• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.5
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• pp.65-76
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• 2018

This study aims to evaluate the legibility distances of variable speed limit sign(VSL) for different sizes, luminances, and fog conditions through a field experiment. For this, extensive fog simulated environment has been constructed, and legibility distances are tested and recorded among test subjects for different luminances and sizes of VSL in control. Results showed that legibility distance increased as the size of VSL increased in the given illumination conditions, but it was not an exact linear trend. The size was also an important factor for determining legibility distance as the fog density increased, especially heavy fog conditions. In addition, the legibility distance also increased as the given illumination levels of VSL improved.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.10
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• pp.962-974
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• 2010

Recently, the convergence of information technology with bio-technology, nano-technology or other technologies has been creating a new paradigm. In a field of transportation, the intelligent transport systems which is a convergence of intelligent technologies and transportation systems have been studied. The Variable Speed Limit(VSL), is one of ITS technologies, is thought to improve safety and efficiency of transportation while controlling speed limit based on road conditions. Legacy studies have considered only one station for VSL algorithm. However, it is not appropriate for an urban freeway installed with many stations. In this paper, new algorithm is proposed to not only enhance effectiveness of VSL based on cooperation of stations but also reflect road conditions within 30 seconds. The proposed algorithm consists of 4 steps: the first is a "searching bottleneck station" step, the second is a "calculating a size of congestion" step, the third is a "calculating the number of controlled stations" step, the final is a "calculating VSL" step. This algorithm guarantees improved safety and minimum additional travel time. The travel time should be considered because drivers would against the VSL algorithm when the proposed algorithm occurs additional travel time. In our experiments, microscopic traffic simulator VISSIM is selected to perform a modeling work. The results show that proposed algorithm provides the improved safety and minimum increase of travel time.

• Reproductive and Developmental Biology
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• v.36 no.3
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• pp.189-192
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• 2012

Male factor infertility or sub-fertility contributed half of all cases of infertility while the semen abnormality is the current topic of argument. Conventional analysis of semen showed poor correlation with fertility. Therefore, evaluation of current semen analysis method is necessary to improve standards of semen assessment. The goal of this study was to investigate that correlation between motion kinematic before and after capacitation and litter size in porcine. Sperm motility and kinematics were measure by computer-assisted sperm analysis (CASA). The motility of spermatozoa was positively correlated with curvilinear velocity (VCL), average path velocity (VAP), and mean amplitude of head lateral displacement (ALH) (p<0.05). Where as VCL positively correlated with VSL, VAP and ALH (p<0.01). Straight-line velocity (VSL) was positively correlated with VAP and ALH (p<0.01). VAP was significantly positively correlated with ALH (p<0.01). Also, we found significant positive correlation among variation of VSL, VAP and ALH (p<0.05). No motility and kinematic parameter are correlated with litter size. However, litter size was significantly correlated with breed (p<0.05). Our results suggested that analysis of sperm motility and kinematics using CASA is questionable for prediction of litter size. However, it has some practical importance to evaluate semen commercially.

• Environmental and Resource Economics Review
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• v.17 no.4
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• pp.845-873
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• 2008

This study estimates the VSL(value of a statistical life) as well as the WTP(willingness to pay) for mortality risk reduction using sample selection model with data on liver cancer examination which is associated with little possibility of multi-purpose(i.e. joint production) in averting behavior. The marginal benefits of mortality risk reduction are estimated by applying for household production function model with medical expense and the time required for medical examination of liver cancer. Individuals are more likely to take liver cancer test if they are male, older, higher educated, those with spouse, smoker, more income of household, and more anxious about their health. The costs of liver cancer examination are statistically significantly affected with expected signs by size of mortality risk reduction, sex, period of eduction, those with spouse, and household income. The marginal effect of mortality risk reduction owing to taking liver cancer examination is estimated at 321,097 won. The costs of liver cancer examination are increased by 905 won with more one year of education period and by 1,743 won with more one million won in household income. On liver cancer examination, male spends more 12,310 won than female and those with spouse pay more 7,969 won than those without spouse. Therefore the VSL from mortality risk reduction due to liver cancer examination is 321.10 million won at mean size of mortality risk reduction and mean cost of liver cancer examination. The results of sensitivity tests on costs and effects of liver cancer test shows that the VSLs are estimated in a range from 160.55 million won to 642.19 million won.