• 한국기계가공학회지
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• 제18권5호
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• pp.53-59
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• 2019

Continuous ship unloaders (CSUs) are used for the uninterrupted transport of material in processing industries, power plants, and harbors in accordance with the stream rate of the material. This study analyzed the structural integrity and fatigue life of a CSU structure using finite element structural analysis in ANSYS APDL software. The stress varied greatly depending on the luffing angle and the slew angle of the boom conveyor. The structural integrity of the CSU girder was evaluated by applying ASME BPVC Section VIII Division 2. The fatigue cycle at the angle with the greatest stress difference was calculated. The fatigue cycle was calculated by applying the JIS B 8821:2013 fatigue curve. It was confirmed that the fatigue cycle of the CSU satisfies the allowable fatigue of 200,000 cycles.

• Nuclear Engineering and Technology
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• 제48권6호
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• pp.1423-1432
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• 2016

The integrity of a reactor pressure vessel (RPV) related to pressurized thermal shocks (PTSs) has been extensively studied. This paper introduces an integrity assessment of an RPV subjected to a PTS transient based on the French codes. In the USA, the "screening criterion" for maximum allowable embrittlement of RPV material is developed based on the probabilistic fracture mechanics. However, in the French RCC-M and RSE-M codes, which are developed based on the deterministic fracture mechanics, there is no "screening criterion". In this paper, the methodology in the RCC-M and RSE-M codes, which are used for PTS analysis, are firstly discussed. The bases of the French codes are compared with ASME and FAVOR codes. A case study is also presented. The results show that the method in the RCC-M code that accounts for the influence of cladding on the stress intensity factor (SIF) may be nonconservative. The SIF almost doubles if the weld residual stress is considered. The approaches included in the codes differ in many aspects, which may result in significant differences in the assessment results. Therefore, homogenization of the codes in the long time operation of nuclear power plants is needed.

• Nuclear Engineering and Technology
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• 제26권4호
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• pp.555-561
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• 1994

핵연료 건전성 점검을 위하여 다중채널분석기로 얻은 감마선 스펙트럼을 자동으로 빨리 분석하는 프로그램을 개발하였다. 핵연료의 건전성은 실시간 감시와 주기적인 시료 분석을 통한 원자로냉각재내의 방사선준위로 확인된다. 영광 3·4 호기의 경우, 실시간 감시 계통인 프로세스 방사선 감시 계통(PRMS)이 핵연료의 건전성을 확인한다. 현재, PRMS의 스펙트로미터 채널의 신호처리기는 단일채널 분석기이어서 오직 하나의 방사성핵종만을 파악할 수 있다. 따라서 PRMS를 개선하기 위해서는 단일채널분석기를 다중채널분석기로 대치하여야 한다. 이 프로그램은 실시간 모드와 수동모드로 실행되며, 모든 과정을 자동으로 수행한다. 미 국가표준국의 혼합 표준 선원에 대한 시험 결과는 상용 다중채널분석기인 Canberra System 100의 결과와 잘 일치하였다. 결론적으로 개발된 프로그램은 원자력발전소의 감마선 감시에 사용할 수 있을 것으로 보인다.

• Nuclear Engineering and Technology
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• 제54권5호
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• pp.1726-1746
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• 2022

This paper presents fracture mechanics analysis results for various cracks located at pressurized water reactor pressure vessel nozzle crotch corners taking into consideration constraint effect. Technical documents such as the ASME B&PV Code, Sec.XI were reviewed and then a fracture mechanics analysis procedure was proposed for structural integrity assessment of various nozzle crotch corner cracks under normal operation conditions considering the constraint effect. Linear elastic fracture mechanics analysis was performed by conducting finite element analysis with the proposed analysis procedure. Based on the evaluation results, elastic-plastic fracture mechanics analysis taking into account the constraint effect was performed only for the axial surface crack of the reactor pressure vessel outlet nozzle with cladding. The fracture mechanics analysis result shows that only the axial surface crack in the reactor pressure vessel outlet nozzle has the stress intensity factor exceeding the low bound of upper-shelf fracture toughness irrespectively of considering the constraint effect. It is confirmed that the J-integral for the axial crack of the outlet nozzle does not exceed the ductile crack initiation toughness. Hence, it can be ensured that the structural integrity of all the cracks is maintained during the normal operation.

