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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society for Railway
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Journal DOI :
Korean Society for Railway
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Volume & Issues
Volume 18, Issue 6 - Dec 2015
Volume 18, Issue 5 - Oct 2015
Volume 18, Issue 4 - Aug 2015
Volume 18, Issue 3 - Jun 2015
Volume 18, Issue 2 - Apr 2015
Volume 18, Issue 1 - Feb 2015
Selecting the target year
Study of the Air-tightness Requirement Decisions of GTX Trains
Yun, Su-hwan ; Cho, Yong-hyeon ; Hong, Seok-woo ;
Journal of the Korean Society for Railway, volume 18, issue 6, 2015, Pages 513~521
DOI : 10.7782/JKSR.2015.18.6.513
When a GTX travels through a deep-level underground tunnel at a speed of 180km/h, ear-discomfort in passengers due to the pressure wave generated could be an issue due to the small cross-sectional area. Therefore, appropriate pressure-tightness values for GTX trains must be secured as a countermeasure. In this paper, a 1D numerical analysis was conducted to determine the pressure-tightness coefficient which allows a pressure change meet the criteria. The pressure transients in a tunnel and in a passenger car are predicted considering an A-line underground tunnel with a length of 37km and its operation schedule. The required pressure-tightness of the car is predicted to be three seconds and 6 seconds respectively for a single track and a double- track tunnel to prevent aural discomfort in passengers. The result of this study are expected to serve as useful information to those involved in the development of various solutions to improve air-tightness of GTX passenger cars.
Noise Protection Roof: Partial Opening Effect for Noise Reduction
Kim, Tae-Min ; Kim, Jeung-Tae ;
Journal of the Korean Society for Railway, volume 18, issue 6, 2015, Pages 522~532
DOI : 10.7782/JKSR.2015.18.6.522
In the present study, a tunnel type soundproof wall with partial opening is proposed to reduce the environmental noise caused by railway vehicles traveling on bridges, which affects residents of high-rise apartment buildings; the study also attempts to minimize load due to wind and the weight of the wall. Applying the principles of computational fluid dynamics and structural mechanics, and the ray tracing method, a reduction in noise as well as of the overall weight of the soundproof walls is estimated. Analysis results show that the proposed soundproof wall with a partial opening weighs less, while reducing the wind loading by up to 30%. To prevent direct propagation of sound through openings in the wall, an acoustic louver, which is a type of silencer, could be considered for the opening. In order to achieve a similar noise effect with existing insulation material, the fluid flow and the insulation effect of the acoustic louver are analyzed. As the considered opening is in the range of 30~40% of the total length of the soundproof wall, the noise effect and wind load are reduced by 10dB and 25% respectively. Consequently, opening some part of tunnel type soundproof walls and installing louvers on the wall openings can have the effects of weight-reduction and reduced wind load. If a partial opening is applied with proper sound material application, a gain of an additional 5~10dB of noise reduction can be achieved.
A Study on the Firing Angle at the Mode Conversion to Improve the Output Characteristics of the Double Converter for Urban Railway DC Power Supply
Seo, Seung-Sam ; Han, Sung-Woo ; Byun, Gi-Sig ;
Journal of the Korean Society for Railway, volume 18, issue 6, 2015, Pages 533~542
DOI : 10.7782/JKSR.2015.18.6.533
This paper suggest away to maintain constant power through trolley wire by transferring increased line voltage to the AC main line while changing the mode from Converter(Forward) to Inverter(Reverse) when the line voltage is increased due to regenerative power when the train stops, This paper suggests a Double Converter DC substation that can create regenerative power when the train stops reusable. We also proposed using a simulation tool, the optimal Thyrister firing angle that can minimize the undershoot and overshoot that occurs when transferring the mode from Converter to Inverter for quality improvement of DC voltage in the Double Converter in the DC substation from the Busan Urban Subway.
Applicability Estimation of Ballast Non-exchange-type Quick-hardening Track Using a Layer Separation Pouring Method
Lee, Il Wha ; Jung, Young Ho ; Lee, Min Soo ;
Journal of the Korean Society for Railway, volume 18, issue 6, 2015, Pages 543~551
DOI : 10.7782/JKSR.2015.18.6.543
Quick-hardening track (QHT) is a construction method which is used to change from old ballast track to concrete track. Sufficient time for construction is important, as the construction should be done during operational breaks at night. Most of the time is spent on exchanging the ballast layer. If it is possible to apply the ballast non-exchange type of quick-hardening track, it would be more effective to reduce the construction time and costs. In this paper, pouring materials with high permeability are suggested and a construction method involving a layer separation pouring process considering the void condition is introduced in order to develop ballast non-exchange type of QHT. The separate pouring method can secure the required strength because optimized materials are poured into the upper layer and the lower layer for each void ratio condition. To ensure this process, a rheology analysis was conducted on the design of the pouring materials according to aggregate size, the aggregate distribution, the void ratio, the void size, the tortuosity and the permeability. A polymer series was used as the pouring material of the lower layer to secure the void filling capacity and for adhesion to the fine-grained layer. In addition, magnesium-phosphate ceramic (MPC) was used as the pouring material of the upper layer to secure the void-filling capacity and for adhesion of the coarse-grained layer. As a result of a mechanics test of the materials, satisfactory performance corresponding to existing quick-hardening track was noted.
