• 미생물학회지
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• 제32권2호
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• pp.102-108
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• 1994

ABF1(Autonomously replicating sequence Binding Factor 1)은 효모 genome에서 $RTCRYN_5ACG$의 염기 서열을 가지고 있는 promoter, mating-type silencer, ARS에 결합하는 DNA binding 단백질이다. E. coli 에서 ABF1 유전자를 발현하기 위하여, ABF1 유전자를 pMAL-c2 벡터에 cloning하였다.(pMAHW). pMAHW를 E. coli에 형질전환하여, ABF1 융합단백질을 발현시키고, amylose resin affinity chromatography에 의하여 분리하였다. Factor Xa protease를 이용하여 분리된 융합단백질로부터 maltose binding protein을 잘라낸 후에 gel retardation analysis 방법으로 분리된 ABF1이 ARS1에 결합하는 능력을 지니고 있음을 확인하였다. DNA 결합에 관련된 부위를 찾기 위하여, 비전형적인 zinc finger motif가 위치하는 자리에서 pMAHW의 ABF1 유전자에 His-61을 다른 아미노산으로 치환하였다. DNA binding 부위로 추정되는 ABF1 단백질의 중간지역에 Leu-353, Leu-360를 다른 아미노산으로 치환하였다. Site-specific mutagenesis 를 통해 만들어진 mutant를 gel retardation analysis와 complementation test를 통해서 비전형적인 zinc finger motif이외에 다른 DNA binding motif가 있는 것을 알 수 있었다.

• 방사성폐기물학회지
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• 제5권2호
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• pp.113-122
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• 2007

본 연구에서는 타당한 지하조건을 모사하기 위한 실험장치를 글로버박스(Glove-box) 내에 설치하고 천연지하수 및 자연균열을 가진 화강암 시추코어를 이용하여 핵종이동 실험을 수행하였다. 암반코어의 균열을 통한 지하수 유동을 해석하기 위하여 비수착성 음이온 핵종인 Br로 지하수 유동실험을 수행하였다. 암반 균열을 통한 우라늄 이동 실험결과에서 유출된 우라늄의 파과곡선이 비수착성 핵종인 Br와 유사한 거동을 보여주었는데, 이는 주어진 지하수 조건에서 우라늄이 주로 탄산염과 결합된 음이온 복합체로 이동하기 때문인 것으로 추정된다. 아울러 균열충전광물에 대한 우라늄의 회분식 수착실험을 수행한 결과, 균열충전광물에 대한 우라늄의 분배계수 $K_d$는 약 2.7 mL/g로 낮게 나타났다. 이러한 우라늄 수착실험 결과는 빠른 유출을 보인 우라늄 이동실험 결과와 일치한다. 균열암반을 통한 우라늄 이동의 지 연 특성을 보다 자세히 분석하기 위하여 회분식 수착실험으로 부터 구한 $K_d$값을 이용해 지연인자 $R_d$값 $({\sim}16.2)$를 구하고 이동실험 결과로부터 구한 $R_d$값 $({\sim}14.3)$과 비교한 결과, 서로 매우 유사한 지연인자 값을 가진다는 것을 알 수 있었다. 이는 화강암 코어의 균열을 통한 우라늄의 이동 지연이 주로 균열충전광물에 의해 이루어지고 있음을 의미하는 것이라고 하겠다.

• 한국기계가공학회지
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• 제14권2호
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• pp.112-120
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• 2015

In this study, the growth rate of surface cracks (da/dN) during the retardation period was analyzed in terms of effective stress intensity factor range(${\Delta}K_{eff}^*$) obtained by using the proposed effective plastic zone concept. Effective stress intensity factors obtained by using the effective plastic zone concept were smaller than those obtained by using Willenborg analysis. On the growth rate of surface cracks analyzed by ${\Delta}K$, the dependence of overload stress levels appears. On the growth rate by ${\Delta}K_{eff}$ obtained by Willenborg analysis, there is a linear relationship with two different slops between da/dN and ${\Delta}K_{eff}$. However, on the growth rate by ${\Delta}K_{eff}^*$ obtained by the proposed effective plastic zone concept, there is a linear relationship between da/dN and ${\Delta}K_{eff}^*$ that coincides with the results of constant amplitude loading.

• 대한기계학회논문집A
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• 제21권2호
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• pp.305-316
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• 1997

A more efficient method for obtaining the fatigue life enhancement of a structure member with fastener holes is described. It is based on the combined process of cold-expansion and ring-indentation. Residual stresses were induced onto premachined holes using ring-indentation process near the fastener hole combined with cold-expansion. And residual stresses at the vicinity of a hole were evaluated using a fracture mechanics approach. The compressive residual stresses were larger using the combined process than is in the case of simple cold-expansion. Fatigue testing of aluminum specimens showed that the fatigue crack growth retardation emanating from a circular hole was greater for the combined process than for a simple cold-expansion alone.

