• Journal of the Korean Geographical Society
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• v.43 no.4
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• pp.544-560
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• 2008

This study seeks to clarify the background and factors for the expansion of bus networks that connect Incheon International Airport with its hinterlands. For this research objective, this paper analyzes the relationships among the change of bus routes, competitive transportation modes, passenger fares, and the shortest time distance. Previously, the hinterlands of route bus networks that connect Gimpo International Airport were Seoul metropolitan area, Chungcheong region, Jeonju and Iksan in Jeollabuk-do(province). However, the opening of Incheon International Airport resulted in the expansion of the hinterlands of bus networks to Gangwon-do, Gwangju, and major cities in Youngnam region. Simultaneously, route bus networks also expanded in Seoul metropolitan area. Each bus route connecting Incheon International Airport with its hinterlands was opened by a single bus company or various bus companies. In many cases, due to the uncertainty of revenues or bus company's regional ties, a bus route was opened by various bus companies. In this paper, the analysis of the number of one-way route bus service and density of flight passengers shows that the frequency of the route bus service for Seoul except Gangseo-gu(ward) and for Seoul's satellite cities(Suwon, Seongnam, Anyang, Gunpo, Guri, and Osan) should be decreased. The analysis also shows that the frequency of the route bus services for the other cities, counties(Guns), and wards(gus) should be increased. In Seoul metropolitan area, although route bus fares are more expensive than subway fares, passengers use route bus more frequency than subway because time distance of route bus is shorter than that of subway and subway transfer is inconvenient. In general, outside Seoul metropolitan area, air flight is preferred in the regions that have airports. In contrast, the route bus is preferred in Daegu and other regions that do not have airports.

• Journal of the Economic Geographical Society of Korea
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• v.18 no.4
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• pp.539-555
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• 2015

This study proposes the methodology for measuring the time-distance accessibility on the Seoul bus system based on the T-card transaction databases and analyzes the results. T-card transaction databases contain the time/space information of each passenger's locations and times of the departure, transfers, and destination. We introduce the bus network graph and develop the algorithms for time-distance accessibility measurement. We account the average speed based on each passenger's get-in and getoff information in the T-card data as well as the average transfer time from the trip chain transactions. Employing the modified Floyd APSP algorithm, the shortest time distance between each pair of bus stops has been accounted. The graph-theoretic nodal accessibility has been given by the sum of the inverse time distance to all other nodes on the network. The results and spatial patterns are analyzed. This study is the first attempt to measure the time-distance accessibility for such a large transport network as the Seoul bus system consists of 34,934 bus stops on the 600 bus routes, and each bus route can have different properties in terms of speed limit, number of lanes, and traffic signal systems, and thus has great significance in the accessibility measurement studies.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.11B no.3
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• pp.112-118
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• 2001

In the near future, the voltage of power system for passenger vehicle will be changed to 42V from existing 14V./ Because of increasing power and voltage ratings used in the vehicle the motor drive system has high switching dv/dt and it generates electromagnetic interference (EMI) To solve these problems multi-level inverter system may be used The feature of multi-level inverter is the output voltage to be synthesized from several levels of voltage Because of this feature high switching dv/dt and EMI can be reduced in the multi-level inverter system But as the number of level is increased manufacturing cost is getting expensive and system size is getting large. Because of these disadvantages the application of multi-level inverter has been restricted only to high power drives. The method to reduce manufacturing cost and system size is to integrate circuit of multi-level inverter into a few chips But isolated power supply and signal isolation circuit using transformer or opto-coupler for drive circuit are obstacles to implement the integrated circuit (IC) In this paper a drive circuit of 4-level inverter suitable for integration to hybrid or one chip is proposed In the proposed drive circuit DC link voltage is used directly as the power source of each gate drive circuit NPN transistors and PNP transistors are used to isolate to transfer the control signals. So the proposed drive circuit needs no transformers and opto-couplers for electrical isolation of drive circuit and is constructed only using components to be implemented on a silicon wafer With th e proposed drive circuit 4- level inverter system will be possible to be implemented through integrated circuit technology Using the proposed drive circuit 4- level inverter system is constructed and the validity and characteristics of the proposed drive circuit are proved through the experiments.

• Tribology and Lubricants
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• v.36 no.4
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• pp.207-214
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• 2020

In this study, we investigated the effects of copper and copper-alloy on the frictional and wear properties of low-steel friction material. The proportions of copper and copper-alloy in the brake friction materials used in passenger cars are very high (approximately 5-20% weight), and these materials have significant effects on friction and wear characteristics. In this study, the effects of cupric ingredients, such as the copper fiber and brass fiber, are investigated using the friction materials based on commercial formulations. After the copper and brass fibers from the same formulation were removed, the frictional and wear characteristics were evaluated to determine the influence of the copper and copper-alloy. We evaluated the frictional and wear characteristics by simulating various braking conditions using a 1/5 scale dynamometer. The results show that the friction material containing copper and brass fibers have excellent frictional stability and a low wear rate compared to the friction material that does not contain copper and brass fibers. These results are attributed to the excellent ductility, moderate melting point, high strength, and excellent thermal conductivity of copper and copper-alloy. We analyzed the surfaces of the friction materials before and after the performing the friction tests using a scanning electron microscope-energy dispersive X-ray spectroscope, confocal microscope, and roughness tester to verify the frictional behavior of copper and copper-alloy. In future studies, it will be applied to the development of copper-free friction materials based on the results of this study.