Study of the Performance of a Dry Cleaning Method for Polluted Ballast Gravel of Railroad Fields
Cho, Youngmin ; Park, Duckshin ; Kwon, Tae-Soon ; Lee, Jae-Young ;
Journal of the Korean Society for Railway, volume 18, issue 6, 2015, Pages 552~557
DOI : 10.7782/JKSR.2015.18.6.552
Ballast gravel in a railroad field is often polluted by grease and heavy metals. In this paper, the performances of a dry cleaning method for polluted ballast gravel in which pollutants on the gravel surface can be physically removed was extensively studied. A polluted ballast cleaning device able to shoot emery blasting media onto the surface using compressed air was prepared. Polluted ballast gravel was put into this device for cleaning, with the treatment time varied from 1 to 10 min. The cleaning efficiency of the total petroleum hydrocarbons and heavy metals were studied. The total petroleum hydrocarbon removal efficiency was 70-80% for gravels sampled from a locomotive waiting line, while it was 40-60% for gravels sampled from a turnout area. The heavy metal removal efficiency exceeded 90% for copper and lead, while it was 65-80% for nickel and zinc. This system was found to be effective for the remediation of polluted ballast gravels.
Comparison Analysis of the Environmental Impact of VSL Anchors and RBanchors Using a Life-Cycle Assessment (LCA)
Ahn, Taebong ; Lee, Jaewon ; Min, Kyoungnam ; Lee, Junggwan ; Kwon, Yongkyu ;
Journal of the Korean Society for Railway, volume 18, issue 6, 2015, Pages 558~566
DOI : 10.7782/JKSR.2015.18.6.558
In this study, quantitative environmental impact assessments of the VSL anchor and RB(Reaming and Bearing) anchor systems were conducted after a life-cycle assessment (LCA). In addition, improvements which reduce the adverse environmental effects of the RB anchor system were confirmed through comparisons with results with a VSL anchor system. Both results showed that water ecotoxicity and global warming are the most important in environmental influences. To determine the effect of reducing the RB anchor system environment, the result was normalized for the environmental impact category. Most items appeared to have been improved with regard to the RB anchor system. The most significant improvement was a 77% decrease in POC levels(photochemical oxidant creation). Greenhouse gas emissions, related to global warming, were decreased by 44%. It is expected that these quantitative environmental impact assessment results will serve as the basis of an anchor system for civil engineering and environmental impact assessments.
Vibration Isolation of Wave Barriers Constructed Near a Shallow Tunnel
Yang, Sin-Chu ;
Journal of the Korean Society for Railway, volume 18, issue 6, 2015, Pages 567~577
DOI : 10.7782/JKSR.2015.18.6.567
This paper presents an assessment method of the ground vibration level with a combination of measured data and an analytic method. The basic concept of the method is similar to that in FRA(Federal Railway Administration) manual for detailed vibration analyses. However, going into detail, the assessment method was modified for a feasible evaluation of the vibration reduction effects of diverse types of wave barriers. The force density was evaluated in a vehicle-track interaction analysis and the transfer mobility of vibration was analyzed through a 2-D ground vibration analysis. The calculated 2-D transfer mobility was corrected to incorporate transfer characteristics of actual ground vibration by comparing the previously measured data and analysis results. Nine types of vibration reduction effects of wave barriers were analyzed on a shallow tunnel section of an urban railway where numerous civil complaints had actually been filed.
Integrated Superstructure Design of Elastic Components to Improve the Track Performance
Kang, Bo Soon ;
Journal of the Korean Society for Railway, volume 18, issue 6, 2015, Pages 578~585
DOI : 10.7782/JKSR.2015.18.6.578
Track elastic components can be technically and economically efficient when integrated well into track superstructure of a railway network. In such cases, the elastic rail pad is larger than a 800m radius curve provides smooth rail branching and allows for high-speed operation (
). High track resistance causes the tamping intervals to stand out because the constantly increasing share of the sleeper pad further extends the increase of the tamping interval and the long grinding period; the engineering and construction of the small curve radius track provides some measures for reducing the solid sounds. Installation of elastic mats under the ballast can have a good effect, particularly in the context of protection against dust during construction or extensive renovation measures when laying new lines. However, such a process requires special attention and proper installation.
