• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.1
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• pp.56-63
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• 2012

In this study, a field applicability of reboiler tube was evaluated by comparing ECT signal with IRIS signal about wall loss rate and remaining wall thickness using worked austenite STS 316L ASME standard calibration tube. In the case of wall-loss rate, as a result, tolerance about $20%{\times}4$ flat bottom hole and 10% O D groove(ECT), 80% defect and 10% O D groove(IRIS) occurred up to ${\pm}15%$. In the case of remaining wall thickness, ECT was satisfied with the both tolerance, but tolerance about 80% defect occurred up to ${\pm}15%$ in IRIS. Therefore, if the IRIS is performed for interpretation of non-relevant indication and measurement of wall-loss rate after ECT, reliability is supposed to be improved.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.5
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• pp.561-564
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• 2001

The cladding area of HANARO Research Reactor fuel rods should be checked not to have any defects larger than the size required at QA documents by using eddy torrent testing method doting fabrication process. To apply eddy current testing inspection to the fuel rods, encircling differential probes and standard specimen were designed and fabricated. The impedance of the fabricated probes was measured with impedance analyzer in order to cheek that the probe has a suitable impedance for the inspection frequency, and with this probe and MIZ-40A eddy current equipment, the detectability of this probes was investigated. The developed probes could detect artificial notch with 2mm length 10% depth of cladding thickness in cladding area. In addition, the probe was successfully applied to detect the defects in cladding area doting fabrication of the research reactor rods.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.5
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• pp.431-437
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• 2000

Standard Test Block(STB) for UT(Ultrasonic Testing) is a block approved by authoritative for material, shape and quality. STB is used for characteristic tests, sensitivity calibration and control of the time base range of UT inspection devices. The material, size and chemical components of STB should be strictly controled to meet the related standards such as ASTM and JIS because it has an effect upon sensitivity, resolution and reproductivity of UT. The STBs which are not approved are sometimes used because the qualified STBs are very expensive. So, the purpose of this study is to survey the characteristics, quality and usability of Non-Standardized Test Blocks. Non-Standardized Test Blocks did not meet the standard requirements in size or chemical components, and ultrasonic characteristics. Therefore if the Non-Standardized Test Blocks are used without being tested, it's likely to cause errors in detecting the location and measuring the size of the defects.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.4
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• pp.330-337
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• 2010

In this paper, 3-dimensional electromagnetic numerical analysis is performed about the eddy current(EC) array probe characteristic which is the next generation probe for accurate diagnosis of steam generator(SG) in nuclear power plants(NPPs). ASME(American Society of Mechanical Engineers) Standard and X-probe combo calibration standard tube are selected for acquisition of eddy current testing(ECT) signals and this result of compared with the real test signals for reasonability of result. Based on the analysis result of calibration standard tube, ECT signals that are about the defects of pitting, stress corrosion cracking(SCC), multiple SCC and wear is obtained. Material of specimen was Inconel 600 which is usually used for SG tubes in NPPs. The operation frequency of 300 kHz were used. The signal characteristics could be observed according to the various defects. The results in this paper can be helpful when the ECT signals from EC array probe are evaluated and analyzed.

• Journal of the Korean Society for Nondestructive Testing
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• v.16 no.3
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• pp.162-173
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• 1996

Dry magnetic particle inspection(MPI) was performed to detect the surface defects of steel ingot cast billets. Magnetic properties of several materials were characterized by the measurement of the B-H hysteresis curve. The inspection results were evaluated in terms of the magnetizing current, temperature, and the amount of magnetic particles applied to billets. Magnetic flux leakage near the defect site of interest was measured and compared with the results of calculation by the finite element method in the case of direct magnetizing current. Direct and alternating magnetizing currents for materials were deduced by the comparison of the inspections. Results of the magnetic particle inspection by direct magnetizing current were compared with those of finite element method calculations, which were verified by measuring magnetic leakage flux above the surface and the surface defects of the material. For square rods, due to the geometrical effect, the magnetic flux density at the edges along the length of the rods was about 30% of that at the center of rod face for a sufficiently large direct magnetizing current, while it was about 70% for an alternating magnetizing current. Thus, an alternating magnetizing current generates rather uniform magnetic flux density over the rods, except for the region on the face across about 10 mm from the edge. The attraction of the magnetic particle by the magnetic leakage field was nearly independent of the surface temperature of the billets up to $150^{\circ}C$. However, the temperature should have been limited below $60^{\circ}C$ for an effective fixing of gathered magnetic particles to the billet surface using methylene chloride. We also found that the amount of applied magnetic particles tremendously affected the detection capability.

