• 비파괴검사학회지
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• 제21권4호
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• pp.383-390
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• 2001

Long-range guided wave inspection is a new emerging technology for rapidly and globally inspecting a large area of a structure from a single test location. This paper describes a general overview of the guided wave properties and its application for long-range inspection of structures the principle and instrument system for a guided wave inspection technology called "magnetostrictive sensor (MsS)" that generates and detects guided waves electromagnetically in the material under testing, and examples of long-range guided wave inspection of structures that can be accomplished using the MsS.

• 한국세라믹학회지
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• 제42권11호
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• pp.703-717
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• 2005

The infiltration of ceramics by liquid metals to fabricate ceramic-metal composites is discussed. In particular, the complexity of infiltrating ceramics by liquid metals at high temperatures due to interfacial reactions, metal oxidation, pore modulation and closure, and transient capillary forces has been highlighted. The role of these factors is discussed in the context of reactive infiltration with examples from ceramic/metal composites of practical interest. In addition to flow through porous ceramics, reactive penetration of dense ceramics via chemical dissolution and reaction is also discussed.

• International Journal of Control, Automation, and Systems
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• 제6권2호
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• pp.160-170
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• 2008

Temperature control of an enclosed thermal system which has many applications including Rapid Thermal Processing (RTP) of semiconductor wafers showed an input-constraint violation for nonlinear controllers due to inherent strong coupling between the elements [1]. In this paper, a constrained nonlinear optimal control design is developed, which accommodates input constraints using the linear algebraic equivalence of the nonlinear controllers, for the temperature control of an enclosed thermal process. First, it will be shown that design of nonlinear controllers is equivalent to solving a set of linear algebraic equations-the linear algebraic equivalence of nonlinear controllers (LAENC). Then an input-constrained nonlinear optimal controller is designed based on that LAENC using the constrained linear least squares method. Through numerical simulations, it is demonstrated that the proposed controller achieves the equivalent performances to the classical nonlinear controllers with less total energy consumption. Moreover, it generates the practical control solution, in other words, control solutions do not violate the input-constraints.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.452-455
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• 2007

This paper provides an overview on the characteristics of a-SiC:H barrier film deposited for flexible display applications. Key characteristics such as high crack resistance, high thermal/hydro stability, excellent adhesion to the polymer substrate, as well as very low permeance has been demonstrated. The excellence of this barrier film has been shown from competitive analysis compared with other barrier coating materials. Finally, flexible Polymer Light Emitting Diode (PLED) test pixels have been fabricated on the barrier coated plastic substrate, demonstrating the viability of the device with lifetime data.

• Structural Engineering and Mechanics
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• 제17권1호
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• pp.29-50
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• 2004

A total life model was developed to assess the service life of aging aircraft. The primary focus of this paper is the development of crack growth life projection using the response surface method. Crack growth life projection is a necessary component of the total life model. The study showed that the number of load cycles N needed for a crack to propagate to a specified size can be linearly related to the geometric parameter, material, and stress level of the component considered when all the variables are transformed to logarithmic values. By the Central Limit theorem, the ln N was approximated by Gaussian distribution. This Gaussian model compared well with the histograms of the number of load cycles generated from simulated crack growth curves. The outcome of this study will aid engineers in designing their crack growth experiments to develop the stochastic crack growth models for service life assessments.

• 소음진동
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• 제4권4호
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• pp.459-467
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• 1994

Various maintenance programs and techniques have been implemented for roating machineries, since machines were invented for commerical use. The earliest type of maintenance was run-to-failure, where the machine was run until a fault caused to fail in service. It was obviously an expensive approach due to the unpredictability of the machine condition. Another type is the periodic maintenance, where machines are disassembled and overhauled on regular schedules. With the advent of reliable data collectors including FFT analyzer and developing of versatile supporting software such as ExpertALERT system, the predictive maintenance is known to be the most feasible maintenance type these days. The vibration analysis enables for a maintenance crew to find the exact cause of fault on a machine and to make a proper maintenance schedule with a trend analysis. The predicitive maintenance is considered to be the most important part of pro-active maintenance.

• Advances in Computational Design
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• 제5권1호
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• pp.91-109
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• 2020

Over the past few decades, the impact of natural, manmade and natech (natural hazard triggering technological disasters) disasters has been devastating, affecting over 4.4 billion people. In spite of recent technological advances, the increasing frequency and intensity of natural disasters and the escalation of manmade threats is presenting a number of challenges that warrant immediate attention. This paper explores the integration of drones or Unmanned Aerial Vehicles (UAV's) into infrastructure monitoring and post-disaster assessment. Through reviewing some of the recent disasters, effectiveness of utilizing UAV's in different stages of disaster life cycle is demonstrated and needed steps for successful integration of UAV's in infrastructure monitoring, hazard mitigation and post-incident assessment applications are discussed. In addition, some of the challenges associated with implementing UAV's in disaster monitoring, together with research needs to overcome associated knowledge gaps, is presented.

• Computers and Concrete
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• 제24권3호
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• pp.271-282
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• 2019

Concrete undergoes a series of thermo-based physio-chemical changes once exposed to elevated temperatures. Such changes adversely alter the composition of concrete and oftentimes lead to fire-induced explosive spalling. Spalling is a multidimensional, complex and most of all sophisticated phenomenon with the potential to cause significant damage to fire-exposed concrete structures. Despite past and recent research efforts, we continue to be short of a systematic methodology that is able of accurately assessing the tendency of concrete to spall under fire conditions. In order to bridge this knowledge gap, this study explores integrating novel artificial intelligence (AI) techniques; namely, artificial neural network (ANN), adaptive neuro-fuzzy inference system (ANFIS) and genetic algorithm (GA), together with traditional statistical analysis (multilinear regression (MLR)), to arrive at state-of-the-art procedures to predict occurrence of fire-induced spalling. Through a comprehensive datadriven examination of actual fire tests, this study demonstrates that AI techniques provide attractive tools capable of predicting fire-induced spalling phenomenon with high precision.

• Clinical and Experimental Reproductive Medicine
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• 제49권3호
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• pp.215-218
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• 2022

Herein, we report an exceptionally rare case of a 25-year-old woman with cloacal exstrophy/omphalocele-exstrophy-imperforate anus-spinal defects (OEIS) syndrome achieving a viable pregnancy despite many gastrointestinal and genitourinary malformations and multiple respective corrective operations. The patient was born with two vaginas, two uteruses, four ovaries, an imperforate anus, a large omphalocele including bowel and bladder exstrophy, and diaphysis of the pubic rami. This patient is the only documented OEIS patient not to have tethered spinal cord as an anomaly, perhaps contributing to her successful pregnancy. After experiencing preeclampsia with severe features at 35 weeks, the baby was born via cesarean section.

• 국제학술발표논문집
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• The 1th International Conference on Construction Engineering and Project Management
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• pp.377-382
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• 2005

The tools, methods and measures used for project control reflect underlying theories of management. Management theory has been neglected in the construction industry, which has rather focused on tools and neglected theory. This paper contributes to the theory of project management by introducing and developing two fundamental and competing conceptualizations of management: MBM (Managing-by-Means) and MBR (Managing-by-results). Current project control and performance measurement practice is based on MBR. However, project control based on MBR may not be appropriate for managing dynamic projects. The paper present the Last Planner^TM System (LPS) and Process Variance Control (PVC) as examples of methods reflecting the MBM view. It is argued first that the MBM view is appropriate for managing uncertain, complex and quick projects. The paper also explores how MBR tools and techniques may be appropriately used within an MBM framework.