• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.8 no.3
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• pp.13-22
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• 2012

According to recent research on leak-rate estimates to assess rupture probabilities of nuclear piping which contains a circumferential surface/through-wall cracks due to PWSCC, i.e., xLPR (Extremely Low Probability of Rupture) program, it has been revealed that the use of crack shape with an idealized circumferential through-wall crack during actual crack growth can lead to overestimate of the leak-rate. Thus, for accurate estimation of the leak-rate during crack growth, the more realistic crack shape that can simulate the crack shape transition from surface crack to through-wall crack should be used. In this context, in the present study, the elastic crack opening displacement of slanted circumferential through-wall crack in thick-walled cylinder was proposed based on 3-dimensional elastic finite element fracture mechanics analyses. To propose the elastic crack opening displacement of slanted circumferential through-wall crack in thick-walled cylinder, the geometric variables affecting crack opening displacement, i.e., thickness of cylinder, reference inner crack length and slant crack ratio were systematically varied. In terms of loading conditions, axial tension, global bending moment and internal pressure were considered. The present results can be applied to calculate the leak-rate considering more realistic crack shape transition from surface crack to idealized through-wall crack, and can be expected to enhance current leak-rate estimation scheme, for instance, in xLPR program etc.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.10
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• pp.829-839
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• 2021

Autonomous system for UAVs has a capability to decide an appropriate current action to achieve the goal based on the ultimate mission goal, context of mission, and the current state of the UAV. We propose a decision-making system that has an ability to operate ISR mission autonomously under the realistic limitation such as low altitude operation with high risk of terrain collision, a set of way points without change of visit sequence not allowed, and position uncertainties of the objects for the mission. The proposed decision-making system is loaded to a Hardware-In-the-loop Simulation environment, then tested and verified using three representative scenarios with a realistic mission environment. The flight trajectories of the UAV and selected actions via the proposed decision-making system are presented as the simulation results with discussion.

• Journal of The Korean Association For Science Education
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• v.35 no.3
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• pp.465-475
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• 2015

The purpose of this study is to analyze the results of physics (optics) in nationwide standardized assessment and to investigate middle-school students' characteristics of achievement by using an option response rate distribution curve. For this purpose, we analyzed the 10 optics problems from the National Assessment of Educational Achievement (NAEA) items for middle school science subject conducted in 2010-2013. The results of this study are as follows; First, students showed a little higher achievement in optics than classical mechanics and electromagnetism. Second, students achieved significantly worse in 'formation of image' in 'light' part and 'variation of phase in propagation of wave' in 'wave' part. Third, students showed a context-dependent problem solving strategy and result. Additionally, we suggested some implications about the readjustment of some optics concepts level of national science curriculum, the need for teaching and learning strategies for basic level students, and the need for teaching and learning strategies focused on the realistic context.

• The Journal of the Korea Contents Association
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• v.15 no.12
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• pp.193-203
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• 2015

This study aims to analyze why South Korea has not used audit system but examination system and suggest policy reform for the system on the institutional context perspective. Institutional context is structured down to institutional legacy, motives, institutional constraints, actors' roles, and changed institution. I researched the literature on the subject and collected research materials from the Department of the Treasury and Audit Office website of New Zealand, Australia, United Kingdom, United States and South Korea. These were analyzed using for suggesting realistic and effective policy. Analysis showed that South Korea has used examination system due to institutional constraints and tried to increase reliability of financial statements by enlarging the meaning of examination, strengthening the ability of the Board of Audit and Inspection, enacting government examination standards, and making a comprehensive public announcement. Comparing with other countries where government audit systems are applied, there are still some vulnerable points in South Korea. In order to make up for the shortcomings, this study suggests several points: strengthening the ability of actors; systemizing internal control; expressing opinion; making a more comprehensive public announcement. It would be desirable for making further detailed studies of the points.

• Journal of Educational Research in Mathematics
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• v.14 no.4
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• pp.347-366
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• 2004

Recently, there have been many assessment researches in Korea. The aim of this study is to reflect on framework for mathematics assessment in RME which is based on Jan de Lange's assessment theory and to induce desirable directions for our mathematics assessment in nation-level and class-level. In order to attain these purposes, the present paper reflects the philosophy of RME, Jan de Lange's framework for mathematics assessment, assessment framework of the unit 'Side Seeing', one of Mathematics in Context textbook series, as an exemplar to which Jan de Lange's framework is applied. Based on these reflections, it is discussed that it needs to specify achievement standards presented in mathematics curriculum more particularly in order to have framework including mathematical abilities of level 2 and level 3 in Jan de Lange's framework appropriate to our situations, to apply the framework to nation-level and class-level consistently, and to enhance abilities of teachers and student teachers for mathematics assessment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.7
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• pp.1444-1452
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• 2009

Probabilistic distribution functions based data generation method is very effective. Probabilistic distribution functions are defined under the assumption that daily routine contexts are mainly depended on a time-based schedule. However, daily life contexts are frequently determined by previous contexts because contexts have consistency and/or sequential flows. In order to refect previous contexts effect, a situation propagation network is proposed in this paper. As proposed situation propagation network make parameters of related probabilistic distribution functions update, generated contexts can be more realistic and natural. Through the simulation study, proposed context-data generation model generated general outworker's data about 11 daily contexts at home. Generated data are evaluated with respect to reduction of ambiguity and confliction using newly defined indexes of ambiguity and confliction of sequential contexts. In conclusion, in case of combining situation propagation network with probabilistic distribution functions, ambiguity and confliction of data can be reduced 6.45% and 4.60% respectively.

