• 한국산학기술학회논문지
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• 제10권7호
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• pp.1549-1555
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• 2009

무선센서 네트워크에서 노드들의 데이터를 수집하고 기지국에 전달하는 중계노드의 위치(Relay Node Placement)를 구하는 문제는 전체 네트워크의 생존시간에 관련되어 있기 때문에 매우 중요하다. 중계노드 위치문제는 전체 네트워크의 센서노드에서 소비되는 에너지를 최소화시키는데 그 초점이 맞추어져 있다. 그러나 중계노드 위치와 센서노드와의 거리가 모두 다르므로 센서노드에서 소비되는 에너지의 불균형이 초래된다. 본 논문에서는 클러스터링 모델에서 에너지 균형비(Energy Balance Ratio)라는 개념을 제안하고 이 에너지 균형비를 최대화시키는 목적함수를 사용하여 중계노드의 위치를 구한다. 에너지 균형비를 최대화시키는 것은 클러스터에 할당된 센서노드들의 에너지 소비를 클러스터 간에 균형 잡히게 한다. 이것은 궁극적으로 대규모 센서 네트워크의 에너지 소비를 최소화시켜서 네트워크 생존기간을 최대화시키는 효과가 있다. 그러나 이 문제의 해를 구하는 것은 NP-hard 문제이므로 완전해(Exact Solution) 를 구하는 것은 현실적으로 힘들다. 따라서 제약프로그래밍 방법을 사용하여 에너지 균형비와 중계노드 위치를 함께 고려하는 EBR-RNP 문제로 모델링하여 근사해를 구한다.

• Wind and Structures
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• 제6권4호
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• pp.307-324
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• 2003

The paper presents results of studies concerning wind-induced aeolian vibration and fatigue of a 110 kV covered conductor overhead line. Self-damping measurement techniques are discussed: power method is found to be the most reliable technique. A method for compensating tension variations during the self-damping test is presented. Generally used empirical self-damping power models are enhanced and the different models are compared with each other. The Energy Balance Analysis (EBR) is used to calculate the aeolian vibration amplitudes, which thereafter are converted to bending stress for the calculation of conductor lifetime estimate. The results of EBA are compared with field measurements, Results indicate that adequate lifetime estimates are produced by EBA as well as field measurements. Generally the EBA gives more conservative lifetime expectancy. This is believed to result from the additional damping existing in true suspension structures not taken into account by EBA. Finally, the correctness of the line design is verified using Cigre's safe design tension approach.

• Nuclear Engineering and Technology
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• 제43권4호
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• pp.335-342
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• 2011

As part of the Department of Energy's Fuel Cycle Research and Development Program an electrochemical technology employing molten salts is being developed for recycle of metallic fast reactor fuel and treatment of light water reactor oxide fuel to produce a feed for fast reactors. This technology has been deployed for treatment of used fuel from the Experimental Breeder Reactor II (EBR-II) in the Fuel Conditioning Facility, located at the Materials and Fuel Complex of Idaho National Laboratory. This process is based on dry (non-aqueous) technologies that have been developed and demonstrated since the 1960s. These technologies offer potential advantages compared to traditional aqueous separations including: compactness, resistance to radiation effects, criticality control benefits, compatibility with advanced fuel types, and ability to produce low purity products. This paper will summarize the status of electrochemical development and demonstration activities with used nuclear fuel, including preparation of associated high-level waste forms.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1998년도 춘계학술발표회논문집(1)
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• pp.678-683
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• 1998

액체금속로의 노심은 핵연료봉과 와이어랩에 의한 부수로로 구성된 복잡한 기하학적 구조의 집합체로 이루어져 있다. 이러한 액체금속로의 정상상태 및 과도상태 노심열수력 상세해석을 위하여 부수로 해석코드 MATRA-LMR 코드를 개발하고 있다. 본 논문에서는 ORNL 19 Pin 실험결과와 EBR-II 실험 모의시 정상상태 노심열수력 해석코드인 SLTHEN 코드 계산에 사용되었던 실험데이타를 사용하여 현재 MATRA-LMR 코드로 계산을 수행한 후 그 결과를 비교.분석함으로써, MATRA-LMR 코드의 개발 상태를 평가해 보았다 ORNL 19 Pin 실험과 MATRA-LMR 계산를 비교한 결과 실험을 정확히 예측하는 것으로 나타났다. SLTHEN 코드 계산결과와의 비교에서는 집합체 평균 출구온도와 부수로 최대 출구온도를 비교한 결과 두 코드의 계산은 약 3% 이하의 차이를 보이고 있다. 현재의 MATRA-LMR 코드는 단일 집합체 계산만 가능하나 앞으로의 작업을 통해 전 노심 해석이 가능하도록 다중 집합체 계산 코드로 개발할 예정이다.

• 방사성폐기물학회지
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• 제18권2호
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• pp.113-118
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• 2020

An options study was performed for the treatment of residual elemental sodium in driver plenums following the chopping operation during the pyroprocessing of used nuclear fuel. Given the pending availability of a multi-function furnace for distillation and consolidation operations in the Fuel Conditioning Facility, the furnace was considered for the processing of driver plenums. Although two options (oxidation and distillation) could be performed in the multi-function furnace, neither option has been developed sufficiently to date to warrant the use of the furnace for treatment operations. Thus, it was decided to defer the treatment of elemental sodium from driver plenums in the multi-function furnace until more developed technologies and/or furnaces become available. In the interim, storage of the plenums and characterization efforts are recommended.

