• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.02a
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• pp.143-149
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• 2004

China is facing the challenging problems in both the potential energy resource shortage and the serious environmental pollutions. The author suggests that nuclear energy could play an important role for ensuring the long term energy security in China. The technical problems to be solved for the sustainable development of nuclear energy in China are also discussed and the R&D work in next 20 years are briefly suggested to meet the requirements of nuclear energy development in China.

• Research in Mathematical Education
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• v.6 no.2
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• pp.171-182
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• 2002

Students approach mathematical problem solving in fundamentally different ways, particularly problems requiring conceptual understanding and complicated strategies such as mathematical word problems. The main objective of this study is to compare students' performance with different cognitive styles (Field-dependent vs. Field-independent) on mathematics problem solving, particularly, in word problems. A sample of 180 school girls (13-years-old) were tested on the Witkin's cognitive style (Group Embedded Figures Test) and two mathematics exams. Results obtained support the hypothesis that students with field-independent cognitive style achieved much better results than Field-dependent ones in word problems. The implications of these results on teaching and setting problems emphasizes that word problems and cognitive predictor variables (Field-dependent/Field- independent) could be challenging and rather distinctive factors on the part of school learners.

• Clinics in Shoulder and Elbow
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• v.27 no.1
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• pp.108-116
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• 2024

Reverse total shoulder arthroplasty (RTSA) is widely popular among shoulder surgeons and patients, and its prevalence has increased dramatically in recent years. With this increased use, the indicated pathologies associated with RTSA are more likely to be encountered, and challenging patient presentations are more likely to be seen. One prominent challenging presentation is RTSA patients with severe glenoid bone loss. Several techniques with varying degrees of invasiveness, including excessive reaming, alternate centerline, bone grafting, and patient-specific implants (PSIs), have been developed to treat patients with this presentation. PSI treatment uses a three-dimensional reconstruction of a computed tomography scan to design a prosthetic implant or component customized to the patient's glenoid morphology, allowing compensation for any significant bone loss. The novelty of this technology implies a paucity of available literature, and although many studies show that PSIs have good potential for solving challenging shoulder problems, some studies have reported questionable and equivocal outcomes. Additional research is needed to explore the indications, outcomes, techniques, and cost-efficiency of this technology to help establish its role in current treatment guidelines and strategies.

• Journal of the Korean Operations Research and Management Science Society
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• v.29 no.3
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• pp.145-155
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• 2004

The design of a communication network has long been a challenging optimization problem. Since the optimal design of a network topology is a well known as a NP-complete problem, many researches have been conducted to obtain near optimal solutions in polynomial time instead of exact optimal solutions. All of these researches suggested diverse heuristic algorithms that can be applied to network design problems. Among these algorithms, a simulated annealing algorithm has been proved to guarantee a good solution for many NP-complete problems. in applying the simulated annealing algorithms to network design problems, generating mechanisms for initial solutions and candidate solutions play an important role in terms of goodness of a solution and efficiency. This study aims at analyzing these mechanisms through experiments, and then suggesting reliable mechanisms.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1446-1449
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• 2008

Immune system is composed of multiple cells with distinct functions, and immune responses are orchestrated by complex and dynamic cell-cell interactions. Therefore, each cell behavior and function should be understood under right spatio-temporal context. Studying such complexity and dynamics has been challenging with conventional biological tools. Recent development of new technologies such as state of art imaging instruments and microfabrication techniques compatible with biological systems have provided many exciting opportunities to dissect complex and dynamic immune cell interactions; new microscopy techniques enable us to observe stunning dynamics of immune system in real time. Microfabrication permits us to manipulate microenvironments governing molecular/cellular dynamics of immune cells to study detailed mechanisms of phenomena observed by microscopy. Also, microfabrication can be used to engineer microenvironments optimal for specific imaging techniques. In this presentation, I am going to present an example of how these two techniques can be combined to tackle challenging problems in immunology. Obviously, this strategy can readily be applied to many different fields of biology other than immunology.

