• Journal of the Korean Geographical Society
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• v.42 no.4
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• pp.506-525
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• 2007

Incision into bedrock channel is the primary control of landform evolution, but research into bedrock incision process stagnated for long time. Due to the scaling problem of the application of results from flume studies to bedrock channel, there is a strong need to simulate the bedrock incision process with more realistic models. As a part of investigation into controls of bedrock channel incision, three-dimensional changes of rock surface with abrasion was investigated with physical modelling. 18 rock plates were abraded with various sediment particle size and sediment load and abraded surfaces of the plates were scanned with high resolution 3-D scanner. To identify the spatial pattern of erosion of the rock plates, various methods were used. There was no synthetic or holistic method that showed all features of bedrock plate produced by abrasion, so each plate was analyzed using some available methods. Contour maps, shaded relief maps and profiles show that abrasion concentrated on the centre of plate (cross profile) and upstream and downstream edges (longitudinal profile) and eroded area extended inwards. It also found that the cracks and boundaries of forming materials easily eroded than other parts. Changing patterns of surface roughness were investigated with profiles, regression analysis and spectral analysis. Majority of plates showed decrease in small-scale roughness, but it depends on microstructures of the plates rather than general hardness or other factors. SEM inspection results supported this idea.

• Journal of the Korea Computer Graphics Society
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• v.24 no.2
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• pp.1-9
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• 2018

In this paper, we propose a method to restore corrupted black and white facial images to color. Previous studies have shown that when coloring damaged black and white photographs, such as old ID photographs, the area around the damaged area is often incorrectly colored. To solve this problem, this paper proposes a method of restoring the damaged area of input photo first and then performing colorization based on the result. The proposed method consists of two steps: BEGAN (Boundary Equivalent Generative Adversarial Networks) model based restoration and CNN (Convolutional Neural Network) based coloring. Our method uses the BEGAN model, which enables a clearer and higher resolution image restoration than the existing methods using the DCGAN (Deep Convolutional Generative Adversarial Networks) model for image restoration, and performs colorization based on the restored black and white image. Finally, we confirmed that the experimental results of various types of facial images and masks can show realistic color restoration results in many cases compared with the previous studies.

• Journal of IKEEE
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• v.1 no.1 s.1
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• pp.31-46
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• 1997

In this paper, a parallel Optimal Best-First search Branch-and-Bound(B&B) algorithm(pobs) is designed and evaluated for MIN-based multiprocessor systems. The proposed algorithm decomposes a problem into G subproblems, where each subproblem is processed on a group of P processors. Each processor group uses tile sub-Global Best-First search technique to find a local solution. The local solutions are broadcasted through the network to compute the global solution. This broadcast provides not only the comparison of G local solutions but also the load balancing among the processor groups. A performance analysis is then conducted to estimate the speed-up of the proposed parallel B&B algorithm. The analytical model is developed based on the probabilistic properties of the B&B algorithm. It considers both the computation time and communication overheads to evaluate the realistic performance of the algorithm under the parallel processing environment. In order to validate the proposed evaluation model, the simulation of the parallel B&B algorithm on a MIN-based system is carried out at the same time. The results from both analysis and simulation match closely. It is also shown that the proposed Optimal Best-First search B&B algorithm performs better than other reported schemes with its various advantageous features such as: less subproblem evaluations, prefer load balancing, and limited scope of remote communication.

• Journal of Technologic Dentistry
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• v.38 no.1
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• pp.23-36
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• 2016