• 대한본초학회지
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• 제29권5호
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• pp.31-38
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• 2014

Objectives : Egg yolk is composed of various important chemical substances for human health. A calcium shortage causes the growth retardation on the body growth. In this study, we examined the therapeutic effects of calcium, vitamin D and egg yolk peptide (EYP) treatment on the retardation of the longitudinal bone growth induced by low-calcium diet in adolescent rats. Methods : Low calcium diets were administrated for 15 days. During the last five days, calcium and/or vitamin D and/or EYP were administrated. The body weights, longitudinal bone growth rates, the heights of growth plates, and bone morphogenetic protein (BMP)-2 and insulin-like growth factor (IGF)-1 expressions were measured using histochemical analysis. Results : Low calcium diets caused the significant reduction in body weight gains and the longitudinal bone growth. The heights of growth plates and the expressions of BMP-2 and IGF-1 showed the impairment of body growth as well. Calcium and/or vitamin D administration could not significantly increase the longitudinal bone growth. However, calcium, vitamin D, and EYP administration significantly increased the bone growth, the growth plate height, and BMP-2 and IGF-1 expressions. Conclusions : These results suggest that EYP enhances the longitudinal bone growth in the calcium and/or vitamin D deficiency and it could be a promising agent for the treatment of children suffering from malnutrition.

• Journal of Photoscience
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• 제9권2호
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• pp.158-161
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• 2002

UV-B radiation gives harmful effects on plants, such as production of several types of DNA lesions, and growth inhibition. On the other hand, plants have some protective mechanisms, including filtering effect due to accumulation of phenolic compounds in epidermal cells and reactivation of DNA lesions, which are enhanced by UV-B irradiation. We have investigated the mechanism of UV-B effects on plants using cucumber seedlings as plant materials. Cucumber plants were cultivated in an artificially lit growth chamber. Supplemental UV-B irradiation, of which intensity was almost equal to the level of natural sunlight, retarded the growth of first leaves. The growth retardation must result trom the inhibition of cell division and/or cell growth. Microscopical observation of leaf epidermis suggested that the growth retardation might be mainly caused by cell growth inhibition. The retardation was, however, restored within 2 or 3 days after the termination of UV-B irradiation. It is known that UV-B irradiation lowers the activity of photo system II (PS II). In the present experimental conditions, however, UV-B irradiation has little effect on PS II activity as estimated by chlorophyll fluorescence. The stomatal conductance, a major factor determining photosynthetic rate, of first leaves increased during the growth. The increase of stomatal conductance was suppressed by UV-B irradiation and restored by termination of the irradiation. It has not been clear, however, what mechanisms are involved in the suppression of increase of stomatal conductance.

• 한국농공학회논문집
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• 제48권7호
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• pp.55-63
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• 2006

Bacterial transport models were evaluated in this study to determine the suitable model at describing bacterial transport in saturated column experiments. Four models used in the evaluation were: advective-dispersive equation (ADE) + equilibrium sorption/retardation (ER) + kinetic reversible sorption (KR) (Model I), ADE + two-site sorption (Model 2), ADE + ER + kinetic irreversible sorption (KI) (Model 3), ADE + KR + KI (Model 4). Firstly, analyses were performed with the first experimental data, showing that Model 4 is appropriate for describing bacterial transport. Even if Model 1 and 2 fit well to the observed data, they have a defect of not including the irreversible sorption, which is directly related to mass loss of bacteria. Model 3 can not properly describe the tailing observed in the data. However, further analysis with the second data indicates that Model 4 can not describe retardation of bacteria, even if the sorption-related parameters are varied. Therefore, Model 4 is modified by incorporating retardation factor into the model, resulting in the improved fitting to the data. It indicates that the transport model, into which retardation, kinetic reversible sorption, and kinetic irreversible sorption are incorporated, is suitable at describing bacterial transport in saturated column experiments. It is expected that the selected transport model could be applied to properly analyze the bacterial transport in saturated porous media.

• Journal of Photoscience
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• 제5권4호
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• pp.149-152
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• 1998

Expression of light-harvesting chlorophyll a/b-binding protein gene(cab) is repressed in the dark and activited by light. However, the detail of its regulatory mechanism is not characterized so far. To identify the interactions of cis-acting elements and trans-acting factors involvedin this regulation, nuclear extracts from the light-grown and dark-adapted Arabidopsis thaliana leaves were anlayzed for mobility shift assay against 134bp fragments had two retarded bands and one retardation band, respectively, both in light-grown and dark-adapted bands in the dark-adapted tissues. A new retardation the cab 3 expression in the dark. Several light regulatory motifs are scattered in the 146 bp region of cab 3 promoter. One of the light-regulatory motifs could be the binding site for the negative regulatory factor.

• 항공우주시스템공학회지
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• 제1권1호
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• pp.45-52
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• 2007

This paper analyzed the extension effects of fatigue life and the application of pre-indentation in aircraft structural material such as aluminum alloys. The test specimen used the thin sheet of aluminum alloy with a single-edged notch. The experiments were conducted after making the pre-crack under a constant amplitude loading. As the fatigue life extension technique, the pre-indentation making an indent on the predicted path of crack propagation was applied. The work presented here discussed about a proper mathematical relation between crack growth rate and the range of stress intensity factor and about the generalization of crack growth mechanism with large retardation effect. A technique to enhance the applicability of pre-indentation if also mentioned.

• 한국정밀공학회지
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• 제18권10호
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• pp.109-115
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• 2001

The compliance approach to the problem of load sharing between a cracked plate and multiple plate used to bridge the crack. The theory is validated by using calculated stress intensity factors for the multiple load path plate to reduce experimentally observed growth rate to a common base. Calculations are them made on the effect of multiple load path plate width on fatigue crack retardation in order to demonstrate the predictive capability of the technique.