• Journal of Chest Surgery
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• v.25 no.1
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• pp.23-31
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• 1992

The ideal approach in the staged management of patients with pulmonary atresia has been a challenging problem and the result has not been always satisfactory. We reviewed our early result of initial palliative surgeries in fifteen cases of pulmonary atresia with interventricular communication Included are eight cases of simple pulmonary atresia with ventricular septal defect and seven cases of pulmonary atresia associated with other complex cardiac anomalies. The ages of the patients were less than one year except one. The morphology of pulmonary vasculature was highly variable and showed unfavorable conditions in most cases. Pulmonary artery was nonconfluent in two. Two-thirds of all cases showed significant problems such as juxtaductal stenosis or diffuse hypoplasia. The ductus arteriosus usually narrowed at its pulmonic end. Initial palliation was done by modified Blalock-Taussig shunt in six, central shunt with or without pulmonary angioplasty in five, right ventricular outflow tract [RVOT] reconstruction in three and direct connection of nonconfluent pulmonary arteries with bilateral cav-opulmonary shunt in one patient. There were 3 hospital deaths. Two of them underwent simultaneous repair of the associated anomaly of TAPVR. Among the six patients who received modified Blalock-Taussig shunt, three needed early second palliative procedure by central shunt, RVOT patch reconstruction and pulmonary angioplasty in each case, All patients who received central shunt showed marked clinical improvement. Among the twelve patients who survived the palliative procedures, two patients underwent total correction 13 months and 18 months after initial palliation respectively. We think that the choice of palliative procedure must be individualized according to the morphology of the pulmonary arteries. More experience and long term follow-up data are necessary to meet this challenging problem.

• Hwankyungkyoyuk
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• v.2 no.1
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• pp.100-106
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• 1991

Environmental professional education in Korea has been mostly concentrated on the scientific and technological approaches to environmental problems. Many undergraduate majors in environmental engineering or sciences are designed to produce more technical manpowers in environmental fields. Most graduate schools on the environment also place an emphasis on teaching the technical aspects of environmental problems. Some environmental administration related courses, such as environmental law, environmental administration, environmental policy, environmental economics, environmental impact assessments, etc. are partically reflected in some curricula of very limited graduate or undergraduate environment majors. However, teaching environmental administration related courses in science or engineering major institutions has not been successfully carried out so far because lack of interests in such courses by most students and the shortage of competent teachers as well. Furthermore, those courses are not widely accepted by the departments of law, political science, public administration, etc. because their major interests are not in the environment-oriented. Environmental problems cannot be solved by the technical approach along. They should be systematically dealt with through interdisciplinary or multidisciplinary approaches, including natural and social sciences covering all relevant disciplines. in this respect, undergraduate environmental education should preferably cover broader courses on the environment, and the education for environmental professionals, including environmental administration specialists, is preferably handled by graduate schools offering many specialty area courses. Education for environmental administration specialist at graduate level is urgently needed in order to supply the competent manpower at government, business, and private organization levels dealing with environmental administration related problem. This is a new challenging area and the education for such specialists will become more important in the near future than technical manpowers which we ate now concentrating on their education.

• Nuclear Engineering and Technology
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• v.54 no.7
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• pp.2625-2634
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• 2022

Discretization errors are extremely challenging conundrums of discrete ordinates calculations for radiation transport problems with void regions. In previous work, we have presented a multi-collision source method (MCS) to overcome discretization errors, but the efficiency needs to be improved. This paper proposes a goal-oriented algorithm for the MCS method to adaptively determine the partitioning of the geometry and dynamically change the angular quadrature in remaining iterations. The importance factor based on the adjoint transport calculation obtains the response function to get a problem-dependent, goal-oriented spatial decomposition. The difference in the scalar fluxes from one high-order quadrature set to a lower one provides the error estimation as a driving force behind the dynamic quadrature. The goal-oriented algorithm allows optimizing by using ray-tracing technology or high-order quadrature sets in the first few iterations and arranging the integration order of the remaining iterations from high to low. The algorithm has been implemented in the 3D transport code ARES and was tested on the Kobayashi benchmarks. The numerical results show a reduction in computation time on these problems for the same desired level of accuracy as compared to the standard ARES code, and it has clear advantages over the traditional MCS method in solving radiation transport problems with reflective boundary conditions.

• Journal of the Korean School Mathematics Society
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• v.10 no.3
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• pp.303-322
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• 2007

This study is to investigate student's processes of problem solving using open-ended Geometric problems to understand student's thinking and behavior. One 8th grader participated in performing her learning in 5 lessons for June in 2006. The result of the study was documented according to Polya's four problem solving stages as follows: First, the student tended to neglect the stage of "understanding" a problem in the beginning. However, the student was observed to make it simplify and relate to what she had teamed previously Second, "devising a plan" was not simply done. She attempted to solve the open-ended problems with more various ways and became to have the metacognitive knowledge, leading her to think back and correct her errors of solving a problem. Third, in process of "carrying out" the plan she controled her solving a problem to become a better solver based on failure of solving a problem. Fourth, she recognized the necessity of "looking back" stage through the open ended problems which led her to apply and generalize mathematical problems to the real life. In conclusion, it was found that the student enjoyed her solving with enthusiasm, building mathematical belief systems with challenging spirit and developing mathematical power.

