• 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.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.3
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• pp.1-6
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• 2017

As the performance and density of IC devices increase, especially the clock frequency increases, power grid network integrity problems become more challenging. To resolve these power integrity problems, the use of passive devices such as resistor, inductor, and capacitor is very important. To manage the power integrity with little noise or ripple, decoupling capacitors are essential in electronic packaging. The decoupling capacitors are classified into voltage regulator capacitor, board capacitor, package capacitor, and on-chip capacitor. For next generation packaging technologies such as 3D packaging or wafer level packaging on-chip MIM decoupling capacitor is the key element for power distribution and delivery management. This paper reviews the use and necessity of on-chip decoupling capacitor.

• Bulletin of the Korean Mathematical Society
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• v.57 no.2
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• pp.459-479
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• 2020

In the last two decades, codes over noncommutative rings have been one of the main trends in coding theory. Due to the fact that noncommutativity brings many challenging problems in its nature, still there are many open problems to be addressed. In 2015, generator polynomial matrices and parity-check polynomial matrices of generalized quasi-cyclic (GQC) codes were investigated by Matsui. We extended these results to the noncommutative case. Exploring the dual structures of skew constacyclic codes, we present a direct way of obtaining parity-check polynomials of skew multi-twisted codes in terms of their generators. Further, we lay out the algebraic structures of skew multipolycyclic codes and their duals and we give some examples to illustrate the theorems.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.3
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• pp.85-91
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• 2008

Robot technology is a remarkably interdisciplinary research area, one that can be employed in various industrial fields as well as higher value-added fields. The construction industry, on the other hand, has been known as one of the most difficult research fields to apply robotic schemes. Therefore, applying robot technologies in the construction industry is quite a challenging topic. This paper aims to introduce the progress of automated robotic systems in construction fields, namely with respect to construction robots. While construction robots have a very wide range of application depending on the huge market size of the construction industry, there still exist a lot of problems such as highly risky working environment and inefficiency due to the labor intensive characteristic. In order to solve these problems, a variety of construction robots have been developed and, in this paper, the current state of the robotic systems for construction works and the vision of future robot technology in the construction field are introduced.

• IE interfaces
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• v.9 no.3
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• pp.236-248
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• 1996

Most of business enterprises today struggle with the coordination of work which is one of the most challenging problems in the business environment. And the situation becomes worse by the increasing complexity and uncertainty. In this paper, suitability of workflow technology for the modelling, optimization, and automation in the complex business structures is discussed. Also, in the abscence of a fully fledged method for analysis and design of workflow systems, this paper proposes a method, ETM(Extended Trigger Modelling), which can solve several problems in other methods. The proposed ETM approach consists of three stages such as situation analysis stage, activity coordination stage and implementation preparation stage. A modelling case of the proposed procedure is also presented.

• ETRI Journal
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• v.37 no.3
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• pp.512-522
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• 2015

Recent developments in identity-based cryptography (IBC) have provided new solutions to problems related to the security of mobile ad hoc networks (MANETs). Although many proposals to solve problems related to the security of MANETs are suggested by the research community, there is no one solution that fits all. The interdependency cycle between secure routing and security services makes the use of IBC in MANETs very challenging. In this paper, two novel methods are proposed to eliminate the need for this cycle. One of these methods utilizes a key pool to secure routes for the distribution of cryptographic materials, while the other adopts a pairing-based key agreement method. Furthermore, our proposed methods utilize threshold cryptography for shared secret and private key generation to eliminate the "single point of failure" and distribute cryptographic services among network nodes. These characteristics guarantee high levels of availability and scalability for the proposed methods. To illustrate the effectiveness and capabilities of the proposed methods, they are simulated and compared against the performance of existing methods.

• Research in Mathematical Education
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• v.12 no.3
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• pp.179-191
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• 2008

Although problem solving was a major focus of mathematics education research in many countries throughout the 1990s, not enough is known about how people best acquire problem-solving skills. This paper is an attempt to advance further development of problem-solving skills of talented school students through combination of some methods accessible from curriculum knowledge and more special techniques that are beyond curriculum. Analysis of various problems is provided in detail. Educational aspects of challenging problems in mathematical contests up to IMO level are, also, taken into account and discussed in the paper.

• Korean Journal of Mathematics
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• v.27 no.1
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• pp.193-219
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• 2019

The Navier-Stokes equations with variable density are challenging problems in numerical analysis community. We recently built the 2nd order stabilized Gauge-Uzawa method [SGUM] to solve the Navier-Stokes equations with constant density and have estimated theoretically optimal accuracy. Also we proved that SGUM is unconditionally stable. In this paper, we apply SGUM to the Navier-Stokes equations with nonconstant variable density and find out the stability condition of the algorithms. Because the condition is rather strong to apply to real problems, we consider Allen-Cahn scheme to construct unconditionally stable scheme.

• Journal of Korea Multimedia Society
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• v.25 no.2
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• pp.247-256
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• 2022

Visual tracking of selected target objects is fundamental challenging problems in computer vision. Object tracking localize the region of target object with bounding box in the video. We propose a Siam-FPN based custom fully CNN to solve visual tracking problems by regressing the target area in an end-to-end manner. A method of preserving the feature information flow using a feature map connection structure was applied. In this way, information is preserved and emphasized across the network. To regress object region and to classify object, the region proposal network was connected with the Siamese network. The performance of the tracking algorithm was evaluated using the OTB-100 dataset. Success Plot and Precision Plot were used as evaluation matrix. As a result of the experiment, 0.621 in Success Plot and 0.838 in Precision Plot were achieved.

• 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.