• Annual Conference of KIPS
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• 2021.11a
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• pp.647-650
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• 2021

The most powerful and modern face recognition techniques are using deep learning methods that have provided impressive performance. The outbreak of COVID-19 pneumonia has spread worldwide, and people have begun to wear a face mask to prevent the spread of the virus, which has led existing face recognition methods to fail to identify people. Mainly, it pushes masked face recognition has become one of the most challenging problems in the face recognition domain. However, deep learning methods require numerous data samples, and it is challenging to find benchmarks of masked face datasets available to the public. In this work, we develop a new simulated masked face dataset that we can use for masked face recognition tasks. To evaluate the usability of the proposed dataset, we also retrained the dataset with ArcFace based system, which is one the most popular state-of-the-art face recognition methods.

• Journal of Fisheries and Marine Sciences Education
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• v.17 no.1
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• pp.35-47
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• 2005

The purpose of this study is to investigate various kinds of discipline problems in middle school classrooms, and the differences in severity and frequency of the classroom discipline problems between male and female students' classrooms in middle schools. This study shows that the discipline problems in the middle school classrooms include using a cellular phone, chattering, sleeping, chewing gum, reading comic books, asking useless questions, challenging a teacher, fighting, calling names, skipping class, throwing trash in the classroom, breaking classroom equipment, creating disorder, losing materials, playing with a ball in the classroom, gambling, and so on. Generally, male students recognized the severity of the classroom discipline problems more than the female students. However, it is shown that the frequency of discipline problems in male students' classrooms is higher than that in female students' classrooms. From the results of this study, male students have more active discipline problems (playing with a ball in the classroom, throwing trash in the classroom, coming to class late, gambling, cutting in line, and so on). On the other hand, female students have more passive discipline problems (making a noise by using a cellular phone, asking useless questions, sending messages to a classmate, studying other subjects, scattering, and so on).

• The Mathematical Education
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• v.60 no.4
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• pp.431-449
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• 2021

Elementary mathematics textbooks present contents for enhancing problem solving competency. Still, teachers find teaching problem solving to be challenging. To understand the supports textbooks are suggesting, this study examined tasks from the challenging/thinking and inquiry mathematics. We analyzed 288 mathematical activities based on an analytic framework from the 2015 revised mathematics curriculum. Then, we employed latent class analysis to classify 83 mathematical tasks as a new approach to categorize tasks. As a result, execution of the problem solving process was emphasized across grade levels but understanding of problems was varied by grade levels. In addition, higher grade levels had more opportunities to be engaged in collaborative problem solving and problem posing. We identified three task profiles: 'execution focus', 'collaborative-solution focus', 'multifaceted-solution focus'. In Grade 3, about 80% of tasks were categorized as the execution profile. The multifaceted-solution was about 40% in the thinking/challenging mathematics and the execution profile was about 70% in Inquiry mathematics. The implications for developing mathematics textbooks and designing mathematical tasks are discussed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1992.03a
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• pp.159-176
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• 1992

Limit analysis has been rendered versatile in many problems such as structural problems and metal forming problems. In metal forming analysis, a slip-line method and an upper bound method approach to limit solutions is considered as the most challenging areas. In the present work, a general algorithm for limit solutions of plastic flow is developed with the use of finite element limit analysis. The algorithm deals with a generalized Holder inequality, a duality theorem, and a combined smoothing and successive approximation in addition to a general procedure for finite element analysis. The algorithm is robust such that from any initial trial solution, the first iteration falls into a convex set which contains the exact solution(s) of the problem. The idea of the algorithm for limit solution is extended from rigid/perfectly-plastic materials to work-hardening materials by the nature of the limit formulation, which is also robust with numerically stable convergence and highly efficient computing time.

• IE interfaces
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• v.9 no.2
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• pp.3-17
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• 1996

Productivity improvement is one of the most challenging problem facing the motor industry. This paper deals with the lot sizing and production scheduling problems of the side frame press shop in a domestic truck manufacturing company. The problems can not be solved simultaneously due to the computational complexity. Thus, we present a heuristic method which solves the two problems sequentially with the objective of maximizing the press utilization while maintaining a minimum inventory level. A micro-computer-based software is developed for easy implementation of the heuristic in the shop floor level.