• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.4
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• pp.304-310
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• 2005

The techniques in order to measure the depth of defect in weldment and structure accurately have been developed. Many researches have made efforts to develop the methods for the accurate depth sizing of defect. TOFD is known as the most accurate method of various methods for measuring depth sizing. However, there is a possibility to miss defects because of the limitation of beam coverage for the ultrasound incident angle. In this study, the results for detectability and depth sizing using phased array ultrasonic technique for thick body were compared with those of conventional TOFD technique. It was experimentally confirmed that the phased array ultrasonic TOFD technique gives good detectability and accurate depth measurement for the various types of defects. The phased array ultrasonic TOFD technique developed in this study will contribute to increase the inspection reliability in thick component such as the pressure vessel of power generation industry.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.2
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• pp.151-157
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• 2004

Ultrasonic testing is a kind of nondestructive test to detect a crack or discontinuity in materials or on material surfaces by sending ultrasound to it. This conventional ultrasonic technique has some limitations in reliably detecting crack or accurately assessing materials in the case of complex-shaped power plant components such as a turbine blade root. An alternative method for such a difficult inspection is highly needed. In this study, application of a phased array ultrasonic testing (UT) system to a turbine blade, one of the critical power plant components, has been considered, and the particular incident angle has been determined so that the greatest track detectability and the most accurate crack length evaluation nay be achieved. The response of ultrasonic phased array was also analyzed to establish a special method to determine the track )ength without moving the transducer. The result showed that the developed method for crack length assessment is a more accurate and effective method, compared with the conventional method.

• Proceedings of the Korea Contents Association Conference
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• 2015.05a
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• pp.161-162
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• 2015

본 연구는 chest PA 검사 시 교과서에서 권고하는 검사자세와 임상에서 주로 이용되고 있는 검사자세의 폐야와 견갑골의 겹침 정도 차이를 비교 고찰함으로써, 임상에서 사용되고 있는 자세의 유용성을 알아보고자 진행한 연구이다. 연구 결과 세 자세 모두 견갑골을 폐야에서 제거하는데 유사한 결과를 보였으며, 연령에 따른 겹침의 차이는 통계적 유의성이 없었으나, 임상에서 현재 임상에서 사용 중인 검사자세가 성별에 따른 겹침 면적에는 차이를 보였으며, 통계적으로도 유용한 결과는 보였다.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06a
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• pp.214-216
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• 2006

검사점 및 복구 도구는 사용자 응용 프로그램의 상태를 주기적으로 안정된 저장소에 저장을 하고, 결함이 발생하였을 경우 가장 최근의 검사점으로부터 효율적으로 복구하게 하는 도구이다. 특히 검사점 및 복구 도구는 장시간 수행되는 프로세스를 위해서는 아주 중요한 의미를 지니며, 결함으로 인해 장시간 수행되는 프로세스에 의해 생성된 중간 결과를 잃어버리지 않게 한다. 본 논문에서는 일반 범용 컴퓨터시스템 상에서 구현된 검사점 및 복구들을 리눅스 기반의 임베디드 시스템에 적용시켜 보고, 그 결과를 통해 임베디드 시스템상에서의 검사정 적용의 가능성을 알아본다.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2023.11a
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• pp.105-106
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• 2023

본연구는 콘크리트 타설과정에서 반복되는 펌프카 사고를 예방하기 위해서 설계 및 제작의 품질관리와 현(現))정기검사 기준을 개선해야 한다는 점을 제안하며, Booms 파단 사고 예방대책 제시가 목적이고, 최근 1~2년 사이에 발생한 펌프카 기계적 결함 사고의 현황조사와 사고 특징을 분석하고, 펌프카 장비의 검사기준 및 조정원의 자격과 기능교육 기준 마련의 필요성 확인한다. 붐대의 안전성 확인하기 위해서는 선행연구의 구조적 안전성 평가와 최대응력 부위에 대한 선행연구의 유한요소 해석모델 자료를 재분석하고, 2단 붐이 타설중 가장 많은 힘을 받는지와 파괴 가능성을 확인한다. Booms의 유한요소 모델 해석 결과 펌프카는 타설 과정에서 진동으로 피로 하중을 받을 수 있다는 동적해석과 정적해석 재검토 결과 가장 취약한 부위는 2단 붐이었으며, 2st 붐은 제작단계에서 부재 두께를 증가시키고, 상단부에 철판 보강을 권장한다. 펌프카 사고를 방지하기 위해서는 제조사는 생산단계에서 2st Boom 상단에 보강판 부착이 필요하고, 정기검사 비용 현실화와 비파괴 검사를 의무 검사로 반영이 필요하다고 제언한다.

