• 한국가금학회지
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• 제27권2호
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• pp.109-114
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• 2000

The objective of these experiments was to develop an attenuated thermostable Newcastle disease virus(NDV), CBP-1 strain isolated from infected pheasants. Safety, pathogenicity and protective effects against velogenic NDV were also investigated to evaluate if the attenuated NDV, CBP-1 strain could be a candidate for a new NDV vaccine strain. CBP-1 strain was passaged up to the 173 times by nine days old embryonated eggs and chicken embryo fibroblast(CEF) cell cultures. Its sensitivitly to lipid solvents and low pH, thermostability, mean death time(MDT), intracerebral pathogenicity index(ICPI) of one day old chicks and intravenous pathogenicity index(IVPI) of four weeks old chicks were examined. Safety, boosting and protective effects were tested by chicks mortality. CBP-1 NDV strain had significant thermostability at 56$\^{C}$ for 30 minutes. by hemagglutinin activity and egg infectivity test, but was not resistant to lipid solvent. It showed possibility to use as a feed or water vaccine because of the resistance to low pH. MDT, ICPI and IVPI of CBP-1 were attenuated from 51.5, 1.96, 2.60 to 112.4, 1.12, 1.45. These results implied that the 173rd passages in embryonated egg and CEF cell cultures induced a substantial attenuation of the pathogenicity of the parent virus, changing the virulence from velogenic to intermediate between mesogenic and lentogenic. After vaccination with CBP-1 at one day old by drinking water mortality was 17.5%. However, spray vaccination with B1 at one day old, CBP-1 at two weeks ild and challenge with velogenic Kyojeongwon strain at four weeks old showed 93.5% survival rate. Mortality of chicks, vaccination with 173rd passaged CBP-1 strain at one day old, two weeks old and challenge with Kyokeongwon strain at four weeks old, was 20.0%. The results of these studies indicated that partial attenuated CBP-1 strain tended to be a low safety for ND of broiler chicks and would need to be more successive attenuation.

• 대한토목학회논문집
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• 제30권3A호
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• pp.265-275
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• 2010

콘크리트 충전형 합성부재와 콘크리트 피복형 합성부재는 압축하중 상태에서 강재에 의한 콘크리트의 구속효과와 콘크리트에 의한 강재의 국부좌굴에 대한 보강효과를 기대할 수 있는 압축부재이다. 기존의 연구결과를 바탕으로 RC, CFT, CET 압축부재에 대한 응력-변형률 관계와 하중-변위 관계를 철근비와 강재비에 따라 해석하였다. 이후 도출된 해석결과를 실험결과와 비교한 후, 구속효과가 하중과 변위에 미치는 영향을 평가하여 기존의 응력-변형률 관계를 수정하였다. 또한 국외 각국의 설계기준의 설계강도와 비교하여 수정된 응력-변형률 관계 제안식을 검토하였다.

• Structural Engineering and Mechanics
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• 제66권6호
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• pp.693-701
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• 2018

This paper develops a nonlocal strain gradient plate model for vibration analysis of graphene sheets under thermal environments. For more accurate analysis of graphene sheets, the proposed theory contains two scale parameters related to the nonlocal and strain gradient effects. Graphene sheet is modeled via a two-variable shear deformation plate theory needless of shear correction factors. Governing equations of a nonlocal strain gradient graphene sheet on elastic substrate are derived via Hamilton's principle. Differential quadrature method (DQM) is implemented to solve the governing equations for different boundary conditions. Effects of different factors such as temperature rise, nonlocal parameter, length scale parameter, elastic foundation and aspect ratio on vibration characteristics a graphene sheets are studied. It is seen that vibration frequencies and critical buckling temperatures become larger and smaller with increase of strain gradient and nonlocal parameter, respectively.

• 한국자동차공학회논문집
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• 제12권4호
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• pp.181-190
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• 2004

The interest of the fatigue life of rubber components such as engine mounts is increasing according to the extension of warranty period of the automotive components. Automotive engine mounts get damaged due to thermal and mechanical loadings. This paper discusses a fatigue life prediction of the 3-dimensional dumbbell specimens for natural rubber compound considering the effects of maximum strain and heat aging temperature. Displacement controlled fatigue life tests were performed using specimens with different levels of maximum strain and various hardness. The basic mechanical properties test and the fatigue test of aged rubber specimen under normal and elevated temperature were executed. A procedure to predicted the fatigue life of vulcanized natural rubber material based on the maximum strain method was proposed, and then this curve was in good agreement with fatigue test data less than 200% error range.

