• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1515-1516
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• 2008

This paper proposes a new delay-dependent stability condition for uncertain time-delay systems, which is simple yet not as conservative as previous ones in the literature. The proposed condition, which is formulated in terms of linear matrix inequalities, does not employ any model transformation and therefore is free from the conservatism due to model transformations. Numerical examples are presented to show the usefulness of the proposed condition.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.729-734
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• 2008

A thermal stratification may occur in the horizontal parts of the surge line during operating transients of the pressurizer, which produces relatively high fatigue usage factor. Heat-up transient is the most severe case among the transient conditions. In this study, to study the relationship between the magnitude of thermal stratification and the length of vertical part of the surge line, some parametric fluid-structure interaction (FSI) analyses with different length variables of the vertical part of the surge line were performed for plant heat-up transient condition by using 3-dimensional numerical analysis. The conservativeness of the traditional finite element model for thermal stratification analysis based on the conservative assumption in the surge line was also discussed by comparison of the results of 3-dimensional transient FSI analysis of this study. Stresses calculated with 3-dimensional transient model were considerably reduced comparing with the traditional analysis.

• Journal of Korean Neurosurgical Society
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• v.54 no.2
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• pp.142-144
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• 2013

A 49-year-old female with a history of several neurosurgical and otolaryngologic procedures for occipital meningioma and cerebrospinal fluid leaks was diagnosed with pneumocephalus after a one hour flight on a domestic jet airliner. Despite multiple operations, the air appeared to enter the cranium through a weak portion of the skull base due to the low atmospheric pressure in the cabin. The intracranial air was absorbed with conservative management. The patient was recommended not to fly before a definite diagnostic work up and a sealing procedure for the cerebrospinal fluid leak site had been performed. Recent advances in aviation technology have enabled many people to travel by air, including individuals with medical conditions. Low cabin pressure is not dangerous to healthy individuals; however, practicing consultant neurosurgeons should understand the cabin environment and prepare high risk patients for safe air travel.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.3
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• pp.289-295
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• 2004

Pressure tubes are major component of nuclear reactor, but only selected samples are periodically examined due to numerous numbers of tubes. Current in-service inspection result show there is high probability of flaw existence at uninspected pressure tube. Probabilistic analysis is applied in this study for the integrity assessment of uninspected pressure tube. All the current integrity evaluations procedures are based on conventional deterministic approaches. So it is expected that the results obtained are too conservative to perform a rational evaluation of lifetime. More realistic failure criteria, based on FAD are also proposed for the probabilistic analysis. As a result of this study failure probabilities for various conditions are calculated, and examined application of FAD and LBB concept.

• Proceedings of the KACD Conference
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• 2001.11a
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• pp.567.1-567
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• 2001

A self-setting calcium phosphate cement (CPC), consisting of tetracalcium phosphate (TTCP) and dicalcium phosphate anhydrous (DCP A), reacts with water and hardens fast (30 min) to form hydroxyapatite (HA) under physiological conditions as the final product. Although this CPC is finding increasing use as a biomaterial, it is presently limited to low stress bearing applications because of its relatively low strength and highly brittle nature. Recently the mechanical properties of CPC reinforced with chopped carbon fiber have been reported.

• Restorative Dentistry and Endodontics
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• v.37 no.4
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• pp.188-193
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• 2012

Mineral trioxide aggregate (MTA) was developed in early 1990s and has been successfully used for root perforation repair, root end filling, and one-visit apexification. MTA is composed mainly of tricalcium silicate and dicalcium silicate. When MTA is hydrated, calcium silicate hydrate (CSH) and calcium hydroxide is formed. Formed calcium hydroxide interacts with the phosphate ion in body fluid and form amorphous calcium phosphate (ACP) which finally transforms into calcium deficient hydroxyapatite (CDHA). These mineral precipitate were reported to form the MTA-dentin interfacial layer which enhances the sealing ability of MTA. Clinically, the use of zinc oxide euginol (ZOE) based materials may retard the setting of MTA. Also, the use of acids or contact with excessive blood should be avoided before complete set of MTA, because these conditions could adversely affect the hydration reaction of MTA. Further studies on the chemical nature of MTA hydration reaction are needed.

• Journal of Chest Surgery
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• v.32 no.10
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• pp.958-961
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• 1999

A case of esophagopleural fistula after pleuropneumonectomy is reported. A 59 years old male underwent right pleuropneumonectomy due to tuberculous empyema. The postoperative small esophagopleural fistula was confirmed by esophagogram and was initially managed by a conservative treatment. There was a persistent fistula on follow up esophagogram, therefore we planned the next treatment modality for obstruction of the fistula. For poor general conditions and arrhythmia, an esophageal stent was applied as a non-surgical method. At first, a covered-form stent was inserted, but it migrated to the stomach after 3 months. By using an uncovered-form stent, a complete obstruction of the esophagopleural fistula was achieved.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.4
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• pp.307-314
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• 2014

Although a laser has been introduced to implant dentistry for decades, its efficacy is still open debate. The aim of this literature review is to analyze and evaluate the efficacy of laser therapy for the treatment of dentinal hypersensitivity and periodontal conditions.

• 전기의세계
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• v.49 no.9
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• pp.9-16
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• 2000

A receding horizon $H_{\infty}$ predictive control method is derived by solving a min-max problem in non-recursive forms. The min-max cost index is converted to a quadratic form which for systems with input saturation can be minimized using QP. Through the use of closed-loop prediction the prediction of states the use of closed-loop prediction the prediction of states in the presence of disturbances are made non-conservative and it become possible to get a tighter $H_{\infty}$ norm bound. Stability conditions and $H_{\infty}$ norm bounds on disturbance rejection are obtained in infinite horizon sence. Polyhedral types of feasible sets for sets and disturbances are adopted to deal with the input constraints. The weight selection procedures are given in terms of LMIs and the algorithm is formulated so that it can be solved via QP. This work is a modified version of an earlier work which was based on ellipsoidal type feasible sets[15].

• 한국방재학회:학술대회논문집
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• 2010.02a
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• pp.83.2-83.2
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• 2010

Stepped I-beams having increased moment of inertia at one end(singly stepped beam) or both ends(doubly stepped beams) can often be seen in construction of bridges due to material economy and easy fabrication of the section. This paper presents the results of the parametric study of lateral torsional buckling of monosymmetric stepped I-beams with constant depth subjected to equal and opposite end moments applied at the end of the beam. Design recommendations were made based on the finite element results of the models having different combinations of monosymmetric ratio, stepped length ratio, flange thickness ratio and flange width ratio,. The proposed approximation is acceptable based on the parameters given having mostly conservative results. The proposed equation can be further used to extend the study to different loading conditions.