• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.3
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• pp.118-126
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• 2008

The levitation stability of a Maglev vehicle utilizing electromagnetic suspension is primarily influenced by the deformation, roughness, and vibration of the guideway. Optimum design for both the vehicle and the guideway is desirable in order to reduce guideway construction cost, while meeting requirements for stability and ride quality. This paper presents an analysis of the levitation stability of the UTM-01, an urban Maglev vehicle, using a numerical simulation. The ODYN/Maglev, a dynamics analysis program, is used to simulate dynamics to evaluate the stability. A running test of the UTM-01 is also carried out to verify the results of the simulation. Using the simulation results, the levitation stability of the UTM-01 can be numerically analyzed at a variety of vehicle speeds.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.11
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• pp.1413-1420
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• 2012

To predict the dynamics behavior, running stability, etc. of a railway vehicle and to understand its physical characteristics, analytical methods are used for the testing and manufacturing of a scale model along with numerical simulations in developed countries (England, France, Japan, etc.). The test of the dynamics characteristics of full-scale models is problematic in that it is expensive and time-consuming because an entire large-scale test plant needs to be constructed, difficulties are involved in the test configuration, etc. To overcome these problems, an analytical study involving dynamics tests and computer simulations using a scaled bogie model that applies the laws of similarity was carried out. In this study, we performed stability analysis on a 1/5 small scaled bogie for parameters such as the running speed and carbody weight by using an analysis model. Furthermore, we verified the reliability by using a small-scaled derailment simulator and examined the dynamic characteristic of the 1/5 small scaled bogie.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.880-887
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• 2020

This study was conducted to investigate the running stability of a high-speed train operated in a tunnel and an open field when external forces such as wind pressure and train crossings were applied to the vehicle. With no external force, the running stability at 400 km/h was examined, and the wheel weight reduction ratio, lateral pressure of the axles, and derailment coefficient satisfied the criteria of the technical standards for a high-speed train. When the distance between the centers of the tracks is 4.6 m, the external force caused by train crossing slightly affects the lateral acceleration of the vehicle but does not significantly affect the wheel weight reduction rate, lateral pressure, and derailment coefficient in a tunnel and open filed. When the distance is 4.6~5.0 m, the wheel weight reduction ratio, lateral pressure, and derailment coefficient satisfy the criteria with 20 m/s wind. When the wind speed was 30 m/s, the derailment coefficient satisfied the criteria, and the other variables exceeded them. It is predicted that a high-speed train can be operated safely at 400 km/h with wind speed of up to 20 m/s, and it should be slowed down at a wind speed of 30 m/s.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1856-1861
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• 2011

As a secondary suspension, the air spring has not good lateral stiffness characteristics. In order to make up for this weak point, lateral damper is used between bogie and carbody. The lateral vibration of carbody can be reduced by the lateral damper. When the damping force of lateral damper becomes worse, the running stability and ride comfort of the railway vehicle go down. Simultaneously the lateral motion of carbody is increased. In this study, the lateral displacement of carbody was studied by the multibody dynamic analysis in accordance with lateral damping force to find the cause of abnormal noise(impact noise) when the vehicle is running. The suitable lateral damping force was reviewed in order not to generate abnormal noise.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.192-198
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• 2004

KTX is the high speed train which is designed for 300km/h in maximum operation speed. But its long train set may cause unstable characters as swaying of the tail of a train and when the train is running on conventional line not on the high speed line, its funning safety is a point to be considered cautiously. In this study, we evaluated the running safety by the numerical analysis using VAMPIRE and compared the result with the test result of KHST, which is being in performance tests, for verifying the validity of analysis results.

• Proceedings of the KSR Conference
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• 2006.11a
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• pp.161-169
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• 2006

To develop a Maglev successfully, it is necessary to develop the core technologies such as levitation and propulsion system and construct engineering system which can integrally evaluate performances of Maglev and provide technical reviews parametrically In this paper, we designed the Maglev running performance simulator which can provide decision-making Information for direction of development of Maglev and examination for running performance about the change of various design parameters such as safety and stability, noise, and ride quality. The designed system is an engineering-based system and can be developed using engineering framework by KIMM which can integrate diverse CAE systems in distributed environments and provide systematic information management. And it also provides VR-based visualization and web-based user interface except VR system which requires special hardware system.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.417-422
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• 2004

The vibration of a running vehicle can be classified on lateral, longitudinal and vertical motions. The important factor on the stability and ride quality of a railway vehicle is the lateral motion. The contact between wheel and rail with conicity influences strongly on the lateral motion. In this study, an experiment for the vibration of a running railway vehicle was performed using a small scale railway vehicle model. Also, the effects on the car body, bogie and wheelset were examined for the weight and the stiffness of the first and second suspension. The experimental results showed that the lateral vibration increases as the wheel conicity and stiffness of the second suspension increase. And the lateral vibration of the bogie increases as the mass ratio between car body and bogie increases. Also, the lateral vibration of the wheel becomes high at low speed, while the wheel of 1/20 conicity makes severe vibration at high speed running.