• 대한기계학회논문집
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• 제14권5호
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• pp.1193-1199
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• 1990

본 연구에서는 가공경화지수 (n)가 서로 다른 몇가지 재료를 선택하고 과대하 중의 비 (%PL)를 달리하는 단일 과대하중 피로 시험을 행하여 재료의 가공경화지수가 피로 균열 진파의 지연거동에 미치는 영향과 아울러 균열닫힘현상과의 관계를 구명하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2001년도 춘계학술대회 논문집
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• pp.249-256
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• 2001

This study investigated the shear stiffness of level of small strain with time effect. Time effect consists of rest time, loading rate of recent and current stress path. In addition, for the measurement of small strain, overconsolidated state was represented in a triaxial cell, and drained stress path tests were carried out. Test results show that the loading rate of recent stress path has no effects on the stiffness of very small strain, but the shear stiffness of level of small strain increases with it. Finally, the rest time and the loading rate of current stress path have the effects on the shear stiffness of initial and small strain.

• Journal of Plant Biology
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• 제1권1호
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• pp.1-6
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• 1958

1. Study was made to investigate effects of desoxyribonucleates on copper-resistance in yeast. 2. It is found that the resistant strain there exists the phenomic lag. 3. In the occurrence of the resistant strain there exists the phenomic lag. 4. Desoxyribonucleate isolated from copper resistant culture is capable of inducing the resistant strain, which is the same type as donor of the resistant type. It accelerated the rate of variation to the resistant, but it is of no effect on the resistant strain. 5. Desoxyribonucleate derived from non-resistant type inhibits growth of the resistant strain and delays the initial phase of growth. However, it is of no effect on the sensitive strain. It is concluded that desoxyribonucleate derived from resistant culture is capable of inducing the resistance, however, nonresistant type desoxyribonucleate is of no effect on inducing the resistance.

• 가정과삶의질연구
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• 제29권6호
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• pp.201-216
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• 2011

The purpose of this study is to investigate the effects of role satisfaction and role strain of employed wives on their marital satisfaction. Data were collected from 297 employed wives who are also mothers and reside in the city of Seoul and the province of Gyeonggi-do. Our findings are also as follows: First, employed wives showed a relatively high level of marital satisfaction. Second, when employed wives experienced less role strain, they experienced more role satisfaction. At the same time, when employed wives experienced greater role satisfaction, they also experienced greater marital satisfaction. It was also found that when employed wives experienced greater role strain they experienced less marital satisfaction. Third, our analysis partially confirmed that there were only three variables that significantly affected marital satisfaction; the age of the employed wife, the level of role satisfaction and the level of role strain.

• 열처리공학회지
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• 제19권4호
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• pp.208-218
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• 2006

The effects of the grain size on the magnetic properties in extra-low carbon steel after strain annealing were investigated. Two kinds of sample were prepared. One is the annealed sheet, which was annealed at $670^{\circ}C$ and $850^{\circ}C$ for various time periods after cold rolling. The other is the strain annealed sheet, which was temper rolled by 0.4% and subsequently strain annealed at the temperature ranging between $670^{\circ}C$ and $850^{\circ}C$ for various time periods. The grains after strain annealing became more coarse than those after primary annealing. The grains were coarsened due to the strain induced grain boundary migration (SIGM). It was found that the permeability tended to be increased and coercivity tended to be decreased with the increase of grain size. The optimum magnetic properties was achieved after strain annealing at $850^{\circ}C$ for 30 minites. Under this condition, the coercivity was measured to be 0.6 and the permeability was measured up to be 13000.

• Nuclear Engineering and Technology
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• 제38권7호
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• pp.619-638
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• 2006

Low temperature irradiation can significantly harden metallic materials and often lead to strain localization and ductility loss in deformation. This paper provides a review on the radiation effects on the deformation of metallic materials, focusing on microscopic and macroscopic strain localization phenomena. The types of microscopic strain localization often observed in irradiated materials are dislocation channeling and deformation twinning, in which dislocation glides are evenly distributed and well confined in the narrow bands, usually a fraction of a micron wide. Dislocation channeling is a common strain localization mechanism observed virtually in all irradiated metallic materials with ductility, while deformation twinning is an alternative localization mechanism occurring only in low stacking fault energy(SFE) materials. In some high stacking fault energy materials where cross slip is easy, curved and widening channels can be formed depending on dose and stress state. Irradiation also prompts macroscopic strain localization (or plastic instability). It is shown that the plastic instability stress and true fracture stress are nearly independent of irradiation dose if there is no radiation-induced phase change or embrittlement. A newly proposed plastic Instability criterion is that the metals after irradiation show necking at yield when the yield stress exceeds the dose-independent plastic instability stress. There is no evident relationship between the microscopic and macroscopic strain localizations; which is explained by the long-range back-stress hardening. It is proposed that the microscopic strain localization is a generalized phenomenon occurring at high stress.