• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.8B
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• pp.1129-1140
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• 2001

본 논문에서는 블록기반 동영상 부호화에서 나타나는 양자화 잡음을 그 특성에 맞게 모델링을 하고, 이를 기반으로 웨이블렛 변환(wavelet transform)을 이용하여 양자화 잡음을 제거하는 후처리 방법을 제안한다. 제안된 방법에서는 양자화 잡음을 특정 프로화일(profile)로 표현되는 블록화 잡음과 비에지 화소(non-edge pixel)에서 백색 가우시안 특성을 가지는 나머지 잡음의 합으로 모델링 한다. 이러한 양자화 잡음의 모델을 기반으로 정칙화 미분(regularized differentiation)을 표현하는 Mallat의 1차원 웨이브렛 변환을 이용하여 영상복원 관점에서 각각의 잡음을 제거한다. 먼저, 웨이브렛 영역의 블록경계에서 임펄스로 나타나는 블록화 잡음 성분들의 크기를 추정하여 줄임으로 해서 블록화 잡음을 제거한다. 이때 임펄스 크기의 추정은 메디안 필터와 양자화 파라미터(quantization parameter), 그리고 국부 활동도(local activity)를 이용하여 이루어진다. 그리고 나머지 잡음은 비에지 화소에서 연역치화(soft-thresholding)을 수행함으로써 제거한다. 이러한 후처리 방법의 구현은 실시간 응용을 위해 웨이브렛 필터를 이용하여 근사적으로 공간 영역에서 이루어진다. 실험 결과, 제안된 방법이 다양한 영상과 압축률에 대해 MPEG-4 VM(verification model) 후처리 필터(post-filter)보다 PSNR 성능뿐만 아니라 주관적 화질면에서도 우수함을 확인하였다.

• Journal for History of Mathematics
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• v.17 no.4
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• pp.45-64
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• 2004

The lambda calculus is a mathematical formalism in which functions can be formed, combined and used for computation that is defined as rewriting rules. With the development of the computer science, many programming languages have been based on the lambda calculus (LISP, CAML, MIRANDA) which provides simple and clear views of computation. Furthermore, thanks to the "Curry-Howard correspondence", it is possible to establish correspondence between proofs and computer programming. The purpose of this article is to make available, for didactic purposes, a subject matter that is not well-known to the general public. The impact of the lambda calculus in logic and computer science still remains as an area of further investigation.stigation.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.6
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• pp.169-176
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• 1994

This paper describes an efficient parallel evaluation algorithm for accelerating fault simulation, which can be applied to combinational circuits. The method is based on a combination of all the advantages in parallel, deductive and concurrent schemes in terms of evaluation and propagation of fautly gates for achieving high performance and handling multi-valued signal. We also propose a new fault grouping procedure to increase parallel operation of fault bits by packing active faults which occur in the same signal line densely into the same fault group. The algorithm has been implemented in C language on a Sun 3/260, and experimental results for ISCAS'85 benchmark circuits have been shown that this algorithm is 2.6 to 8.2 times faster than the conventional cocurrent fault simulation algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.10A
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• pp.1011-1020
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• 2002

The current paper presents an effective deblocking algorithm for block-based coded images using singularity detection in a wavelet transform. In block-based coded images, the local maxima of a wavelet transform modulus detect all singularities, including blocking artifacts, from multiscale edges. Accordingly, the current study discriminates between a blocking artifact and an edge by estimation the Lipschitz regularity of the local maxima and removing the wavelet transform modulus of a blocking artifact that has a negative Lipschitz regularity exponent. Experimental results showed that the performance of the proposed algorithm was objectively and subjectively superior.

• Journal of the Korean earth science society
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• v.30 no.6
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• pp.759-772
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• 2009

The purpose of this study was to understand characteristics of eighth graders' conclusions presented in their self-directed scientific inquiry reports. We developed a framework, Analysis of Conclusions of Self-Directed Scientific Inquiry, to analyze students' conclusions. We then compared the conclusions with the inquiry questions students generated to find out whether the questions affected students' conclusions. In addition, we analyzed students' responses from the survey about their perceptions of drawing conclusions. According to the results, the conclusions were characterized into two categories, i.e., scientific basic assumption and scientific explanation. Almost half of the students' conclusions fall under the scientific basic assumptions. Most of the scientific explanations were deductive explanations and inductive explanations. Then, the kinds of conclusions were affected by the inquiry questions because the scientific explanations were made more than the scientific basic assumptions in answering the inquiry questions. Some students couldn't recognize differences between conclusions and experiment results.

