• 한국수학교육학회지시리즈A:수학교육
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• 제42권3호
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• pp.353-368
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• 2003

Analogy, based on a similarity, is to infer the properties of the similar object from properties of an object. It can be a very useful thinking tool for learning mathematical patterns and laws, noticing on relational properties among various situations. The purpose of this study, when manipulating hint condition, figure and table conditions and the amount of original learning by using algebra word problems, is to verify the effects of analogical transfer in solving equivalent, isomorphic and similar problems according to the similarity of source problems and target ones. Five study questions were set up for the above purpose. It was 354 first grade students of S and G middle schools in Seoul that were experimented for this study. The data was processed by MANOVA analysis of statistical program, SPSS 10.0. The results of this studies would indicate that most of the students would be poor at solving isomorphic and similar problems in the performance of analogical transfer according to the similarity of source and target problems. Hints, figure and table conditions did not facilitate the analogical transfer. Merely, on the condition that amount of teaming was increased, analogical transfer of the students was facilitated. Therefore, it is necessary to have students do much more analogical problem-solving experience to improve their analogical reasoning ability through the instruction program development in the educational fields.

• KIEAE Journal
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• 제13권3호
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• pp.3-13
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• 2013

As climate change is increasingly recognised as an important global problem, a wide variety of policies and measures are emerging at global and local level to deal with the challenges from the anthropogenic global warming. While national and inter-national efforts characterized by limiting GHG emissions shows very little progress because of their expanse spatial scale and complicated political situations, local efforts have the potentials to ensure effective implementation, monitoring and continual improvement. In the context of local-scale climate policy, the city of Portland is known as one of the best leading cities for its progress of implementing climate change strategies. This paper will briefly discuss the city's efforts to solve the climate change problem and its achievements. The latest climate action plan is selected for the analysis on the followings; the framework of the action plan, the types of implementation methods, and the coordinating agencies. The progress status of each action plans is also reviewed. The purpose of this paper is to describe the main characteristics of the climate action plans and their implications from the intensive analysis on the city of Portland's case.

• 정보처리학회논문지B
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• 제18B권3호
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• pp.157-164
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• 2011

본 논문은 유전자 알고리즘을 이용해서 동적으로 변하는 네트워크상에서 빠르게 최단 경로를 재탐색할 수 있는 알고리즘을 제안한다. 제안 알고리즘은 다익스트라 알고리즘과 유전자 알고리즘을 통합한 형식의 알고리즘이다. 이 제안 알고리즘은 최초 탐색 시 다익스트라(Dijkstra) 알고리즘을 이용해서 유전자 알고리즘의 초기화 과정을 용이하게 하는 선행자 배열을 정의한다. 그 후 유전자 알고리즘은 적절한 유전 연산자를 통해 동적으로 변하는 트래픽 상황에서 최적의 경로를 재탐색한다. 실험 결과를 통해 제안 알고리즘이 거대한 네트워크 데이터에 대해서 다른 유전자 알고리즘 기반의 최단경로 찾기 알고리즘이나 다익스트라 알고리즘보다 적은 계산시간으로 더 짧은 주행시간의 경로를 제시한다는 것을 보였다.

• 한국항공운항학회지
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• 제22권4호
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• pp.42-55
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• 2014

The purpose of this research was to identify expertise in ait traffic control by using cognitive skill analysis for novices and experts in routine and non-routine situations. The result of study was to understand expertise in air traffic control tasks in terms of what cognitive processes are responsible for the expert's high performance levels. The problem solving task was difficult for novices, but performed relatively automatically by experts in a routine situation. The difficulty could indicate the presence of controlled processing. Rather than rules and strategies, novices focused more on environmental factors, which merely increase cognitive load. In a non-routine situation, novices showed that they did not categorize the information consistently and alternative resources were not available for them. Experts, however, performed automatically a task by arranging and organizing information related to problem solving components in contexts without regard to a routine and non-routine situation. Especially experts developed a stable representation and directed alternative resources for air traffic flow and efficiency. Based on the results, cognitive processes of experts could be useful to understand expert performance and analyze the learning process, which imply the necessity of developing expertise systematically.

• 전기학회논문지
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• 제57권8호
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• pp.1416-1421
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• 2008

A 10 dB branch line hybrid coupler included with defected ground structure (DGS) is proposed. In this contribution, a contact between the grounded metal housing and DGS is avoided, which has been a serious problem in applying DGS to high frequency circuits. An isolation between the metal housing and the DGS pattern is provided by inserting additional substrate between DGS and the metal package. Therefore, it is possible to design branch line hybrid couplers having highly asymmetric power dividing ratio using these DGS structure, which is demonstrated in this paper. The designed and fabricated branch line hybrid coupler using DGS is well packaged in a metal housing without touching the ground metal directly. The measurement is performed under realistic practical operating situations because it is packaged in a metal housing. The measured performances of the fabricated 10dB coupler shows a 1:9 asymmetric power dividing ratio at output ports, as predicted. In addition, the measured performances in terms of matching, isolation, and phase difference are in excellent agreement with the simulated characteristics.

