• 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.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.4
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• pp.685-694
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• 2016

Visibility of lane marking is impaired at night, or in case of rain, and thereby threatens traffic safety. Recently, various studies and technology have been developed to improve lane marking visibility, such as the extension of lane marking life expectancy (up to 1.5 times), improvement of lane marking equipment, improvement of lane marking visibility (32.7%) by applying phosphorescent material mixed paint, and expressway lane design standards alternative (length 6m, gap 12m, width 13cm: 27.8% of painted surface are reduced) adoption with ergonomic analysis. In this study, a set of cost-benefit analyses was performed for the cases where such techniques were applied. Based on the literature review, 26.9% of traffic accidents would be prevented by improving lane marking visibility by 32.7%; accident reduction benefit was calculated as much as 12.5 billion KRW. Meanwhile, total increased cost when introducing phosphorescent material mixed paint and lane design standards alternative is calculated as 30.6 billion KRW. However, economic feasibility could not be secured with 0.41 of cost-benefit ratio when applied to the expressway network as a whole. Additionally, cost-benefit (B/C) analysis was applied to each of the top 20 night accident hot spots and the results of B/C ratios were between 0.67 and 4.20, showing that 11 out of 20 spot sections of expressway can have economic feasibility. This results indicate, with this kind of pavement marking applied to accident hot spots in rural expressway, better visibility and economic feasibility can be guaranteed through traffic accident reduction. Some limitations and future research agenda have also been discussed.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.3
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• pp.139-141
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• 2003

Disease severity, percent ripened grains, and yield were investigated in the seven mixtures by using near-isogenic lines having different resistant gene(s) to bacterial blight(BB) of rice. The seven mixtures including the four pure stands were inoculated with a 1:1:1 mixture of races $K_1$, $K_2$, and $K_3$ of BB. Among the seven mixtures-ML01, ML02, ML03, MLl2, MLl3, ML23 and ML0123-, disease severiety, percent ripened grains, and yield of ML01 and ML12, respectively did not show significant difference with those of mean values of their components. But degree of disease severity of the other mixtures, respectively -ML02, ML03, MLl3, ML23, and ML0123-was less than the mean of their components. Percent ripened grains and yield of them were higher than those of mean of their components. ML03, MLl3, ML23 and ML0123 comprised of the equal amount of two or four components having different resistant gene, these mixtures appeared to be a desirable combination for delaying spread of the pathogen, stabilizing of the race structure of the pathogen population, and extending durability of a cultivar with monogenic resistance.

• The Journal of the Korea Contents Association
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• v.8 no.3
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• pp.234-243
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• 2008

The aim of this study was to provide the way of activation plans of leisure activities for older people through the current status and problems in welfare center for the elderly in Korea. Various social phenomena and issues have been found to occur in rapidly social-structure changes and urban civilization. Especially, processing an aging society for no preparation is one of the broader question of our country. Developing the scientific and civilization lengthening our span of life is given more leisure time than past. Unfortunately, older people could not independently stand for in their leisure, if society does not support for them. It means that they might feel the enough time to monotone life, depression and a sense of alienation. The following ideas would be expressed to the way of activation plans of elderly leisure. First, the elderly leisure facilities for leisure and publicity activities should be supplemented or strengthened. Second simple entertainment-oriented programs in the physical and psychology learning to adapt for them should be obtained through leisure activities for older people. Third, more senior recreation specialists or therapists should be educated for leisure activities. Fourth, the concept of leisure in older people's idea should be changed through the education. Fifth, people who work in the welfare center for the elderly should develop the leisure programs or activities for older people. Last the new culture of leisure concept should be constructed in our society between the two and three generation for sharing and participating the leisure.

• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.2
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• pp.237-248
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• 2014

Linear cutting test is known to be very effective to determine machine parameters (i.e. thrust force and torque) and to estimate penetration rate of TBM and other operation conditions. Although the linear cutting test has significant advantages, the test is expensive and time-consuming because it requires large size specimen and high load capacity of the testing machine. Therefore, a few empirical prediction models (e.g. CSM, NTNU and QTBM) alternatively adopt laboratory index tests to estimate design parameters of TBM. This study discusses the estimation method of TBM machine parameters and disc cutter consumption using punch penetration test and Cerchar abrasion test of which the researches are rare. The cutter forces and cutter consumption can be estimated by the empirical models derived from the relationship between laboratory test result with field data and linear cutting test data. In addition, the estimation process was programmed through which the design parameters of TBM (e.g. thrust, torque, penetration rate, and cutter consumption) are automatically estimated using laboratory test results.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.565-573
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• 2000

Sewer pipe in Korea is generally constructed with concrete pipes. Moreover, the sewer system is susceptible to the corrosion problem due to the regulation employing anaerobic treatment processes, such as domestic sewage treatment facilities, nightsoil septic tanks and so on. The objective of this study is investigated to experimental test of $H_2S$ production rate affecting corrosion of sewer pipe in Korea. In this study, tube-type and sealed-type reactor were used to examine the reactions in the microorganism suspended growth and biofilm. Furthermore. concentration changes were investigated with COD and sulfate reduction in each reactor. Sulfide production rate was $50.4mg-H_2S/g-VSS{\cdot}d$ in the sealed-type reactor and in the tube-type biofilm reactor was $2.8{\sim}18.8g-H_2S/m^2{\cdot}d$.

