• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.1278-1281
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• 2007

초고속 인터넷망이 발달됨으로써 분산 컴퓨팅 시스템 구축이 용이해졌다. 분산 컴퓨팅 시스템은 저비용과 유휴 계산 자원의 활용으로 기존의 슈퍼컴퓨터와 유사한 능력을 발휘할 수 있다는 장점을 지닌다. 암호 알고리즘의 실질적인 안전성 요소인 키의 길이는 전수조사 계산량에 의존한다. 키 전수조사를 위한 대용량 계산은 슈퍼컴퓨터, 클러스터, 분산 컴퓨팅 등의 환경에 따라 세부적인 메커니즘에 차이를 보인다. 본 논문에서는 분산 컴퓨팅 시스템을 소개하고, 이러한 환경 하에서 암호 알고리즘의 키 전수조사 작업을 수행하기 위한 세부적인 절차에 대해서 논하고, 구체적으로 키 전수조사 작업을 효율적으로 수행하기 위한 방법을 제안한다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.23 no.3
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• pp.331-340
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• 2005

Digital map is very important digital geographic information which is the base for various fields such as building and using the geographic information system (GIS), planing the regional development, and etc. Therefore, it needs high accuracy. Then we offer the advanced technique which minimizes errors on digital maps, using the automated inspection through the whole figures. In addition this new technique raises the economical efficiency as well as accuracy applying the automated error detection method which can recognize, search and classify errors automatically.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.4
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• pp.87-94
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• 2022

This paper researched a study to find a combination of acquisition scores for 9 dart throws, which is the minimum number of dart tactile throws in 501 point dart games. The maximum score that can be obtained by throwing once in a dart game is 60 points, which can end the perfect dart game with 60 points eight times according to 60×8+21×1=501, and if you earn 21 points once, you can finish the game with 9 throws. This is called 9-dart finish. As such, only 18 and 14 studies on the combination of scores that can obtain 501 points with 9 throws are known, and no studies have been conducted applying the exhaustive search algorithm. This paper proposed a division branch-and-bound algorithm as a method of simplifying the O(2ⁿ) exponential time performance complexity of the typical branch-and-bound method of a exhaustive search method, to polynomial time complexity. The proposed method limited the level to 8, jumped to a quotient level of 501/60, and backtracked to explore only possible score combinations in the previous level. The possible score combinations of the nine perfect games found with the proposed algorithm were 90(101 cases).

• Journal of the Korea Society of Computer and Information
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• v.17 no.10
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• pp.155-165
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• 2012

This paper suggests traveling salesman problem algorithm that have been unsolved problem with NP-Hard. The proposed algorithm is a heuristic with edge-swap method. The classical method finds the initial solution starts with first node and visits to mostly adjacent nodes then decides the traveling path. This paper selects minimum weight edge for each nodes, then perform Min-Min method that start from minimum weight edge among the selected edges and Min-Max method that starts from maximum weight edges among it. Then we decide tie initial solution to minimum path length between Min-Min and Min-Max method. To get the final optimal solution, we apply previous two-opt to initial solution. Also, we suggest extended 3-opt and 4-opt additionally. For the 7 actual experimental data, this algorithm can be get the optimal solutions of state-of-the-art with fast and correct.

• Journal of Broadcast Engineering
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• v.9 no.4 s.25
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• pp.446-454
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• 2004

With the growth of multimedia systems, compressing image data has become more important in the area of multimedia services. Since a compressed image bitstream can often be seriously distorted by various types of channel noise, an error concealment algorithm becomes a very important issue. In order to solve this problem, Hsia proposed the error concealment algorithm where he recovered lost block data using 1D boundary matching vectors. His algorithm, however, requires high computational complexity since each matching vector needs MAD (Mean Absolute Difference) values of all pixels, which is either a boundary line top or a boundary line bottom of a damaged block. We propose a hierarchical search-based fast error concealment scheme as well as its approximated version to reduce computational time. In the proposed scheme, a hierarchical search is applied to reduce the number of checking points for searching a vector. The error concealment schemes proposed in this paper can be about 3 times faster than Hsia's with keeping visual quality and PSNR.