• 한국수학교육학회지시리즈A:수학교육
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• 제52권1호
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• pp.43-63
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• 2013

The purpose of this study is to find meaningful implications for developing curriculum and textbooks by comparison between Korean middle school mathematics textbooks and U.S.A.'s CMP textbooks. After comparing and analysing how the contents are composed focusing on the equations and functions and how the contents are presented according to 'Project 2061' mathematical textbook analytical framework, and how the contents ere different in terms of the mathematical connectivity, the research reached the following conclusions. First, compared to Korean textbooks, the CMP textbooks clearly present learners' behavior goals in a detailed way, and emphasize communication and connectivity. Second, Korean textbooks focus on explaining concepts and solving problems related to their concepts and discussion questions are briefly introduced. But all the textbooks contain a lot of problems required to be solved with algorithms. On the other hand, CMP textbooks provide students with opportunities to find the necessary concepts on their own, through problem solving processes, after presenting various real-life problem situations.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권10호
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• pp.3867-3886
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• 2015

This article investigates the problem of opportunistic spectrum access in dynamic environment, in which the signal-to-noise ratio (SNR) is time-varying. Different from existing work on continuous feedback, we consider more practical scenarios in which the transmitter receives an Acknowledgment (ACK) if the received SNR is larger than the required threshold, and otherwise a Non-Acknowledgment (NACK). That is, the feedback is discrete. Several applications with different threshold values are also considered in this work. The channel selection problem is formulated as a non-cooperative game, and subsequently it is proved to be a potential game, which has at least one pure strategy Nash equilibrium. Following this, a multi-agent Q-learning algorithm is proposed to converge to Nash equilibria of the game. Furthermore, opportunistic spectrum access with multiple discrete feedbacks is also investigated. Finally, the simulation results verify that the proposed multi-agent Q-learning algorithm is applicable to both situations with binary feedback and multiple discrete feedbacks.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권12호
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• pp.3219-3236
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• 2012

A tree routing structure is often adopted for many-to-one data gathering and aggregation in sensor networks. For real-time scenarios, considering lossy wireless links, it is an important issue how to construct a maximum-lifetime data gathering tree with delay constraint. In this work, we study the problem of lifetime-preserving and delay-constrained tree construction in unreliable sensor networks. We prove that the problem is NP-complete. A greedy approximation algorithm is proposed. We use expected transmissions count (ETX) as the link quality indicator, as well as a measure of delay. Our algorithm starts from an arbitrary least ETX tree, and iteratively adjusts the hierarchy of the tree to reduce the load on bottleneck nodes by pruning and grafting its sub-tree. The complexity of the proposed algorithm is $O(N^4)$. Finally, extensive simulations are carried out to verify our approach. Simulation results show that our algorithm provides longer lifetime in various situations compared to existing data gathering schemes.

• 한국환경교육학회지:환경교육
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• 제15권1호
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• pp.1-17
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• 2002

The aim of this study is to establish an object of environmental education in liberal arts, and to develop a teaming program and search for the most effective environmental teaching method. At first this study analyzed the current situations and problems of the present environmental education in the liberal arts. As a result of this analysis, I found that, most of environmental educations have been conducted mainly by an approach of natural science, inevitably they should have limits in which students can't have holistic view in solve the environmental problem. Due to the fact that, many students were attending lectures, teaching methods were limited in the forms lecture and video tapes. As I applied educational programs with various teaching methods for students in order to change cognition and value toward environment, I found that there was no significant difference of cognition even after applying the programs. This may be interpreted as, most students already had very sound and sustainable environmental view. But some programs with teaching method using role play, debate, cyber-debate lead students to have interest in environments, thus actively participating in the class. These methods, taking into consideration, the hundreds of enrolled students, seem to pose a problem in actual application. The most important matter is, how to develop a cognition and value toward environment into environmental behavior. Therefore, in the future, aim is to study what determines the factors for causing environmental behavior from a cognition and value of the environment, and a development of programs in this regard will be necessary.

• 한국경영공학회지
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• 제23권4호
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• pp.1-18
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• 2018

Emergency response has been considered as an important task in practice, because it is directly associated with the survival of patients. However, it is very difficult to increase the number of fire stations due to the budget and efficiency problem. Under this circumstances, it is critical to consider the suitability of current arrangement for 911 fire station. This is especially true in Gyeonggi-Do where the characteristics of each sub-area are different. In response, this study aims to identify types of areas that are vulnerable for emergency situations, and try to find relevant solutions for each type. For this purpose, we collected 151,463 data for emergency declaration data which exceeds 10 minutes for its response. Total 19 clustering variables which are used as input variables are selected, considering the characteristics of each area. As a result of clustering analysis, three clusters are identified and analyzed. Finally, areas whose emergence response time is in top 10% are selected and analyzed. This paper is expected to find current issues and problems of emergency response for each area, and help to understand and solve the problem for the local government.