• 동력기계공학회지
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• 제11권3호
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• pp.53-58
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• 2007

The ruptured blade which is rotating at high speed can damage severely the all stage compressor blades and the turbine components. If the shattered blades flow downstream inside the turbine parts, then the turbine blades and vanes can be damaged. The small parts of shattered blades which are flowed into the turbine parts pass through without any damages in the leading edge of the first stage stationary blades. Then they bump against the convex side of the leading edge of the first stage moving blades and the trailing edge of the first stage stationary blades repeatedly. The debris of shattered blades may plug the cooling holes in the turbine blades and vanes. The dent damage and the coating delamination could be also occurred by the debris of shattered blades flowed downstream inside the combustion liner and the transition piece. This paper analyzes the influence on the turbine components and the damage mechanism and characteristics in case of the damaged blade of the multiple-stage axial flow compressor.

• Composites Research
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• 제23권6호
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• pp.7-13
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• 2010

CNG 차량에서 실사용 중 Type3 복합재료 압력용기의 외부 복합재 층에 결함이 발생된다면, 용기의 구조적 성능 즉, 원래의 설계수명보다 반복수명이 감소되는 현상을 초래할 수 있다. 이에 따라, 본 연구에서는 복합재 결함을 고려한 복합재료 압력용기의 유한요소 모델링과 해석 기법을 제시하였다. Type3 복합재료 압력용기의 유한요소해석은 자긴처리 공정에서 알루미늄 라이너의 소성 변형으로 인해 경로 의존적 현상을 보이므로, 실사용 중 결함이 발생되는 실제 환경을 고려한 해석에서 결함은 자긴압력 이후에 도입되어야한다. 이러한 상황의 사실적인 시뮬레이션을 위해, 해석의 중간단계에서 결함이 도입되는 유한요소 모델링과 해석 기법이 제시되었으며, 해석결과는 해석의 시작단계에서부터 모델에 초기결함을 내포하는 일반적 유한요소해석과 비교되었다. 제안된 해석 기업은 Type3 복합재료 압력용기의 복합재층 손상에 따른 영향성 평가 및 실사용 중에서의 검사 기준을 마련하는데 효과적으로 사용될 수 있다.

• 한국환경과학회지
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• 제29권4호
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• pp.395-402
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• 2020

This study was conducted to analyze seasonal variations of de-icing salt ions harvested from soils and plants according to salt damage of Pinus densiflora f. multicaulis, a evergreen conifer, on roadsides. Pinus densiflora f. multicaulis was divided into three groups referred to SD, ND, and WD (serious salt damage (SD) = 71-100%, normal salt damage (ND) = 31-70%, and weak salt damage (WD) = 0-30%) based on the degree of visible foliage damage, and measured acidity (pH), electrical conductivity(EC), and de-icing salt ions (K⁺, Ca²⁺, Na⁺, and Mg²⁺) harvested from soils and plants. The results indicated that acidity, electrical conductivity, and de-icing salt ions of soils and plants were significantly affected by seasonal variation and salt damage. In addition, a strong positive liner relationship was observed in plants between the concentration of de-icing salts and salt damage in spring, while the relationship among seasonal variation and salt damage in soil were not significant. The results from this study has important implications for the management of conifer species in relation to salinity and roadsides maintenance.

• 한국터널지하공간학회 논문집
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• 제4권3호
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• pp.195-205
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• 2002

터널에서의 배면공동은 설계 시공 유지관리중 다양한 원인들이 복합적으로 작용하여 발생하게 된다. 특히, 터널 천단부 라이닝 부분에는 콘크리트 타설후 재료분리 등으로 인해 터널 천단부에 배면공동이 발생이 되는데, 이러한 터널 배면공동은 라이닝 균열, 누수 등과 밀접한 연관이 있는 것으로 밝혀지고 있다. 본 연구는 석산에서 발생되는 석분을 이용하여 터널 배면공동 및 지하공동의 충전용 모르타르를 개발하고 이를 노후터널에 적용함으로서 개발재료의 현장적용성 등에 대한 시험을 수행하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.798-804
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• 2009

Damaged liners may be detected by using leakage detection systems. For the reason, many types of leakage detection systems are applied to analyze or detect damages of lining system such as electrical detection method for the landfill sites. However, most of them can be applied in the new landfill construction sites because sensors should be installed in the bottom of liner systems. This paper shows a case study reviewing the development of a fence type leakage detection method, monitoring system and pilot plant test results, so that they can be economically and efficiently applied to actual used or in-use sites without a leakage detection system.

