• 대한수학교육학회지:학교수학
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• 제13권3호
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• pp.405-422
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• 2011

본 연구는 행렬 연산지도의 실태를 분석하여 행렬 연산에 관한 이해의 필요성을 제시한 후, 행렬의 연산이 정의되는 이론적 배경의 탐구를 통하여 일대일 대응의 의의에 대해 고찰한다. 대수적 관점에서의 일대일 대응의 의의는 '이미 구조를 알고 있는 집합에서 일대일 대응을 통하여 새로운 집합에 대수적 체계를 도입할 수 있게 하는 수단'이라는 것이다. 즉, 동형구조를 만드는데 있어 핵심 아이디어라는 것이다. 행렬의 연산을 예로 한 일대일 대응에 관한 이러한 고찰과정은 수학적 사실의 필연성 및 개연성을 경험하게 하여, 그러한 수학적 아이디어들이 단순히 주어지는 것이 아니라, 특정의 목적성 있는 활동의 결과물임을 인식하게 한다. 또한 일대일 대응의 본질적 이해는 행렬에 대한 논의에 그치지 않고 지수법칙, 대칭차집합, 순열 등 다양한 수학적 지식을 전개하기 위한 기저가 된다. 이러한 연구의 목적은 교사와 학생들에게 수학적 개념의 의미 충실한 이해를 돕는데 있으며, 나아가 교사의 가르칠 지식에의 전문성을 높이는데 있다.

• 대한수학교육학회지:수학교육학연구
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• 제27권4호
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• pp.765-789
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• 2017

산술 지도 시 산술적 사고의 측면을 강조해야 한다는 데에 다수의 동의가 있어왔음에도 불구하고, 국내에서 산술적 사고 자체에 주목한 연구는 찾아보기 어렵다. 산술적 사고에 초점을 맞춘 지도를 위해서는 산술적 사고의 의미와 요소를 면밀히 분석할 필요가 있다. 본 연구에서는 산술적 사고의 의미와 요소를 파악하기 위해 문헌 분석을 실시하였고, 산술적 사고의 요소를 추출하기 위한 이차적인 방법으로 전문가 델파이 조사를 실시하여 종합적으로 산술적 사고의 요소를 추출하였다. 연구 결과, 내용적 사고로서 산술적 사고의 의미를 파악하고, 수 관련 5가지, 연산 관련 11가지, 공통 요소 2가지로 총 18가지의 산술적 사고 요소를 추출하였다.

• Computers and Concrete
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• 제6권3호
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• pp.203-223
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• 2009

Regression analysis (RA) can establish an explicit formula to predict the strength of High-Performance Concrete (HPC); however, the accuracy of the formula is poor. Back-Propagation Networks (BPNs) can establish a highly accurate model to predict the strength of HPC, but cannot generate an explicit formula. Genetic Operation Trees (GOTs) can establish an explicit formula to predict the strength of HPC that achieves a level of accuracy in between the two aforementioned approaches. Although GOT can produce an explicit formula but the formula is often too complicated so that unable to explain the substantial meaning of the formula. This study developed a Backward Pruning Technique (BPT) to simplify the complexity of GOT formula by replacing each variable of the tip node of operation tree with the median of the variable in the training dataset belonging to the node, and then pruning the node with the most accurate test dataset. Such pruning reduces formula complexity while maintaining the accuracy. 404 experimental datasets were used to compare accuracy and complexity of three model building techniques, RA, BPN and GOT. Results show that the pruned GOT can generate simple and accurate formula for predicting the strength of HPC.

• KIEAE Journal
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• 제14권6호
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• pp.105-110
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• 2014

The basic factors determining the amount of energy used in hospital buildings are weather conditions and building factors. But the real energy consumer is central plant equipment such as boilers and chillers that produce thermal energy for heating and cooling. Inaccurate decision of the primary equipment's size can cause a high initial-cost, an excessive equipment space, a wasted energy by low operation-efficiency and shortening of the machine's life. In this reason, the decision of optimal size for central plant equipment is very important. There are several factors for the decision such as an operation factor, a factor (equipment factor), piping losses and a simultaneous usage factor applied in the sizing process except a basic cooling load. But there is no standard method for applying those factors. Usually, factors are applied individually by an experience or custom of each engineer. In this study, the authors emphasize the meaning and the problem of those factors, examine them by analyzing factors which were applied to actual practices, and propose the recommendation value of safety, load, operation factors and application methods.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1326-1329
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• 1997

In designing the controller by changing the weighting matrix for the pirpose of satisfying constraints, the physical meaning of weighting matrix may disapperar and the system may not yield best performance because operation condition such as periodic disturbance was not considered. In this paper, the weighting matrix is fixed and controller is designed to minimize the new performance index to reduce the effects of periodic-type disturbances. This method is applied to design the satellite controller to verify the effetiveness.

