• 대한기계학회논문집A
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• 제29권8호
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• pp.1139-1145
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• 2005

Most failures of ductile materials in metal forming processes occurred due to material damage evolution - void nucleation, growth and coalescence. In this paper, the modified yield function of Liao et al in conjunction with the Hosford's yield criterion is studied to clarify the plastic deformation characteristic of voided anisotropic sheet metals. The void growth of an anisotropic sheet under biaxial tensile loading and damage effect of void growth on forming limits of sheet metals are investigated. Also the characteristic length defining the neck geometry is introduced in M-K model to incorporate the effect of triaxial stress in necked region on forming limits. The forming limits theoretically predicted are compared with experimental data. Satisfactory agreement was obtained between the predictions and experimental data.

• 한국디지털건축인테리어학회논문집
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• 제4권2호
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• pp.44-51
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• 2004

It is generally known in seismic design that the beam yield type frames have more advantages than column yield type of which damage is likely to concentrate to any story. However we may design a building as a beam yield type, it becomes actually a column yield type collapse mode for slab floor diaphragm effect. Considering these points, the column yield type frames are selected and designed as the specimens. The object of this study is to grasp quantitatively the restoring force characteristic values and to estimate the seismic performances of column yield type steel rahmen.

• Earthquakes and Structures
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• 제9권4호
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• pp.851-873
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• 2015

A methodology for estimation of statistical properties (viz. mean and standard deviation) of the expected seismic damage to reinforced concrete framed structures subject to corrosion of reinforcement, over a specified reference time (typically the service life of the structure) is proposed in this paper. The damage to the structure under the earthquake loading is characterised by the damage index, determined using the modified Park and Ang damage model. The reduction in area, yield strength and strain at ultimate of steel reinforcement, and the reduction in compressive strength of cover concrete due to corrosion are taken into account in the estimation of damage. The proposed methodology is illustrated through an example problem. From the results obtained, it is noted that there is an increase of about 70% in the mean value of expected seismic damage to the reinforced concrete frame considered over a reference time of 30 years when effect of corrosion is taken into consideration. This indicates that there is a need to consider the effect of corrosion of reinforcement on the estimation of expected seismic damage.

• 한국작물학회지
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• 제26권3호
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• pp.219-225
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• 1981

Strong wind of 6.5m/s from electric fan was applied to rice at heading stage to find out the nature of wind damage to panicle. Damaged panicles caused by typhoon were sampled out of field to measure the yield and milling components. Wind-treated glumes were developed into two forms, fertile and sterile, and each of them showed all degree of glume discoloration. The number of fertile grains were higher than sterile grains in a damaged panicle. Averagesdegree of glume discoloration was higher in not flowered glume than in flowered glume. The more recently flowered glumes resulted the higher degree of discoloration among flowered glume. The percent of sterile grain to total number of grains was the highest at stage of just flowering. The glume discoloration representing wind damage at heading state advanced in degree in ten days after treatment compared to that just after treatment. Grain length and grain width were decreased with the increased degree of glume discoloration, while grain thickness was not changed greatly. Chalkiness was a little higher in damaged grain than in normal grain without definite trends by degree of discoloration. Ripening ratio, 1000 grain weight and yield decreased with increased degree of glume discoloration in damaged panicle by typhoon. Decreasing order in yield was white rice, rough rice and brown rice. Ratio of brown rice to rough rice increased, white rice to brown rice decreased, and milling recovery was not changed greatly with increased degree of 히ume discoloration.

• Nuclear Engineering and Technology
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• 제55권9호
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• pp.3229-3240
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• 2023

Due to neutron radiation, atomic displacement has a significant effect on material in nuclear reactors. A range of secondary displacement models, including the Kinchin-Pease (K-P), Lindhard, Norgett-Robinson-Torrens (NRT), and athermal recombination-corrected displacement per atom (arc-dpa) have been suggested to calculate the number of displacement per atom (dpa). As neutron elastic interaction is the main cause of displacement damage, the focus of the current study is to calculate the atomic displacement caused by the neutron elastic interaction in order to estimate the exact amount of yield strength in a WWER-1000 reactor pressure vessel. To achieve this purpose, the reactor core is simulated by MCNPX code. In addition, a program is developed to calculate the elastic radiation damage induced by the incident neutron flux (RADIX) based on different models using Fortran programming language. Also, due to non-elastic interaction, the displacement damage is calculated by the HEATR module of the NJOY code. ASME E-693-01 standard, SPECTER, NJOY codes, and other pervious findings have been used to validate RADIX results. The results showed that the RADIX(arc-dpa)/HEATR outputs have appropriate accuracy. The relative error of the calculated dpa resulting from RADIX(arc-dpa)/HEATR is about 8% and 46% less than NJOY code, respectively in the ¼ and ¾ vessel wall.