• 한국지반공학회논문집
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• 제27권12호
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• pp.5-15
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• 2011

본 연구는 매립지의 최종복토층으로 사용되는 점토 혹은 지오멤브레인의 부등침하 및 기상조건변화에 의한 균열에 취약한 점을 고려하여 균열 발생시 자가형성된 물질로 인하여 균열치유 작용을 할 수 있는 SRSL(Self Recovering Sustainable Liner)의 매립지 최종복토층으로서의 적용성을 파악하였다. SRSL 기법은 2개의 층을 두어 상, 하부층 사이 계면에 불투수성 물질을 생성하는 동시에, 균열발생 시에도 2가지 성분이 다시 결합하여 불투수성 물질을 재형성하는 역할을 수행한다. SRSL의 최종복토층의로서의 적용성 파악을 위해서 실험실에서 연성벽체 투수시험기를 사용하여 투수 특성을 파악하였고 일축압축시험을 통하여 강도 및 강성 특성을 파악하였다. 또한 최종 복토층의 경우 환경적인 요인에 직접적으로 노출되어 있기 때문에 동결/융해 및 건조/습윤에 따른 SRSL의 투수 및 강도 특성 또한 알아보았다. 시험 결과, SRSL은 낮은 투수계수와 기준보다 높은 강도를 가진 매립장의 복토층 재료로 적합한 물질로 판단되며, 동결/융해 및 건조/습윤의 환경적인 영향에 대해서도 안정한 것으로 판명되었다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(2)
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• pp.637-642
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• 1996

This paper presents the analysis results for the core degradation processes and the fission product release of the PHEBUS FPT0 experiment using MELCOR1.8.3. The objective of this study is to assess models associated with the core damage and fission product behavior in MELCOR. The calculation results were much improved through sensitivity studies. Thermal/hydraulic behavior in the core and the circuit was well predicted under the intact core geometry. In non-eutectic model case. the UO$_2$ dissolution model in the MELCOR always showed such a tendency that the resulting dissolved UO$_2$ mass was small at the highly oxidized condition due to the model logic. Total H$_2$ generation mass was underpredicted because the stiffner was not modeled and the liner in the shroud was not allowed to be oxidized in MELCOR. Some difficulties were found in modeling the activation product were solved by manipulating the RN input associated with the initial fission product inventory. These problem were occurred because there are no control rod model in MELCOR. Generally the fission product release ratio showed a similar trend compared with the measured data except the activation product. which have no model to simulate in MELCOR.

• Nuclear Engineering and Technology
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• 제55권12호
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• pp.4504-4517
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• 2023

After a loss of coolant accident (LOCA) in the prestressed concrete containment vessels (PCCVs) of nuclear power plants, the coupling of temperature and pressure can significantly affect the mechanical properties of the PCCVs. However, there is no consensus on how this coupling affects the failure mechanism of PCCVs. In this paper, a simplified finite element modeling method is proposed to study the effect of temperature and pressure coupling on PCCVs. The experiment results of a 1:4 scale PCCV model tested at Sandia National Laboratory (SNL) are compared with the results obtained from the proposed modeling approach. Seven working conditions are set up by varying the internal and external temperatures to investigate the failure mechanism of the PCCV model under the coupling effect of temperature and pressure. The results of this paper demonstrate that the finite element model established by the simplified finite element method proposed in this paper is highly consistent with the experimental results. Furthermore, the stress-displacement curve of the PCCV during loading can be divided into four stages, each of which corresponds to the damage to the concrete, steel liner, steel rebar, and prestressing tendon. Finally, the failure mechanism of the PCCV is significantly affected by temperature.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.279-282
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• 2006

Upon a turbopump's running, cavitation may occur at the inlet of the LOx pump by pressure drop and heat transfer along the LOx feeding line. Since the cavitation can cause serious damage to the pump or to stop running, the absence of the cavitation at the inlet of a turbopump should be confirmed before the using the turbopump. In the present study, the calculation of the volume fraction of LOx gas phase at the inlet of the pump are performed with different temperatures of LOx in the tank, pressure drops and heat transfers along the feeding line. This calculation method can be applied to define the limits of thermal and hydraulic characteristics during the design of a LOx feeding system.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.453-458
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• 2008

Pump of high lift use to development of a technological level according as a building grow big. Water-Hammer to increase by valve of fast to closing agreeably to pipe laying to accept electronic valve, because by a damage of piping-system and the devil knows injury of vibration. Water-Hammer take a low effect to various method for solve. A New type manufacture develop and testing of pipe line to same to axis use to accumulator for water-Hammer to low effect and liner control of pressure. Impact-pressure of absorption ability and confirmation to decrease of vibration level through to preexistence manufactures and comparative test. Water-hammer and pipe vibration make low of piping system.