• KDI Journal of Economic Policy
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• v.11 no.3
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• pp.131-146
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• 1989

본고(本稿)에서는 가계(家計)의 저축행태(貯蓄行態)가 일생적기(一生適期)(life cycle)에 걸쳐 연령(年齡)-자산관계(資産關係)(age-wealth profile)를 통해 어떻게 나타나는가를 이론적으로 그리고 미시적(微視的) 시뮬레이션의 결과로 살펴보았다. 본고(本稿)에서는 기존의 Ando-Modigliani의 모형(模型)에 성인상당수(成人相當數)라는 개념(槪念)을 도입(導入), 무자녀가구(無子女家口)와 유자녀가구(有子女家口) 사이에 자산저축경로(資産著畜經路)의 차이가 존재함을 밝혔다. 즉, 유자녀가구(有子女家口)의 경우, 자녀의 교육비를 지원함으로써-좀 더 정확히 표현하면 또다른 형태의 세대간교부(世代間交付)(intergenerational transfer)라고 할 수 있는 자녀의 인적자산형성(人的資産形成)에 투자함으로써-소비(消費)가 이 시기에 급상승하게 되고 따라서 자산저축(資産著畜)이 무자녀가구(無子女家口)의 경우보다 완만해질 수 있음을 밝혔다.

• Journal of Korean Society of Transportation
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• v.28 no.6
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• pp.109-120
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• 2010

This study aims to develop mathematical models for estimating saturation flow rates at the stop line of signalized intersection due to Workzones in the vicinity, since the saturation flow rate is the most critical parameter in capacity analysis for signalized intersections. It was found by reference review that saturation flow rates are sensitively influenced by the location of Workzone, the number of lanes, cycle length and effective green time. Extensive microscopic simulation runs were also performed and compared to the those of mathematical models for model verification. Mathematical models were developed based on traffic flow theory and dualizing them by the location of workzones. And then each result produced by changing important parameter values was carefully examined and analyzed. Small but consistent differences in saturation flow rate values between mathematical models and simulations exist. However, the pattern of changes in saturation flow rates depending on each variable was similar.

• Journal of Korean Society of Transportation
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• v.26 no.4
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• pp.205-215
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• 2008

As static traffic assignment has reached its limitation with ITS policy applications and due to the increase of interest in studies of ITS policies since the late 1980's, dynamic traffic assignment has been considered a tool to overcome such limitations. This study used the Dynameq program, which simulates route choice behavior by macroscopic modeling and dynamic network loading and traffic flow by microscopic modeling in consideration of the feasibility of the analysis of practical traffic policy. The essence of this study is to evaluate the feasibility for analysis in practical transportation policy of using the dynamic traffic assignment technique. The study involves the verification of the values estimated from the dynamic traffic assignment with South Korea's expressway network and dynamic O/D data by comparing results with observed link traffic volumes. This study used dynamic O/D data between each toll booth, which can be accurately obtained from the highway Toll Collection System. Then, as an example of its application, exclusive bus-lane policies were analyzed with the dynamic traffic assignment model while considering hourly variations.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.2
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• pp.29-43
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• 2019

The calibration of microscopic traffic simulation models has received much attention in the simulation field. Although no standard has been established for it, a genetic algorithm (GA) has been widely employed in recent literature because of its high efficiency to find solutions in such optimization problems. However, the performance still falls short in simulation analyses to support fast decision making. This paper proposes a new calibration procedure using a dual GA and central composite design (CCD) in order to improve the efficiency. The calibration exercise goes through three major sequential steps: (1) experimental design using CCD for a quadratic response surface model (RSM) estimation, (2) 1st GA procedure using the RSM with CCD to find a near-optimal initial population for a next step, and (3) 2nd GA procedure to find a final solution. The proposed method was applied in calibrating the Gipps car-following model with respect to maximizing the likelihood of a spacing distribution between a lead and following vehicle. In order to evaluate the performance of the proposed method, a conventional calibration approach using a single GA was compared under both simulated and real vehicle trajectory data. It was found that the proposed approach enhances the optimization speed by starting to search from an initial population that is closer to the optimum than that of the other approach. This result implies the proposed approach has benefits for a large-scale traffic network simulation analysis. This method can be extended to other optimization tasks using GA in transportation studies.