• Journal of the Korean Society for Nondestructive Testing
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• v.13 no.2
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• pp.94-100
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• 1993

이번 호부터 해설란을 통하여 비파괴검사(非破壞檢査) 기술(技術)에 대한 연재를 시작한다. 앞으로 비파괴검사(非破壞檢査) 기술(技術) 각 분야에 대해 다룰 예정이며 우선 1차적으로 와전류탐상법(渦電流探傷法)에 관해 3회에 걸쳐 게재하기로 한다. 특정한 비파괴검사(非破壞檢査)의 전문가가 아니더라도 쉽게 이해할 수 있도록 가급적 수식은 배제하고 기초적인 이론을 소개할 것이며 특히 현장 적용에 중점을 두어 기술(記述)하고자 한다. 본 원고에서는 원거리 와전류탐상법(渦電流探傷法)(remote field eddy current testing) 이나 펄스 와전류탐상법(渦電流探傷法)(pulsed eddy current testing)과 같은 특수 와전류(渦電流) 기술(技術)은 제외하였으며 본 연구실에서 내부 교육용으로 사용하는 "와전류탐상법(渦電流探傷法) Level I 과정"과 미국금속학회에서 발행한 Metal Handbook, 9th ed., Vol. 17, "Non-destructive Evaluation and Quality Control" 및 기타 관련 기술 자료들을 참고하였으나 일일이 명기하지는 않는다.

• Journal of Ocean Engineering and Technology
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• v.13 no.4 s.35
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• pp.45-54
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• 1999

Non destructive test is applied to revise mechanical strength and assume material strength or defect of material, equipment and structure, instead of fracture test. Especially, ultrasonic test has the characteristics such as an excellent permeability high-sensitiveness to fine defect and an almost exact measurement for position, size and direction of inner defect which differ from other non destructive tests. In this study, the program is developed to evaluate optimal testing condition, to distinguish obstacle echo and defect position. This program on the basic of Ray-Tracing model shows generation and processing of ultrasonic pulse. The simulation is compared with testing in the 3 cases of an oblique angle transducer like $45^{\circ},\;60^{\circ}\;and\;70^{\circ}$. The test result for all conditions is well compared with simulation result when relative not is within $0.1{\sim}7.2%$. And the course of several echos is simply assumed through simulation.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.62-64
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• 2007

자기누설 탐상(Magnetic Flux Leakage)시스템은 비파괴 검사의 일종으로 대상 물체를 자화시켜 결함 부위에서 자기 누설량을 측정함으로써 구조물의 결함 및 부식 등을 탐지하는 시스템이다. 지하 가스배관의 결함 판정에 있어 기존의 신호처리 기법을 통한 노이즈 제거와 검출 성능 향상은 한계가 있다. 이는 후처리 단계로써 각종 노이즈를 포함하고 있기 때문이다. 따라서 검출 신호 크기의 증가를 통한 결함 검출 성능을 향상시키기 위해 논문에서는 브러쉬와 백요크의 크기 및 형상 변화에 따른 자기장 분포 해석을 하고 시스템 제작 및 실험을 통해 자기누설 탐상 시스템의 성능 향상을 검증하였다.

• Proceedings of the KWS Conference
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• 2003.11a
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• pp.106-109
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• 2003

지능형 초음파 탐상 시스템은 재래식 초음파 탐상시험에서 주된 논란의 대상이 되는 검사의 객관성과 신뢰성, 그리고 일반화된 검사자료의 데이터베이스화 문제를 해결할 수 있는 해법으로 제시 되었다. 또한 이 시스템은 검사의 자동화(혹은 간이자동화)를 통해 검사자에 의해 수작업으로 작성되던 피검체 및 결함관련 정보를 자동으로 계산하고 데이터베이스화함으로써, 열악한 검사환경에서도 최선의 능률을 제공할 수 있는 기반을 제공한다. 본 논문에서는 지능형 시스템의 개발을 위해 필요한 요소기술과 개발된 시스템의 전반에 관하여 논한다.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.19-21
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• 2005

자기누설탐상시스템은 비파괴 검사의 한 방법으로 검사 대상물체를 자화시켜 부식이나 결함부위에서 자기누설을 측정하는 방법으로 Magnetic Flux Leakage(MFL) PIG는 자기누설 탐상시스템을 가스관에 적용하여 결함 유 무를 검사하는 시스템이다. 가스관에는 결함이외에 가스공급을 위해 필요한 여러 가지 구조물이 있으며 이러한 구조물은 부식이나 결함에 의해 발생하는 자기누설과는 구별이 된다. 따라서 가스관의 구조물과 결함을 구분하기 위하여 가스관의 구조물에 대한 자기적 영향 해석과 결함 신호와의 차이점을 비교, 분석하였다.