• THE JOURNAL OF KOREAN ORIENTAL ONCOLOGY
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• v.4 no.1
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• pp.159-175
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• 1998

In order to investigate the antitumor effect by Chungsangbohahwan after B-16 cells were transplanted in C57BL/6 mice, and the immune responses in mice induced by methotrexate, the extract of Chungsangbohahwan was orally administered to the mice for 21 days. Experimental studies were performed for measurance of metastasis, cell cytotoxicity in vitro, natural killer cell activity, productivity of interleukin-2. The results were summarized as follows: 1. Inhibition of metastasis in Chungsangbohahwan-treated group was higher than control group with significance on 7th day and 14th day. 2. On the MTT assay, cell viability was significantly inhibited by $5{\mu}g/well$, $2.5{\mu}g/well$, $1.25{\mu}g/well$, and $0.625{\mu}g/well$ of Chungsangbohahwan concentration inhibited cell viability significantly(P<0.05). $IC_{50}$ for cell viability was $2.17{\mu}g/well$. 3. Natural killer cell activity in Chungsangbohahwan-treated group was significantly increased on 100:1, 50:1 E/T(effect cell/target cell) ratio(P<0.05). 4. Production of interleukin-2 in Chungsangbohahwan-treated group was significantly increased(P<0.05).

• The Journal of the Korea Contents Association
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• v.18 no.3
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• pp.611-625
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• 2018

With innovative advances in wireless communication technology, many researches for extending network lifetime in maximum by using energy harvesting have been actively performed on the area of network resource optimization, QoS-guaranteed transmission, energy-intelligent routing and etc. As known well, it is very hard to guarantee end-to-end network delay due to uncertainty of the amount of harvested energy in multi-hop RF(radio frequency) energy harvesting wireless networks. To minimize end-to-end delay in multi-hop RF energy harvesting networks, this paper proposes an energy efficient routing metric based on interference aware and protocol which takes account of various delays caused by co-channel interference, energy harvesting time and queuing in a relay node. The proposed method maximizes end-to-end throughput by performing avoidance of packet congestion causing load unbalance, reduction of waiting time due to exhaustion of energy and restraint of delay time from co-channel interference. Finally simulation results using ns-3 simulator show that the proposed method outperforms existing methods in respect of throughput, end-to-end delay and energy consumption.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.190-199
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• 2017

People's interest in how to lead a happy life when they get older is increasing because of the extension of life span due to thedevelopment of medical technology. Factors that can affect happiness or the strength of the influence of those factors may vary according to age. Previous studies, have found that individuals with promotion focus are more likely to experience happiness than those with prevention focus. However, whether this effect of regulatory focus on happiness is consistent regardless of age has not been sufficiently investigated. Therefore, 1,250 Korean adults from each age group and residence were randomly selected as thesample, and the moderating effect of age on the relationship between regulatory focus and subjective well-being was examined. The results indicated that promotion focus and age have a significant interaction effect on subjective well-being, while the interaction effect of prevention focus and age was not significant. More concretely, the positive effects of promotion focus on life satisfaction and affective balance grew stronger with increasing age. This finding implies that it is especially important for old adults to use promotion focus by actively setting challenging goals and motivating themselves to gain a sense of accomplishment to experience subjective well-being. In addition, social support is proposed as being especially important to activate their promotion focus.

• International Journal of Highway Engineering
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• v.13 no.1
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• pp.139-148
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• 2011

Asphalt concrete overlay method is used by general maintenance and rehabilitation of construction for aged concrete pavement in Korea. However, in case of the AC overlay method to extend service life of the existing concrete pavements, various distresses of reflection crack, pothole and rutting are the typical problems of the asphalt overlay on existing concrete pavement since it has different physical characteristics between asphalt overlay and existing concrete pavement. To achieve this, application of concrete overlay method is required instead of AC overlay method. Concrete overlay method has advantages that can reduce maintenance cycle and costs since it has excellent bearing value for heavy vehicles and no rutting. However, technical problems of detour road construction, traffic control and other disadvantages happened by long curing time. Thus, in this study and experimental research were launched to evaluate the workability, durability and resistance against environmental loading of Very Rapid Hardening Acrylic Polymer Modified Concrete(VRH-APMC) for application of bonded concrete overlay method. Test results showed that the compressive and bond strength were exceed 21MPa and 1.4MPa of target strength after four hours for rapid traffic opening properties. And tests of resistance against environmental loading results showed that VRH-APMC secured excellent durability. Thus, it was known that VRH-APMC was suitable material for large scale bonded concrete overlay method, and it was possible to use maintenance and rehabilitation method which needs enough workability and rapid traffic opening.