• 한국철도학회논문집
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• 제11권1호
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• pp.1-6
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• 2008

본 연구에서는 현 고속 차량의 차체바닥 구조의 투과손실 특성 파악을 연구하고자 하였다. 이를 위하여 우선 허니콤 구조인 알루미늄 시편을 제작하여 투과손실 측정 실험을 수행하였다. 측정된 결과에서는 800Hz이상부터 질량 법칙을 따르는 투과손실의 특성을 파악할 수 있었다. 상용프로그램인 NASTRAN, AUTOSEA2를 사용하여 구조물에 대한 투과손실을 해석한 후 이를 실험치와 비교하여 신빙성 있는 결과를 얻을 수 있었다. 아울러 다른 단면 형상을 갖는 허니콤 구조물에 대한 투과손실 해석을 수행하여 특성을 예측해 보았다.

• 전기학회논문지
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• 제64권2호
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• pp.342-348
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• 2015

In this paper, fuel cell power generation system that is being studied in recent railway field was applied to compensate for the voltage drop due to the load as driving electric vehicle. PSIM simulation program is to be used to implement the modeling of the electric railway for AC AT feeder system. For it, It was applied to the product-type single-phase PLL algorithm, step-down converter is controlled as power so as to have the fuelcell generation system. Based on it's result, a reactive power due to the catenary impedance in accordance with the current flowing is compensated as linked with fuelcell generation system which supplied the current to the power supply grid. and then its performance was confirmed that voltage compensation effect obtained at SubStation (SS), SubSectioning Post (SSP), Sectioning Post (SP).

• 한국철도학회논문집
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• 제8권2호
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• pp.176-181
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• 2005

The purpose of this thesis is, based on the cognitive response of employees, to depict the phenomenon and the pattern of organizational culture in A Subway system, To attain this purpose, several aspects of organizational culture are surveyed through questionaire and analyzed by SPSS. The major findings are . 1) In general, the cognitive response of employees in railway-concerned firms on culture-related aspects is awfully negative. 2) Job satisfaction and involvement in A Subway is highly related to achievement factor in terms of culture. 3) According to the analysis based on four kinds of Job Groups, certain job groups such as drivers and vehicle maintenance are seen as having exceptionally negative attitude towards every aspects of their organization. So, some careful diagnosis and approaches to the symptoms, the causes, and the treatments are urgently needed.

• 한국철도학회논문집
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• 제8권3호
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• pp.222-227
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• 2005

This study investigates the change of the temperature and mechanical properties of the braking disk for the railway vehicle. The average temperature is measured about $100^{\circ}C$ and the maximum temperature is measured over $200^{\circ}C$ by non-contact sensor from Seoul to Chun-an. As a result of measuring, we determine the temperature of test(tensile and J-integral) at $20^{\circ}C,\;100^{\circ}C,\;200^{\circ}C$ and $300^{\circ}C$. In the test, the material values are decreased by the increasing of the temperature. But ratio of decreasing is the largest at $200^{\circ}C$, the tensile test value is decreased about $10\%$ and the J-integral test value is decreased $30\%$. The mechanical properties of this material are mostly changed at $200^{\circ}C$.

• 한국철도학회논문집
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• 제8권3호
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• pp.216-221
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• 2005

In electric motor coaches, the rolling stocks move by the adhesive effort between rail and driving wheel. Generally, the adhesive effort is defined by the function of both the wright of electric motor coach and the adhesive effort between rails and driving wheel. The characteristics of adhesive effort is strongly affected by the conditions between rails and driving wheel. When the adhesive effort decreases suddenly, the electric motor coach has slip phenomena. This paper proposes a re-adhesion control based on disturbance observer and sensor-less vector control. The numerical simulation and experimental results point out that the proposed re-adhesion control system has the desired driving wheel torque response for the tested bogie system of electric coach. Based on this estimated adhesive effort, the re-adhesion control is performed to obtain the maximum transfer of the tractive effort.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.115-122
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• 2005

This study analyzed the characteristics of four kinds of bridge rubber pads and suggested how to determine the stiffness the pads. The stiffness of rubber pads can be estimated by a direct static test. In the procedure to estimate the stiffness of a pad, the dead load(preload) of a bridge and live load of a vehicle are considered. The polyurethane rubber pads have larger hardness than natural and chloroprene rubber pads and thus carry larger load bearing capacity. In addition, they showed higher stiffness with the same shape factor than the others and thus are more avaliable as for bridge bearings. Although natural and chloroprene rubber pads are elongated to large deformation in horizontal direction due to vertical loads, polyurethane rubber pads almost do not generate horizontal deformation due to vertical loads regardless to the thickness and hardness of the pads. Therefore, they do not need reinforced plate to restrict horizontal deformation.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.440-446
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• 2005

The truck frame of railway vehicle is important structure supporting the various loadings during running on the railway. The verification of sufficient strength on truck frame is essential in case of EMU carrying many people. To verify the safety of truck frame, the actual loading conditions should be considered ast design stage. This paper is describing that the development procedure of truck frame and bolster changed from existing casting frame to new welded frame for New-York EMU, also introducing the design regulations for new welded truck frame. Additionally the dynamic accelerations on the truck were measured to insure the actual loadings on service running condition, and the procedure and results of this test are described in this paper.

• 한국철도학회논문집
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• 제5권4호
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• pp.267-275
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• 2002

The traction drive system for the urban transit maglev system is described in this paper. To control the magnitude and frequency of the output voltage of induction motor transiently, the vector control strategy is generally used. But in case of the traction drive system for the railway vehicle, it is difficult to use the vector control caused by the one-pulse mode in the high speed region. Therefore, this paper proposes the control strategy combined the vector control in the low speed region and the slip frequency control in the high speed region. And also, the overmodulation PWM method is discussed to make the change to the one-pulse mode softly. The performance of the proposed traction drive system is verified by the MATLAB simulation results.

• 한국철도학회논문집
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• 제9권5호
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• pp.618-623
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• 2006

Understanding the contact between wheel and rail is a starting point in railway vehicle dynamic research area and especially analysis for the contact geometry between wheel and rail is important. On the one hand, the critical speed as the natural characteristics of rolling-stock is generally tested on the roller rig. The geometrical characteristics of the wheel/roller contact on the roller rig are different from these of the general wheel/rail contact because the longitudinal radius of roller is not infinite compared with rail. Thus, in this paper we developed the algorithm to analyze the wheel/roller contact geometry of our roller rig which is constructed now and analyzed the difference between whee/roller contact and wheel/rail contact. In conclusion, we found that the yaw motion of wheelset and the roller radius influence the geometrical contact parameters in wheel flange contact area.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 특별세미나 특별세션
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• pp.123-134
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• 2006

Putting the urban maglev train to practical use requires the systematic management to predict and solve the problems in advance, which are expected to occur in the operation of the vehicle, at each lifecycle step such as concept design, manufacture, commissioning and maintenance. In this article, we review the trend of international specification for railway RAMS and suggest the RAMS program from the viewpoint of system engineering. In addition, RAMS requirements for the advance into the foreign market are presented through the investigation of RAMS specifications for Metro transit in various principal countries. Lastly, we suggest the direction of RAMS research on maglev train for putting it to use by analysing the trend of RAMS researches in Japanese railway.