• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.3
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• pp.239-245
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• 2002

Many civil and infrastructures continue to be used despite aging and the associated potential for damage accumulation. Therefore, the ability to monitor the health of these systems is becoming increasingly important. The purpose of this paper is to propose a real-time health monitoring system of cable-stayed bridge, based-on non-destructive measurement. And also this paper focuses on the safety assessment for bridge from health monitoring system to accomplish this safety assesment. Using the proposed health monitoring system, it helps bridge maintenance and reduces the economic cost of a life-cycle costs. Also it give important data to develop the design and analysis method for cable-stayed bridges.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.3
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• pp.307-312
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• 2001

Ultrasonic signals from Charpy impact test specimen have been analyzed in order to evaluate the integrity of reactor pressure vessel. Base and weld metal that were extracted from reactor vessel doting plant outages according to the schedule of the surveillance test required by the related regulations have been used and the ultrasonic test parameters including velocity, attenuation, etc. showed a close correlations with the amount of neutron irradiation for base metal, relatively homogeneous materials. This result showed certain possibility where a nondestructive method could be used to predict the fluence of the Irradiation due to neutron in nuclear reactor vessel materials.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.5
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• pp.497-502
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• 2010

Many forces are pressuring utilities to reduce operating and maintenance costs without cutting back on reliability or availability. Many utility managers are re-evaluating maintenance strategies to meet these demands. To utilities how to reduce maintenance costs and extent the effective operating life of equipment, predictive maintenance technique can be adapted. Predictive maintenance has three types program which arc in-house program, engineering company program and mixed program. We can approach successful predictive maintenance program with "smart trust" concept.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.6 no.3
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• pp.189-203
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• 2008

The physical and chemical properties of radioactive waste drums, which have been temporarily stored on site, should be characterized before their shipment to a disposal facility in order to prove that the properties meet the acceptance guideline. The investigation of NDT(Nondestructive Test) method was figured out that the contents in drum, the quantitative analysis of free standing water and void fraction can be examined with X-ray NDT techniques. This paper describes the characteristics of X-ray NDT such as its principles, the considerations for selection of X-ray system, etc. And then, the waste drum characteristics such as drum type and dimension, contents in drum, etc. were examined, which are necessary to estimate the optimal X-ray energy for NDT of a drum. The estimation results were that: $(R)\acute{A}$ the proper X-ray energy is under 3 MeV to test the drums of 320 ${\beta}\S$ and less; $(R)\ddot{E}$ both X-ray systems of 450 keV and/or 3 MeV might be needed considering the economical efficiency and the realization. The number of drums that can be tested with 450 keV and 3 MeV X-ray system was figured out as 42,327 and 18,105 drums (based on storage of 2006. 12), respectively. Four testing scenarios were derived considering equipment procurement method, outsourcing or not, etc. The economical and feasibility assessment for the scenarios was resulted in that an optimal scenario is dependent on the acceptance guide line, the waste generator's policy on the waste treatment and the delivery to a disposal facility, etc. For example, it might be desirable that a waste generator purchases two 450 keV mobile system to examine the drums containing low density waste, and that outsourcing examination for the high density drums, if all NDT items such as quantitative analysis for 'free standing water' and 'void fraction', and confirmation of contents in drum have to be characterized. However, one 450 keV mobile system seems to be required to test only the contents in 13,000 drums per year.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.4
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• pp.331-338
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• 2008

Ultrasonic testing for welds is widely used to ensure the integrity of facilities in NPPs. Automated ultrasonic testing(AUT) is more consistent than the manual ultrasonic testing(MUT). It can scan welded parts, examines the scanned images, and saves the results as data files. AUT in NPPs is making use of commercial systems, and there has been some difficulties in calibration of the system. An AUT system is developed. It comprises of pulser/receiver, scanner and a control program(SonicWizard). The performance demonstration for piping welds in NPPs and the piping wall thickness measurement on site were conducted to verify this system. The test results of the ultrasonic testing system developed is satisfactory and effective.

