• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.10a
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• pp.267.2-272
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• 1998

The fine blanking is a process of press-working which makes possible to produce thick sheet metal parts of finished sheared surface and close dimensional accuracy over whole material thickness in single blanking operation. Fineblanked parts in general are characterized by their cleanly sheared surface over the whole stock thickness and accurate size for the specific functions. The fine blanking technology is urgently needed to remove secondary operations which are necessary in conventional blanking operation and cost reduction. In this study, the effect of material texture and vee-ring on parts for automobile is investigated by experimental observation and analysis.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.03a
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• pp.148-152
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• 1997

A numerical method is presented to predict and analyze the shape and the temperature history of a growing billet produced form the "spray forming" which is a fairly new near net-shape manufacturing process. It is important to understand the mechanism of billet growing and the cooling history of the spray deposited body, because one can obtain a billet with the desired final shape without secondary operations by accurate control of the billet shape and, moreover, growing velocity together with the cooling rate define the microstructure of the final formed product. In the present study, a theoretical model is first established to predict the shape of the billet and next the transient axisymmetric heat conduction problem with growing domain is solved using the so called "front tracking finite element technique".ent technique".uot;.

• Journal of Chest Surgery
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• v.22 no.1
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• pp.50-58
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• 1989

The emergence and expansion of cardiac surgery over the past decade has resulted in an increasing number of patients undergoing cardiac operations but many kinds of heart surgery was realized only palliative, resulting in increasing numbers of secondary cardiac procedures. From 1978 to 1988, 10 cases of various congenital heart diseases and 17 cases of acquired heart diseases were reoperated at Hanyang University Hospital. The leading indication of second operation was residual shunt or valvular malfunction due to technical failure in congenital heart disease and primary valve failure, endocarditis, paravalvular leakage were for acquired heart disease. The mortality of reoperation was 0% for congenital heart disease and 11.7%[2 death among the 17 patients] for acquired heart disease. The leading causes of death were myocardial failure, sepsis with endocarditis, acute renal failure and congestive heart failure.

• The Mathematical Education
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• v.3 no.10
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• pp.7-20
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• 1965

One of the prerequisites for the improvement of the teaching of mathematics in our country is an improved curriculum-one which takes account of the increasing use of mathematics in science and technology and in other areas of knowledge and at the same time one which reflects recent advances in mathematics itself. In the new curriculum of mathematics, we have found the problems to teach the concept of sets at secondary level. The idea of a set is the most fundamental one in mathematics. So, this thesis contains the studies of the systematic analysis of sets in dealing with the traditional textbook. The scope of the work is limited to the fundamental ideas, and so it merely touches on the topics of the Concpets, Operations, Cardinal Numbers, Application of Logic, one-to-one Correspondence, Probability and so on. It provides only the essentials, definitions, proofs and some example which are already known and understood in their traditional context. It also presents at the appropriate stages the concepts required (illustrated by examples) in a much clearer fashion than classical teaching does. To compete a study of the sets covered in the textbook of each year, greater detail is needed at the appropriate level.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 1997.11a
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• pp.417-433
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• 1997

A real-time operating system has focused primary on techniques to minimize processing time, with a secondary emphasis on system reliability issues. Conversely, fault-tolerant system has concentrated on using recourse and information redundancy to maximize the availability and reliability of the system, with a lesser emphasis on performance. We have developed a fault-tolerant and real-time operations system which support a powerful concurrent runtime environment under the above requirements. In this paper, we present an overview of real-time systems, design and implementation of a duplex architecture using advanced concepts and technologies such as fast " fault detection", "fault isolation" and "fault recovery" Because the duplex architecture has two dentical hardware elements and has several recovery steps and hierarchy to facilitate a fast recovery which must be proceeded by a prompt fault detection and isolation. Thus it makes possible to minimize the overhead of the systems including hardware and software and guarantee the service continuity of he systems.

• Journal of the Korean Solar Energy Society
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• v.28 no.6
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• pp.33-39
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• 2008

The purpose of this study is not only to evaluate the stress behavior of tubes in superheater in HRSG during the load change operation but also to find root causes of failure from stress behavior. Firstly, temperature during operation was collected to perform stress analysis from actual HRSG. Part load and full load stress analysis which can be represented as the whole load change operations were performed using commercial finite element software. The possibility that can lead to tubes failure is found by stress analysis and its results is compared with metallurgical mircrostructure of failed tube which was taken from actual HRSG.

• Imaging Science in Dentistry
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• v.48 no.2
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• pp.131-137
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• 2018

Cemento-osseous dysplasia (COD) is a benign fibro-osseous lesion of bone, in which normal bone is replaced by fibrous tissue, followed by calcification with osseous and cementum-like tissue. COD is classified into 3 categories according to its location: periapical, focal, and florid COD (FCOD). On radiography, FCOD appears radiolucent in its early stages. As it matures, radiopacities appear within the lesion, causing them to show a mixed appearance of radiolucency and radiopacity. Because FCOD is usually asymptomatic and grows in a self-limited manner, it does not require treatment. Secondary infection is the most frequent cause of symptomatic cases. We report a case of FCOD with symptoms that appeared after a dental restoration procedure and persisted after repeated operations. The purpose of this report is to emphasize the importance of thorough radiological evaluations of patients with FCOD before treatment.

• Journal of Power System Engineering
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• v.15 no.5
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• pp.67-71
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• 2011

Fine blanking is a specialized form of blanking where there is no fracture zone when shearing. This is achieved by compressing the whole part and then an upper and lower punch extract the blank. This allows the process to hold very tight tolerances, and perhaps eliminate secondary operations. In the present study, tensile test and numerical simulation has been performed to investigate distribution of deformation and stress of car seat recliner. The commercial ABAQUS/Explicit software was applied for analyzing the stress and strain of the recliner. In analysis, three lock gear has reached the maximum moment on rotational degree of 2.27. This is more than two times than maximum moment of same size recliner, and can be used safely. Therefore, these can use as criterion of actual structural design.

• Transactions of Materials Processing
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• v.19 no.2
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• pp.113-119
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• 2010

Hydroforming is the technology that utilizes hydraulic pressure to form tube or sheet materials into desired shapes inside die cavities. Tube hydroforming provides a number of advantages over the conventional stamping process, including fewer secondary operations, weight reduction, assembly simplification, adaptability to forming of complex structural components and improved structural strength. In many case, hydroformed parts have to be structurally joined at some point. Therefore it is useful if the hydroformed automotive parts can be given a localized attachment flange. In this study for the numerical process design FE analysis was performed with DYNAFORM 5.5. Die parting angle and circumferential expansion ratio was optimized. With optimized condition, bulge and hydroforming experiments to form flange were performed. Forming characteristic at various pressure conditions was analyzed and optimized internal pressure condition was evaluated. The results show that flanged parts can be successfully produced by tube hydroforming process.

• Archives of Plastic Surgery
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• v.46 no.5
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• pp.475-479
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• 2019

The Goldilocks technique for breast reconstruction utilizes redundant mastectomy flap tissue to construct a breast mound. This technique is suitable for women who decline, or are poor candidates for, traditional postmastectomy reconstruction. Moreover, this technique can be applied in secondary operations after the failure of initial reconstruction efforts. A 74-year-old patient underwent the Goldilocks procedure after reconstruction failure with an implant and acellular dermal matrix. At her 6-month follow-up, the cosmetic outcome of the procedure was satisfactory, and no complications were noted. Therefore, the Goldilocks procedure is a safe alternative to reconstruct breast mounds following reconstruction failure, especially in obese patients.