• 대한기계학회논문집A
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• 제29권5호
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• pp.734-742
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• 2005

The present study proposes the integrity evaluation model for a straight pipe with local wall thinning defect, which reflects the characteristics of training shape and loading condition in the Piping of nuclear power plant. For this purpose, a series of finite element analyses are performed under various defect geometries and loading conditions, and real pipe experiment data performed previously is employed. The model includes the effect of thinning length as well as thinning depth and width, and also it considers the combined loading effect between internal pressure and bending moment. The proposed model has been validated using the results of finite element analysis and pipe experiment data. The results indicate that the proposed model provides more reliable predictions of pipe failure than the current existing model, in terms of accuracy, consistency, and conservativeness of results.

• 제어로봇시스템학회논문지
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• 제11권7호
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• pp.595-601
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• 2005

A mobile robot system utilizing NDT (Non-Destructive Testing) method is designed and fabricated f3r automatic integrity evaluation of large sized industrial reservoirs and pipelines. The developed mobile robot can crawl over the outer surface of the industrial facilities even though the shape of the structures is various and unsymmetric. The robot detects defects such as pinholes, cracks and thickness reduction at the wall of the facilities using EMAT (Electro-Magnetic Acoustic Transducer). Image processing technology for weld line detection at the surface of the target and host programs including defect detecting algorithms are also developed. Automation of defect detection for these kinds of large facilities using mobile robots is helpful to prevent significant troubles of the structures without danger of human beings under harmful environment.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.825-830
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• 2001

Many techniques have been developed to evaluate the structural integrity for the traction motor with squirrel cage. However, the former approaches are not appropriate to our problems and there is no reliable specification for evaluation of squirrel cage motor. In this study, an improved boundary condition and the criteria for evaluation are proposed. Using 3-dimensional solid element, finite element model is generated. The number of meshes can be reduced by considering the symmetry of geometry. Stress analyses are carried out for three types of traction motors.

• 대한기계학회논문집
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• 제18권12호
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• pp.3136-3148
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• 1994

This paper proposed the method of fracture integrity evaluation for semi-elliptical crack. Plane strain fracture toughnesses are used to compare with the thermal shock stress intensity factors for semi-elliptical crack obtained by Vainshtok weight function method. The method is applied to the finite Cr Mo V and 2.25Cr Mo steel plates with semi-elliptical crack under the thermal shock. For the purpose, tensile property and fracture toughness with respect to the temperature are measured. To verify the method, thermal shock experiments are carried. The theoretical predictions are in good agreement with the experiments.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.3059-3066
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• 2008

It is reported that the life of generator stator windings is expected about 30 years and a leak and water absorption phenomena can be progressed by fatigue, vibration, and corrosion. The water-cooled generator stator windings which were operated over 15 years are over 20 units and the mechanical problems such as leak and water absorption were found in the generator stator windings. In this paper, the systematic mechanical integrity evaluation methods which are applied to the water-cooled generator stator windings within the country are introduced.

• 한국철도학회논문집
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• 제3권2호
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• pp.77-83
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• 2000

This study proposes the integrity evaluation of the bogie frame using ultrasonic fractography analysis. Analysis objectives in this study are to investigate fracture planes of damaged zone by the A-scan method. The surface condition of fracture planes shows degree of degradation by the stress concentration. The detection of the natural defects in the bogie frame is performed using the characteristics of echodynamic pattern in ultrasonic signal. Results of ultrasonic testing agree fairly well with those of actual fracture plane. In quantitative fractography analysis, microstructures of actual fracture plane turned out to be intergranular and transgranular fracture. Proposed ultrasonic fractography analysis in this study can be used for the integrity evaluation of the bogie frame.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.525-525
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• 2005

This study is for the seismic analysis and the structural integrity evaluation of the box beam for supporting nuclear fuel-transfer-basket of the HANARO reactor pool. For performing the seismic analysis and evaluating the structural integrity in air or submerged condition, the finite element model of the fuel-transfer-basket and its supporting box beam(the coupled model) was developed. The hydrodynamic effect is also considered by using added mass concept. The seismic response spectrum analyses of the coupled model under the design floor response spectrum loads of Safe Shutdown Earthquake(SSE) were performed. Through the numerical experiments, the analysis results show that the stress values of the coupled model lot the structural integrity are within the ASME Code limits.

• 대한기계학회논문집A
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• 제25권7호
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• pp.1031-1038
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• 2001

In order to verify the analytical methods predicting failure behavior of cracked piping, full-scale pipe tests are crucial in nuclear power plant piping. For this reason, series of international test programs have been conducted. However, full-scale pipe tests require expensive testing equipment and long period of testing time. The objective of this paper is to develop a test system which can economically simulate the full-scale pipe test regarding the integrity evaluation. This system provides the failure behavior of cracked pipe by testing a wide-plate specimen. The system provides the failure behavior of cracked pipe by testing a wide-plate specimen. The system was developed for the integrity evaluation of nuclear piping based on the methodology of hardware-in-the-loop (HiL) simulation. Using this simulator, the piping integrity can be evaluated based on the elastic-plastic behavior of full-scale pipe, and the high cost full-scale pipe test may be replaced with this economical system.

• 한국지반공학회논문집
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• 제30권4호
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• pp.81-92
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• 2014

하천제방 건전도 평가는 하천설계기준 해설(2009), 구조물기초 설계기준 해설(2009) 등 관련 기준을 토대로 한계동수경사법, 한계유속법 등에 의한 파이핑 안전성과 제내지 및 제외지의 활동안전성 평가에 의하여 수행된다. 이때 수위파형은 건전도 평가 시 가장 중요한 설계입력자료이나 관련 국가기준에서 그 결정방법을 제시하지 못함으로서 부정확한 설계가 이루어지고 있다. 본 논문에서는 낙동강 문산제를 대상으로 평수위 상승, 홍수위 지속, 수위하강, 홍수빈도 등 개별 수위파형을 변화시켜가면서 제방 안정성에 미치는 영향 정도와 합리적인 수위파형특성을 제안하였다. 평가결과, 문산제 조립토 제방의 설계수위파형은 최대 57시간 이상의 평수위상승시간 및 53시간 이상의 홍수위지속시간 등을 반영할 것을 제안하였다.

• 한국철도학회논문집
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• 제13권5호
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• pp.469-475
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• 2010

본 논문은 국내에서 개발중인 모노레일 대차 프레임에 대해 구조 안전성 및 피로강도를 평가하였다. 현재 모노레일 대차 프레임에 대한 평가기준은 없는 실정이며, 이에 구조 안전성 및 피로강도 평가는 유럽규격인 UIC 615-4 기준을 적용하여 수행하였다. 이때, 설계된 대차 프레임에 대해 각 하중조건에서의 변위 및 Von-Mises 응력 결과를 통해 구조 안전성을 평가하였다. 그리고 피로강도는 UIC 615-4 기준의 규정에 따라 조합 주 운용하중조건에 의해 평가되고, 일괄처리 기능을 갖는 winLIFE v3.1을 이용한 피로해석 결과와 비교 검증하였다. 본 연구를 통하여 설계된 대차 프레임은 구조적 안전성 및 피로강도를 만족하였으며, 일괄처리 기능을 갖는 피로해석은 조합하중을 이용한 기존 피로해석보다 더 효율적임을 확인하였다.