• Nuclear Engineering and Technology
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• 제45권2호
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• pp.249-256
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• 2013

In accordance with the US Nuclear Regulatory Commission (US NRC), Regulatory Guide 1.20, the reactor vessel internals comprehensive vibration assessment program (RVI CVAP) has been developed for an Advanced Power Reactor 1400 (APR1400). The purpose of the RVI CVAP is to verify the structural integrity of the reactor internals to flow-induced loads prior to commercial operation. The APR1400 RVI CVAP consists of four programs (analysis, measurement, inspection, and assessment). Thoughtful preparation is essential to the measurement program, because data acquisition must be performed only once. The optimized design of a vibration and stress measurement system for the RVI CVAP is essential to verify the integrity of the APR1400 RVI. We successfully designed a vibration and stress measurement system for the APR1400 RVI CVAP based on the design materials, the hydraulic and structural analysis results, and performance tests of transducers in an extreme environment. The measurement system designed in this paper will be utilized for the APR1400 RVI CVAP as part of the first construction project in Korea.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2005년도 연구개발 발표회 논문집
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• pp.636-642
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• 2005

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1999년도 추계학술발표회요약집
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• pp.268-268
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• 1999

• 한국산학기술학회논문지
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• 제7권6호
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• pp.1034-1039
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• 2006

본 논문은 내진등급 IIA 글로브 밸브의 지진하중에 대한 구조 건전성을 평가하였다. 밸브 구조물을 3차원 모델링하여 유한요소법을 사용하여 모달 해석 및 등가 정적 응력해석을 수행하였다. 모달 해석 결과 구조물은 충분히 강건하므로 지진 가속도 값을 사용한 등가 정적 응력해석이 가능하였다. 정적 응력 해석에서 구한 응력을 조합하여 원자력 규격집에 근거한 허용기준에 따라 밸브의 구조 건전성을 평가하였다. 지진하중에서 발생한 응력값이 허용값 아래에 분포하므로 글로브 밸브 구조물은 구조적 건전성을 유지할 수 있다고 평가할 수 있다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.498-498
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• 2001

Seismic qualification of the Main Control Boards for nuclear power plants has been performed with the guideline of AS ME Section III. US NRC Reg. Guide and IEEE 344 code. The analysis model of the Main Control Boards is consist of beam. shell and mass element by using the finite element method. and, at the same time. the excitation forces and other operating loads for each model are encompassed with respect to different loading conditions. As the fundamental frequencies of the structure are found to be less than 33Hz. which is the upper frequency limit of the seismic load, the response spectrum analysis using ANSYS is performed in order to combine the modal stresses within the frequency limit. In order to confirm the structural and functional integrity of the major components, modal analysis theory is adopted to derive the required response spectrum at the component locations. As all the combined stresses obtained from the above procedures are less than allowable stresses and no mechanical or electrical failures are found from the seismic testing, it concludes the Main Control Boards is dynamically qualified for seismic conditions. Although the authors had confirmed the structural and functional integrity of both Main Control Boards and all the component, in this paper only the seismic analysis of the Main Control Board is introduced.

• 한국산업융합학회 논문집
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• 제27권5호
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• pp.1137-1144
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• 2024

This paper is about an electric water pump used in an electric vehicle cooling system. An electric water pump is operated by a BLDC motor compared to a mechanical one, so it operates only as much as necessary, improving fuel efficiency. The use of an electric water pump reduces exhaust gas and has the advantage of being free to install, so it can be applied to automobiles, ships, and aircraft. In order to optimize the production of a BLDC motor used as an electric water pump, FEM and electromagnetic field analysis were performed. The dimensions and materials of the stator and rotor were selected by applying the values obtained through the analysis. In addition, the output characteristics of the motor were analyzed through parameter analysis and shape change through self-equivalent circuit analysis to reduce the outer diameter and increase the torque. The electromagnetic hazard of the PCB board was verified, and power integrity analysis was performed to reduce resonance and noise.