• 식물병연구
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• 제13권1호
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• pp.20-23
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• 2007

2002년부터 2005년까지 4년간 벼 흰잎마름병 초발병 조사결과 2002년보다 초발병일이 20$\sim$30일 이상 빨라지고 있음을 확인하였다. 벼 흰잎마름병 발병시기 및 병반면적율에 따라 수량이 감소하였는데 병반면적률이 10% 이하에서는 피해가 적었으나, 병반적율이 증가함에 따라서 수량감소가 점점 많아졌고, 25% 이상일 때부터 수량감소 및 현미천립중 등에서 현저히 낮아지고 병반면적율이 50% 이상이고 유수형성기 발병시 수량 29%, 현미천립중 2.3g, 현미완전립률 18%까지 감소되었다. 밥맛의 기준이 되는 식미치인 점도에서도 병반면적율이 증가함에 따라 낮은 식미치를 보였다.

• Composites Research
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• 제14권3호
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• pp.42-50
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• 2001

본 연구에서는 집중하중을 받는 일방향 보강 섬유 금속 적층판의 손상 개시 모델을 연구하였다. 기존의 복합재료 적층판의 해석에 사용하는 일타 전단변형이론을 수정하여 섬유 금속 적층판의 하중 변위 관계를 구하였고, 유한 요소 해석을 통하여 응력을 계산한 다음 Tsai-Hill failure criterion과 Miser yield criterion을 사용하여 섬유층과 금속판의 파괴 지수를 계산하는 방법으로 섬유 금속 적층판의 손상 개시를 모델링하였다. 단순 인장과 원통형 굽힘 하중에서의 적층 각도에 따른 섬유 금속 적층판의 파괴 지수 분포를 통하여 해석의 타당성을 검증하였으며, 이를 바탕으로 집중하중을 받는 경우 섬유 방향에 따른 파괴 지수를 계산하였다. 계산된 파괴 지수를 손상 개시 하중과 비교하기 위하여 압입 시험을 수행하였다. 압입 시험은 섬유 방향의 영향을 보기 위하여 양단 고정인 경계 조건에서 수행하였다. 손상 개시 하중은 압입 선도의 앞 부분을 Hertz식을 이용하여 회귀 분석한 곡선이 실제 하중 곡선과 달라지는 점으로부터 결정하였다. 다양한 섬유 방향에 따른 압입 시험을 수행하였으며 각각의 손상 개시 하중을 파괴 지수와 비교하였다.

• 한국토양비료학회지
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• 제14권3호
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• pp.157-162
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• 1981

농작물(農作物)에 대(對)한 불화수소(弗化水素)가스의 피해(被害)를 경감(輕減)시키기 위(爲)하여 피해경감제(被害輕減制)로서 소석회(消石灰) 규회석(硅灰石), 인산질(燐酸質)을 토양(土壤)에 시용(施用)하여 수도(水稻)를 재배(裁培)하고 $0.1g/m^3$의 불화수소(弗化水素)가스를 1시간(時間)씩 접촉(接觸)한후(后) 수량감소정도(收量減少程度), 피해엽율(被害葉率), 식물체중(植物體中)의 불소함량(弗素含量) 및 규산함량(珪酸含量)을 조사(調査)한 결과(結果)는 다음과 같다. 1. 불화수소(弗化水素)가스 피해경감효과(被害輕減效果)는 소석회(消石灰) 및 규회석(硅灰石)이 가장 좋았다. 2. 불화수소(弗化水素)가스를 접촉(接觸)하지 않은 구(區)에서는 개량제처리간(改良劑處理間)에 수량착이(收量着異)가 없었으나 불화수소(弗化水素)가스를 접촉(接觸)하므로서 개량제간(改良劑間)에 유의성(有意性) 있는 수량 수량착이(收量着異)가 있었다. 3. 식물체내(植物體內) 불소함량(弗素含量)은 감수율(減收率) 및 피해엽율(被害葉率)과 각각(各各) 정(正)의 상관(相關)이 있었다.

• 한국농공학회지
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• 제39권6호
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• pp.31-40
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• 1997

Potential impacts for unfavourable weather conditions and the assessment of the magnitudes of their adverse effects on crop yields were studied. EPIC model was investigated for its capability on crop yield predictions for rice and soybean. Weather generationmodel was used to generate long-term climatic data. The model was verified with ohserved climate data of Suwon city. Fifty years weather data including abnormal conditions were generated and used for crop yield simulation by EPIC model. Crop yield probability function was derived from simulated crop yield data, which followed normal distribution. Probable crop yield reductions due to abnormal weather conditions were also analyzed.

• 환경생물
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• 제23권4호
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• pp.390-397
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• 2005

The inhibition of cell recovery might be proceeded via either the damage of the mechanism of the recovery itself or via the formation of irreversible damage which could not be repaired at all. Both these processes may take place at the same time. Any of these possibilities would result in a decrease in both the rate and extent of cell recovery. To distinguish them, a quantitative approach describing the process of recovery as a decrease in the effective radiation dose was applied to experimental data on the recovery from potentially lethal damage in Chinese hamster cells exposed to X-rays alone or combined with various chemicals (pyruvate, novobiocin, lactate, nalidixic acid, 3-aminobenzamide). For these particular cases, it is concluded that the recovery process itself is not damaged and the inhibition of the recovery is entirely due to the enhanced yield of the irreversibly damaged cells.