubes (CNTs), the effective properties of CNT-reinforced composites remain below expectations. The composite's microstructure has been identified as a key factor in explaining this discrepancy. In this contribution, a method for generating representative volume elements of aligned CNT sheets is presented. The model captures material characteristics such as random waviness and entanglement of individual nanotubes. Thus it allows studying microstructural effects on the composite's effective properties. Simulations investigating the strengthening effect of the application of a pre-stretch on the CNTs are carried out and found to be in very good agreement with experimental values. They highlight the importance of the nanotube's waviness and entanglement for the mechanical behavior of the composite. The presented representative volume elements are the first to accurately capture the waviness and entanglement of CNT sheets for realistically high volume fractions.

• Smart Structures and Systems
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• 제24권2호
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• pp.193-207
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• 2019

This study concerns with morphing structures, e.g. as applied in the aerospace industry. A morphing aerofoil structure capable of variable geometry was developed, which was shown to be able to cater for the different aerodynamic requirements at different stages of flight. In this work, the useful and relatively simple method has been applied, which provides a direct method for calculating required morphing shape displacements via finding the most effective bar through calculating bar sensitivity to displacement and calculating set of length actuations for bar assembly to control/adjust shape imperfection of prestressable structural assemblies including complex elements ("macro-elements", e.g., the pantographic element), involving Matrix Condensation. The technique has been verified by experiments on the physical model of an aerofoil shaped morphing pantographic structure. Overall, experimental results agree well with theoretical prediction. Furthermore, the technique of multi-iteration adjustment was presented that effective in eliminating errors that occur in the practical adjustment process itself. It has been demonstrated by the experiments on the physical model of pantographic morphing structure. Finally, the study discusses identification of the most effective bars with the objective of minimal number of actuators or minimum actuation.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제26권3호
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• pp.317-338
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• 2012

본 연구는 교사들이 생각하는 좋은 수학 수업을 알아보기 위해 4개의 대영역(교육과정과 교육내용, 교수 학습, 교실환경 및 수업 분위기, 평가)과 48개 하위 요소로 구성된 설문지를 이용하여 초등학교 교사 223명과 중학교 수학 교사 151명의 반응을 비교 분석하였다. 분석 결과 초등 교사는 대영역 중 교육과정과 교육내용 영역을, 중등 교사는 교수 학습 영역을 가장 중요하게 생각하였다. 세부 요소 별로 살펴보면, 초 중등 교사는 공통적으로 자기주도적 학습 능력을 신장시키는 수업, 학생 수준에 맞게 교육과정을 재구성하여 실시한 수업, 학생과 교사간의 상호작용이 잘 이루어지는 수업 등을 좋은 수학 수업이라고 생각하였다. 그러나 초등 교사는 좋은 수학 수업과 관련된 23개 요소에 대해서 중등 교사보다 더 중요하다고 인식하였으며, 중등 교사는 수학적 표현 능력을 신장시키는 수업, 동기 유발이 잘 이루어지는 수업의 2개 요소에 대해서만 초등 교사보다 유의미하게 더 중요하다고 인식하였다. 이러한 연구 결과를 토대로 우리나라 본연의 좋은 수학 수업에 대한 교사의 인식 및 이에 따른 시사점을 논의하였다.