• Structural Engineering and Mechanics
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• 제77권5호
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• pp.637-650
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• 2021

The paper presents an investigation of the widely varying mechanical performance and behaviour of steel and Glass Fibre Reinforced Polymer (GFRP) reinforced concrete beams using non-destructive techniques of Acoustic Emission (AE) and Digital Image Correlation (DIC) under four-point bending. Laboratory experiments are performed on both differently reinforced concrete beams with 0.33%, 0.52% and 1.11% of tension reinforcement against balanced section. The results show that the ultimate load-carrying capacity increases with an increase in tensile reinforcement in both cases. In addition to that, AE waveform parameters of amplitude and number of AE hits successfully correlates and picks up the divergent mechanism of cracking initiation and progression of failure in steel reinforced and GFRP reinforced concrete beams. AE activity is about 20-30% more in GFRP-RC beams as compared to steel-RC beams. It was primarily due to the lower modulus of elasticity of GFRP bars leading to much larger ductility and deflections as compared to steel-RC beams. Furthermore, AE XY event plots and longitudinal strain profiles using DIC gives an online and real-time visual display of progressive AE activity and strains respectively to efficaciously depict the crack evolution and their advancement in steel-RC and GFRP-RC beams which show a close matching with the micro-and macro-cracks visually observed in the actual beams at various stages of loading.

• 비파괴검사학회지
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• 제7권2호
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• pp.52-57
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• 1988

This article presents a newly developed equipment system for computer-aided, magneto-inductive testing of metals for material properties. The advantages of ultramodern computer technology over conventional test mothods are illustrated, in particular the greatly simplified equipment adjustment and the extended possibilities of test data evaluation. The characterisitics of the new system of equipment are demonstrated by way of practical testing examples.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2005년도 춘계학술발표회
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• pp.469-470
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• 2005

• Journal of Magnetics
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• 제16권3호
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• pp.276-280
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• 2011

This paper presents a non-destructive evaluation study on a radiator with cooling fins as a complex shaped specimen. Radiator structures are used in various heat exchangers, such as automobiles, air conditioners and refrigerators. An eddy current testing method, namely multi-frequency excitation and spectrogram method (MFES), was employed to detect a defect on the radiator tube surrounded by cooling fins. Overall, experimental results suggested that the influence of cooling fin is not as noticeable as that of the defect signals.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2001년도 정기학술대회
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• pp.239-244
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• 2001

Today, Ultrasonic is used as an important non-destructive test tool of semiconductor reliability evaluation and failure analysis. The semiconductor packaging trend goes to develop thin package, this trend makes difficult to inspect to defect in semiconductor package. One of the important problem in all semiconductor is moisture absorption in the atmosphere. This moisture causes crack or delamination to package when the semiconductor package is soldered on PCB. Reliability evaluation of semiconductor's object is investigating the effect of this moisture. For that reason, this study is investigating the effect of this moisture and reliability evaluation of semiconductor after preconditioning test and scanning acoustic microscope.

• Journal of Welding and Joining
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• 제22권5호
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• pp.32-37
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• 2004

Application of bonding by adhesives can be found in many industries, particularly in advanced technological domains such as aeronautical and space, automobile and electronics industries. Periodic inspection with conventional ultrasonic NDE techniques is capable of indicating the presence and possible location of crack. Continuous ultrasonic attenuation monitoring has potential to supply information. This article discusses the use of pulse-echo ultrasonic testing for the inspection of adhesive bonds between metal sheets. The method is based on the measurement of the reflection coefficient at the metal/adhesive interface. By means of a control experiment it is shown that Quantitative Nondestructive Evaluation in Adhesive Joints are evaluated together with Ultrasonic Testing and Fracture Testing.

