• Journal of Advanced Marine Engineering and Technology
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• 제26권1호
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• pp.99-107
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• 2002

Recently all kinds of structural materials are subjected to the severe corrosive environment. Especially corrosion problems of heat exchanger such as galvanic corrosion, erosion and cavitation raised by both contaminated solution and high velocity of fluid to increase cooling effect of heat exchanger have been frequently reported in these days. In this study two kinds of sheet materials and five kinds of tube materials are used for galvanic corrosion characteristics and their corrosion current density calculation. The tube materials having the most galvanic corrosion resistance between tube and sheet of heat exchanger were Al Brass(68700) and Al Brass(C6872TS) and although Ti tube predominantly indicated the highest individual corrosion resistance among those five tube materials. it appeared that Ti tube can be allowed as sheet materials to get galvanic corrosion easily. However it is considered that Cu-Ni tube materials is not only easy to produce galvanic corrosion significantly between tube and sheet regardless of kinds of sheet materials but also is appeared considerably its own high corrosion current density

• 한국해안·해양공학회논문집
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• 제23권1호
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• pp.70-78
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• 2011

2009년 8월 13일과 15일, 부산 해운대 해수욕장 앞 해상에서 이안류가 발생하였다. 또한, 올 여름인 2010년 7월 29일과 30일에도 이안류가 발생하여 피서객 들이 조난된 사고가 발생하였다. 해수욕객들은 전원 구조되어 인명 피해는 발생하지 않았지만 최근 이안류 발생이 너무 잦아져 이에 대한 원인파악과 대책마련이 시급한 실정이다. 본 논문에서는 파랑모형과 조류가 결합된 해빈류 모형을 기본으로 튜브거동까지 재현되는 사용자 편의를 위하여 GUI로 개발된 HAECUM 모형(HAEundae CUrrent Model)을 이용, 해운대 해수욕장의 이안류 발생 수치모의를 실시하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 추계학술대회 논문집
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• pp.359-360
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• 2007

• ETRI Journal
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• 제35권6호
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• pp.1164-1167
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• 2013

We correlate the failure in miniature X-ray tubes with the field emission gate leakage current of gated carbon nanotube emitters. The miniature X-ray tube, even with a small gate leakage current, exhibits an induced voltage on the gate electrode by the anode bias voltage, resulting in a very unstable operation and finally a failure. The induced gate voltage is apparently caused by charging at the insulating spacer of the miniature X-ray tube through the gate leakage current of the field emission. The gate leakage current could be a criterion for the successful fabrication of miniature X-ray tubes.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2006년도 하계학술대회
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• pp.241-245
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• 2006

In the examination of Steam Generator (SG) tube in Nuclear Power Plant (NPP) Eddy Current Testing (ECT) probes play an Important role in detecting the defects. Bobbin probe and Rotating Pancake Coil (RPC) probe is usually used for the inspection of SG tube. Bobbin probe is good at high speed inspection, but ability of detection of circumferential defect is very weak. On the contrary RPC probe, which moves for inspection in the direction of axial and circumferential simultaneously, has very slow inspection speed, but it was excellent detection capability fur small cracks, which is hardly detected by bobbin probe. Many examinations of SG tube examination of NPP are achieved during short period. Therefore, solution about this must develop probe of new form for examination performance and examination time shortening of other probe. In this paper, analyzed technological present condition of Bob-bin probe and RPC probe been using in Nondestructive Testing (NDT) for SG tube defect detection and Appeared about background theory and view of developed probe newly.

• 정보관리학회지
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• 제37권3호
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• pp.1-24
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• 2020

5G 시대 단말기의 다양화, 고화질 및 몰입형 중심의 SNS 전개로 동영상 중심의 소셜 미디어 패러다임이 계속적으로 심화되고 있다. 본 연구의 목적은 공공도서관에서 운영되고 있는 유튜브 채널의 운영과 제공 콘텐츠 현황에 대한 분석을 통해 다양한 활용 전략과 방안을 제안하는 데 있다. 본 연구에서는 도서관 유튜브 채널을 개설 및 운영하고 있는 국내의 44개 도서관과 구독자 수 1,000명 이상 도서관 유튜브 채널을 활발하게 활용하고 있는 국외 도서관 12개를 대상으로, 도서관 유튜브 채널의 구독자 수, 조회 수, 비디오 수 데이터 현황, 그리고 콘텐츠 내용과 전달 방식을 조사하였다. 분석 결과를 종합하여, 1) 도서관 유튜브 채널만이 가지는 특수성과 목적성을 확보, 2) 유튜브 채널의 홍보 및 접근성 제고, 3) 공공도서관에서 개설 및 운영하는 유튜브 채널임을 명시, 4) 이용자 친화적인 인터페이스로의 개선, 5) 도서관 전문성과 교육적 콘텐츠를 기획 및 제공, 6) 통합 유튜브 채널의 운영, 7) 이용자 기반 콘텐츠 제공 등의 도서관 유튜브 채널 활용방안을 제안하였다.

