• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.5
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• pp.83-89
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• 2002

The purpose of this paper is to assess experimentally system stability of the 154［㎸］transmission system due to the current of the forthcoming AC High-Speed Railway (HSR) era. It introduces a simple method to evaluate the system stability. The proposed method also shows the relationship between stability and power losses, and the stability indices made by the numerical process proposed in this paper will be used to assess whether a system can be stabilized or not. This paper also presents the improvement of the stability via loss reduction using a shunt compensator. Reactive power compensation is often the most effective way to improve both power transfer capability and system stability. The suitable modeling of the traction power system should be applicable to the PSS/E. The proposed method is tested on a practical system which will be expected to accommodate the heavy HSR load.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1681-1698
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• 2011

According to the demands of the times, Inchon international airport railroad opened up step by step but It is situation that much government subsidies are paid because It does not competitive power with road traffic by decline of schedule speed. Inchon international airport railroad users will convert by other transportation and minimize damage their time as travel time is prolonged. Therefore, need high speedization of airport railroad, this may act big role competitive power security as well as airport railroad activation with another public transportation. Thus, this paper suggests that a high speedization possibility section in the sections of airport railroad and train speed elevation effect analysis by roadbed, railroad, system improvement and the most efficient operation intervals analyzing each vehicles (AREX (120km/h), KTX (230km/h), EMU(Electric Multiple Unit, 180km/h) train running pattern.

• Journal of Korean Society of Transportation
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• v.17 no.1
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• pp.41-52
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• 1999

Recently, much literature has surveyed the economic effects of transportation investment, focusing on the relationship between transportation infrastructure investment and economic development. Although the conventional views assume that transportation investment stimulates economic growth, the results of recent studies are not conclusive and in some cases reject the conventional views. The contradictory results are linked with double counting Problem and Keynesian/Neo-classical economics theory. This article investigates the economic effects of road transportation with regard to freight transport using Stated Preference technique. This study examines, in particular, the value of time saving for freight which has been rarely studied in this area. In the first part, the value of time saving, excluding the value for driver and operating cost, is theoretically investigated through the model of continuous review system and periodic review system. At last, the empirical study using the Seated Preference technique shows the value of time saving for freight and the value of reliability, compared with other studies and the value of those in COBA. The result makes us conclude that road investment produces the secondary effects as well as the direct benefit such as time saving for passengers, operating cost saving. and accident cost reduction. The secondary effect includes the contribution to economic development.

• Journal of Korean Society of Transportation
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• v.28 no.3
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• pp.85-98
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• 2010

As transit networks are becoming more multimodal, the concept of connectivity of transit networks becomes important. This study aims to develop a quantitative model for measuring the connectivity of multimodal transit networks. To that end, we select, as evaluation measures of a transit line, its length, capacity, and speed. We then define the connecting power of a transit line as the product of those measures. The degree centrality of a node, which is a widely used centrality measure in social network analysis, is employed with appropriate modifications suited for transit networks. Using the degree centrality of a transit stop and the connecting powers of transit lines serving the transit stop, we develop an index quantifying the level of connectivity of the transit stop. From the connectivity indexes of transit stops, we derive the connectivity index of a transit line as well as an area of a multimodal transit network. In addition, we present a method to evaluate the connectivity of a transfer center using the connectivity indexes of transit stops and passenger acceptance rate functions. A case study shows that the connectivity evaluation model developed in this study takes well into consideration characteristics of multimodal transit networks, adequately measures the connectivity of transit stops, lines, and areas, and furthermore can be used in determining the level of service of transfer centers.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.6
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• pp.1069-1073
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• 2016

The current free-riding subway system for the elderly over 65 years old has been implemented since in 1980. As the aging population increases, the number of free riders also increases. It results eventually in the increase of subsidy from government. In addition, a transfer between subway and bus is not good enough since the free ride system is applied to only subway not to bus. The aim of this study is to analyze the transport card data to understand the impact of free-riding in the viewpoint of economic issues. It aims also to analyze the transfer patterns between public transport. At the end it compares Korea case with international cases and finds out some issues on free-ride systems. Finally, counter-measures aimed at improving the current free-rider system is suggested.

• Journal of the Korean Geographical Society
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• v.44 no.6
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• pp.723-744
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• 2009

The purpose of this paper is to clarify the prospects and problems in the study of geography related to the concept of commodity, transport, and supply chains. The geography studies related to commodity chains are expanded to each field of industry focusing on the subjects and economic difference which lead the commodity chain in core and periphery regions. These vertical connection are studied with the political economy approach that gives attention to geographical pattern of agricultural products and foods. But in viewpoint of commodity circuit and commodity network, the culture or subjects of micro regions and interaction are also studied. The contents of these study are to clarify the importance of cultural turn and local. And the study of chain standpoint appears that the series of transport process by transportation modes can be understood by transport chains and the physical distribution process of sea freight is to be grasped by supply chains.

