• Journal of Korean Society of Transportation
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• v.22 no.6
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• pp.159-173
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• 2004

Using a generalized translog multiproduct cost function model, this paper examines economies of scale and scope in the vertically-integrated Korean railway industry. The paper then conceptualizes that the Korea National Railroad (KNR) produces four outputs (passenger-kilometers, ton-kilometers of freight, average length of passenger trips, and average length of freight haul) using three input factors(labor, fuel and maintenance, and rolling stock and capital). Using time series data collected from the KNR's annual records for the years from 1977 to 2002, the simultaneous equation system consisting of a cost function and two input share equatins is estimated with the Zellner's iterative seemingly unrelated regression. The findings show that the cost function corresponding to a non-Cobb-Douglas, non-homothetic, and non-homogeneous production technology adequately represents the KNR's cost structure. On the other hand, the Korean railway industry experiences sizeable overall scale economies, which result from substantial product-specific scale economies associated with passenger-kilometers and freight ton-kilometers and from scope economies associated with their joint production. In addition, the magnitude of economies of scope is influenced largely by the ratio of passenger trips, and has increased over time as the former has increased while the latter has decreased.

• Journal of the Korean Society for Railway
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• v.20 no.3
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• pp.339-348
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• 2017

Power supply for railway cars can be divided into propulsion system power supply and auxiliary power units (APU). The propulsion system power supply is for propulsion of railway cars, and regenerative braking; the APU provides power for the air compressor, lighting, car control and other auxiliary parts. According to high voltage and high current specifications, generally, an insulated-gate bipolar transistor (IGBT) is adopted for the switching component. For appropriate switching operation, a gate driver unit (GDU) is essentially required. In this paper, the technical trends of GDU for railway cars are analyzed and a design consideration for IGBT GDU is described.

• Journal of the Korean Geotechnical Society
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• v.35 no.2
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• pp.5-17
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• 2019

Dynamic centrifuge model test was conducted to evaluate the dynamic stability of the pile-supported slab track method during dynamic railway loading and earthquake loading. The centrifuge tests were carried out for various condition of embankment height and soft ground depth. Based on test results, we found that the bending moment was increased with embankment height and decreased with soft ground depth. In addition, it was confirmed that the pile-supported slab track system could have dynamic stability for short-period seismic loading. However, in case of long-period seismic loading, such as Hachinohe earthquake, the observed maximum bending moment reached to pile cracking moment at the return period of 2,400 year earthquake. The criterion of ratio between embankment height and soft ground depth was suggested for dynamic stability of pile-supported slab track system.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.487-491
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• 2007

Recently, rainfall induced hazard has been increased gradually, for example, typhoon Rusa in 2002 and Maemi in 2003. In addition, localized heavy rainfall has been also caused tremendous damage to railroad systems. Measured data from the Meteorological Adminstration sometimes, However, are not in accordance with those of rain gauges in local area, because of its good distance. This study develop automatic alarming software to estimate and prevent these kind of rainfall induced hazards in railroad system with online transportation.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.230-235
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• 2003

최근의 무선통신 시스템은 유지, 보수 및 구축이 유선통신 시스템에 비해 용이하고 이동성을 제공할 수 있다는 장점에 의해, 열차, 차량, 미사일 등의 이동체 제어와 관련된 분야에서의 연구가 활발히 진행되고 있다. 열차 또는 차량 제어와 같이 안전성이 중요시되는 분야에 있어서 전파에 의한 무선 링크는 가장 문제가 되는 부분으로서, 일반적으로 통신시스템은 어느 한 경로에서 고장이 발생하더라도 설계시 정해진 일정수준의 기능을 제공하는 생존성(survivability)을 지니도록 설계되어진다. 이와 관련한 연구와 개발은 대부분 공중 전화망과 고속 데이터 통신망을 대상으로 수행되었다. 본 논문에서는 유럽의 차세대 열차제어시스템에 적용하기 위해 기존의 유럽 표준 이동통신 시스템인 GSM(Global System for Mobile Communications)을 철도분야의 특수성에 맞도록 보완한 GSM-R(GSM-Railway)을 사례로 무선통신 시스템의 생존성을 검토한다.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.8-14
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• 2003