• Journal of The Korean Association of Information Education
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• v.3 no.2
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• pp.1-12
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• 2000

Recently, multimedia in information society are renovating the methods of creating, communicating, and delivering information between people. Due to the rapid technological development of storing information through a digital network structure and a renewal on-line system, we cannot solve current various problems related to copy rights under our present law system. This study will find out a concept of copy right in digital media, introduce a relationship between the characteristics of multimedia and the copy right environment and analyze international trends in protecting copy right of digital media. Finally, the some problems and suggestions will be summarized to give new directions to using the copy right challenging in 21 century.

• The Mathematical Education
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• v.48 no.4
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• pp.419-442
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• 2009

This study was to find the difficulties students faced in their mathematical learning and to identify the instructional dimensions a teacher provided for the students from multi-cultural background. Since the study was focused on the process of students' learning, the qualitative method was chosen through clinical interviews with 2 students in a total of 11 units which played a role of compensating their learning of mathematics as an extra curriculum. The students solved the computational problems relying on formal procedure without understanding of concepts and principles and solved the word problems based on own interpretation of certain words without semantic comprehension out of math sentences. As the instructional dimensions of teaching mathematics, tasks, a tool and classroom norm were found in the activities they performed. For the tasks, situated tasks, challenging tasks, tasks with lack of conditions, and open-ended exploratory tasks were used. As the tool, pictorial representations were very useful to describe their ideas. Finally, as the classroom norm, consider equity for everyone, and cooperate and encourage each other were found.

• Archives of Plastic Surgery
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• v.41 no.6
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• pp.728-733
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• 2014

Background Periareolar Augmentation Mastopexy is one of the most challenging operations in plastic surgery. Problems with scar quality, areolar widening, and distortion are frequent problems that interfere with a predictable result. Methods A retrospective review was performed on fifty consecutive patients who underwent a periareolar augmentation mastopexy with the interlocking approach. Of the 50 patients, 30 had both preoperative and postoperative photographs and were the basis of the study. Results The age of the patients ranged from 19 to 56 years with the average age being 39 years. The postoperative follow-up averaged 9.5 months and the implants averaged 316 mL. There were no deaths, pulmonary embolism, deep vein thrombosis, or infected implants. Four patients had complications following surgery for an overall complication rate of 13%. Two patients developed an infected Gore-Tex suture. Two of these complications were treated with revision surgery. Five patients required reoperation for an overall reoperative rate of 16% (one patient was converted to a full mastopexy). Conclusions As a result of this retrospective study, we have found the interlocking approach to periareolar augmentation/mastopexy to be a safe and reliable operation.

• The KIPS Transactions:PartB
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• v.15B no.5
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• pp.407-412
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• 2008

Color segmentation is one of the most challenging problems in image processing especially in case of handling the images with cluttered background. Great amount of color segmentation methods have been developed and applied to real problems. In this paper, we suggest a new methodology. Our approach is focused on background extraction, as a complimentary operation to standard foreground object segmentation, using self-organizing feature selective property of unsupervised self-learning paradigm based on the competitive algorithm. The results of our studies show that background segmentation can be achievable in efficient manner.

• Earthquakes and Structures
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• v.12 no.5
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• pp.543-557
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• 2017

Results of an extensive study aiming to properly extend the well known pushover analysis into 3-D problems of asymmetric buildings are presented in this paper. The proposed procedure uses simple, 3 DOF, one-story models with shear-beam type elements in order to quantify the effects of inelastic torsional response of such buildings. Correction coefficients for the response quantities at the "stiff" and "flexible" sides are calculated using results from non-linear time history analyses of the simple models. Their values are then applied to the results of a simple, plane pushover analysis of the detailed building models. Results from the application of the new method for a set of three, conventionally designed, five-story buildings with high values of uniaxial eccentricities are compared with those obtained from multiple non-linear dynamic time history analyses, as well as from similar pushover methods addressing the same problem. This initial evaluation indicates that the proposed procedure is a clear improvement over the simple (conventional) pushover method and, in most cases, more accurate and reliable than the other methods considered. The accuracy, however, of all these methods is reduced substantially when they are applied to torsionally flexible buildings. Thus, for such challenging problems, use of inelastic dynamic analyses for a set of two component earthquake motions appears to be the preferable solution.

• The Journal of the Korea Contents Association
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• v.20 no.9
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• pp.355-364
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• 2020

The performance plan of the budget was introduced to link the budget with the performance and to implement performance-oriented policies. This study reviewed the adequacy of indicators of the 2020 agricultural sector budget performance plan to find out how performance indicators were planned and achieved. As a result, there were problems such as low linkage between policy projects and targets, weighting of performance indicators and unclear grounds for targets, and underwhelming performance indicators. To improve these problems, challenging performance indicators and the establishment of practical performance indicators through incentives is necessary.