• Journal of Creative Information Culture
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• v.5 no.3
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• pp.295-306
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• 2019

Despite the popularity and convenient accessibility of puzzles, the variety of puzzles have led to a lack of research on the nature of the puzzle itself. In guiding certain skills, such as abstractness, creativity, and logic, a teacher should have the thinking skill and strategy that appear in solving puzzles. In this study, the mathematical thinking that appears in solving puzzles from the perspective of experts is identified, and the strategies and characteristics are described and classified accordingly. For this purpose, we analyzed 85 math puzzles including the well-know puzzles to the public, plus puzzles from a popular book for the gifted student. The research analysis shows that there are 6 types of mathematics puzzles in which require mathematical thinking.

• Journal of Educational Research in Mathematics
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• v.18 no.2
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• pp.223-237
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• 2008

In this paper, We focus on grasping De Morgan's perspectives on mathematics education systematically. His perspectives can be summarized as followings. First, historico-genesis of mathematics must be considered in the teaching and learning of mathematics. Second, mathematical conception of students must be formulated progressively. Third, it is important to use errors which come out continually in the process of passing from inductive stage to deductive stage. Fourth, personal knowledge of students is important in the teaching and learning of mathematics. These De Morgan's four perspectives are the way of approach for experiencing moral certainty first of all to get to mathematical certainty. Moral certainty which he presented is a combination of rationality and humanity to fill up gaps between Platonism and general public education.

• Journal of The Korean Association For Science Education
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• v.23 no.5
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• pp.458-469
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• 2003

Hypothesis is defined as a proposition intended as a possible explanation for an observed phenomenon. The purpose of this study was to generate a grounded theory on the process of undergraduate students' generating hypothesis-knowledge about scientific episodes. Three hypothesis-generating tasks were administered to four college students majored in science education. The present study showed that college students represented five types of intermediate knowledge in the process of hypothesis generation, such as question situation, hypothetical explicans, experienced situation, causal explicans, and final hypothetical knowledge. Furthermore, students used six types of thinking methods, such as searching knowledges, comparing a question situation and an experienced situation, borrowing explicans, combining explicans, selecting an explican, and confirming explicans. In addition, hypothesis-generating process involves inductive and deductive reasoning as well as abductive reasoning. This study also discusses the implications of these findings for teaching and evaluating in science education.

• Journal of Elementary Mathematics Education in Korea
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• v.15 no.3
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• pp.619-640
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• 2011

The study aims the introducing the items for the assessment of mathematical thinking including mathematical reasoning, problem solving, and communication and the analyzing on the responses of the 5th grade pupils. We categorized the area of mathematical reasoning into deductive reasoning, inductive reasoning, and analogy; problem solving into external problem solving and internal one; and communication into speaking, reading, writing, and listening. And we proposed the examples of our items for each area and the 5th grade pupils' responses. When we assess on pupil's mathematical reasoning, we need to develop very appropriate items needing the very ability of each kind of mathematical reasoning. When pupils solve items requesting communication, the impact of the form of each communication seem to be smaller than that of the mathematical situation or sturucture of the item. We suggested that we need to continue the studies on mathematical assessment and on the constitution and utilization of cognitive areas, and we also need to in-service teacher education on the development of mathematical assessments, based on this study.

• Journal of Korea Port Economic Association
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• v.24 no.4
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• pp.363-384
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• 2008

This study aims at improving Korea's competitiveness in port logistics through marketing strategy with integrating the conceptual approach into the empirical one and combining both the oldest military treatise and the newest evaluating model in social science that was applied by the HFP(hierarchical fuzzy process) model enhanced by the KJ method. The empirical results of this study show Busan in the middle among subject ports. At present, Korea plays a reciprocal role in the port market in East Asia, but in the medium- and long-term, Korea's ports will vie together with most major ports in the East Asian region. A descriptive investigation shows that Korea's developing tasks in port logistics must be considered in the context of the direction for developing port policies, the necessity of expanding port facilities in the capital region, securing the sufficient traffic volume through the establishment of the hinterland linking system and its positive utilization, and reforming the direction for developing the global logistics through increased port competitiveness. In the short- and medium-term, Korea must use the opportunity factor of 'Growth and open door policy of China' as a geoeconomic advantage and to utilize Korea's ports as a gate to Chinese foreign trade. With the rise of China's economy, China also plays a significant role in both port and airport markets. Hence, the linking system between the two must be established to meet the expanding traffic volume, especially in the capital area. Moreover, it is necessary for Korea to secure port logistics through the establishment of the hinterland linking system and its positive utilization. The great accomplishment of this paper is to present strategies to increase Korea's port competitiveness in the rapidly changing environments of world logistics with the focus on both the oldest military strategic treatise and the newest empirical method in social science. In order to reinforce this study, it needs further compensative research because the evaluation structure could be subdivided with more extensive and precise criteria.