• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.803-808
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• 2001

Mathematical basis of interpretation of data from nondestructive evaluation (NDE) methods in bridge inspection is presented. In bridge inspection with NDE methods, NDE data are not assessments. NDE data must be interpreted as condition of element. Interpretation is then assessment. Correct assessments of conditions of bridge elements depend on the accuracy and variability in test data as well as on the uncertainty of correlations between attributes (what is measured) and conditions (what is sought in the inspection). Inaccuracy and variability in test data defines the qualify or NDE test. The qualify or test itself is important, but in view of condition assessment, the significance of uncertainty in correlations of attributes and conditions must be combined. NDE methods that are accurate in their measurements may still be found to be poor methods if attributes are uncertain indicators of condition of bridge elements. This paper reports mathematical presentation of inaccuracy and variability in test data and of uncertainty in correlation of attributes to element conditions with three examples of NDE methods.

• 한국구조물진단유지관리공학회 논문집
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• 제11권3호
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• pp.167-175
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• 2007

정밀한 구조물의 상태진단 혹은 안전성 평가는 비파괴 시험의 정밀성(Accuracy), 변이성(Variability) 등과 같은 여러 가지 요소에 의하여 좌우된다. 특히 비파괴 시험을 이용한 측정값과 구조물의 상태에 있어서의 불확실성(Uncertainty)은 정밀한 상태진단에 큰 영향을 미친다. 비파괴 시험을 활용함에 있어서의(간접조사) 신뢰할만한 비파괴 장비라면 현 구조물의 상태(피해면적)를 정확하게 나타낼 수 있어야 한다. 본 논문은 현재 사용이 증가되고 있는 비파괴 장비의 올바른 선택과 정확한 구조물의 안전 진단을 위하여, 비파괴장비의 성능 평가에 있어 확률적 기초를 제공한다.

• 한국구조물진단유지관리공학회 논문집
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• 제13권5호통권57호
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• pp.101-108
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• 2009

비파괴 시험을 이용한 RC 구조물의 진단에 있어서 비파괴 측정값의 적절한 해석을 통해서만 현 구조물의 상태진단이 가능하다. 보다 정확한 구조물의 상태진단은 비파괴 시험의 정밀성, 변이성 등과 같은 여러 가지 요소에 의하여 좌우된다. 특히 비파괴 시험을 이용한 측정값과 구조물의 상태에 있어서의 불확실성은 정밀한 상태진단에 큰 영향을 미친다. 본 논문은 현재 사용이 증가되고 있는 비파괴 장비의 올바른 선택과 정확한 구조물의 진단을 위하여, 비파괴 측정값의 확률적 해석법의 기초를 제공하고 있다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.190-194
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• 2003

Two different types of nondestructive evaluation (NDE) techniques were employed to investigate the tensile behavior of ceramic matrix composites (CMCs). Two NDE methods, ultrasonic testing (UT) and infrared (IR) thermography, were used to assess defects and/or damage evolution before and during mechanical testing. Prior to tensile testing, a UTC-scan and a xenon flash method were performed to obtain initial defect information in light of UT C-scans and thermal diffusivity maps, respectively. An IR camera was used for in-situ monitoring of progressive damages. The IR camera measured temperature changes during tensile testing. This paper has presented the feasibility of using NDE techniques to interpret structural performance of CMCs.

• Journal of the Korean Wood Science and Technology
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• 제31권2호
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• pp.31-37
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• 2003

목재의 결함을 탐지하는 비파괴 진단법 중에서 초음파를 이용한 비파괴 시험법은 그 경제성과 사용에서 큰 장점을 지니고 있어, 그 활용과 관련된 연구가 활발히 진행 중이다. 그러나 현재까지의 연구는 입목 또는 원목 등과 같이 비파괴 평가를 위한 측정이 비교적 적은 경우에 국한되어 있어, 목조 문화재 등을 비롯한 구조물의 부재와 같이 부재의 일부 면만을 측정할 수 있는 경우에 대한 연구가 미비한 실정이다. 따라서 본 연구에는 이러한 초음파 시험기의 측정방법의 제한을 극복하는 방법을 모색하고자 그 첫 번째 단계로 결함을 갖는 목재 내에서 초음파 전달 경로를 구명하고자 하였다. 다양한 전달 경로 모델을 가정하고 실제 실험과 비교를 통해 초음파 전달의 가장 적합한 모델을 제시하고자 한다. 실험 시편에 인위적인 결함을 만들어 실험한 결과 초음파가 직접 전달될 수 없는 부분의 경우 그 결함을 피해서 전달되고 전달 경로는 탐촉자의 반대 측면에서 일차반사를 통해 전달되는 것으로 판단되었다.

