• Proceedings of the KSR Conference
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• 2008.11b
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• pp.666-672
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• 2008

Train wheels are the most important part of the high-speed rail system with supporting body, running stably and safely. Wheel exchange and fix plan is computed by the worker who managing entire Train Maintenance Process based on his know-how so that this system is losing its reliability and accuracy. And predicting of the wheel's lifetime is absolutely difficult matter because of uncertainty between trains like mileage of the type of trains, condition of operation, curve section and wheel's cutting pattern. Therefore workers always used to hold many wheels. For this reason, the cost of stock is soar when the level of stock was normal. If the stock is sufficient, the cost of stock will rise. On the other hand, If the stock is deficient, we would have trouble that the plan of the train maintenance process will be failed. Thus this paper aimed at application that "Wheel Managing System" which is able to predict wheel's life-cycle and demands under the RIMS(Rolling-Stock Information Maintenance System) with analysing wheel exchanging and cutting status considering economical or stable aspects.

• Journal of the Earthquake Engineering Society of Korea
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• v.27 no.2
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• pp.83-90
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• 2023

The recent increase in earthquake activities has highlighted the importance of seismic performance evaluation for civil infrastructures. In particular, the container crane essential to maintaining the national logistics system with port operation requires an exact evaluation of its seismic response. Thus, this study aims to assess the seismic vulnerability of container cranes considering their seismic characteristics. The seismic response of the container crane should account for the structural members' yielding and buckling, as well as the crane wheel's uplifting derailment in operation. The crane's yielding and buckling limit states were defined using the stress of crane members based on the load and displacement curve obtained from nonlinear static analysis. The derailment limit state was based on the height of the rail, and nonlinear dynamic analysis was performed to obtain the seismic fragility curves considering defined limit states and seismic characteristics. The yield and derailment probabilities of the crane in the near-fault ground motion were approximately 1.5 to 4.7 and 2.8 to 6.8 times higher, respectively, than those in the far-fault ground motion.

• Journal of Biosystems Engineering
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• v.37 no.3
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• pp.155-165
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• 2012

This study was performed to offer the data for design of the seedling bed transfer equipment to make the automation of working process in a plant factory. The seedling bed transfer equipment pushing the seedling bed with bearing wheels on the rail for interconnecting each working process by a pneumatic cylinder was made and examined. The examined transfer force to push the seedling bed with a weight of 178.9 N by the pneumatic cylinder with length of 60 cm and section area of 5 $cm^2$ was measured by experiments. The examined transfer forces was compared with theoretical ones calculated by the theoretical formula derived from dynamic system analysis according to the number of the seedling bed and pushing speed of the pneumatic cylinder head at no load. The transfer function of the equipment with the input variable as the pushing speed $V_{h0}$(m/s) and the output variable as the transfer force f(t)(N) was represented as $F(s)=(V_{h0}/k)(s+B/M)/(s(s^2+Bs/M+1/(kM))$ where M(kg), k(m/N) and B(Ns/m) are the mass of the bed, the compression coefficient of the pneumatic cylinder and the dynamic friction coefficient between the seedling bed and the rail, respectively. The examined transfer force curves and the theoretical ones were represented similar wave forms as to use the theoretical formular to design the device for the seedling bed transfer. The condition of no vibration of the transfer force curve was $kB^2>4M$. The condition of transferring the bed by the repeatable impact and vibration force according to difference of transfer distance of the pneumatic cylinder head from that of the bed was as $Ce^{-\frac{3{\pi}D}{2\omega}}<-1$, where ${\omega}=\sqrt{\frac{1}{kM}-\frac{B^2}{4M^2}}$, $C=\{\frac{\frac{B}{2M}-\frac{1}{kB}}{\omega}\}$, $D=\frac{B}{2M}$. The examined mean peak transfer force represented 4 times of the stead state transfer force. Therefore it seemed that the transfer force of the pneumatic cylinder required for design of the push device was 4Bv where v is the pushing speed.