• Journal of Korean Society of Transportation
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• v.21 no.5
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• pp.19-29
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• 2003

The purpose of this study is to analyse the effect of the parking information on the waiting time using the simulation method. Stated Preference survey has been implemented to construct the parking lot choice model. A queue simulation is carried out to investigate the effect of various parking information on the waiting time. The results show that providing parking information is likely to increase the utilization of parking place and to decease the waiting time of individual vehicle. Furthermore, as the parking demand increases, the detailed and quantitative parking information such as "5 minutes delay" is more effective than qualitative parking information such as "available".

• Journal of Korean Society of Transportation
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• v.25 no.6
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• pp.65-77
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• 2007

A two-way left-turn lane is a continuous center left-turn lane that could be used as a deceleration and refuge area for both directions of left-turning vehicles. TWLTL's have been used effectively for access management treatment when applied to a highway that has wide-spread left turning traffic demand and a high-density of side streets. In this study, an effective analysis was carried out using a computer-based simulation tool, VISSIM, in order to evaluate performance and safety effects of TWLTLs and develop a warrant. In conclusion, the results indicated that there was a remarkable decrease of through and left-turning vehicle travel time delay on the main road and improvement of traffic safety.

• Journal of Korean Society of Transportation
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• v.27 no.5
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• pp.113-124
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• 2009

This paper suggests a new approach for providing information for driver safety at signalized intersections. Particularly dangerous situations at signalized intersections such as red-light violations, accelerating through yellow intervals, red-light running, and stopping abruptly due to the dilemma zone problem are considered in this study. This paper presents the development of a dangerous vehicle determination algorithm by collecting real-time vehicle speeds and times from multiple point detectors when the vehicles are traveling during phase-change. For an evaluation of this algorithm, VISSIM is used to perform a real-time multiple detection situation by changing the input data such as various inflow-volume, design speed change, driver perception, and response time. As a result the correct-classification rate is approximately 98.5% and the prediction rate of the algorithm is approximately 88.5%. This paper shows the sensitivity results by changing the input data. This result showed that the new approach can be used to improve safety for signalized intersections.

• International Journal of Highway Engineering
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• v.9 no.4
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• pp.105-116
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• 2007

A ROUNDABOUT is more effective way to improve safety and prevent delays than signal intersection. ROUNDABOUT has been known highly safe treatment that could be used as a method to reduce conflicts between vehicles, to reduce travel speed in inner or approach of intersection, and to have no speed difference between drivers than intersection. In this study, the effective analysis on the installation of ROUNDABOUT was carried out using computer-based simulation tool VISSIM, in order to evaluate performance and safety of ROUNDABOUT and develope a warrant. In conclusion, the results indicated that there was remarkable increase of Y-intersection capacity and decrese of delay, and improvement of traffic safety. Finally, A nice feature of this study is to firstly attempt to use microscopic simulator to evaluate the effectiveness of ROUNDABOUT and suggest a passible operation boundary.

• Journal of Korea Port Economic Association
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• v.26 no.3
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• pp.130-142
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• 2010

The purpose of this paper is to propose applying agent-based model(ABM) for analyzing logistics system. Logistics problems become more complex and multi-faceted. As a result, the behavior of the system becomes more and more difficult to predict, we see the limitations of the traditional top-down approach in handling complexity. The ABM, that is the bottom-up approach, provides new modeling framework in system modeling. The ABM focuses on the interactions of subsystem or agents in whole system. Then the macroscopic picture of the whole system behavior is emerged as the microscopic interactions of agents are aggregated. The ABM assumes that each agent acts based on simple rules learned from dynamic interactions among other agents or its surrounding environment. The ABM has a great advantage in understanding emergent phenomenon that cannot be explained only through considering individual attributes. The ABM is an extremely useful method to analyze complex system such as logistics system. Therefore, the great research efforts and applications on the ABM to logistics system are encouraged in future.

• International Journal of Highway Engineering
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• v.10 no.2
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• pp.221-227
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• 2008

This study identifies the relationship between traffic data quality obtained from loop detectors and their location. Traffic data basically shows traffic flow conditions and thus, these information can be used as inputs for various transportation management strategies. Out study presents how to determine optimal downstream detector location on merging area in order to enhance the effects of ramp metering strategies. Microscopic simulation model, PARAMICS, is used as the main analytical tool. Assuming that detector location relies heavily on traffic flow characteristics in each roadway segment, we perform statistical analysis to identify homogeneous traffic conditions on merging area.