• 비파괴검사학회지
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• 제25권3호
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• pp.189-200
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• 2005

Ultrasonic inspection methods are widely used for detecting flaws in materials. One of the more popular methods involves the extraction of an appropriate set of features followed by the use of a neural network for the classification of the signals in the feature space. This paper describes an approach which uses LMS method to determine the coordinates of the ultrasonic probe followed by the use of SAFT to estimate the location of the ultrasonic reflector The method is employed for classifying NDE signals from the steam generator tubes in a nuclear power plant. The classification results using this scheme for the ultrasonic signals from cracks and deposits within steam generator tubes are presented.

• Journal of Korean Neurosurgical Society
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• 제48권6호
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• pp.506-517
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• 2010

Objective : We investigated whether Disability Evaluation (DE) situations influence patients' neuropsychological test performances and psychopathological characteristics and which variable play a role to establish an explanation model using statistical analysis. Methods : Patients were 536 (56.6%) brain-injured persons who met inclusion and exclusion criteria, classified into the DE group (DE; n = 300, 56.0%) and the non-DE group (NDE; n = 236, 44.0%) according to the neuropsychological testing's purpose. Next, we classified DE subjects into DE cluster 1 (DEC1; 91, 17.0%), DE cluster 2 (DEC2; 125; 23.3%), and DE cluster 3 (DEC3; 84, 15.7%) via two-step cluster analysis, to specify DE characteristics. All patients completed the K-WAIS, K-MAS, K-BNT, SCL-90-R, and MMPI. Results : In comparisons between DE and NDE, the DE group showed lower intelligence quotients and more severe psychopathologic symptoms, as evaluated by the SCL-90-R and MMPI, than the NDE group did. When comparing the intelligence among the DE groups and NDE group, DEC1 group performed worst on intelligence and memory and had most severe psychopathologic symptoms than the NDE group did. The DEC2 group showed modest performance increase over the DEC1 and DEC3, similar to the NDE group. Paradoxically, the DEC3 group performed better than the NDE group did on all variables. Conclusion : The DE group showed minimal "faking bad" patterns. When we divided the DE group into three groups, the DEC1 group showed typical malingering patterns, the DEC2 group showed passive malingering patterns, and the DEC3 group suggested denial of symptoms and resistance to treatment.

• 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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• 제28권3호
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• pp.263-272
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• 2008

Many technical methods are used for nondestructive testing field for solid materials. Among those, ultrasonic inspection methods are widely used and one of the popular methods involves the extraction of an appropriate set of features followed by the use of a neural network for the classification of the signals in the feature space. This paper describes an approach which uses LMS method to determine the coordinates of the ultrasonic probe followed by the use of SAFT with centroid technique to estimate the location of the ultrasonic reflector. The method is employed for classifying UT-NDE signals from the steam generator tubes in a nuclear power plant. The classification results are presented for the ultrasonic signals from cracks and deposits within steam generator tubes.

• Tribology and Lubricants
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• 제26권6호
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• pp.341-345
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• 2010

The NAUT(Non contact Air coupled Ultrasonic Testing) is one of the ultrasonic wave inspection methods. It compensates High power ultrasound Pulser Receiver, pre-amp, air probe of high sensitivity in air to generate loss energy by NAUT methods. Generally, in case of ultrasound inspection, it applies contact methods by using couplant. However it can inspect of UT without couplant by this NAUT. The ultrasound transmission reception is composed in stable condition in NAUT. It can inspect high low material or the specimen of rough part, the narrow spot, too. The spot welding is applying the inosculation of automobile component, car body, all boards. The CFRP is necessity of NDE because of the solidity changes material according to lamella tearing. Therefore it checked on realization whether and commercialization in the spot welding and CFRP inspection that the NAUT would be applied them.