• Communications of Mathematical Education
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• v.19 no.4 s.24
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• pp.733-767
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• 2005

During the past decades, there has been a fundamental change in the objectives and nature of mathematics education, as well as a shift in research paradigms. The changes in mathematics education emphasize learning mathematics from realistic situations, students' invention or construction solution procedures, and interaction with other students of the teacher. This shifted perspective has many similarities with the theoretical . perspective of Realistic Mathematics Education (RME) developed by Freudental. The RME theory focused the guide reinvention through mathematizing and takes into account students' informal solution strategies and interpretation through experientially real context problems. The heart of this reinvention process involves mathematizing activities in problem situations that are experientially real to students. It is important to note that reinvention in a collective, as well as individual activity, in which whole-class discussions centering on conjecture, explanation, and justification play a crucial role. The overall purpose of this study is to examine the developmental research efforts to adpat the instructional design perspective of RME to the teaching and learning of differential equation is collegiate mathematics education. Informed by the instructional design theory of RME and capitalizes on the potential technology to incorporate qualitative and numerical approaches, this study offers as approach for conceptualizing the learning and teaching of differential equation that is different from the traditional approach. Data were collected through participatory observation in a differential equations course at a university through a fall semester in 2003. All class sessions were video recorded and transcribed for later detailed analysis. Interviews were conducted systematically to probe the students' conceptual understanding and problem solving of differential equations. All the interviews were video recorded. In addition, students' works such as exams, journals and worksheets were collected for supplement the analysis of data from class observation and interview. Informed by the instructional design theory of RME, theoretical perspectives on emerging analyses of student thinking, this paper outlines an approach for conceptualizing inquiry-oriented differential equations that is different from traditional approaches and current reform efforts. One way of the wars in which thus approach complements current reform-oriented approaches 10 differential equations centers on a particular principled approach to mathematization. The findings of this research will provide insights into the role of the mathematics teacher, instructional materials, and technology, which will provide mathematics educators and instructional designers with new ways of thinking about their educational practice and new ways to foster students' mathematical justifications and ultimately improvement of educational practice in mathematics classes.

• The Mathematical Education
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• v.44 no.3 s.110
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• pp.435-456
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• 2005

This research aims to analyse implementation effects of the Real mathematics Education(RME) in the high school probability and statistics For this aim, two research questions are estabilished as fellows. (1) Is there any improvement of mathematical achievement in the class by RME's lecture than in the class by the mathematics text's lecture ? (2) Is there any improvement of mathematisation level in the class by RME's lecture than in the class by the mathematics text's lecture ? Before answering the above research questions, RME.`s lecture notes and ordinary lecture notes are developed based on the learning principles of the RME and mathematics textbook respectively. Two classes are randomly chosen from a high school located at midium size city and assigned as the experimental group and the control group respectively. The 20 hours of the RME's lecture notes is administerd to the experimental group and the 20 hours of the odinary lecture notes is administerd to the control group. It is shown that the class by RME's lecture is more effective in both of the mathematical achievement and the mathematisation activity than the class by the ordinary lecture. Hence, it is urged from the result of this research that RME's context will be developed and the RME's lecture will be implemented in the other field of high school mathematics.

• Journal of Construction Engineering and Project Management
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• v.9 no.4
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• pp.16-33
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• 2019

The increasing size and complexity of modern construction projects demands mature capabilities of onsite personnel with regard to recognizing unsafe situations. Construction safety training is paper or computer-based and suffers from a distinct gap between the classroom training environment and real-world construction sites; even trained personnel can find it difficult to recognize many of the potential safety hazards at their jobsites even after receiving construction safety training. Immersive technologies can overcome the current limitations in construction safety training by reducing the gap between the classroom and a real construction environment. This research developed and tested a new Augmented Reality (AR)-based assessment tool to evaluate the hazard recognition skills of students majoring in construction management as part of a construction safety course. The quantitative and qualitative results of this research confirmed that AR-based assessment can become a very effective assessment tool to evaluate safety knowledge and skills in a construction safety course, outperforming both paper and computer-based assessment methods. The students preferred AR-based assessment because it provides a realistic visual context for real world safety hazards.

• Journal of Preventive Medicine and Public Health
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• v.41 no.2
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• pp.69-73
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• 2008

To curb a rapid increase in expenditures for pharmaceuticals, the Korean government introduced a positive list system and a negotiation process for drug prices at the end of 2006. Economic evaluation of pharmaceuticals has begun to have a pivotal role in the listing and pricing of drugs for the Korean National Health Insurance. There are some points to discuss regarding the use of economic evaluation in the listing and pricing in the context of the Korean system. First, the listing and pricing processes have been fragmented, evoking complaints from pharmaceutical companies and delaying the access of new drugs to patients. Second, there is a concern that the positive list system may limit the range and availability of drugs for patients to choose for treatment. Third, the time schedule for de-listing of existing drugs may not be realistic. Fourth, it is not always easy to provide reliable evidence of cost-effectiveness due to a lack of materials. Fifth, there is no consensus on the range of the ICER (incremental cost-effectiveness ratio) acceptable to the Korean society. In conclusion, in the near future, it will be necessary to evaluate the achievements that the economic evaluation has provided to the Korean society.