• Journal of Radiation Protection and Research
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• 제34권1호
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• pp.31-36
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• 2009

일부지역의 병원에 설치, 운영되고 있는 진단용 X선 발생장치틀 의원, 병원, 종합병원별로 관 전압, 관 전류/량, 조사기간, 조사선량 성능을 평가하여 측정방법과 기술을 배우고 중요성을 알리고자 한다. 진단용 X선발생장치를 그룹별로 10대씩 총 30대에 대하여 관전류/량, 조사시간측정기를 사용하여, 백분율평균오차로 평가하였고 그에 따른 조사선량의 재현성은 변동계수를 계산하여 평가하였다. 진단용 X선 발생장치 30대 중 부적합한 장치는 관전압정확도 시험에서 5대(16.7%), 관전류정확도시험에서 3대(10,0%), 관전류량정확도 시험에서는 4대(13.3%), 조사시간정확도 시험에서는 5대(16.7%), 조사선량의 재현성 시험에서는 7대(23.3%)로 조사되었다. 진단용 X선 발생장치를 관리규정에 의거하여 성능검사 결과에 의해 성능관리의 심각성을 알 수 있었고, 이에 주기적으로 실시하여야 함은 물론 안전하게 관리함으로써 환자 및 방사선관계종사자에 대하여 방사선으로 인한 방사선 피폭경감, 화질영상관리, 재촬영 감소 둥에 의해 환자에게 양질의 의료서비스를 제공하게 될 것이다. 따라서 정기적인 성능검사가 필요하다고 사료된다.

• 비파괴검사학회지
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• 제33권6호
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• pp.519-523
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• 2013

A steam generator (SG) tube is an important component of a nuclear power plant (NPP). It works as a pressure boundary between the primary and secondary systems. The integrity of a SG tube can be assessed by an eddy current test every outage. The eddy current technique(adopting a bobbin probe) is currently the main technique used to assess the integrity of the tubing of a steam generator. An eddy current signal analyst for steam generator tubes continuously analyzes data over a given period of time. However, there are possibilities that the analyst conducting the test may get tired and cause mistakes, such as: missing indications or not being able to separate a true defect signal from one that is more complicated. This error could lead to confusion and an improper interpretation of the signal analysis. In order to avoid these possibilities, many countries of opted for automated analyses. Axial ODSCC (outside diameter stress corrosion cracking) defects on the tubes of OPR1000 steam generators have been found on the tube that are in contract with tube support plates. In this study, automated analysis software called CDS (computer data screening) made by Zetec was used. This paper will discuss the results of introducing an automated analysis system for an axial ODSCC on the tubes of an OPR1000 steam generator.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2009년도 정보통신설비 학술대회
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• pp.54-58
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• 2009

In this paper, the ECT(eddy current testing) signal analysis of eddy current array probe for inspection of SG(steam generator) tube in NPP(nuclear power plant) using electromagnetic FEM(finite element method) was performed. To obtain the electromagnetic characteristics of probes, the governing equation was derived from Maxwell's equation, and the problem was solved by using the 3-dimensional FEM. The types of defects were FBH(flat bottomed hole) and OD groove, Spiral groove, natural defects(pitting, SCC, multiple SCC, wear). The depth of FBH defects were 20%, 40%, 60%, 80%, 100 of SG tube thickness, and it was assumed that the defects were located on the tube outside. And the operation frequency of 100kHz, 300kHz and 400kHz were used. Material of specimen was Inconel 600 which is usually used for SG tubes in NPP. The signal difference could be observed according to the variation of size and depth on FBH defects and operation frequencies. The results in this paper can be helpful when the ECT signals from EC array probe are evaluated and analyzed.

• 방사선산업학회지
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• 제12권4호
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• pp.267-276
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• 2018

A Hoffman 3D Brain Phantom was used to evaluate two PET/CT scanners, BIO_40 and D_690, according to the radiation dose of CT (low, medium and high) at a fixed kilo-voltage-peak (kVp) with the tube current(mA) varied in 17~20 stages(Bio_40 PET/CT scanner: the tube voltage was fixed to 120 kVp, the effective tube current(mAs) was increased from 33 mAs to 190 mAs in 10 mAs increments, D_690 PET/CT scanner: the tube voltage was fixed to 140 kVp, tube current(mA) was increased from 10 mAs to 200 mAs in 10 mAs increments). After obtaining the PET image, an attenuation correction was conducted based on the attenuation map, which led to an analysis of the difference in the image. First, the ratio of white to gray matter for each scanner was examined by comparing the coefficient of variation (CV) depending on the average ratio. In addition, a blind test was carried out to evaluate the image. According to the study results, the BIO_40 and D_690 scanners showed a <1% change in CV value due to the tube current conversion. The change in the coefficients of white and gray matter showed that the Z value was negative for both scanners, indicating that the coefficient of gray matter was higher than that of white matter. Moreover, no difference was observed when the images were compared in a blind test.