• Journal of Korean Society of Transportation
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• v.25 no.3
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• pp.111-121
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• 2007

A transit assignment model can forecast the behaviors of transit users. thereby playing an important role In the evaluation of transit policies. Most existing transit assignment models are based on the models for passenger cars; therefore they cannot reflect the specific characteristics of transit modes. In addition most of the existing models are based on a single transit mode (bus or rail), and they cannot forecast the behaviors of transit users in a changing mass transportation system. The goal of this study is to overcome these problems with the exiting models and to develop a more realistic model. The newly developed model is based on mixed transit modes and is a stochastic model that can reflect the different preferences of each transit user for travel time and transfering. Data gathered from the Seoul metropolitan area's smart card are used to calibrate this model. This study is expected to be used for the evaluation of transportation policies and to attribute the development of transit revitalization strategies.

• Journal of Digital Convergence
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• v.14 no.11
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• pp.289-295
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• 2016

Subway is a future-oriented means of transportation that can be safely and quickly mass transport many passengers than buses and taxis. Congestion growth due to the increase of the metro users is one of the factors that hinder citizens' rights to comfortably use the subway. Accordingly, congestion prediction in the subway is one of the ways to maximize the use of passenger convenience and comfort. In this paper, we monitor the level of congestion in real time via the existing congestion on the metro using multiple regression analysis and big data processing, as well as their departure station and arrival station information More information about the transfer stations offer a personalized congestion prediction system. The accuracy of the predicted congestion shows about 81% accuracy, which is compared to the real congestion. In this paper, the proposed prediction and recommendation application will be a help to prediction of subway congestion and user convenience.

• Journal of the Korean Society for Railway
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• v.13 no.6
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• pp.552-558
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• 2010

Ride comfort of railway vehicles is affected by many factors, such as vibration, noise, smell, temperature, visual stimuli, humidity and a seat design. In general, vibration, which originates from vehicle motion, is considered as the primary concern. In evaluating the ride comfort, relationship between passenger's feeling and vibration characteristics is very important because human feeling is dependent on frequency spectrum of vibration. Therefore, the weighing functions in frequency domain are used to evaluate the ride comfort of railway vehicles. In the present paper, we have analyzed the characteristics of the frequency weighting curves defined in many standards and reviewed the effect resulting from their difference on the ride comfort.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.1
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• pp.25-38
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• 2023

Seoul Metropolitan Urban Railroad has an undecided route that does not estimate the passenger transportation route. For this reason, the fare of the urban railroad is calculated by the assumption that passengers pass through the minimum distance. Therefore, if a transfer station on the urban railroad is added, the trip shortest distance could be decreased and the fare also reduced. In this study, this phenomenon defines the fare paradox(Shin, 2022) and estimates the impact of the fare paradox by opening the GTX-A. For this purpose, a scenario before and after the opening of the GTX-A has been established, and an additional fare has been estimated by proportional planning of the Seoul Metropolitan Integrated Distance Based Fare Policy. Fare Paradox was analyzed to about 0.024 % of daily income. It is expected to be used as a plan to determine a rate policy, such as the establishment of a GTX-A, B, C, D, and a light rail line.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2D
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• pp.183-190
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• 2009

In order to improve continuous success and stabilization of high-speed rail in the future, Using Frequency of high-speed rail should be enhanced by improving satisfaction of high-speed rail passenger. High-speed rail is needed to hold the priority in competition means by comparing the traits of service of domestic air lines. This study utilizes structural equation modeling to develop model for estimating factors influencing to service through conducting survey questionnaire. It also uses reliability analysis, correlation analysis, factor analysis to examine the rationalization of items and to establish hypothesis of this research. The results show that KTX contains 'inner service' item that is considered to be ameliorated and that domestic airline present low performance of 'outer service' item. In other words, moving section which partly is under a limited condition is needed to be improved. In addition, access to airport and transfer to other transportations have to be improved as they show the lowest satisfaction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.77-83
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• 2020

4WD technology is being actively applied to passenger cars. Therefore, dry multi-plate clutches are used for transfer cases. On the other hand, dry clutches have problems related to large vibrations and poor ride quality. To solve this problem, this paper proposes a multi-plate clutch with an MR fluid. When fastening the multi-plate clutch in the transfer case, the proposed MR clutch was applied to reduce the shock and friction, which is a key component in a four-wheel-drive system. MR multi-plate clutch has a fluid coupling mode and a compression mode. A torque model equation was derived for the optimal design. The analysis was performed using Ansys Maxwell to optimize the design parameters of the multi-plate clutch. Electromagnetic field analysis confirmed the strength of the magnetic field when the number of disks and plates were changed, and the maximum strength of the magnetic field was 0.45 Tesla. By applying this to the torque equation, the spacing between the plates was 2 mm, and the inner and outer diameters of the plates were selected to be 45 mm and 55 mm, respectively. Overall, this paper proposes an optimal design technique to maximize the performance of an MR multi-plate clutch.