• 대한기계학회논문집A
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• 제24권6호
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• pp.1398-1407
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• 2000

The structural steels of power plant show the decrease of mechanical properties due to degradation such as temper embrittlement, creep damage and softening during long-term operation at high temper ature. The typical causes of material degradation damage are the creation and coarsening of carbides(M23C6, M6C) and the segregation of impurities(P, Sb and Sn) to grain boundary. It is also well known that material degradation induces the cleavage fracture and increases the ductile-brittle transition temperature of steels. So, it is very important to evaluate degradation damage to secure the reliable and efficient service condition and to prevent brittle failure in service. However, it would not be appropriate to sample a large test piece from in-service components. Therefore, it is necessary to develop a couple of new approaches to the non-destructive estimation technique which may be applicable to assessing the material degradation of the components with not to influence their essential strength. The purpose of this study is to propose and establish a new electrochemical technique for non-destructive evaluation of material degradation damage for Cr-Mo steels which is widely used in the high temperature structural components. And the electrochemical anodic polarization test results are compared with those of semi-nondestructive SP test.

• 시스템엔지니어링학술지
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• 제12권1호
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• pp.59-71
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• 2016

The Nuclear and Fossil Steam Turbines record a considerable number of failures annually. Some of these failures reported are as result of blade failure. The failure of the L-0 blade in a Steam Turbine is one of the most reported blade failure in Nuclear and Fossil steam turbines. This paper seeks to identify the best Non Destructive Evaluation (NDE) method or methods to be used in the steam turbine L-0 blades inspection process. The development of systems engineering processes presents an opportunity to apply NDE inspection to the L-0 blades. This process apply computer modelling of the L-0 using ANSYS and by simulating the stresses experienced by the L-0 blade during operation it is possible to identify the most susceptible areas for crack formation and growth. The results from these models compared to industry data for validation. The analysis of these results used to predict the most probable failure location and failure modes. Therefore NDE inspection can be applied to these areas with greater degree of accuracy. This would be beneficial in the increasing the accuracy in the detection of cracks and hence save inspection time and the overall inspection cost. Furthermore, not only the location for crack formation and NDE inspection determined but also best the NDE inspection technique/techniques to be applied appropriately on the L-0 blade are prescribed.

• 비파괴검사학회지
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• 제26권1호
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• pp.12-17
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• 2006

원자력발전소의 증기발생기는 수천 개의 매우 얇은 두께의 튜브로 구성되어 있다. 이러한 증기발생기의 튜브는 원자력발전소의 1차 계통과 2차 계통의 압력경계를 유지하는 데에 매우 중요한 역할을 하고 있으며, 고온 고압의 열 수력적 상호작용으로 인한 가혹한 운전조건으로 인하여 손상되기 쉽다. 따라서 증기발생기의 구조적 건전성을 평가하기 위하여 많은 시간과 노력이 투입되고 있다. 와전류 검사 방법이 증기발생기 튜브의 건전성을 평가하기 위한 가장 보편적인 비파괴 방법이지만, 와전류 검사의 특성상 결함의 전체 체적에 의하여 신호의 특성이 나타나게 되어 정확한 결함의 크기를 평가하기에는 한계가 있다. 본 연구에서는 증기발생기 튜브의 결함 검출과 정확한 측정을 위하여 초음파 검사기법의 적용 가능성을 확인하였으며, 연구결과를 증기발생기 튜브 검사에 적용 할 경우 검사결과가 크게 향상 될 것으로 기대된다.

• 한국식품과학회지
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• 제22권6호
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• pp.675-680
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• 1990

관능검사에 의존하여 오던 종래의 고추 품질평가법을 탈피하여 매운맛 성분인 capsaicin, 적색색소인 capsanthin, total sugar 및 수분함량을 근적외 분광분석법으로 화학약품을 사용하지 않고 신속, 정확하게, 동시에 측정 할 수 있는 방법을 조사하였다. 기존의 화학분석 방법에 의해 측정한 상기 성분들의 함량치와 근적외 스펙트럼 데이타간에 중회귀분석을 행하여 각각의 성분측정을 위한 검량식을 작성하였다. 이들 검량식을 미지의 고추시료에 적용시켜 구한 분석치와 기존 분석법으로 구한 분석치를 비교한 결과, capsanthin과 total sugar는 근적외 분광분석법에 의해 정량적으로 측정할 수 있음을 알 수 있었다.