• The Transactions of the Korea Information Processing Society
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• v.4 no.10
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• pp.2470-2476
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• 1997

We propose a new real-time search algorithm and provide experimental evaluation and comparison of the new algorithm with mini-min lookahead algorithm. Many other real-time heuristic-search approached often divide the problem space to several sub-problems. In this paper, the proposed algorithm guarantees not only the sub-problem deadline but also total deadline. Several heuristic real-time search algorithms such as $RTA^{\ast}$, SARTS and DYNORA have been proposed. The performance of such algorithms depend on the quality of their heuristic functions, because such algorithms estimate the search time based on the heuristic function. In real-world problem, however, we often fail to get an effective heuristic function beforehand. Therefore, we propose a new real-time algorithm that determines the sub-problem deadline based on the status of search space during sub-problem search process. That uses the cut-off method that is a dynamic stopping-criterion-strategy to search the sub-problem.

• Journal of Ginseng Research
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• v.18 no.1
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• pp.32-38
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• 1994

Male rats aged 15 months, which had been over-trained with 12 arm radial maze up to the criterion of 1 or 2 errors an average per trial, were divided into two groups and 7 months after the over-training and were studied the effect of red ginseng trial saponin fraction (PT) on the spatial memory function. The rats which could be improved the performance of 9.75$\pm$1.26 (within 185$\pm$8.2 1 sec) were classified into "normal group" (n=4) and the ones, which showed R-maze performance of 7.0$\pm$2.87 within 300 sec, "deteriorated memory group" (n=5). PT was dissolved in distilled water and injected into the deteriorated memory group intraperitoneally at 30 min before R-maze for 3 consecutive days. The injected amount of PT on the 1st day was 10mg/rat, 1mg/rat both on the 2nd the 3rd day. As results, the performance was restored to 9.4$\pm$2.0 after stopping ginseng administration, although the lower performance values (1.4$\pm$0.89, 2.8$\pm$0.83, 3.8$\pm$0.84, respectively) were exerted during the three days of PT administration than before PT administration (7.0$\pm$2.87) since 1 day after administratitan of PT. The restored performance values were continuously maintained up to the level of the "normal group". However, any lower performance values were not observed when PT was administered via intraperitoneal route to the normal group in about of 2 mg/rat except 10mg1ra1. The number of errors when the foods in arms were put at only 6 places was clearly reduced during the 9 days of consecutive administration of PT as compared with untreated control. These results indicated that PT administration may enhance their cognitive function after a long lapse of time not only in the memory deteriorated rats but also in normal ones. The reason exerted lower performance values during PT administration in this paper was discussed as compared with the results of T-maze behavior of another 3-month-aged rats. of another 3-month-aged rats.

• Journal of the Korean Society for Railway
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• v.19 no.4
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• pp.555-563
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• 2016

Line capacity of railways is a core criterion to decide maximum trips in accordance with traffic demand and a priority in railway investment to improve transportation capability. Particularly, because two operators will start revenue services in the HSR from mid-2016, the line capacity should be carefully calculated and controlled to avoid conflicts between the maximum number of KTXs, and the number needed to guarantee the effective competition of the operators. Meanwhile, there have been many arguments about calculating the line capacity, because this number is affected by the number of trips by train types, stopping pattern and dwell time in each station, journey time, crossing or passing, safety headway between trains, etc. To deal successfully with these kinds of problems, this study proposes a simulation method to calculate the line capacity that considers train operation according to the operator's service policies.

• Journal of Korean Society of Transportation
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• v.31 no.1
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• pp.3-13
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• 2013

This paper reviews the characteristics of dilemma zone by analysing the influence exerted by actual location of intersection traffic signal on behaviour of drivers approaching signalized intersection in urban area. The analysis of approach speed was based upon a 'before and after' comparison, measured at three sites where the locations of traffic signals were changed. The study demonstrated that, when traffic signal changed to yellow, the scales of dilemma zone were narrowed in case of stopping cars by moving up the starting point of the dilemma zone due to lowered spot speed. On the other hand, in case of passing cars, the end points of dilemma zone were moved further out to the rear due to increased spot speed. Therefore, changing traffic signal locations could make an impact to increase intersection safety through reducing the scales of dilemma zone. This study also found that, in cases involving vehicles with similar approach speeds, spot speeds could be differentiated following the change of signal locations due to the fact that there can be greater differences in both braking point and deceleration rate. Thus, when considering the appropriate measuring of dilemma zone, 'spot speed' rather than 'approach speed' appeared to be more appropriate criterion.