• 한국철도학회논문집
• /
• 제7권3호
• /
• pp.239-244
• /
• 2004

The use of frequency-dependent spectral element matrix (or exact dynamic stiffness matrix) in structural dynamics may provide very accurate solutions, together with drastically reducing the number of degrees of freedom to improve the computation efficiency and cost problems. Thus, this paper develops a spectral element model for the coupled thermoelastic beam which axially moves with constant speed under a uniform tension. The accuracy of the spectral element model is then evaluated by comparing the natural frequencies obtained by the present element model with those obtained by the conventional finite element model.

• 한국철도학회논문집
• /
• 제3권3호
• /
• pp.125-130
• /
• 2000

DES software is a Computer Aided Design(CAD) tool. It is built based on objected-oriented principle. Utilizing strong processing capability and quirk calculation of computer, it can search out all possible routes, and give out interlocking table on the base of chosen routes by user. It can provide a large number of data for computers included in computer interlocking system. It is efficient and reliable.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2010년도 춘계학술대회 논문집
• /
• pp.850-856
• /
• 2010

With skyrocketing number of people who use smartphone, the technology of wireless internet that is mobile-phone, Wi-Fi, Wibro, HSDPA has been developed remarkably. The environment that one can use wireless internet easily and inexpensively anywhere has been made. So, the customer of railway have needs and desire that could use the wireless internet network as travelling in rolling-stock. Although KTX, KTX-II and some subway agency has built-up wireless internet network and serviced it, it's closed infra and inconvenient environment has been criticized. So, we survey the wireless internet network that is serviced at present and the way to build wirelee internet infra to satisfy the needs of customers.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 하계학술대회 논문집 B
• /
• pp.1384-1386
• /
• 2000

To determine operational requirement, the environmental condition for an equipment must be investigated, and to certify equipment's normalized operation, appropriate test must be carried out under the considered environmental condition. The actual environmental conditions to which equipment is likely to be exposed are normally complex and will comprise a number of environmental factors and corresponding parameters, When defining the environmental conditions for a certain application it is, therefore, necessary to list the factors involved and select the appropriate severity. The operational environment is structured in two separate such as requirements, guidance and test specifications. For the preparation to determine operational requirement, operational environment of railway signalling equipment is investigated.

• 한국철도학회논문집
• /
• 제16권1호
• /
• pp.65-70
• /
• 2013

지방간선노선은 대체로 적자운영을 함에도 불구하고 철도운영자는 공공복리 차원에서 적자상태인 지방간선노선의 운영을 수행한다. 따라서 철도 운영자는 적자운영노선에서 운영자입장에서의 최적의 자산운용을 열차 편성 수 또는 열차운행 횟수를 조정하는 방식으로 최소화하려고 한다. 이때 열차운행 횟수나 편성수를 결정하는 지표로 영업계수(비용/수입 비율)가 주로 사용된다. 그러나 이것은 단기적인 수요공급측면의 영향만을 지나치게 반영하여 장기적인 관점에서의 전략적인 열차운영이 고려되지 않는다. 따라서 철도운영의 재정 건전성을 악화시키지 않으면서 이해당사자들의 정책방향과 지역 현황을 반영하는 의사결정이 가능하도록 업계종사자와 전문가를 대상으로 전통적인 경영성과 산정방식인 영업계수 등 주요지표와 이를 보완하는 보조지표 평가항목을 도출할 필요가 있다. 본 연구는 평가항목을 도출하고 계층적 분석기법(AHP)을 통해 각 평가항목별 중요도를 산정하여 열차운행 의사결정의 명확한 이론적 근거와 계량화된 기준을 제시하고 이를 적용하고자 한다.

• 한국철도학회논문집
• /
• 제8권6호
• /
• pp.602-609
• /
• 2005

In this paper, we consider the train-fleet assignment problem to determine fleet assignment and seat allocation synchronously. An integer programming model of the problem and a decomposition-based solution approach are developed to handle short-term period deterministic orgin-destination demands. The primary objective used in the developed model is to maximize the total number of passengers transported during peak load periods, such as Chuseok national holiday period. Thus, in developing the model we choose to profit-pursuing system. We also show how the proposed model can be readily modified to incorporate profit-maximization. Using the empirical data sets provided by a Korean railroad company, we have tested the proposed solution approach and carried out various comparison analyses by varying traffic demand patterns and train schedules. The computational experiments reveal that the proposed solutions approach produces high quality solutions in reasonable computation time.