Purpose: The purpose of this study is to suggest direction for dental technicians and management of dental laboratories to contribute to the improvement of oral health of citizens with high-quality dental prosthesis by researching operational status and management satisfaction of dental laboratories. Methods: In order to investigate operational status and management satisfaction of dental laboratories, this study conducted a questionnaire survey by mailing questionnaires to heads of dental laboratories designated as clinical training workshops of Department of Dental Technology of G University and a total of 158 questionnaires were used for analysis. Results: As for gender, males were 142 persons (89.9%) and females were 16 persons (10.1%). For location of the laboratories, number of laboratories in metropolitan cities was 94 (59.5%) while small and that in mid-sized cities was 64 (40.5%). As for the satisfaction with job, those who have managed dental laboratories for 23-30 years ($1.92{\pm}77$), transact with 7-12 dental clinics ($1.70{\pm}75$), had monthly income of 4-8 million won ($1.74{\pm}.80$) and had 8-10 employees ($2.33{\pm}.68$) were the highest in their satisfaction. As for satisfaction with management, those who have managed their business for 15-20 years ($2.86{\pm}.52$), transact with more than 20 dental clinics ($2.00{\pm}.04$), had monthly income of less than 4 million won ($2.00{\pm}.85$) and had less than 3 employees ($2.00{\pm}.62$) were the highest in their satisfaction. As for monthly income, those with less than 2 million won were 24 persons (15.2%), 2-4 million were 64 persons (40.5%), 4-6 million were 40 (25.3%), 6-8 million were 14 (8.9%) and over 8 million won were 16 persons (10.2%). As for number of employees, those with less than 3 employees were 32perosns (20.3%), 4-7 were 82 (51.9%), 8-10 were 26 (16.5%) and more than 11 were 10 persons (6.3%). As for severance payment, 84 persons practiced it according to Labor Standard Act (53.2%) and 34 practice it to a proper degree (21.5%) while 20 did not practice it at all (12.7%) and 20 persons did not respond to the question (12.7%). Conclusion: Although dental laboratories have rapidly expanded in number from 473 in 1986 to 2,400 in 2015, dental technician circles are facing difficulty in their management due to fierce competition and low profitability. Therefore, in order to improve this problem, it is necessary to readjust prices for dental prosthesis to realistic ones.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.51-59
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• 1993

This paper develops practical and realistic reliability models and methods for the evaluation of system-reliability and system reliability-based rating of various types of box-girder bridge superstructures. The strength limit state model for box-girder bridges suggested in the paper are based on not only the basic flexural strength but also the strength interaction equations which simultaneously take into account flexure, shear and torsion. And the system reliability problem of box-girder superstructure is formulated as parallel-series models obtained from the FMA(Failure Mode Approach) based on major failure mechanisms or critical failure states of each girder. In the paper, an improved IST(Importance Sampling Technique) simulation algorithm is used for the system reliability analysis of the proposed models. This paper proposes a practical but rational approach for the evaluation of capacity rating in terms of the equivalent system-capacity rating corresponding to the estimated system-reliability index which is derived based on the concept of the equivalent FOSM(First Order Second Moment) form of system reliability index. The results of the reliability evaluation and rating of existing bridges indicate that the reserved reliability and capacity rating at system level are significantly different from those of element reliability or conventional methods especially in the case of highly redundant box-girder bridges.

• Communications of Mathematical Education
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• v.27 no.4
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• pp.449-472
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• 2013

Instructional materials including problem situations or problems or tasks on real-life situations are considered as an important and significant factor to lead a successful math instruction. MiC Textbook is a representative one showing good examples and tasks including fluent realistic situations on the basis of the background of the Freudenthal's theory. This study explores concretely and in detail the type of level of mathematical tasks, by the subject of MiC Textbook. To accomplish this, this study reconstructs and establishes an elaborated analysis framework using 'the cognitive demand level' suggested by Stein, et, al. The cognitive demand level is comprized of four elements such as Memorization Tasks, Procedures Without Connections Tasks, Procedures With Connections Tasks, and Doing Mathematics Tasks. Memorization Tasks and Procedures Without Connections Tasks are considered as low level tasks, and Procedures With Connections Tasks and Doing Mathematics Tasks are as high level tasks. MiC Textbook is comprized of the four areas of 'number', 'algebra', 'geometry and measurement', and 'data analysis and statistics'. This study deals with the tasks relevant to Function content dealt with in MiC 3 level Textbook, and explore the level of cognitive demands on each task.

