• International Journal of Highway Engineering
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• v.9 no.3
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• pp.123-134
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• 2007

This study was carried out for evaluating correlation of aging level and deformation resistance of asphalt mixtures conditioned by artificial aging treatment. The specimens were made of the short-term aged loose asphalt mixture which was kept in a convection oven at $154^{\circ}C$ for 2 hours, and then were artificially aged at $110^{\circ}C$ for 24, 48, 72 and 96 hours for long-term aging. Deformation strength ($S_D$) and large molecular size ratio (LMS(%)) were measured after short-term and each long-term aging treatment to evaluate aging extents of each mixture with aging time using GPC(Gel-permeation chromatograph) test. It is shown that the $S_D$ and LMS(%) were increased with aging time increment, and that LMS(%) quantity and $S_D$ have relatively good correlation each other. This study found that the aged asphalt mixture had better resistance against rutting and it was possible to estimate rutting characteristics of asphalt mixtures by using LMS(%) without a binder recovery.

• International Journal of Highway Engineering
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• v.9 no.4
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• pp.45-54
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• 2007

This study was carried out for developing artificial short-term aging(SA) and long-term aging(LA) methods of asphalt mixtures in which the aging level is properly matched with those of RTFO and PAV aged binders, respectively. The specimens were made of the short-term aged loose asphalt mixture which was kept in a convection oven at $154^{\circ}C$ for 2 hours and were aged at $110^{\circ}C$ for 24, 48, 72 and 96 hours for SA. Large molecular size(LMS) were measured using GPC after SA and LA to evaluate aging extents of each mixture with aging time. It is shown that the LMS was increased with aging time increment and that from the LMS(%) change ratio, it was possible to suggest an appropriate artificial aging time which is corresponding level of aging with RTFO and PAV. It was found that SA was somewhat strong and LA for 48 hours at $110^{\circ}C$ would be appropriate if sort-term aging is properly controlled.

• International Journal of Highway Engineering
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• v.7 no.4 s.26
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• pp.203-210
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• 2005

The penetration and viscosity tests have been used for the evaluation of the aged asphalt binder performance change. The improved test method has been required because the conventional tests could not evaluate the viscoelastic characteristics and the real behaviour of the aged asphalt binder. The conventional test methods using a different short term aged asphalt binder were tested and the test results were expressed as the penetration index and the residual penetration. The oscillatory and rotational mode tests were performed to find out the rheological characteristics of the short term aged asphalt binder in this study. The test results showed that the change of testing frequency, the speed of the vehicle effects the complex modules and phase angles. The creep compliance and shear viscosity also showed the different test results when the short term aged asphalt binders were tested. The rheological behavior should consider when the pavement design is conducted.

• International Journal of Highway Engineering
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• v.4 no.4 s.14
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• pp.53-66
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• 2002

Asphalt binder characteristics in asphalt mixture are changed due to aging. However. depending upon aggregate and binder used, asphalt mixture dose not show the same level of stiffness and brittleness under the same ageing level. The factors affecting Physical Properties change of the asphalt binder within aged asphalt concrete are not well known and there is limited study which is dealing with this topic This study dealt with evaluation of physical properties of asphalt binder recovered from the mixtures after short-term and long-term aging. Two asphalts. two aggregates. two gradations and four polymers were used to make 32 mixture combinations. The mixtures were prepared and aged artificially in a forced draft oven. The measured physical properties included absolute viscosity, kinematic viscosity and penetration. Statistical analyses were carried out to find out the factor(s) having a significant effect on change of physical property of asphalt binder due to asphalt mixture aging. The results of study shown that aggregate, gradation and polymer had a significant effect on change of physical properties of asphalt binder.

• International Journal of Highway Engineering
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• v.13 no.2
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• pp.1-8
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• 2011

The objective of this paper is to evaluate the performance of low $CO_2$ asphalt binder properties using LEADCAP$^{(R)}$(Low Energy and Carbon Asphalt Pavement) additive as function of various aging methods such as RTFO(Rolling thin film oven), Ultraviolet(UV) lay. In order to simulate the short-term aging of asphalt binder that occurs during the hot-mixing asphalt process, the Rolling Thin Film Oven(RTFO) was used. Asphalt binder using LEADCAP$^{(R)}$ is prepared by addition of a photoinitiator activated by ultraviolet lay. The mechanical and rheological properties of the asphalt binder were estimated using UTM(Universal Testing Machine) and DSR(Dynamic Shear Rheometer). The test results showed that the asphalt binder using LEADCAP$^{(R)}$ additive was improved the rutting resistance at testing temperature ($70^{\circ}C$) and increased tensile strength at low temperature. Also, Thermal analysis shows that the Melting Point(Tm) of asphalt binder using LEADCAP$^{(R)}$ additive was constant although the asphalt binder was aged by Ultraviolet.

