• Journal of Korea Spatial Information System Society
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• v.9 no.3
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• pp.25-33
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• 2007

The local governments of major cities in Korea are giving focus on public transportation to reduce congestion and improve accessibility in city areas. In this regards, the proper measurement of accessibility is now a key policy requirement for reorganizing the public transport network. Public transport routing problems, however, are considered to be highly complicated since a multi-mode travel generates different combinations of accessibility. While most of the previous research efforts on measuring transport accessibility are found at zone-levels, an alternative approach at a finer scale such as bus links and stops is presented in this study. We proposes a method to compute the optimal route choice of origin-destination pairs and measure the accessibility of the chosen modes combination based on topological configuration. The genetic algorithm is used for the computation of the journey paths, whereas the space syntax theory is used for the accessibility. This study used node-link data in GIS instead of axial lines which are manually drawn in space syntax. The resulting accessibilities of bus stops are calibrated by O-D survey data and the proposed process is tested on a CBD of Seoul.

• Journal of Korea Soil Environment Society
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• v.2 no.2
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• pp.81-94
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• 1997

In many solute transport studies, either flux or resident concentration has been used. Choice of the concentration mode was dependent on the monitoring device in solute displacement experiments. It has been accepted that no priority exists in the selection of concentration mode in the study of solute transport. It would be questionable, however, to accept the equivalency in the solute transport parameters between flux and resident concentrations in structured soils exhibiting preferential movement of solute. In this study, we investigate how they differ in the monitored breakthrough curves (BTCs) and transport parameters for a given boundary and flow condition by performing solute displacement experiments on a number of undisturbed soil columns. Both flux and resident concentrations have been simultaneously obtained by monitoring the effluent and resistance of the horizontally-positioned TDR probes. Two different solute transport models namely, convection-dispersion equation (CDE) and convective lognormal transfer function (CLT) models, were fitted to the observed breakthrough data in order to quantify the difference between two concentration modes. The study reveals that soil columns having relatively high flux densities exhibited great differences in the degree of peak concentration and travel time of peak between flux and resident concentrations. The peak concentration in flux mode was several times higher than that in resident one. Accordingly, the estimated parameters of flux mode differed greatly from those of resident mode and the difference was more pronounced in CDE than CLT model. Especially in CDE model, the parameters of flux mode were much higher than those of resident mode. This was mainly due to the bypassing of solute through soil macropores and failure of the equilibrium CDE model to adequate description of solute transport in studied soils. In the domain of the relationship between the ratio of hydrodynamic dispersion to molecular diffusion and the peclet number, both concentrations fall on a zone of predominant mechanical dispersion. However, it appears that more molecular diffusion contributes to the solute spreading in the matrix region than the macropore region due to the nonliearity present in the pore water velocity and dispersion coefficient relationship.

• Journal of Korean Society of Transportation
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• v.29 no.1
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• pp.81-93
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• 2011

This research deals with the multi-modal continuous network design problem to resolve the transportation policy problems for constructing and operating transportation facilities with considering the mutual decision-making process between transportation operator and user in the multi-modal network. Particularly, in the consideration of changes in travel pattern between transport modes due to the changes in transportation policy, road network for passenger car and transit network for public transportation are considered together. In the development of network design model, more rational Stackelberg equilibrium(cooperative game) rather than more general Nash equilibrium(non-cooperative game) approach is used and sensitivity analysis considering transport mode is used. A multi-modal continuous network design model in this study is developed for the arbitrary continuous network design parameters(${\epsilon},\hat{\epsilon},p$) of transportation policy decisions. As examples of application and evaluation for these design parameters, the developed model is applied to calculate 1)the optimal capacity of road link in the road transport policy, 2)the optimal frequency of transit line in public transport policy and 3)the optimal modal split in transport modal share policy.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.3
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• pp.1-11
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• 2016

The present study aims to evaluate transfer resistance factors in railway stations and draw new implications. The data used for the model estimation are RP (revealed preference) data and SP (stated preference) data. Two types of models were used for the analysis: integration model which combined line-haul stage, transfer stage and shuttle stage and separation model which assessed the three stages separately. The results revealed that while bulk freight shippers mainly focused on line-haul stage, they put emphasis on transfer stage as well. It's especially notable that transfer stage was considered more important than shuttle stage. Therefore, in future transportation policies concerning rail freight, it would be crucial not only to enhance the competitiveness of line-haul stage but also make improvements in transfer stage regarding railway stations.

• Journal of Korean Society of Transportation
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• v.30 no.3
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• pp.17-30
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• 2012

This study analyzes the basic characteristics needed for motivating modal shift from truck to rail. The object of the study is to consider the resistance factor for container transported inland and the object point is the transfer node where modal shift occurs. The main contents of the study are as follows. First, the study looks at what shippers, engaged in inland transport of container, think of current transfer node environment. From this, the study analyzes what resistance factors are attributable to the lack of motivation in modal shift from truck to rail. Second, the study estimates mode choice models in which the resistance factors at transfer node are applied. Also by using this, the study draws out elasticities, and analyzes characteristics of resistantance factors in modal shift. Third, as its result, the study suggests methods to promote modal-shifting container transport from truck to rail.