• Structural Engineering and Mechanics
• /
• 제75권4호
• /
• pp.435-444
• /
• 2020

Ultrasonic guided wave testing is a very promising non-destructive testing method for rails, which is of great significance for ensuring the safe operation of railways. On the basis of the semi-analytical finite element (SAFE) method, a analytical model of 59R2 grooved rail was proposed, which is commonly used in the ballastless track of modern tram. The dispersion curves of ultrasonic guided waves in free rail and supported rail were obtained. Sensitivity analysis was then undertaken to evaluate the effect of rail elastic modulus on the phase velocity and group velocity dispersion curves of ultrasonic guided waves. The optimal guided wave mode, optimal excitation point and excitation direction suitable for detecting rail integrity were identified by analyzing the frequency, number of modes, and mode shapes. A sinusoidal signal modulated by a Hanning window with a center frequency of 25 kHz was used as the excitation source, and the propagation characteristics of high-frequency ultrasonic guided waves in the rail were obtained. The results show that the rail pad has a relatively little influence on the dispersion curves of ultrasonic guided waves in the high frequency band, and has a relatively large influence on the dispersion curves of ultrasonic guided waves in the low frequency band below 4 kHz. The rail elastic modulus has significant influence on the phase velocity in the high frequency band, while the group velocity is greatly affected by the rail elastic modulus in the low frequency band.

• 전기학회논문지
• /
• 제64권9호
• /
• pp.1391-1397
• /
• 2015

Recently, various researches are conducted in the application of regenerative energy produced during the operation of an electric locomotive. Regenerative energy is produced by a generator in the brake procedure. The generator is operated by kinetic energy of an electric railroad using an electric motor. The process of producing regenerative energy varies with the current type of a railroad and its running condition. The quality of electric power can be improved and electric energy can be utilized effectively, especially in the use of an energy storage system (ESS). Thus, it is necessary to apply ESS into AC section and high speed railway. This study analyses the composition of the regenerative ESS equipment installed in Yong-Jeong sectioning post, operational principle, charge and discharge algorithm and energy efficiency. The analysis shows that CO2 emissions can be reduced about 0.5 ton per a day. In addition, ESS helps saving the energy and the compensation of the voltage drop caused by the operation of high speed train when it is installed at the end of the feeder section. The number of high speed train will be increased continuously related to the electrification rate. Therefore, applying the ESS to high speed railway is expected to solve the instability of the feeder voltage and the equipment capacity problem caused by the high speed trains.

• Structural Engineering and Mechanics
• /
• 제81권2호
• /
• pp.219-230
• /
• 2022

Due to the large number of railway bridges along China's high-speed railway (HSR) lines, which cover a wide area with many lines crossing the seismic zone, the possibility of a HSR train running over a bridge when an earthquake occurs is relatively high. Since the safety performance of the train will be threatened, it is necessary to study the safety of trains running over HSR bridges during earthquakes. However, ground motion (GM) is highly random and selecting the appropriate ground-motion intensity measures (IMs) for train running safety analysis is not trivial. To deal this problem, a model of a coupled train-bridge system under seismic excitation was established and 104 GM samples were selected to evaluate the correlation between 16 different IMs and train running safety over HSR bridges during earthquakes. The results show that spectral velocity (SvT₁) and displacement (SdT₁) at the fundamental period of the structure have good correlation with train running safety for medium-and long-period HSR bridges, and velocity spectrum intensity (VSI) and Housner intensity (HI) have good correlation for a wide range of structural periods. Overall, VSI and HI are the optimal IMs for safety analysis of trains running over HSR bridges during earthquakes. Finally, based on VSI and HI, the IM thresholds of an HSR bridge at different speed were analyzed.

• 한국철도학회논문집
• /
• 제17권4호
• /
• pp.245-250
• /
• 2014

본 연구에서는 콘크리트 궤도 교량의 사용성 설계를 위한 연구로서 궤도 및 교량 설계변수들이 콘크리트 궤도의 레일지지점에서의 작용력에 미치는 영향을 나타내었다. 궤도 구조에 작용하는 작용력을 구하기 위해서 각 레일 지지점의 간격이 다른 부등간격 이산지지보 모델을 유도하였다. 해석 변수는 교량의 교대 또는 교각 위치 부근의 신축이음부의 레일 지지점의 간격, 교량 거더의 받침에서부터 교량 거더 단부측의 마지막 레일지 지점까지의 거리, 그리고 추가 배치한 레일지지점의 수이다. 궤도 구조의 변위를 일으키는 요인으로는 축하중, 거더의 단위 수직단차와 단부회전각이다. 해석결과로부터 레일지지점에서의 최대압축력과 최대부상력을 구하였으며 레일지지점의 간격이 작용력에 미치는 영향을 나타내었다.