• Journal of Korean Society of Transportation
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• v.27 no.5
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• pp.17-28
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• 2009

There are many limitations in dealing with rapidly changing traffic demand in urban cities. Thus recently, traffic operation and management skills are more emphasized rather than the expansion of traffic facilities. In particular, in the interrupted flow formed by signalized intersections, it is quite important to give optimal signal timing to each intersection with consideration of progression. However, as fixed signal times per direction can affect passing capacity in signalized intersections, the present four-signal phase including a left-turn signal has many limitations, including reduction of directional road capacity when traffic demand is increases dramatically during peak hours. Because of this problem, lots of studies about internal metering techniques for oversaturated signal control skills have progressed but these techniques are not used widely due to the absence of detectors for queue sensing in real-time signal control systems. In this research, a new methodology called the "restrictive left-turn signal control", which is already used at the intersection above Samsung subway station, is suggested in order to reduce control delay of urban arterial roads. The restrictive left-turn signal control allows a driver to make a U-turn and then a right turn instead of turning left in that intersection. With this change, the restrictive left-turn signal control can contribute to increased intersection capacity by reducing the number of signal phases and maximizing the through phase time. However, road structure and traffic conditions at the target intersections should be considered before the adoption of the proposed signal control.

• Journal of Life Science
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• v.17 no.3 s.83
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• pp.328-333
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• 2007

Genetic diversity and population structure of eleven Liriope platyphylla (Liliaceae) populations in Korea were determined using genetic variation at 20 allozyme loci. The percent of polymorphic loci within the enzymes was 55.9%. Genetic diversity at the species level and at the population level was high(Hes = 0.178; Hep = 0.168, respectively), whereas the extent of the population divergence was relatively low ($G_{ST}$ = 0.064). $F_{IS}$, a measure of the deviation from random mating within the 11 populations, was 0.311. Total genetic diversity values ($H_T$) varied between 0.0 and 0.535, giving an average over all polymorphic loci of 0.323. The interlocus variation in within population genetic diversity ($H_S$) was high (0.305). An indirect estimate of the number of migrants per generation (Nm = 3.66) indicates that gene flow is high among Korean populations of the species. In addition, analysis of fixation indices revealed a substantial heterozygosity deficiency in some populations and at some loci. Mean genetic identity between populations was 0.988. It is highly probable that directional toward genetic uniformity in a relatively the homogenous habitat is thought to be operated among Korean populations of L. platyphylla.

• Journal of Korean Philosophical Society
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• v.129
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• pp.291-313
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• 2014

The aim of this paper is to clarify the Aristotle's conception of change(kinesis). Aristotle defines the change as a process which actualize a potentiality. From Aristotle's definition of the change, a number of consequences flow directly about how to conceptualize it. First, the change is fundamentally directional. Second, if we do not know what the change is directed toward, we do not understand what the change is. Third, everything that changes is caused to change by a distinct cause of change, a changer. Fourth, there is a single actualization of cause and subject of the change. All change, for Aristotle, is the change of an enduring subject. And all change occur in the infinite(to apeiron) which is time, space, matter. It would be absurd to equate the whole and the infinite, for that would be to say that the unlimited had a limit. The infinite does not contain, but in so far as it is infinite, is contained. And due at least in part to its potentiality, the infinite is unknowable. Because it lacks a form. The infinite traditionally derived its dignity from being thought of as a whole in which everything is contained. But Aristotle removes the infinite from its position of majesty. Aristotle's this idea was a revolution in philosophical perspective.

• Journal of Korean Society of Transportation
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• v.36 no.2
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• pp.155-168
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• 2018

In this study, we studied the directional pattern of entering the intersection from the intersection upstream link prior to predicting short future (such as 5 or 10 minutes) intersection direction traffic volume on the interrupted flow, and examined the possibility of traffic volume prediction using traffic assignment model. The analysis method of this study is to investigate the similarity of patterns by performing cluster analysis with the ratio of traffic volume by intersection direction divided by 2 hours using taxi DTG (Digital Tachograph) data (1 week). Also, for linking with the result of the traffic assignment model, this study compares the impact area of 5 minutes or 10 minutes from the center of the intersection with the analysis result of taxi DTG data. To do this, we have developed an algorithm to set the impact area of intersection, using the taxi DTG data and traffic assignment model. As a result of the analysis, the intersection entry pattern of the taxi is grouped into 12, and the Cubic Clustering Criterion indicating the confidence level of clustering is 6.92. As a result of correlation analysis with the impact area of the traffic assignment model, the correlation coefficient for the impact area of 5 minutes was analyzed as 0.86, and significant results were obtained. However, it was analyzed that the correlation coefficient is slightly lowered to 0.69 in the impact area of 10 minutes from the center of the intersection, but this was due to insufficient accuracy of O/D (Origin/Destination) travel and network data. In future, if accuracy of traffic network and accuracy of O/D traffic by time are improved, it is expected that it will be able to utilize traffic volume data calculated from traffic assignment model when controlling traffic signals at intersections.