• Proceedings of the KIEE Conference
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• 2006.11a
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• pp.272-274
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• 2006

본 논문에서는 한국전력공사의 배전계통 운영계획시스템(Distribution Line PLANning system)에서 배전계통 재구성 최적화에 적용하고 있는 선로간의 부하 평준화 알고리즘에 대하여 연구하였다. 기존의 알고리즘은 계통 내 임의의 연계 개폐기 혹은 구분 개폐기를 조작한 후 방사상의 운전조건을 만족하면 선로별 부하를 계산한다. 그리고 최대부하 선로와 최소부하 선로간의 부하 편차를 구하고 직전의 최적해와 비교하여 최적의 해를 찾아내는 방법이다. 그러나 계통이 커질 경우 시험해야할 경우의 수가 많아져서 시간이 많이 소요되고 또한 수렴속도를 빠르게 하기위하여 반복횟수를 제한하기 때문에 절대적인 최적의 해를 보장하지 못하였다. 따라서 본 연구에서는 탐색시간을 만족시키면서 전수조사하는 정도의 부하 평준화 최적해를 찾아서 배전계통의 재구성을 최적화하는 알고리즘을 구현하고자 한다.

• Journal of the Korea Society of Computer and Information
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• v.18 no.12
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• pp.75-82
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• 2013

This paper proposes a $O(n^2)$ polynomial time algorithm to obtain optimal solution for Traveling Salesman problem that is a NP-complete because polynomial time algorithm has been not known yet. The biggest problem in a large-scale Traveling Salesman problem is the fact that the amount of data to be processed is $n{\times}n$, and thus as n increases, the data increases by multifold. Therefore, this paper proposes a methodology by which the data amount is first reduced to approximately n/2. Then, it seeks a bi-directional route at a random point. The proposed algorithm has proved to be successful in obtaining the optimal solutions with $O(n^2)$ time complexity when applied to TSP-1 with 26 European cities and TSP-2 with 46 cities of the USA. It could therefore be applied as a generalized algorithm for TSP.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.3
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• pp.103-108
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• 2024

Kakuro puzzles are NP-complete problems where no way to solve puzzles in polynomial time is known. Until now, a brute-force search method or a linear programming method has been applied to substitute all possible cases. This paper finds a magic rule, a rule for box sizes and unfilled numbers according to sum clues. Based on the magic rule, numbers that cannot enter empty cells were deleted from the box for row and column sum clues. Next, numbers that cannot enter the box were deleted based on the sum clue value. Finally, cells with only a single number were confirmed as clues. As a result of applying the proposed algorithm to seven benchmarking experimental data, it was shown that solutions could be obtained for all problems.

• Journal of Korean Home Economics Education Association
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• v.18 no.2 s.40
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• pp.1-13
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• 2006

The main purpose of this thesis is to research various theories in Cultural Education. It is to rebuild the value of home economics, and to demonstrate its potential to bring out a true human being. Until now, home economics education had been focused on developing ability to solve problems, only to fail us in training students to have ability to cope with different conditions in daily life by themselves. With the society rapidly changing, such a temporizing education system would lose its value immediately, and the identity of home economics education is at stake today. The present situation is resulted from the failure in approaching the culture education properly. With the fact that the elements of home economics are culture themselves. the failures in organizing and teaching the subject would urge us to rearrange curriculum of home economics. We need to bear in mind that the curriculum of home economics cannot contain every cultural value. A careful consideration is necessary in order to include the essence of the culture at the minimum quantity. Through analyzing different types of theories and methods of education in Cultural Education, this research is aimed at reviewing home economics education with its concept. Further study in the future should be proceeded with more comprehensive researches on instruction and learning methods with Cultural Education perspective, based on the analysis.

• Journal of Educational Research in Mathematics
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• v.24 no.3
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• pp.387-407
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• 2014

This study investigeted secondary math teachers' difficulties of technology in geometry class with grounded theory by Strauss and Corbin. 178 secondary math teachers attending the professional development program on technology-based geometry teaching at eight locations in January 2014, participated in this study with informed consents. Data was collected with an open-ended questionnaire survey. In line with grounded theory, open, axial and selective coding were applied to data analysis. According to the results of this study, teachers were found to experience resistance in using technology due to new learning and changes, with knowledge and awareness of technology effectively interacting to lessen such resistance. In using technology, teachers were found to go through the 'access-resistance-unaccepted use-acceptance' stages. Teachers having difficulties in using technology included the following four types: 'inaccessible, denial of acceptance, discontinuation of use, and acceptance 'These findings suggest novel perspectives towards teachers having difficulties in using technology, providing implications for teachers' professional development.