• 비파괴검사학회지
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• 제33권1호
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• pp.26-33
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• 2013

원자로 BMI 노즐은 원자력발전 설비의 운영을 위한 핵심요소 중 하나이며 하부헤드에 설치되어 있다. 상부헤드에 비해 비교적 저온영역에 있지만 최근 외국사례에 비추어 볼 때 PWSCC의 발생 가능성이 크기 때문에 가동중 비파괴검사가 반드시 필요하다. 그러나 BMI 노즐은 원자로 하부에 있기 때문에 고방사선 구역이며 원자로 내부는 붕산수로 채워져 있기 때문에 접근이 매우 어렵다. 본 연구에서 BMI 노즐 검사를 위하여 TOFD를 이용한 탐촉자를 개발하였고, 자동화검사를 위해 내방수 기능을 가진 스캐너를 개발하였다. 또한, BMI 노즐과 동일한 재질 및 형상으로 인공결함시험편을 제작하여 자동화 비파괴검사 시스템의 성능검증을 수행하였다.

• 비파괴검사학회지
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• 제34권4호
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• pp.311-317
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• 2014

가압경수로형 원자력발전소 소유자 그룹은 ASME Sec. XI 코드의 배관 샘플링검사법 대안으로 리스크 정보를 활용한 가동중검사 프로그램(RI-ISI)을 개발 및 적용하였다. RI-ISI 프로그램은 파손 메커니즘이 있는 고위험도 배관에 검사를 집중함으로써 발전소의 전반적인 안정성을 향상시켰다. 또한, RI-ISI 프로그램은 비파괴검사 물량, 검사자 방사선 피폭, 검사 시간 등을 줄일 수 있다. 배관 RI-ISI 방법은 한국 표준형 원자력 발전소 3개호기에 적용되고 있으며 다른 발전소도 개발중에 있다. 이 논문에서는 프라마톰형(프랑스형) 원전에 대한 RI-ISI 방법을 연구하고 그 결과를 나타내었다. 프라마톰형 원전에 대한 RI-ISI 적용은 발전소 안전성을 향상시키고 유지시키며 계량화할 수 없는 이익을 준다는 결론에 도달하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제3권4호
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• pp.173-178
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• 1999

KS-code(KS B 0896) for nondestructive ultrasonic testing classifies the quality level by ratio of flaw size to plate thickness only. But stress distributions using verification(3 point bending test) show that location of the flaws is more important than the flaw size. So. KS-code should take the effect of flaw location for classifying the quality level of welded steel structures.

• 한국구조물진단유지관리공학회 논문집
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• 제3권3호
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• pp.157-165
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• 1999

The nondestructive testing methods are commonly used to determine the in-situ compressive strength of concrete. The correlation curves to evaluate the effect of aging on the development of concrete strength was proposed. Thirty two ${\Phi}10{\times}20cm$ cylinder specimens were cast from 5 batches having different strength levels. The correlation curves for rebound hammer method, ultrasonic pulse velocity method and combined method were derived from the laboratory tests and multiple regression analysis. To account for the change of condition such as surface hardness, internal moisture contents, the aging coefficients are applied to the correlation curves. From the comparison the nondestructive strength with the core strength taken from the existing reinforced concrete structures, the validity of the proposed correlation curves are verified.

• 비파괴검사학회지
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• 제35권3호
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• pp.215-220
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• 2015

최근 널리 사용되는 모든 비파괴검사 기술 중 적외선열화상 카메라는 점차 적용 범위를 확대하고 있다. 초음파적외선 열화상은 절대온도 0 K 이상의 모든 물체가 방출하는 적외선 에너지를 검출하여 검사자가 볼 수 있는 화상으로 이미지를 만들어 검사하는 기술에 초음파를 접목하여 결함 부위만을 검출하는 방법으로 비접촉으로 넓은 범위를 빠른 시간에 검사할 수 있는 장점이 있는 기술이다. 본 연구에서는 고유주파수를 변화할 수 있는 터패놀-D 소재의 가변초음파 가진검사 방법을 이용하여 결함 검출의 적용가능성을 연구하였다.

• 센서학회지
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• 제27권5호
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• pp.328-334
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• 2018

The paper reviews an improved continuous-wave (CW) terahertz (THz) imaging system developed for nondestructive inspection, such as CW-THz quasi-time-domain spectroscopy (QTDS) and interferometry. First, a comparison between CW and pulsed THz imaging systems is reported. The CW-THz imaging system is a simple, fast, compact, and relatively low-cost system. However, it only provides intensity data, without depth and frequency- or time-domain information. The pulsed THz imaging system yields a broader range of information, but it is expensive because of the femtosecond laser. Recently, to overcome the drawbacks of CW-THz imaging systems, many studies have been conducted, including a study on the QTDS system. In this system, an optical delay line is added to the optical arm leading to the detector. Another system studied is a CW-THz interferometric imaging system, which combines the CW-THz imaging system and far-infrared interferometer system. These systems commonly obtain depth information despite the CW-THz system. Reportedly, these systems can be successfully applied to fields where pulsed THz is used. Lastly, the applicability of these systems for nondestructive inspection was confirmed.

• 비파괴검사학회지
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• 제29권3호
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• pp.256-263
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• 2009

After several PWSCCs were found in Bugey(France), Ringhals(Sweden), Tihange(Belgium), Oconee, Arkansas, Crystal Fever, Davis-Basse, VC Summer(U.S.A.), Thuruga(Japan), USNRC and PNNL started the research on PWSCC, that is, the PINC project. USNRC required KINS to participate in the PINC project in May 2005. KINS organized the Korean consortium at March 2006 and Pre-RRT for RVHP were performed for the preparation of PINC RRT. Through these preliminary RRT, Korea NDE teams can learn and develop the detection and sizing technique for RVHP dissimilar metal weld. These techniques are now being prepared in Korea and need to be utilized for the In-service inspection of the RVHP and BMI of Korea Nuclear Power Plants. PINC RRT mock-ups will be helpful to training.

• 산업경영시스템학회지
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• 제11권18호
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• pp.27-34
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• 1988

This study is concerned with the development of the economic sampling inspection plan when it is possible to carry out a nondestructive screening inspection for the rejected lots by substitutive characteristics closely related to the original quality characteristic. It is assumed that the probabilities of those errors depend linearly on the fraction defective of the process sampling inspection policy for isolated lot is studied where the probability of accepting the lot with bad quality from the results of sampling inspection is restricted to be small.

• 비파괴검사학회지
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• 제1권1호
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• pp.22-31
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• 1981

• 비파괴검사학회지
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• 제27권3호
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• pp.239-245
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• 2007

A torsional guided wave mode in a tubular structure has many advantages in obtaining a higher sensitivity and lower attenuation for a defect, because it shows no dispersion characteristics and no radial displacement for a tubular structure. Many attempts have been made to excite and receive torsional guided waves by conventional piezoelectric transducers, but only a few examples are used during a practical field inspection. In this study, an array of electromagnetic acoustic transducers (EMATs) were for an excitation and reception of the torsional guided waves in a pipe was designed and fabricated. The signal patterns were analyzed based on various beam path length. The feasibility of detecting the defects was investigated through a series of experiments with artificial notches on a pipe.