• Journal of Welding and Joining
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• v.12 no.4
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• pp.1-10
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• 1994

이 글에서는 비파괴검사개론에 관하여 알아보았다. 1. 비파괴검사의 의의 1.1 비파괴검사의 역사 1.2 비파괴검사의 원리 1.3 비파괴검사의 목적과 역할 1.3.1 품질관리 1.3.2 생산원가의 절감 1.3.3 품질의 평가 1.3.4 점검 1.4 비파괴검사자의 역할 2. 비파괴검사자의 방법 2.1 방사선투과시험 2.1.1 직접촬영법 2.1.2 투시법 2.1.3 전자사진법 2.1.4 계기법 2.2 초음파탐상시험 2.2.1 음향검사와 초음파탐상 2.2.2 초음파의 성질과 종류 2.2.3 접촉매질 2.2.4 초음파 탐상 방법 2.2.5 초음파 탐촉자 2.3 자기탐상시험 2.3.1 자기탐상 원리 2.3.2 자기탐상 방법 1) 자장측정 탐상법 2) 자기기록 탐상법 3) 탐사 코일법 4) 자분탐상시험 2.3.3 자분탐상시험 2.4 침투탐상시험 2.4.1 침투탐상시험의 원리 2.4.2 침투탐상시험법의 기본 1) 침투탐상시험의 종류 2) 현상체의 종류 2.4.3 침투탐상시험의 장단점 2.5 전자유도시험 (와전류탐상법) 2.5.1 와전류의 발생과 탐지 2.5.2 와전류의 탐지 2.5.3 와전류 탐촉자 2.5.4 와전류 탐상시험의 적용과 장단점.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.2
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• pp.197-203
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• 2001

Micro-defects induced by design and production failure or working environments are known as the cause of SCC(Stress Corrosion Cracking) in aged structures. Therefore, the evaluation of structural integrity based on micro-cracks is required not only a manufacturing step but also in-service term. So we introduce a new nondestructive inspection method using the magneto-optical film to detect micro-cracks. The method has some advantage such as high testing speed, real time data acquistion and the possibility of remote sensing by using of a magneto-optical film that takes advantage of the change of magnetic domains and domain walls. This paper introduces the concept of the new nondestructive inspection method using the magneto-optical film, also proves the possibility of this method as a remote testing system under oscillating load considering application on real fields by applying the method to four types of specimens.

• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.5
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• pp.384-390
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• 2005

In the numerical analysis of En (eddy current testing) using 3-dimensional FEM (finite element method), MVP (magnetic vector potential) and electric scalar potential are used as variables in conductor region. Three dimensional modeling makes number of unknowns increase, and the degree of freedom of variables also makes number of unknowns increase. Because of this reason, modified UP is used to reduce the number of unknowns. Gauge condition is enforced artificially on existing FEM formulations to insure the uniqueness of MVP. So in this paper the effects of these FEM formulation procedures on ECT are investigated and the appropriate FEM formulation is suggested for accurate ECT simulation.

• Journal of Welding and Joining
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• v.21 no.4
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• pp.19-24
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• 2003

• Journal of the Korean Institute of Gas
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• v.15 no.2
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• pp.27-32
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• 2011

In this paper a new defect length estimation algorithm using SQI(self quotient image) is presented for the MFL(magnetic flux leakage) inspection of underground gas pipelines. Gas pipelines are magnetized by the permanent magnets of the MFL PIG(pipeline inspection gauge) when the PIG runs through pipelines. If defects or corrosions exist in the pipeline, magnetic leakage flux is increased. The MFL signals measured by hall sensors are analyzed to estimate defect length using SQI. For 74 real defects carved in KOGAS pipeline simulation facility(KPSF) the accuracy of defect length estimation of the proposed algorithm was compared with that of conventional methods.

• Journal of the Korean Magnetics Society
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• v.10 no.6
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• pp.302-309
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• 2000

An MFL (Magnetic Flux Leakage) testing system has been developed in order to inspect the non-metallic inclusions in the thin steel sheets. We have made a differential type flux-gate magnetometer using the measurement of apparent coercive field strength of soft magnetic core. The specifications of the electromagnet was determined using FEM software, and MFL testing system with 3 axis degree of freedom was constructed. The feasibility testing for non-metallic inclusion was shown using the system. By digitizing MFL signal and using 2-D graphic display, we could identify various surface defects other than the inclusions.

• Journal of the Korean Magnetics Society
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• v.15 no.6
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• pp.325-331
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• 2005

The magnetic Hut leakage (MFL) type nondestructive testing (NDT) method is widely used to detect corrosion and defects, mechanical deformation of the underground gas pipelines. The object pipeline is magnetically saturated by the magnetic system with permanent magnet and yokes. Because of the strong magnetic field enough to saturate the pipe, there could be distortion of the sensing signals because of the magnetization of the pipeline itself, To detect the defects precisely, the sensing signals are need to be compensated to eliminate the distortions coming from the media hysteresis. In this paper, the magnetizations of the pipeline in MFL type NDT are analyzed by Preisach model and 3D FEM. The distortions of the sensing signals are analyzed.

• Journal of the Korean Magnetics Society
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• v.15 no.5
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• pp.292-297
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• 2005

Steam generator of a nuclear power plant has important rolls for the heat transfer and the isolation of radioactive materials. So bursting of the steam generator tube is directly related to the accident of nuclear power plants. Incone1600 has been used for the steam generator tube material. The material shows non-magnetic and metallic properties, eddy current NDT method has been employed for defects detection. In this work, a differential type of eddy current probe was developed to improve resolution of defect detection. To verify properties of the developed differential type eddy current probe, we have made reference material with SUS304 which has similar magnetic and electrical properties of Inconel600. Using the developed differential type eddy current probe, we can detect defect size of 0.25 mm in diameter and 0.2 mm in depth (volume of $1{\times}10^{-3}\;mm^3$) with the reference material.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.5
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• pp.485-492
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• 2001

In this paper, electro-magnetic numerical analysis of MFL(magnetic flux leakage) method is presented. For the electromagnetic numerical analysis, 2-D FEM(finite element method) is used. The magnetic vector potential is used as a variable. The analysis of the magnetic field considering the magnetic nonlinearity is performed for the effect of the magnetic salutation. For the verification of the validity of the numerical simulation results, by using the lab-made experimental setup, non-destructive inspection is performed. The SM 45C carbon steel is used as a specimen and the artificial defects are made on the specimen. The non-destructive testing for the detection of the defect is performed. The results according to the variation oi the defect depth and the defect shape are obtained. The experimental results are compared to the numerical ones, and we conclude that the numerical results are similar to the experimental ones. So the possibility of simulation of the MFL by using the numerical analysis is shown in this paper.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.405-407
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• 2006

자기누설 탐상시스템은 자성체인 구조물에 서검사 대상 물체를 자화시켜 결함부위에서 자기 누설의 여부를 측정함으로써 구조물의 결함, 부식 등을 탐지하는 시스템이다. 본 논문에서는 소형 비파괴 검사시스템을 설계하고 제작하였다. 또한 3차원 유한요소법을 이용하여 해석하고 측정하여 결과를 비교 분석하였다.