Tracing a Logical Path of Passengers: A Case study of Seoul Metro Line 9
Kim, Kyung Min ; Oh, Suk Mun ; Hong, Sung-Pil ; Ko, Suk-Joon ;
Journal of the Korean Society for Railway, volume 18, issue 6, 2015, Pages 586~595
DOI : 10.7782/JKSR.2015.18.6.586
Based on an observation that tag-out times of passengers from Smart Card data were clustered, Hong et al. recently developed a precise algorithm that detects a logical path for metro passengers. The logical path means the sequence of train boarding and alighting. In this paper, we observe that tag-out times of passengers in Seoul Metro Line 9 were also clustered; we trace an actual logical path of passengers by applying the algorithm. As a result, we identify 91% of passengers successfully and find their logical paths; we also investigate passengers'preferences between express and local trains.
Transfer Resistance Factors and Policy Directions in Railway Stations of Bulk Freight
Choi, Chang Ho ;
Journal of the Korean Society for Railway, volume 18, issue 6, 2015, Pages 596~608
DOI : 10.7782/JKSR.2015.18.6.596
Freight transport by railway is gaining more attention at present as a countermeasure against global warming. In keeping with this purpose, the present study examined various methods for promoting railway use through minimization of the transfer resistance of bulk freight at railway stations. First, the transfer-related factors that shippers consider as important when choosing railway as a transport mode were identified. Also, the relative importance and the level of influence of each factor during the transfer stage were evaluated. Policy directions for reducing transfer resistance in railway stations were then proposed based on the analysis of the transfer resistance factors. The policy directions include both hardware and software approaches. The necessary reduction ranges with regard to the transfer cost and time through policy implementation efforts were suggested as well.
The Effect of Railway Corporation Leadership of Middle Manager Employees' on Empowerment and Innovative Behavior
Hwang-Bo, Jak ;
Journal of the Korean Society for Railway, volume 18, issue 6, 2015, Pages 609~618
DOI : 10.7782/JKSR.2015.18.6.609
This paper empirically analyzed the effect that the leadership of middle managers had on empowerment and innovative behavior, as measured by employees of a domestic railway corporation. The results demonstrate that transactional leadership had a positive effect on both empowerment and innovative behavior. However, transformational leadership did not exhibit immediate effects on innovative behavior. In addition, it was also found that empowerment completely mediated the relationship between transformational leadership and innovative behavior. Therefore, the results of this study imply that the leadership of middle managers in a railway corporation is an important influential factor which causes innovative behavior in employees. Specifically, to induce voluntary innovative behaviors in employees through transformational leadership, utilizing empowerment to instill a right to make decisions through the delegation of the right is a very important factor.
The Train Conflict Resolution Model Using Time-space Network
Kim, Young-Hoon ; Rim, Suk-Chul ;
Journal of the Korean Society for Railway, volume 18, issue 6, 2015, Pages 619~629
DOI : 10.7782/JKSR.2015.18.6.619
The train conflict resolution problem refers to an adjustment of the train operation schedule in order to minimize the delay propagation when a train conflict is predicted or when a train conflict occurs. Previous train studies of train conflict resolutions are limited in terms of the size of the problems to be solved due to exponential increases in the variables. In this paper, we propose a train conflict resolution model using a time-space network to solve the train conflict situation in the operational phase. The proposed model adjusts the size of the problem by giving only the dwell tolerance in the time-space network only for stops at the station after a train conflict. In addition, the proposed model can solve large problems using a path flow variable. The study presents a train delay propagation analysis and experimental results of train conflict resolution assessments as well using the proposed model.
Estimation of Hourly Variations in Public Transit Demand according to the Addition of Sales Facilities to Railway Stations: Focusing on Metro and Bus Transit Demand
Jang, Jaemin ; Moon, Dae Seop ; Kim, Sujeong ; Gim, Tae-Hyoung Tommy ;
Journal of the Korean Society for Railway, volume 18, issue 6, 2015, Pages 630~638
DOI : 10.7782/JKSR.2015.18.6.630
The total number of passengers on the KTX since its construction in 2004 surpassed 500 million in October, 2015. The operation of KTX made it possible to reach anywhere in a country in half a day, which subsequently altered people's lifestyle. As the KTX has become an important mode of transportation, there is a growing interest in the optimal size and location of its stations. Currently, the stations are constructed through public-private partnerships since a sufficient amount of budget is hard to secure only from the public sector; however, because railway stations are traditionally aimed at promoting public interests, an emphasis on the profitability of the private sector could compromise public interests. At this juncture, this study separately computes the number of users based on each of the two primary functions of the stations-as a railway station and as a sales facility-and estimates the numbers of people according to various transportation modes that are taken to access the stations. This estimation is applied to the case of Dongdaegu Station, which will open in 2016. Such an application helps to predict and respond to possible congestion as brought about by the expansion of the sales facility.