• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.10
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• pp.1931-1933
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• 2015

This paper proposes inter-cell cooperative transmission scheme in order to improve the reliability of the wireless communication system at the heterogeneous network environments. The heterogeneous network can increase data rate by using existing network technologies. However, degradation of communication performance in the cell edge has been a serious problem. Therefore, this letter proposes an adaptive transmission scheme according to the diverse situations in order to solve this problem.

• Journal of the Korean School Mathematics Society
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• v.9 no.2
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• pp.163-177
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• 2006

A new teaching-learning method is needed to improve creative problem-solving ability of the gifted students at mathematics. In response to this demand, I applied mentor-project studying to the mathematically gifted class students of Chungnam Science High School. The purpose of this monograph is to analyze in what situations they demonstrated mathematical creativity and whether the interactions among the gifted in the process of studying were of great help toward improving creativity. The effectiveness of mentor-project studying was especially verified by the analysis of creative problem-solving test results.

• Journal of Korean Institute of Industrial Engineers
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• v.21 no.2
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• pp.207-216
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• 1995

Constructing a distributed management system has its own advantages in addressing the issue of implementing a quick responsive management system in dynamically changing environment of enterprise. We suggest a basic scheduling methodology applicable to a distributed production management system. A new concept of "flexible schedule" is introduced as a tool to accommodate dynamically changing situations of job shops. Then a search technique (referred to as CSP-CBA search) is presented to obtain such a schedule for the job shop scheduling problem, which is converted into a constraint satisfaction problem(CSP), by using the constraint based analysis(CBA). This approach is tested on more than 100 test problems. The results show that the suggested approach required shorter CPU time and solved more problems in given time than another fixed schedule method.

• Proceedings of the Technology Innovation Conference
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• 2005.02a
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• pp.42-56
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• 2005

Firms cooperating in R&D face a moral hazard problem, because with R&D effort not being observable each partner will focus on its own profit when choosing its effort level. This paper aims to explain the use of optimal license contract for R&D cooperation such as cross-licensing agreement. We argue that in the situations of asymmetric information, the optimal incentive scheme that can solve moral hazard problem is . a linear function of the likelihood ratio. Especially in the case of parallel research, each firm has an extra incentive for cooperative R&D effort, given by the license fee that considers the profit of the cooperating firm, which solely depends on his R&D success if the cooperating firm fails.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.68 no.1
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• pp.159-166
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• 2019

Due to the various engagement situations, it is very difficult to generate the optimal trajectory with several constraints. This paper investigates the sequential convex programming for the impact angle control with the additional constraint of altitude limit. Recently, the SOCP(Second-Order Cone Programming), which is one area of the convex optimization, is widely used to solve variable optimal problems because it is robust to initial values, and resolves problems quickly and reliably. The trajectory optimization problem is reconstructed as convex optimization problem using appropriate linearization and discretization. Finally, simulation results are compared with analytic result and nonlinear optimization result for verification.

• Earthquakes and Structures
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• v.23 no.5
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• pp.419-430
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• 2022

The metallic energy dissipation device (EDD) has been widely accepted as a useful tool for passive control of buildings against earthquakes. The distribution of metallic EDDs in a multi-story building may have significant influence on its seismic performance, which can be greatly enhanced if the distribution scheme is properly designed. This paper addresses the optimal distribution problem in the aim of achieving a desired level of performance using the minimum number of metallic EDDs. Five local search heuristic algorithms are proposed to solve the problem. Four base structures are presented as numerical examples to verify the proposed algorithms. It is indicated that the performance of different algorithms may vary when applied in different situations. Based on the results of the numerical verification, the recommended guidelines are finally proposed for choosing the appropriate algorithm in different occasions.

• ETRI Journal
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• v.45 no.3
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• pp.492-504
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• 2023

Researchers have recently shown an increased interest in estimating the direction-of-arrival (DOA) of wideband noncircular sources, but existing studies have been restricted to subspace-based methods. An off-grid sparse recovery-based algorithm is proposed in this paper to improve the accuracy of existing algorithms in low signal-to-noise ratio situations. The covariance and pseudo covariance matrices can be jointly represented subject to block sparsity constraints by taking advantage of the joint sparsity between signal components and bias. Furthermore, the estimation problem is transformed into a single measurement vector problem utilizing the focused operation, resulting in a significant reduction in computational complexity. The proposed algorithm's error threshold and the Cramer-Rao bound for wideband noncircular DOA estimation are deduced in detail. The proposed algorithm's effectiveness and feasibility are demonstrated by simulation results.

• The Mathematical Education
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• v.47 no.4
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• pp.519-543
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• 2008

The study has been conducted with 29 children from 4th to 6th grades to realize how they understand addition, subtraction, multiplication, and division of whole numbers, and how their understanding influences solving of one-step word problems. Children's understanding of operations was categorized into "adding" and "combination" for additions, "taking away" and "comparison" for subtractions, "equal groups," "rectangular arrange," "ratio," and "Cartesian product" for multiplications, and "sharing," "measuring," "comparison," "ratio," "multiplicative inverse," and "repeated subtraction" for divisions. Overall, additions were mostly understood additions as "adding"(86.2%), subtractions as "taking away"(86.2%), multiplications as "equal groups"(100%), and divisions as "sharing"(82.8%). This result consisted with the Fischbein's intuitive models except for additions. Most children tended to solve the word problems based on their conceptual structure of the four arithmetic operations. Even though their conceptual structure of arithmetic operations helps to better solve problems, this tendency resulted in wrong solutions when problem situations were not related to their conceptual structure. Children in the same category of understanding for each operations showed some common features while solving the word problems. As children's understanding of operations significantly influences their solutions to word problems, they needs to be exposed to many different problem situations of the four arithmetic operations. Furthermore, the focus of teaching needs to be the meaning of each operations rather than computational algorithm.

• Journal of Convergence for Information Technology
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• v.11 no.11
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• pp.185-194
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• 2021

The purpose of this study is to identify the chaotic state of school education caused by COVID-19 and to seek the role of the principal in responding quickly to the national crisis. To solve this problem, 34 elementary school principals in Seoul, Busan, Daegu, Daejeon, and Jeju were surveyed with open questions through the first SNS on what leadership is needed to cope with COVID-19, and the second in-depth interview was conducted through phone calls. In the New Normal era, principal's leadership requires insightful and responsible leadership in supporting educational activities, class support, and problem prevention that can occur due to rapid response to crisis situations, rapid budgeting and input, and promotion of teacher-to-teacher communication, according to a survey. In crisis situations such as COVID-19, it is necessary to establish a role of principal for schools to cope stably and to establish an educational environment in which students learn in a safe environment. For this, national and educational policy support is needed.

• Journal of the Korea Convergence Society
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• v.10 no.5
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• pp.267-278
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• 2019

The objective of the current study was to engage in an in-depth discussion and analysis about the process of overcoming hardships in students that play varsity sports as student athletes and who grew up under incomplete family structures, To achieve this end, the current study conducts a narrative inquiry into the subjects, which found the following: First, in terms of improvement and expansion of interpersonal relationships, the student athletes were able to change their personalities to be more confident and active in their daily routines. Second, in forming positive emotions through playing sports, the student athletes were able to actively search for ways to overcome difficult situations and self-regulated their emotions. Third, in relation to improvement of problem-solving skills, the student athletes were able to find the most effective ways to overcome hardships caused by their broken family situations, in addition to exhibiting advanced problem-solving skills that enabled them to find courses that are most adequate for solving future problems.