• The Journal of Engineering Geology
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• v.20 no.1
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• pp.47-60
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• 2010

This study is focused on the analysis of tunnel behavior to estimate the stability on tunnel design. An estimation method was proposed as a hybrid consideration, which contains the displacement analysis by 3D numerical simulation, the maximum displacement obtained after field measurement, and an assessment of tunnel stability using a deformation analysis proposed by Sakurai(1988, 1997). The points of case study by Sakurai(1988, 1997) were replotted considering his analysis. From the new analysis of the tunnel case study, the trend line for analyzed points is analogized, which curve is divided into stable, unstable and failure zone. To evaluate the estimation method, a special shape of railway tunnel was selected, which are the Inchon international airport rail way connected to subway line 9 in Gimpo, Korea. The point s of upper and below track on the Inchon international airport rail way were satisfied to the stability of tunnel after reinforcing. Also the points shows the higher apparent Young's modulus, which resulted from improvement on shear strength by the micro silica grouting and the supporting of umbrella method. Therefore, if new analysis used, proper tunnel reinforcing method could be selected according to tunnel strain and geological property.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.185-185
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• 2011

기존 장대레일 궤도의 안정성 평가는 궤도 매개변수에 대하여 고정된 안전측의 값을 사용하는 결정론적인 해석에 의존해서 평가되어져 왔다. 그러나 실제현장의 궤도조건은 많은 영향인자들에 의해 그 특성이 불확실하게 변하고 있다. 따라서 온도하중에 의한 궤도 좌굴에 영향을 미치는 궤도 구성인자들의 불확실성 및 임의성을 보다 합리적으로 고려하기 위해서 확률론적 기법을 적용하는 것이 필수적이다. 본 연구에서는 기존 본 연구진에 의해 개발된 장대레일 궤도의 좌굴확률 평가시스템을 이용하여 좌굴 취약도 곡선을 나타내었으며, 궤도 좌굴에 영향을 미치는 주요변수 중 하나인 도상횡저항력에 대한 영향을 분석하였다. 좌굴확률 평가시스템에서는 장대레일 궤도의 좌굴확률을 산정하기 위하여 구조물의 안정과 파괴를 판단할 수 있는 기준을 한계상태방정식으로 표현하고, 이 한계상태방정식으로부터 확률론적 기법 중 하나인 AFOSM(Advanced First Order Second Moment) 방법을 이용하여 파괴확률의 간접적인 지표인 신뢰도지수(${\beta}$)를 통해 좌굴확률을 계산한다. 한계상태방정식에서 구조물의 강도(보유성능)에 해당하는 부분은 궤도의 허용좌굴온도이고, 하중(요구성능)에 해당하는 부분은 레일온도하중으로써 현재 레일온도와 중립온도의 차로 반영된다. 허용좌굴온도 산정에 고려되는 주요변수는 곡선반경(Radius), 도상횡저항력(Lateral Ballast Resista nce), 연직도상강성(Vertical Ballast Stiffness), 궤도 틀림량(Misalignment), 틀림길이(Half Wave Length), 열차운행속도(Velocity)이다. 각 확률변수들이 갖는 확률분포는 모두 정규분포로 가정하였다. 궤도의 기하학적 특성은 곡선반경 5,000m에 대해 고려하였으며, 열차는 KTX의 제원을 사용하여 정지된 상태에서 고려하였다. 틀림량과 틀림길이는 이에 대한 통계적 특성자료가 부족하여 확률변수로 고려하지 않고 결정론적 값으로 취급하였다. 레일온도의 통계적 특성치는 본 연구진에 의해 구축된 기후요소 및 레일온도 DB를 근거로 결정하였으며, 중립온도는 선로관리지침에 따라 $25{\pm}3^{\circ}C$를 기준으로 결정하였다. 또한 도상횡저항력은 실측 데이터를 참고로 하여 평균값에서 10%의 변동량을 갖는 것으로 보고 통계적 특성치를 결정하였다. 도상횡저항력이 좌굴확률에 미치는 영향을 매우 큰 것을 알 수 있었으며, 레일온도 $60^{\circ}C$일 때 도상횡저항력이 증가하면서 감소되는 좌굴확률이 도상저항력이 커질수록 그 감소량이 작아지는 것을 알 수 있었다.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.4
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• pp.243-250
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• 2011

Noise levels of the three subway lines of Busan city have been investigated. Averaged cabin noise of the train has been measured during the train trip for each station. It has been measured with separation of day time (9:00~18:00) and night time (18:00~22:00) measurements but there was no big difference on the measured data. Repeating for the measured data has been confirmed with twice measurements in May and June 2010. Several noise effects to the subway noise levels of Busan are explained. Those are screen door effect, rail road surface condition, subway train type and curvature of railway. Among three subway lines of Busan city, the line 2 is relatively noisy and its reasons are studied. It has been shown that the screen door effect is 10 dB(A) and S shape of sharp curve contributes in high noise level.