• Journal of Korea Multimedia Society
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• v.13 no.4
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• pp.512-525
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• 2010

A PDP(Plasma Display Panel) Frame is critical part of PDP and also produces couple hundred thousand every month. In the process of mass production, product inspection is very important process. Also to increase the reliance, inspection each part and every final product is asked quite often. Purpose of this paper is to use computer vision system to inspect the PDP parts which is Automated visual process inspection. This paper contains the system design for inspecting defects of hole, tab, stud, rivet of PDP Frame. The system also can inspect various kinds of PDP frames. Quick and accurate 100% inspection of all shapes can improve the manufacturing productivity. Inspection results can be stored in a database and analyzed to find the cause of defects. After applying the system to the industry, the result shows the possibility of fast and accuracy of the inspection.

• Clinical and Experimental Pediatrics
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• v.45 no.6
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• pp.700-711
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• 2002

Purpose : Early identification and treatment of developmental disabilities is of considerable importance in the health care of children. Screening of development is aimed at identifying infants who may need more comprehensive evaluations. Methods : A new test, the Ewha Infant Development Screening Test(EDST) has been created to screen the development of infants, 0-4 years of age. EDST was constructed so that results can be calculated into developmental ages and developmental quotients. The test consists of three sectors, e.g. language, social-adaptive and motor, and of 158 test items. A total of 104 infants, aged from one month to four years, including healthy infants as well as 10 with chief complaints of developmental delay, who visited the pediatric clinic of Ewha Womans University Dongdaemun Hospital, from June, 25 to November 30, 2001, were given the Bayley Scale of Infant Development as a base test and EDST. Results : The result showed the appropriate cut-off of EDST was 90 with better sensitivity and specificity, compared to cut-offs of 85 or 80. Conclusion : Further study with a large number of infants in the future is needed to make EDST more reliable and accurate.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.5
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• pp.536-542
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• 2011

Dissimilar metal welds in nuclear power plant are known as very susceptible to PWSCC flaws, and periodically inspected by the qualified inspector and qualified procedure during in-service inspection period. According to field survey data, the majority of their DMWs are located on tapered nozzle or adjacent to a tapered component. These types of configurations restrict examination access and also limit examination volume coverage. Additionally, circumferential scan for axially oriented flaw is very difficult to detect located on tapered surface because the transducer can't receive flaw response from reflector for miss-orientation. To overcome this miss-orientation, it is necessary adapt skewed ultrasonic transducer accomodate tapered surface. The skewed refracted longitudinal ultrasonic transducer designed by modeling and manufactured from the modelling result for axial flaw detection. Experimental results showed that the skewed refracted longitudinal ultrasonic transducer get higher flaw response than non-skewed refracted longitudinal ultrasonic transducer.

• Journal of the Korean Society for Nondestructive Testing
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• v.13 no.3
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• pp.24-30
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• 1993

The necessity of ultrasonic inspection to detect the cracks in turbine blade is being increased as the forced outage of nuclear power plants have been occurred due to blade failure in turbine components. However, the complex blade root geometry causes the ultrasonic inspection technique not to be established yet and much effort is required to set up a more reliable inspection. In this paper, the ultrasonic inspection technique for flaw detectability, skew angle effect, identification of flaw and geometric signal have been investigated with a test block and discussed the interpretation of ultrasonic signal through the acquisition and analysis of RF waveform. The experimental results show that the proper examination procedure can be established. It is required that the skew angle is essential to decrease the effect of signals from the complex blade geometry. The present results of this study can be applied to the site inspection without blade disassembly.

• Journal of Welding and Joining
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• v.12 no.4
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• pp.35-40
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• 1994

비파괴검사(NDT)란 시험품에 손상을 주지 않고 내.외부에 존재하는 불연속부(결함)을 찾아내는 방법으로 다음과 같이 그 종류를 분류할 수 있다. (1) 표면결함 검출을 위한 비파괴검사 - 육안검사(VT) : 확대경 등에 의한 치수, 형상확인 - 자분탐상검사(MT) : 강자성체에 적용, 표면(하) 결함검출 - 침투탐상검사(PT) : 금속, 비철금속에 적용, 표면개구 결함검출 - 와류탐상검사(ET) : 도체 표층부(봉, 관 등) (2) 내부결함 검출을 위한 비파괴검사 - 방사선 투과검사(RT) : 결함의 종류, 형상의 판별 우수 - 초음파 탐상검사(UT) : 균열 등 면상 결함검출 등 우수 (3) 기타 비파괴검사 - Strain 측정 : 안전성 평가 - 음향방출시험(AET) - 누설시험(LT) - 중성자 방사선시험(NRT) 이상에서 보는 바와 같이 여러 종류의 비파괴검사가 있으나, 그 중에서 용접부에 적용되는 가장 일반적인 검사방법인 방사선 투과검사에 대해 기술하고자 한다.