• Korean Journal of Applied Biomechanics
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• v.31 no.3
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• pp.205-213
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• 2021

Objective: The aim of this study was to analyze body stability Joint coordination pattern though as bending stiffness of shoes during stance phase of running. Method: 47 male subjects (Age: 26.33 ± 2.11 years, Height: 177.32 ± 4.31 cm, Weight: 65.8 ± 3.87 kg) participated in this study. All subjects tested wearing the same type of running shoes by classifying bending stiffness (A shoes: 3.2~4.1 N, B shoes: 9.25~10.53 N, C shoes: 20.22~21.59 N). They ran 10 m at 3.3 m/s (SD ±3%) speed, and the speed was monitored by installing a speedometer at 3 m intervals between force plate, and the measured data were analyzed five times. During running, ankle joint, MTP joint, coupling angle, inclination angle (anterior-posterior, medial-lateral) was collected and analyzed. Vector coding methods were used to calculate vector angle of 2 joint couples during running: MTP-Ankle joint frontal plane. All analyses were performed with SPSS 21.0 and for repeated measured ANOVA and Post-hoc was Bonferroni. Results: Results indicated that there was an interaction between three shoes and phases for MTP (Metatarsalphalangeal) joint angle (p = .045), the phases in the three shoes showed difference with heel strike~impact peak (p1) (p = .000), impact peak~active peak (p2) (p = .002), from active peak to half the distance to take-off until take-off (p4) (p = .032) except for active peak~from active peak to half the distance to take-off (p3) (p = .155). ML IA (medial-lateral inclination angle) for C shoes was increased than other shoes. The coupling angle of ankle angle and MTP joint showed that there was significantly difference of p2 (p = .005), p4 (p = .045), and the characteristics of C shoes were that single-joint pattern (ankle-phase, MTP-phase) was shown in each phase. Conclusion: In conclusion, by wearing high bending stiffness shoes, their body instability was increased during running.

• Journal of Korean Physical Therapy Science
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• v.26 no.3
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• pp.70-75
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• 2019

Purpose: The purpose of this study was to investigate the changes of static and dynamic balance control ability according to the stability of shoes in elderly woman and female university student. Design: Cross-sectional study. Methods: Six elderly women and seven female university students were recruited for this study. The subject's static and dynamic balance were evaluated while wearing two different types of shoes (comfortable running shoe and masai walking shoe). The BT4 system was used to measure the static (postural sway area and velocity) and dynamic balance (limit of stability on forward, backward and left and right side). The measurement of static and dynamic balance control ability was performed in standing posture wearing comfortable running shoes and masai walking shoes. Results: In the static balance control ability, both female university students and elderly women showed significant increase in postural sway area and velocity when wearing unstable shoes (p<0.05) In addition, in the dynamic balance control ability, both female university students and elderly women showed significant decrease in limit of stability on forward and backward when wearing unstable shoes (p<0.05). Conclusion: In selecting shoes for the elderly, the stability of shoe should be considered for prevention of falls.

• Wind and Structures
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• v.29 no.5
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• pp.299-312
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• 2019

Due to the rugged terrain, metro lines in mountain city across numerous wide rivers and deep valleys, resulting in instability of high-pier bridge and insecurity of metro train under crosswind. Compared with the conditions of no-wind, crosswind triggers severer vibration of the dynamic system; compared with the short-pier viaduct, the high-pier viaduct has worse stability under crosswind. For these reasons, the running safety of the metro vehicle traveling on a high-pier viaduct under crosswind is analyzed to ensure the safe operation in metro lines in mountain cities. In this paper, a dynamic model of the metro vehicle-track-bridge system under crosswind is established, in which crosswind loads model considering the condition of wind zone are built. After that, the evaluation indices and the calculation parameters have been selected, moreover, the basic characteristics of the dynamic system with high-pier under crosswind are analyzed. On this basis, the response varies with vehicle speed and wind speed are calculated, then the corresponding safety zone is determined. The results indicate that, crosswind triggers drastic vibration to the metro vehicle and high-pier viaduct, which in turn causes running instability of the vehicle. The corresponding safety zone for metro vehicle traveling on the high-pier is proposed, and the metro traffic on the high-pier bridge under crosswind should not exceed the corresponding limited vehicle speed to ensure the running safety.