• Journal of Korean Society of Transportation
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• v.18 no.1
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• pp.27-34
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• 2000

This study analyzes the price elasticities of airline Passenger demand through the 'Stated Preference' technique which uses survey data. Because the domestic airfare has been regulated by the government. it is not easy to derive Price elasticity through the usual regression analysis with aggregate data and thus a special methodology is required for elasticity estimation. Therefore, in this study we estimated the Price elasticities of domestic air passenger demand and the modal share change rates to the alternative modes with logit model and sample enumeration method, by analyzing the survey data on air Passengers' demand behavior about the mode choice between air-rail. air-bus, and air-car. As the results, the estimated price elasticities are in the range of -0.6~-0.9, and rail is mainly chosen as an alternative mode. bus is chosen Partly, and car is barely used.

• Journal of Korean Society of Transportation
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• v.11 no.1
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• pp.37-54
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• 1993

본 연구는 화물수송수단 선택 모형이론과 그 적용측면을 개괄적으로 살펴봄으로써 관련 현황수준(state of the art)에 대한 이해를 높이고, 발전방향을 모색함에 그 목적이 있다. 이러한 관점에서 먼저, 모형구성 정황(context)과 집단화(aggregation)를 포함한 화물수송수요 모형화의 몇가지 기본과제를 고찰한다. 이어서 집단모형과 비연속선택 개별모형으로 대별되는 모형이론과 그 세부적 구조(specification)를 설명하고 각 모형들의 중요성(significance)에 관하여 언급하며, 비연속선택모형의 추정과 관련된 기존의 투입자료형태 및 표본추출방법들에 대하여 문헌조사를 통하여 고찰함으로써 그 장단점과 중요성을 검증한다. 마지막으로 이러한 논의 및 검토결과를 토대로 화물수송수요예측을 위한 앞으로의 연구방향을 제시하여 본다.

• Journal of Korean Society of Transportation
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• v.4 no.1
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• pp.12-27
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• 1986

This study examined user preferences toward transportation modes in Seoul. Two multidimensional scaling models, the ideal point and vector models, were applied to data on mode preferences of 114 adults in the metropolitan area. While both models produced fairly similar results, the vector model performed slightly better than the other in terms of interpretability of the results. The transport attributes elicited are comfort, flexibility, travel cost, travel time, privacy, and safety; among which comfort is salient most. The comfort variable is a multi-faceted attribute in nature. The variations of attribute preferences are most significant between the gender groups as well as worker/nonworker groups. In particular, male workers, female workers and female nonworkers form three distinctive market segments. An unidimensional scaling of the preference data reveals that subway, auto-driver, and subscription bus modes are preferred most, whereas motorcycle and bicycle least. The other modes of express bus, taxt, auto-passenger, bus and walk rank intermediately. An examination of how preference orders vary among modal groups hints that users align their stated attitudes to their choice in order to reduce cognitive dissonance.

• Journal of Korean Institute of Industrial Engineers
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• v.4 no.1
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• pp.33-47
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• 1978

This paper attempts to develop a method which combines a subway system with a feeder bus system in order to increase the efficiency of the performance of the subway system. The 'feasible region' where a subway system is more desirable than a conventional bus in its travel time far the CBD-bound trip is determined and the service-specification models of the two systems in this region have been formulated and analyzed in an aggregate manner. The model developed in this study is applied to the Subway Line No. 1 in Seoul. The result obtained in the analysis indicates that the combined system can be guaranteed as a desirable mode in the point of travel time and cost within the feasible region. The concept of the model will lead to a proper assessment of the system's potentials for the choice of an optimal combination of the existing transport technologies.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.5
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• pp.1-11
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• 2016

The purpose of this study is to contribute the use of special taxi for the transportation vulnerable such as elderly and pregnant woman in terms of improving transportation mobility and extending social participation. We analyzed the DB users of STS system operating in Suwon, and surveyed the preference statement. Specifically, we have built transportation mode choice models for the elderly and pregnant woman, and then we drew the activating STS plan by comparing influence factors for each model. Based on the results of the study, 23% of STS user was the elderly people and pregnant women, 31% of user was for hospital passage purpose, and short-haul passage within 2 ~ 5km was 70% level of the passage. According to preference survey results between STS and Bus, fare was the highest impact factor in the mode choices for the elderly, and the participants who are older and car owners have been found to prefer the special taxi. For the pregnant woman, travel time and fare were the main influence factors of choices, and it was discovered that they preferred the special taxi when they are car owners and trips was frequented. Also, if the fare of special taxi is about 70% of the regular taxi fare, The share rates of Special Taxi comparing to bus for the elderly and pregnant woman are analyzed to be 51.1% and 63.6% each. Therefore, the adjustment of the fare would be effective to encourage the use of the special taxi. The results of this study can be used as a basis for establishing the rational fare structure of the special taxi.