• Nuclear Engineering and Technology
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• 제33권3호
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• pp.298-306
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• 2001

As fuel burnup proceeds, thermal gradients, differential swelling, and inter-assembly loading may induce assembly duct bowing. Since duct bowing affects the reactivity, such as long or short term power-reactivity-decrement variations, handling problem, caused by top end deflection of the bowed assembly duct, and the integrity of the assembly duct itself. Assembly duct bowing were first observed at EBR-ll in 1965, and then several designs of assembly ducts and core restraint system were used to accommodate this problem. In this study, NUBOW-2D KMOD was used to analyze the bowing behavior of the assembly duct under the KALIMER(Korea Advanced Liquid MEtal Reactor) core restraint system conditions. The mechanical behavior of assembly ducts related to several design parameters are evaluated. ACLP(Above Core Load Pad) positions, the gap distance between the ducts, and the gap distance between the duct and restraint ring were selected as the sensitivity parameter for the evaluation of duct deflection.

• Structural Engineering and Mechanics
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• 제53권6호
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• pp.1083-1104
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• 2015

This paper provides the results of an experimental investigation into the flexural behavior of continuous two-span unbonded post-tensioned high strength concrete (HSC) beams, strengthened by end-anchored CFRP laminates of different configurations in the hogging region. Implementing two different configurations of end-anchorage systems consisting of steel plates and bolts and carefully monitoring the development of strains throughout the load history using sufficiently large number of strain gauges, the response of beams including the observed crack propagations, beam deflection, modes of failure, capacity enhancement at service and ultimate and the amount of moment redistribution are measured, presented and discussed. The study is appropriate in the sense that it covers the more commonly occurring two span beams instead of the simply supported beams investigated by others. The experiments reconfirmed the finding of others that proper installation of composite strengthening system is most important in the quality of the bond which is essential for the internal transfer of forces. It was also found that for the tested two span continuous beams, the capacity enhancement is more pronounced at the serviceability level than the ultimate. This is an important finding as the design of these beams is mostly governed by the serviceability limit state signifying the appropriateness of the suggested strengthening method. The paper provides quantitative data on the amount of this capacity enhancement.

• Nuclear Engineering and Technology
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• 제48권2호
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• pp.330-338
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• 2016

The U-Zr or U-TRU-Zr cylindrical metallic fuel slug used in fast reactors is known to swell significantly and to grow during irradiation. In neutronics simulations of metallic-fueled fast reactors, it is assumed that the slug has swollen and contacted cladding, and the bonding sodium has been removed from the fuel region. In this research, a realistic burnup-dependent fuel-swelling simulation was performed using Monte Carlo code McCARD for a single-batch compact sodium-cooled breed-and-burn reactor by considering the fuel-swelling behavior reported from the irradiation test results in EBR-II. The impacts of the realistic burnup-dependent fuel swelling are identified in terms of the reactor neutronics performance, such as core lifetime, conversion ratio, axial power distribution, and local burnup distributions. It was found that axial fuel growth significantly deteriorated the neutron economy of a breed-and-burn reactor and consequently impaired its neutronics performance. The bonding sodium also impaired neutron economy, because it stayed longer in the blanket region until the fuel slug reached 2% burnup.

• Structural Engineering and Mechanics
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• 제88권1호
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• pp.67-81
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• 2023

The reinforced concrete (RC) structures might need strengthening or upgradation due to adverse environmental conditions, design defects, modification requirements, and to prolong the expected lifespan. The RC beams have been efficiently strengthened using the near surface mounted (NSM) approach over the externally bonded reinforcing (EBR) system. In this study, the performance of RC beam elements strengthened with NSM-steel rebars was investigated using an experimental program and nonlinear finite element modeling (FEM). Nine medium-sized, rectangular cross-section RC beams total in number made up for the experimental evaluation. The beams strengthened with varying percentages of NSM reinforcement, and the number of grooves was assessed in four-point bending experiments up to failure. Based on the experimental evaluation, the load-displacement response, crack features, and failure modes of the strengthened beams were recorded and considered. According to the experimental findings, NSM steel greatly improved the flexural strength (up to about 84%) and stiffness of RC beams. The flexural response of the tested beams was simulated using a 3D non-linear finite element (FE) model. The findings of the experiments and the numerical analysis showed good agreement. The effect of the NSM groove and reinforcement on the structural response was then assessed parametrically.

• 대한토목학회논문집
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• 제33권1호
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• pp.131-136
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• 2013

본 연구에서는 탄소섬유판을 콘크리트 표면에 매립하는 표면매립(NSM) 공법을 적용하여 콘크리트 구조물 보강을 수행하고, 콘크리트 내구성 증진 뿐 아니라 구조물 수명을 향상 시킬 수 있는 노후구조물 보수 보강 체계를 구축하고자 하였다. 이를 위하여, 표면매립 탄소섬유판 및 고성능 단면복구 모르터로 보강된 철근 콘크리트 부재를 제작하여 실험을 수행하였다. 실험결과, 에폭시로 탄소섬유판을 매립 부착한 철근콘크리트 부재는 보강되지 않은 부재보다 초기 강성 및 휨강도가 현저하게 증가하는 것으로 나타났다. 탄소섬유판으로 보강된 철근콘크리트 부재는 탄소섬유판의 인장 파괴로 인하여 시작되며, 탄소섬유판의 저항능력은 매우 우수하며, 보강 효율이 우수한 것으로 나타났다. 탄소섬유판을 매립하고 표면부에 고성능 모르터로 단면을 복구하는 보강 방식은 보의 강성 및 내구성을 향상시킬 뿐 아니라 미관이 우수하여 보수와 보강이 혼합된 적절한 보강 방식으로 판단된다.