• Journal of the Korea Society of Computer and Information
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• v.19 no.12
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• pp.187-196
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• 2014

In this paper, Minimize driving energy for operation within a defined distance yeokgan fixed time-resolved and determine the nature of the train is traveling, and to model mathematically. Urban rail car cruise in general by the PID controller is used instead of automatically tracking a target value while traveling in energy consumption to be minimized by using optimal control model railroad charyangreul was designed under real operating conditions the same. The actual track conditions apply to the minimum value or a separate listing of cars around the track facility without a driving energy of the automatic operation and to reduce the driving energy. Therefore, actual route chosen straight line 8 / gradient segment / curve for the measured data analysis, such as sections within the city-minute drive each section and presented how the trains to save energy, depending on the pattern of the train station in the region.

• Journal of the Korean Society for Railway
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• v.20 no.5
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• pp.612-624
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• 2017

As the existing metropolitan area metropolitan railway operates on a one-to-one basis, which leads to long travel times, its competitiveness with other means of transportation is deteriorating. Since there is a limit to attracting road traffic by rail, there is a continuing societal demand to expand express train service. Especially in the northern and the southwestern parts of the metropolitan area, a public transportation network system with express function, connecting to the city center of Seoul, is needed because of the social cost of the increase of traffic congestion and the increase of the travel time. The most efficient express service in Korea is Seoul Subway Line 9, which runs in 27 minutes from Gimpo Airport to the high speed terminal; this is a 40% shorter time compared to 44 minutes by car; the congestion in this area is up to 240%, so the preference for this train is quite high. The technical results of this study are expected to contribute to the implementation of an express service metropolitan railway.

• Journal of the Korean Society for Railway
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• v.7 no.4
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• pp.332-338
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• 2004

The two projects about the high speed train have been performed in Korea, one project is the commercial run of high speed train(KTX) from Seoul to Busan and the other is the development of original high speed train(HSR 350x). As the successful results, the service run of KTX had been launched on the 1st of April, 2004 and HSR 350x had been fabricated in June, 2002 and has been tested in the Kyoungbu line and Honam line since then. The railway has the track irregularities which cause vibrations, such as rail joints, turnout, level crossing, transition curves and super-elevation ramps, and variations in the track level(z-axis) and the gauge(y-axis). Generally, the ride comfort for railway is evaluated by using the vibrations. In this paper, the ride comfort indices according to mc 513R and ISO 10056 have been reviewed when the high-speed trains are operated on both Kyoungbu line and Honam line. Also, the ride characteristics for KTX and HSR 350x on the high speed line and the conventional line have been analyzed and evaluated. The results show that the high-speed train has no problem from the viewpoint of the comfort ride on the high speed line and the conventional line and the ride index for HSR 350x is same as that for KTX in the high speed(300 km/h).

• Wind and Structures
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• v.35 no.2
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• pp.83-92
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• 2022

When the rolling stocks run on the curve, the external rail has to be lifted to a certain level to balance the centrifugal force acting on the train body. Under such a situation, passengers may feel uncomfortable, and the slanted vehicle has the potential overturning risks at high speed. This paper conducted a wind tunnel test in an annular wind tunnel with φ=3.2 m based on a 1/20^th scaled high-speed train (HST) model. The sensitivity of Reynolds effects ranging from Re = 0.37×10⁶ to Re = 1.45×106 was tested based on the incoming wind from U=30 m/s to U=113 m/s. The wind speed covers the range from incompressible to compressible. The impact of roll angle ranging from γ=0° to γ=4° on train aerodynamics was tested. In addition, the boundary layer development was also analyzed under different wind speeds. The results indicate that drag and lift aerodynamic coefficients gradually stabilized and converged over U=70 m/s, which could be regeared as the self-similarity region. Similarly, the thickness of the boundary layer on the floor gradually decreased with the wind speed increase, and little changed over U=80 m/s. The rolling moment of the head and tail cars increased with the roll angle from γ=0° to γ=4°. However, the potential overturning risks of the head car are higher than the tail car with the increase of the roll angle. This study is significant in providing a reference for the overturning assessment of HST.