곡선부가 많은 국내 기존선의 속도향상을 위한 틸팅차량의 개발은 기존선의 전철화에 따른 고속화를 위해 그 필요성이 부각되고 있다. 일반 고속차량과 다른 주행 메카니즘을 가지고 있는 틸팅차량의 주요 기술을 확보하기 위한 틸팅대차와 틸팅시스템의 개발과 연구는 한국철도의 기술력 향상에 큰 역할을 할 것이다. 180km/h급 한국형 틸팅차량의 틸팅 메카니즘 기구동역학 해석을 통하여 틸팅 대차를 형성하는 주요 파라메터들의 변화에 따른 틸팅 메카니즘의 특성과 영향력을 검토한다. 이를 통하여 최적의 틸팅운동을 수행할 수 있는 주요 파라메터의 값을 제시함으로서 틸팅차량이 요구하는 최적의 틸팅 메카니즘을 구현하고자 한다. 이 연구를 통해서 얻어지는 결과들은 팅팅 대차용 엑츄에이터의 성능 설계와 해석의 기반 자료로 사용되어진다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1205-1206
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• 2007

철도시스템에서 열차운행의 안전성과 효율성은 열차제어시스템에 의해 결정된다. 기존의 열차제어는 일반적으로 궤도회로를 기반으로 이루어졌으나, 궤도회로의 문제점으로 부각되는 단락감도, 유지보수 비용증대 등을 해소하기 위해 궤도회로를 대신할 새로운 방법으로 무선통신기술을 기반으로 하는 새로운 형태의 열차제어로 변화를 서두르고 있다. 그러나 이러한 방식으로의 변화는 중저속구간인 도시철도에서는 일부 실용화를 추진하고 있으나 도시간을 이동하는 철도에서는 유럽에서 개념을 정립하여 시험중에 있다. 따라서 본 논문에서는 현 상황에서 도시간 및 고속용 열차제어에 적용하기 위한 무선통신기술에 대하여 선행검토를 수행한다.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.417-418
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• 2020

효율 및 내환경성에서 우수한 성능을 갖는 매입형 영구자석 동기전동기(IPMSM, Interior Permanent Magnet Synchronous Motor)는 최근 철도차량용 견인전동기로서 주목받고 있다. 일반 도시 철도차량의 추진제어시스템은 장시간 연속 운행 및 자연통풍냉각 방식의 설계가 요구되므로 대전력 스위칭으로 인한 발열 문제가 고려된 낮은 스위칭 주파수 및 6-스텝 제어 아래 인버터의 고성능 제어가 필요하다. 따라서 본 논문에서는 6-스텝 및 낮은 스위칭 주파수로 IPMSM을 제어하기 위한 PWM(Pulse Width Modulation) 동기화 방법을 기술하고 시뮬레이션을 통하여 제어 성능을 검증하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.6D
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• pp.761-770
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• 2009

The energy efficiency and environment-friendly aspect of the railway system would be superior to other on-land ransportation systems. In a preliminary feasibility study stage and selection of optimal railway route, the energy efficiency and problems related to environment are usually considered. For the selection of optimal railway route, geographical features and facility of management are generally considered. Environment effect factors for the selection of environment-friendly railway router are focused and studied in this paper. In this study, various analysis of opinion of specialists (railway, environment, transport, urban planning, survey) and the guideline for construction of environment-friendly railway were accomplished. From these results of various analysis, 7 major categories (topography/geology, flora and fauna, Nature Property, air quality, water quality, noise/vibration, visual impact/cultural assets) were extracted. To select environment friendly railway route, many alternatives should be compared optimal route must be selected by a comprehensive assessment considering these 7 categories. To solve this problem, the selected method was AHP which simplifies the complex problems utilizing hierarchy, quantifying qualitative problems through 1:1 comparison, and extracting objective conclusions by maintaining consistency. As a result, a GUIbased program was developed which provides basic values of weighted parameters of each category defined by specialists, and a quantification of detailed assessment guidelines to ensures consistency.

• Journal of Korean Society of Transportation
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• v.32 no.3
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• pp.256-265
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• 2014

A sudden increase of old people's free urban railway transportation resulted from the acceleration of aging trend causes the chronic deficit. As continuous deficit caused by the free urban railway transportation of old people is expected, a fairness problem about the fare system of using public transportation is issued because only the urban railway provides free-rides to them, which is contrast to bus-riders paying full payments. Therefore, the study intends to draw an alternate to solve the problem of the free urban transportation uses by calculating an appropriate fare ratio between the two transportation modes, which is expected to alleviate the fairness issue between the urban railway and the bus.