• The Mathematical Education
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• v.58 no.4
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• pp.567-588
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• 2019

This study is a follow-up to Lee(2019). Lee(2019) investigated the method of collecting information on the curriculum of elementary and middle school math teachers, when differences were observed between elementary and middle school math teachers in the method of collecting information on the curriculum. Following Lee(2019)'s study, this study looked at the perceptions and experiences of high school math teachers in their curriculum.At the time when the curriculum was changed from time to time, the authority for restructuring curriculum was strengthened. In addition, the role of teachers as 'curriculum restructuring practitioners' became important. However, previous studies have pointed out the structural problem that teachers empathize with the necessity of restructuring the curriculum and have a negative perception of the willingness to practice the curriculum. Therefore, the researcher examined high school teachers who are sensitive to the characteristics and evaluation of the highly hierarchical mathematics subjects. A total of six interviews were conducted with ten high school mathematics teachers in three groups of ten years of teaching experience. Through this, it was possible to observe how teachers as curriculum reconstruction practitioners had thought about curriculum restructuring, and I could observe what difficulties teachers' experienced. This suggests that teachers have two ideas for restructuring the curriculum: 'realistic curriculum reconstruction' and 'ideal curriculum reconstruction'. In addition, the teachers found that there are 'sides of incongruity in the school system' and 'difficulties in the management of teachers'.

• The Korean Society of Law and Medicine
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• v.20 no.1
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• pp.25-43
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• 2019

This study analyzed the problem of the time difference of medicine price cut in Korea according to the administrative and judicial process and sought to present the amendment in the related law to achieve substantial fairness. We considered unfairness of medicine price cut caused by the administrative and judicial process in three situations, the approval-patent linkage system, realistic differences in the practice of administration and suspension of price cut execution. Based on it, we reasoned out the solution to get substantial fairness in the administrative and judicial process of medicine price cut in Korea. Although each step of the administrative and judicial process is lawful and reasonable, the time difference of medicine price cut according to the administrative and judicial process can result in damages or windfall to both of pharmaceutical company and National Health Insurance Service. In the present legal system of Korea, it is unable to be correct. Thus, we present the amendment to correct the damages and windfall when it happens.

• Journal of the Korean Society of Radiology
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• v.11 no.6
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• pp.475-481
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• 2017

As the research about supplementary education of radiological technologist who works in Gyoungsangnam province, this study was conducted to draw the improvements by analyzing the satisfaction level and problems of the supplementary education. During November 01, 2016 to December 15, 2016, after we sent out a total of 250 questionnaires for the survey to radiological technologists working at medical institution located in Gyoungsangnam province, 200 questionnaires suitable for research were analysis by using SPSS 18.0 statistical analysis software. As the satisfaction factors, 21 items such as system, subject, help, appropriateness of lecturer selection, professionalism were used. And as the problem factors, 18 items such as place, transportation, diversity, administrative treatment, education promotion, proceed method were used. Consequentially, the satisfaction level(3.12 point) and problems(3.01 point) of the supplementary education were confirmed as normal level. The supplementary education is an essential education that any health and medical service personnel must complete. In order to improve the effectiveness and efficaciousness of the education, the diverse opinions and efforts to improve the education levels must be supported. Futhermore, through the realistic educational program, the continuous education for radiological technologist with excellent qualities and competence should be done.

• Geophysics and Geophysical Exploration
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• v.7 no.2
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• pp.148-154
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• 2004

This article reviews the development of three-dimensional (3-D) magnetotelluric (MT) modeling. The 3-D modeling of electromagnetic fields is essential in understanding the physics of MT soundings, and in implementing an inversion method to reconstruct a 3-D resistivity image. Although various numerical schemes have been developed over the last two decades, practical methods have been quite limited. However, the recent rapid improvement in computer speed and memory, as well as the advance in iterative solution algorithms for a large system of equations, makes it possible to model the MT responses of complex 3-D structures, which have been very difficult to simulate before. The use of staggered grids in finite difference method has become popular, conserving a magnetic flux and an electric current and allowing for realistic discontinuous fields. The convergence of numerical solutions has been greatly accelerated by adopting Krylov subspace methods, proper preconditioning techniques, and static divergence corrections. The vector finite-element method using edge elements is also free from the discontinuity problem, and seems a natural choice for modeling complex structures including irregular topography because its flexibility allows one to capture full geometric complexity.