• International Journal of Highway Engineering
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• v.6 no.2 s.20
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• pp.15-24
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• 2004

Oxidation causes increment of the quantity of large molecular size or LMS in asphalt and is a major reason for hardening of asphalt binder. An extended service life of pavement on a road is expected by reducing oxidation of binder. Oxidation of binder occurs during hot mixing with aggregates before placement on road and then during in-service after the asphalt pavement is constructed. Quantitative increase of LMS as result of aging after RTFO and PAV was analyzed based on the data from high-pressure gel-permeation chromatography (HP-GPC). Polymer modified asphalt (PMA) after RTFO procedure showed 20-30% increment in LMS and then after PAV procedure more than twice, although the percentage of increment was different according to asphalt brand and grade. The PMAs containing LDPE or SBS, which showed a great mechanical property improvement in previous studies, were selected for characterizing PMA aging In this study. Considerably reduced increment of LMS was observed from the PMA containing LDPE after RTFO and PAV procedures. The GPC result showing the binder with less LMS increment means that the asphalt while being mixed with LDPE was aged less during the aging treatment. The dispersed particle of LDPE in asphalt cement seems to disturb oxidative aging reaction and evaporation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.2
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• pp.166-173
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• 1991

In order to determine the relationships between the rates of leaf senescence and photosynthate translocation during the grain filling periods in barley, field experiments were conducted through 1989/1990 crop year. Thirty barley varieties and lines having different leaf senescence were used for the experiments. Varieties differed significantly in the rate of leaf senescence and rate of grain filling. The rate of leaf senescence at early (10-20days after heading) and late period (20-30days after heading) during of grain filling were positively correlated with the rate of grain filling in same period, respectively. But the rate of leaf senescence at 10-20 days after heading negatively correlated with the rate of grain filling during the whole grain filling period (10-35 days after heading). Whereas, the rate of leaf senescence at late period was positively associated with the rate of grain filling during the whole grain filling period. Rates of grain filling at the late and whole periods have positively influence on grain weight(r=0.62**～-0.93**), but rate of leaf senescence at early period and duration of grain filling negatively correlated with the grain weight (r=-0.33～ -0.15). The patterns of leaf senescence index for the varieties tested were grouped by four. Among these patterns, the most ideal pattern was IV type.

• International Journal of Highway Engineering
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• v.1 no.2
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• pp.121-133
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• 1999

This study was based on the evaluation of 9 asphalts that were produced in five major Korean refineries. The study was concentrated to identify the problems of the current asphalt specification (KS M 2201) and to determine the ranges of visco-elastic asphalt behavior. As a conventional asphalt property. asphalt penetration, ring and ball(R&B) softening point, asphalt viscosity, and flash point of asphalt were measured. Also Dynamic Shear Rheometer (DSR) were used to evaluate visco-elastic properties of asphalts in the $-20^{\circ}C$ through $30^{\circ}C$ temperature range. These properties before and after the short-term (RTFO) and long-term (PAV) aging were compared and analyzed to achieve the research objectives. The conclusion from this study can be summarized by the followings. The low temperature rheological behavior of all the straight asphalt from five major Korean refineries is similar regardless of asphalt grade. In the mean while, the rheological behavior at high and intermediate temperature of Korean straight asphalt varies depending on asphalt grade.

• Korean Chemical Engineering Research
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• v.48 no.6
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• pp.695-699
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• 2010

The propellant KM10, a single propellant manufactured from nitrocellulose, was known to cause natural degradation phenomena at long term storage. In this study, the self-life was estimated using high temperature acceleration aging tests and stockpile analysis test. For the life expectancy estimation, Arrhenius equation and Berthelot equation were used in the high temperature acceleration tests, and the first order regression was used in the Stockpile analysis test. The self-life of propellant KM10 using the Arrhenius equation and Berthelot equation showed significantly different results as 43.73, 16.53 years in the high temperature acceleration test, and it showed 42.94 years in the Stockpile analysis test. The value of self-life predicted by Arrhenius equation was reasonable when compared with the result of E. R. Bixon.

• Korean Journal of Plant Resources
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• v.9 no.2
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• pp.157-163
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• 1996

This study was carried out to control the decrease of yield and the deterioration of quality of Angelica gigas roots by bolting. This phenomenon resulted from lignificartion and dwarfishness of roots because of bolting formed for inflorescence and fruition. Seedlings were grown for 60,90 and 120 days in nursery of the green house, and transplanted in main field to compare with traditional seedling that grew for 1 year. Growth of the petiole length compare with length and leaf width of aerial parts in nursery showed a remarkably progress, and root characters as root length, root diameter and root weight grew more vigorously in the order of nursery periods. Bolting was not entirely formed in plots transplanted the seedlings which grown for short-time; 60, 90 and 120days, but showed the high bolting rate, 64.3%,in traditional seedling plots. Yield was higher in plots that transplanted short-time growing seedlings than that transplanted traditional seedlings, and among 3 kinds of nursery periods yields were high in the order of nursery periods. For the increase of yield and decrease of bolting rate, it was needed to transplant small seedlings of 3-4g/plant which grew in nursery for 90-120 days.