• 전기의세계
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• 제29권11호
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• pp.693-698
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• 1980

We T.E.C. have commenced to develop the O.F. cable in April, 1977. Now we have finished the Type-Test and produced in full-operation of 154KV 1x600mm$^{2}$ and 154KV 1x1200mm$^{2}$ O.F. cables. Especially we have completed pulling and splicing of the 24.82kms O.F. cable in KaeBong-OuRyu Route, and now it is operating well. This has important meaning that Extra High Voltage Under Ground Transmission Line has constructed by domastic engineers for the first time in Korea. Thank to arrange and publish it, and hope it can be helpful to the related.

• 한국수학교육학회지시리즈A:수학교육
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• 제49권4호
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• pp.489-500
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• 2010

This study makes clear justification of contents of set in secondary school through the scientific consideration and contents consideration of curriculum about two points - lattice and ring - of set deal with 'number and operation'. In this process, we make clear the greatest common divisor, the least common multiple and operation of set, especially the meaning of symmetric difference, we suggest direction about constitution of contents of set in secondary school. This study helps to raise the specificity on the elements of textbook and presents the first step about the range of teaching in a construct of curriculum.

• 수산해양교육연구
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• 제28권2호
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• pp.564-581
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• 2016

The purpose of this research was to provide basic data to childcare consulting scholarship which will be expanded completely in the future by examining awareness on childcare consulting, requests for childcare consultant, operation method of childcare consulting and tendency and meaning of childcare consulting for 500 early childhood pre-service teachers who are attending senior classes of departments related to childcare teachers in Busan. The results of research, obtained by the above process, are as follows. In the awareness of early childhood pre-service teachers on childcare consulting, they replied that they know concept and method of childcare consulting well. Also, qualifications of childcare consultant are actual knowledge and technology related to childcare process, they wanted consultants to provide ideas about class technology and problems which are expected among the consultants are lack of time by heavy works, etc. As expanded in the aspects of educational necessities and qualitative and quantitative system as the awareness or publicity of childcare consulting is insufficient.

• 대한인간공학회지
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• 제27권4호
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• pp.109-117
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• 2008

Compared to the existing PC which uses a mouse and a keyboard, the touchscreen-based portable PC allows the user to use fingers, requiring new operation methods. However, current touchscreen-based web browser operations in many cases involve merely having fingers move simply like a mouse and click, or not corresponding well to the user's sensitivity and the structure of one's index finger, making itself difficult to be used during walking. Therefore, the goal of this study is to develop finger gestures which facilitate the interaction between the interface and the user, and make the operation easier. First, based on the frequency of usage in the web browser and preference, top eight functions were extracted. Then, the users' structural knowledge was visualized through sketch maps, and the finger gestures which were applicable in touchscreens were derived through the Meaning in Mediated Action method. For the front/back page, and up/down scroll functions, directional gestures were derived, and for the window closure, refresh, home and print functions, letter-type and icon-type gestures were drawn. A validation experiment was performed to compare the performance between existing operation methods and the proposed one in terms of execution time, error rate, and preference, and as a result, directional gestures and letter-type gestures showed better performance than the existing methods. These results suggest that not only during the operation of touchscreen-based web browser in portable PC but also during the operation of telematics-related functions in automobile, PDA and so on, the new gestures can be used to make operation easier and faster.

• 한국CDE학회논문집
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• 제4권3호
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• pp.247-258
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• 1999

With the contemporary CAD/CAM system, where the tool path is generated and verified purely based on the geometric operation, geometric accuracy of the machined surface cannot be guaranteed dut to the cutting mechanics, meaning that the cutting mechanics should be incorporated in some fashion. In this paper, we incorporate the instantaneous cutting force and the tool deflection phenomena in predicting the machined surface for the finish-cut and milling operation. For the given NC dat including cutting conditions, the developed algorithm computes cutting force and deflection amount along the tool trajectory, and outputs the 3D graphic model of the machined surface together with error analysis. The validity and accuracy of the presented method has been tested by the actual cutting experiments. Experimental results and accuracy enhancement method together with implementing architecture of the VMCS (Virtual Machining CAM System) are discussed in the paper.