• Spatial Information Research
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• v.19 no.4
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• pp.11-20
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• 2011

In accordance with low carbon and green growth paradigm, a subway is one of major public transit systems for resolving traffic congestion and decreasing traffic accidents. In addition, as subway networks expand, passengers' travel pattern in the subway network change and consequently affect the urban structure. Generally, new subway route has been planned and developed, mainly considering a travel demand forecast. However, it is desired to conduct an empirical analysis on the forecast model regarding change of travel accessibility and passenger demand pattern according to new subway line. Therefore, in this paper, an alternative method, developed based upon a spatial syntax model, is proposed for evaluating new subway route in terms of passenger's mobility and network accessibility. In a case study, we constructed subway network data, mainly targeting the no 9 subway line opened in 2009. With an axial-map analysis, we calculated spatial characteristics to describe topological movement interface. We then analyzed actual modal shift and change on demand of passengers through the number of subway passenger between subway stations and the number of passenger according to comparative bus line from Smart Card to validate suggested methods. Results show that the proposed method provides quantitative means of visualizing passenger flow in subway route planning and of analyzing the time-space characteristics of network. Also, it is expected that the proposed method can be utilized for predicting a passengers' pattern and its impact on public transportation.

• Journal of Navigation and Port Research
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• v.31 no.6
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• pp.447-454
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• 2007

To assess the port development and maritime traffic environment, the future traffic volume has been estimated using the number of inbound and outbound vessel for a specific port. The estimation of future traffic volume should be considered as an important factor to establish the degree of fairway congestion, the determination of fairway width and the operational role. Until now, the number of in and out vessel for the port has been only estimated mainly, but the type and size of inbound and outbound ships are different depending on the port's characteristics. So, it is difficult to estimate the future traffic volume using the change of only one item. This paper calculates the future traffic volume using the marine traffic characteristic factors as the number of coastal ship and ocean-going ship, the size of ship and the change of cargo volume per a ship etc. And it compared with the results of Artificial Neural Network(ANN) for accurate identification of nonlinear system.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4D
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• pp.565-571
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• 2006

This study aimed to analyze access mode choice behavior for KTX Passengers. To fulfill the aims of this study, Dong-Daegu Station was selected as a station for a case study. This study takes place in two stages. These are (i) descriptive statistical analysis of transportation status before and after introduction of the KTX, (ii) empirical model estimation for analyzing access mode choice behavior. This study makes use of the data from travel survey from Daegu metropolitan area. The main part of the survey was carried out in the KTX Dong-Daegu station. The data was collected from a sample of 1,800 individuals. The survey data includes the information on travel from Dong-Daegu station to Seoul. From descriptive statistical analysis of transportation status before and after introduction of the KTX, it is found that revealed demand of the KTX is lower than that expected. Moreover, it is found that the low demand of the KTX stems from high cost for the KTX itself and inconvenience( including travel time and cost) of access mode. In order to analyze mode choice behavior for accessing Dong-Daegu station, multinomial logit model structure is used. For the model specification, a variety of behavioral assumptions about the factors which affect the access mode choice, were considered. From the empirical model estimation, it si found that access travel time and access travel cost are significant in choosing access mode. Given the empirical evidence, we see that improvement of access transportation system for Dong-Daegu station is very important for enhancing the use of KTX.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10b
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• pp.142-144
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• 2004

다양한 지리 관측 기술 및 GPS 그리고 무선통신 기술의 발달로 인해, 해수의 흐름 변화 관측이나 PDA를 장착한 물류 차량 관리와 같이 시간에 따라 이동하는 여러 객체들의 변화를 추적하고 관리하는 것이 용이해지고 있다. 그리고. 이로 인해 지능형 교통 시스템. 물류 차량 관리 시스템 등이 활발히 개발되고 있다. 그러나 개발된 시스템에서 차량 운송 계획 평가 및 테스트를 할 경우 차량의 실제 데이터가 부족하기 때문에 적절한 평가 및 다양한 테스트를 하기 힘들고, 실생활에 알맞은 시스템을 만들기 어려움 점이 있다. 이렇게 부족한 차량 데이터를 보충하기 위해, 대부분의 연구에서는 몇몇의 이동 객체 위치 데이터 생성기를 활용하고 있다. 그러나 기존의 이동 객체 데이터 생성기는 단순히 정규 분포, 가우스 분포. 랜덤 데이터. 도로 정보 등을 고려하여 데이터를 생성하기 때문에. 사용자가 물류 수송 계획 등에 활용하기 위해 의도한 시나리오에 따른 데이터를 생성하지 못하고 있다. 따라서, 이 논문에서는 차량 위치 데이터 생성기에 사용자가 지정한 시나리오를 생성, 저장하는 이동 객체 패턴 제공기를 추가하여. 사용자 지정 시나리오를 지원하는 차량 위치 데이터 생성기를 설계한다 이 논문에서 설계된 차랑 위치 데이터 생성기는 사용자가 원하는 계획대로 차량의 위치 정보를 생성함으로써, 물류 수송 및 도로 건설계획 등을 검토할 때 도움이 될 수 있을 것이다.