• Proceedings of the Korean Society of Computer Information Conference
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• 2020.07a
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• pp.81-82
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• 2020

Non-convex 최적화 문제의 복잡도를 완화하도록 해주는 오목함수 결정규칙을 제안한다. 전송용량을 나타내는 유틸리티 함수는 신호와 간섭의 함수이며, non-convex이다. 유틸리티 함수를 간섭관점에서 분석한다. '상대간섭'과 '간섭주요화'를 정의한다. 상대간섭은 D2D 수신단에서의 간섭레벨을 나타낸다. 간섭주요화는 간섭을 주요간섭으로 간략화한다. 간섭주요화를 기반으로 하는 오목함수 결정규칙을 제안한다. 실험결과를 통하여 유틸리티 함수는 상대간섭 0.1 이하에서는 오목함수임을 확인하였다.

• Journal of the Korean Society of Radiology
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• v.81 no.6
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• pp.1364-1376
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• 2020

A pericardial recess is frequently seen in patients undergoing chest computed tomography (CT). It is important to be aware of the normal anatomy of the pericardium as it is often mistaken for normal variants and/or disease. Therefore, we will describe the anatomy and location of the pericardial recess and the specific findings in various diseases associated with the pericardial recess.

• Journal of the Korea Convergence Society
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• v.7 no.5
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• pp.213-219
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• 2016

This paper presents a branch-and-bound algorithm for solving the concave minimization problem with upper bounded variables whose single constraint is linear. The algorithm uses simplex as partition element. Because the convex envelope which most tightly underestimates the concave function on the simplex is uniquely determined by solving the related linear equations. Every branching process generates two subsimplices one lower dimensional than the candidate simplex by adding 0 and upper bound constraints. Subsequently the feasible points are partitioned into two sets. During the bounding process, the linear programming problems defined over subsimplices are minimized to calculate the lower bound and to update the incumbent. Consequently the simplices which do certainly not contain the global minimum are excluded from consideration. The major advantage of the algorithm is that the subproblems are defined on the one less dimensinal space. It means that the amount of work required for the subproblem decreases whenever the branching occurs. Our approach can be applied to solving the concave minimization problems under knapsack type constraints.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.6
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• pp.3074-3080
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• 2013

Amplification of wave height at concave corner was investigated by three dimensional hydraulic tests. A typical rubble mound structure was tested with two-layer Tetrapod and the slope of 1:1.5. The irregular waves with Bretschneider-Mitsuyasu spectrum were applied to the tests. The center angles of concave corner were 120 degree, 140 degree and 160 degree. According to the test results, the maximum wave height amplification ratio at concave corner was about 1.5 times of incident wave height among the all test conditions, and the W-shaped wave height distribution was shown.

• Journal of the Korea Convergence Society
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• v.10 no.11
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• pp.71-77
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• 2019

This paper defines a multi-selection knapsack problem and presents an algorithm for seeking its optimal solution. Multi-selection means that all members of the particular group be selected or excluded. Our branch-and-bound algorithm introduces a simplex containing the feasible region of the original problem to exploit the fact that the most tightly underestimating function on the simplex is linear. In bounding operation, the subproblem defined over the candidate simplex is minimized. During the branching process the candidate simplex is splitted into two one-less dimensional subsimplices by being projected onto two hyperplanes. The approach of this paper can be applied to solving the global minimization problems under various types of the knapsack constraints.

• Journal of The Korean Association For Science Education
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• v.35 no.5
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• pp.871-876
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• 2015

The purpose of this research was to investigation of elementary preservice teachers' understanding of the image observed in a diverging lens. To achieve the research purpose, Scientific inquiry activity of 'Observing Objects through a Diverging Lens' in the 2009 Revised Science Curriculum was carried out by 29 junior elementary preservice teachers, and preservice teachers' difficulties were analyzed during scientific inquiry activity. The results were as follows. First, preservice teachers had difficulties in comparing the size of the images. Second, preservice teachers couldn't correctly explain the reason about the changing of the image size according to distance from the lens to the object. Third, preservice teachers couldn't correctly explain the changing of the image size according to distance from the lens to the eyes. Fourth, preservice teachers were classified into five levels according to their conceptions of the image formation by the diverging lens, and most of them stayed in the first level. The result of this research suggests that reformations in text and preservice teachers' education.

• Communications of Mathematical Education
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• v.38 no.2
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• pp.215-230
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• 2024

Congruences and symmetry are familiar concepts that can be encountered in everyday life. In order to effectively understand and acquire these concepts, the role of appropriate visual examples is important. This analysis examined various visual examples used in the process of learning the concepts of congruence and symmetry in elementary mathematics textbooks and focused on the use of convex polygons and concave polygons. As a result of the analysis, various types of polygons were used as visual examples for teaching and learning of congruence and symmetry in textbooks. The frequency of use of concave polygons was higher in the order of congruence, line symmetry, and point symmetry, and it was confirmed that it was used more frequently in the process of exploring properties than in the introduction of the concept. Based on these results, a plan to utilize concave polygons in teaching and learning of congruence and symmetry was sought.

• Journal of Chest Surgery
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• v.37 no.6
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• pp.536-538
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• 2004

There are still some controversies regarding one stage repair of pectus deformity with congenital heart disease due to probable complications after extensive resection of deformed cartilages. We performed Nuss operation with simul-taneous intracardiac repair in 8 year old patient with pectus excavatum and partial atrioventricular septal defect. The result of operation was satisfactory without prolongation of operation time, bleeding or instability of chest wall.

• Korean Journal of Environment and Ecology
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• v.24 no.4
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• pp.345-350
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• 2010

In the Vinous-throated Parrotbill Paradoxornis webbianus, potential intraspecific nest parasitism was observed in four nests (0.38%, n=1,062) during twelve breeding seasons between 1988 and 2007. At first, a nest involved 9 white eggs was found in Puyong-ri, Yangpyong-gun, Kyonggi Province in 1995. This nest would be parasitized by the same species, given that this is out of range of normal clutch size (5 eggs) in Vinous-throated Parrotbills. The second and third cases were recorded in 2001 and 2005 in Sa-dong, Ansan City, Kyonggi Province, respectively. In these nests, two eggs were added to the clutch in a single day. The final observation was made in Puyong-ri in 2007, in which one white egg was laid in the nest at the pre-laying stage. The color of the egg was different from that of the original clutch (blue). The above four things suggest that intraspecific nest parasitism can occur in Vinous-throated Parrotbills although it is an uncommon phenomenon in their life history.

• Korean Journal of Cognitive Science
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• v.1 no.2
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• pp.317-346
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• 1989

A congnitive shape decomposition method that agrees with human intuition is proposed for the conceptual recognition from sillouettes of objects. Descriptions specifying the structure of shape in terms of meaningful parts and relations have cognitive power and anthropomorphism. In general, man-made objects have a lot of collinear lines and regularity. For the cognitive decomposition of man-made objects, many heuristic rules based on the cognitive experimentation are applied on the context of collinerarity and regularity. The cognitive shape decomposition for the natural shape is carried out by analyzing the possible configuraitions of vertices and line segments for one concave vertex. A cost function for the configuation is designed by weighted sum of five criteria such as, the length of split line segment, the number of split line segments at concave vertex, the proximity of concave vertex, and the correspondence of vertices. These criteria are vased on the property of human perception such as proximtiy, symmetry, and simplicity. The most promising vertex os selected among three set of visible vertices by evaluating the cost function. A number of experiments conducted on the different types of shapes shows that the results correspond with human intuition.