• 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.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.5
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• pp.508-515
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• 2011

Bovine incisor was investigated using active infrared thermography(IRT) to visualize crack on bovine teeth. An artificial crack was carefully created in bovine incisor sample by compression load of universal tensile machine. While applying a sinusoidal heat wave to the cracked bovine incisor through halogen lamp, consecutive digital infrared images was captured from the sample surface at a frequency synchronized with heat excitation. Phase information of thermal image was calculated by four-point correlation method and processed to produce the phase image of bovine incisor. This phase image showed clearly the crack on the incisor, which was hardly detected in traditional passive thermography.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.2
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• pp.181-186
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• 2013

We present nondestructive characterization for remanent life of advanced ferritic steels, next-gen energy facility materials by reversible permeability. The reversible permeability is based on the theory that the value of reversible permeability is the same differential of the hysteresis loop. The measurement principle is based on the foundation of harmonics voltage induced in a sensing coil using a lock-in amplifier tuned to the frequency of the exciting one. The peak interval of reversible permeability(PIRP), Vickers hardness, and tensile strength(TS) of the aged samples decreased with aging time. We could estimate the remanent life of advanced ferritic steel by using the relationship between the peak interval of reversible permeability and Larson-Miller parameter(LMP), non-destructively.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.5
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• pp.518-525
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• 2012

In this study, the feasibility of hyperspectral reflectance imaging technique was investigated for the discrimination of viable and non-viable lettuce seeds. The spectral data of hyperspectral reflectance images with the spectral range between 750 nm and 1000 nm were used to develop PLS-DA model for the classification of viable and non-viable lettuce seeds. The discrimination accuracy of the calibration set was 81.6% and that of the test set was 81.2%. The image analysis method was developed to construct the discriminant images of non-viable seeds with the developed PLS-DA model. The discrimination accuracy obtained from the resultant image were 91%, which showed the feasibility of hyperspectral reflectance imaging technique for the mass discrimination of non-viable lettuce seeds from viable ones.

• Journal of the Korean Society for Nondestructive Testing
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• v.12 no.3
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• pp.20-32
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• 1992

국제표준화기구(國際標準化機構)(ISO)의 비파괴시험(非破壞檢査) 기술자(技術者)의 기량인정(技量認定)및 인증에 관(關)한 국제친격안(國際規格案) DIS 9712를 번역, 소개(紹介)한다. 이 문서(文書)는 현재(現在)로는 안(案)에 불과하지만 부원간(不遠間) 회원국(會員國) 각국(各國)이 투표(投票)에 의(依)해서 결정(決定)되게될 것이다. 구주(歐州)의 대부분(大部分) 국가(國家)는 적극적(積極的)으로 찬성(贊戚)을 하고 있고 개발도상국(開發途上國)에서는 동조(同調)를 하고 있으며 일본(日本)도 찬성(贊成)을 표명하고 있다. 반대(反對)하는 나라는 놀랍게도 미국(美國)과 서독(西獨)이지만 대립점(對立點)이 몇가지로 좁혀지고 있고 타협책(妥協策)이 모색되고 있어서 국제규격(國際規格)으로써 확정(確定)되는 것은 시간문제(時間問題)인 것으로 보이며 정식(正式) 문서화(文書化) 하기까지는 아마도 시간(時間)이 좀 걸릴 듯하다. 많은 나라가 이 문서(文書)를 전제(前提)로 해서 비파괴시험(非破壞檢査) 기술자격(技術資格)에 대(對)한 인정(認定)의 국제통합(國際統合)을 추진(推進)하고 있다. 일본(日本)도 1989년(年)에 종래사용(從來使用)해오던 규정(規程)을 개정(改訂)하였으며 국제통합(國際統合)을 더욱 진전(進展)시키기 위(爲)하여 자국(自國)의 인정규정(認定規程)과 국제규격안(國際規格案)과의 항목별(項目別)로 비교검토(比較檢討)하고 있다. 우리나라의 기술자격인정제도(技術資格認定制度)는 국가기술자격법(國家技術資格法)에 의거(依據)하여 한국산업인력관리공단(韓國産業人力管理公團)에서 주관(主管)하여 실시(實施)하고 있는 반면(反面) 미국(美國), 구주(歐州) 등(等) 대다수(大多數)의 나라가 정부(政府)의 위임하(委任下)에 협회(協會) 등(等)의 단체(團體)에서 주관(主管)하여 실시(實施)하고 있는 것이 특징(特徵)이며 기술자격(技術資格)의 등급면(等級面)에서도 대부분의 국가(國家)가 Level 1, 2 및 Level 3의 3등급(等級)으로 구분(區分)하여 실시(實施)되고 있는데 현행(現行) 우리나라는 기능사(技能師), 기능장(機能長) (기능대졸업자(機能大卒業者) 대상), 기사(技師) 1, 2급 및 기술사(技術士)로 세분(細分)되어 실시(實施)되고 있다. 국제표준화(國際漂準化) 기구(機構)(ISO)의 비파괴검사(非破壞檢査) 기술자(技術者)의 기량인정(技量認定)및 인증에 대(對)한 국제규격(國漂規格)이 마무리 단계에 있고 많은 나라에서 국제통합(國際統合)을 추진(推進)하고 있는 추세여서 우리나라도 이에 대응해 나아가야 할 것으로 사료(思料)된다.