• Title/Summary/Keyword: Primary Suspension

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Prediction of Dynamic Characteristics of Railway Vehicle by Stiffness Variation of Chevron Rubber Spring (세브론 스프링의 강성 변화에 따른 철도차량의 동특성 예측 연구)

  • You, Wonhee;Park, Joonhyuk;Park, Namcheol;Koo, Jeongseo
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.27 no.2
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    • pp.162-167
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    • 2017
  • The chevron rubber spring is used for subway vehicle as a primary suspension. Generally, the primary suspension has an influence to the running performance and not so much effect on the ride comfort in railway vehicle. But the stiffness of chevron spring is harder and harder as time goes on because of rubber characteristics. Therefore the dynamic characteristics such as ride comfort and derailment coefficient should be reviewed according to the stiffness variation of chevron rubber spring. In this paper the effect of chevron rubber spring on dynamic characteristics was studied by considering multi-body dynamics of railway vehicle on one straight line and seven curved lines.

Dynamic Simulation of Magnetically-Levitated Vehicle (자기부상열차의 다이나믹 시뮬레이션)

  • Kim, Jong-Moon;Bae, Jong-I1
    • Proceedings of the KIEE Conference
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    • 2005.04a
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    • pp.34-36
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    • 2005
  • In this paper, dynamic simulation results for magnetically-levitated vehicles are presented. The dynamic equations and models for a half-bogie system are derived. They include primary suspension system, module, secondary suspension and cabin. Also, the dynamic characteristics for the derived models are analysed.

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Synthesis of Ultra-fine Calcium Phosphate Powders from Ca(OH)2 Suspension and Various Phosphoric Aqueous Solutions (Ca(OH)$_2$ 현탁액과 각종 인산 수용액으로부터 인산칼슘 초미분말의 제조)

  • 민경소;최상흘
    • Journal of the Korean Ceramic Society
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    • v.29 no.1
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    • pp.74-82
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    • 1992
  • Ultra-fine calcium phosphate powders were synthesized by the reaction of Ca(OH)2 suspension with various phosphoric aqueous solutions such as (NH4)2HPO4, H4P2O7 and H3PO4, and the characterization of powders was examined for each synthetic condition. When (NH4)2HPO4 and H3PO4 were used, hydroxyapatite powders with poor crystallinity were obtained. In the case of H4P2O7, amorphous calcium phosphate was obtained up to 0.3 mol/ι Ca(OH)2 suspension, but above the concentration, poor crystalline hydroxyapatite was produced. Crystalline phases of powders heat-treated at 80$0^{\circ}C$ were hydroxyapatite, $\beta$-tricalcium phosphate and $\beta$-tricalcium phosphate for the case of (NH4)2HPO4, H4P2O7 and H3PO4, respectively. SEM observation revealed that the shapes of synthesized powders were vigorously agglomerated spherical with the size below 100 nm, but TEM observation revealed that primary shapes of particles were rod for (NH4)2HPO4 and H3PO4 and were sphere for H4P2O7. There was no dependence of the concentration of Ca(OH)2 suspension. In the case that reaction temperature and pH of the suspension were raised, the inclination to the hydroxyapatite were remarkable. The amorphous calcium phosphate synthesized in this experiment contained water about 20% , and was crystallized to $\beta$-tricalcium phosphate at 69$0^{\circ}C$.

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A Study on the Effect of Changes in Chevron Rubber Characteristics on the Vibrational Ride Comfort Level of a Subway Vehicle (도시철도차량 세브론 고무 특성 변화가 진동승차감 레벨에 미치는 영향 연구)

  • Park, Nam Cheol;Koo, Jeong Seo
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.15 no.2
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    • pp.57-65
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    • 2016
  • The suspension system of a subway vehicle is composed of $1^{st}$ and $2^{nd}$ springs. The suspension system is the most important parameter in determining the vibration ride comfort. If the $1^{st}$ suspension spring is designed as a spring with strong stiffness to improve the running stability at high speed, it causes vehicle vibrations. In this paper, by testing and analyzing changes of the characteristics of Chevron springs, which have been the primary suspension springs used for about 20 years, we study how changing the characteristics affects vehicle acceleration and ride comfort. The lateral and longitudinal vibrational ride comfort index levels were lower than the vertical ones. Therefore, as increasing the stiffness of Chevron springs has the greatest effect on the vertical vibrational ride comfort index level, a countermeasure for vertical vibration reduction is needed when the stiffness increases owing to aging. Finally, maintenance guidelines, including the replacement time for the Chevron rubber, were proposed based on these findings.

Experimental Evaluation of Direct Measurement for Excitation Forces Acting on the Hard-points of Suspension System to Predict Road-noise Performance (로드노이즈 성능 예측을 위한 현가장치 하드포인트의 가진력 직접 측정법에 대한 실험적 평가)

  • Kang, Yeon June;Kim, Heesoo;Song, David P.;Ih, Kang-Duck;Kim, HyoungGun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.25 no.3
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    • pp.184-190
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    • 2015
  • NVH engineering has become a hot issue due to radical technology changes and development in automotive industry since customers' expectations and needs for their vehicle is taken to a higher level. However, the source identification and quantification of the road noise within a vehicle is still not at the level where it needs to be to meet their expectations due to its' complex transfer path and difficulties in path optimization. The primary focus of this research is on direct force obtaining method at suspension hard points using suspension test rig. Directly obtained forces at suspension to body mounting points are critical and crucial for determining the effects of design changes of the suspension has on road noise performance. Direct force obtaining method has its limitation in sensor installation within an actual vehicle therefore, many has been indirectly calculating forces using full matrix inversion method or dynamic stiffness method. In this study, to circumvent this limitation, a suspension rig is used. Then, the suspension rig is verified through a comparative analysis of its dynamic behavior between the actual vehicle by cleat test on chassis dynamometer.

Study of the Capsule Train Ride Comfort Improvement by using the Damping Control in Suspension System (현가장치 내 감쇠 제어를 이용한 캡슐트레인 승차감 향상 연구)

  • Lee, Jin-Ho;Lim, Jungyoul;You, Won-Hee;Lee, Kwansup
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.10
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    • pp.547-557
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    • 2020
  • In this study, damping control devices were applied to the suspension system of a capsule train, and the effects were investigated to improve the ride comfort. The superconductor electrodynamic suspension (SC-EDS) method is used for the capsule train levitation. This method has advantages such as no gap control and a large gap. However, the SC-EDS method has disadvantages such as large gap variation and small damping characteristics against outer vibration, which causes degradation of the ride comfort. In this study, the damping control devices in the primary and secondary suspension were considered to improve the ride comfort in the capsule train. Damping control devices in the primary and secondary suspension can reduce the vibration transmission from outer disturbances to the bogie and from the bogie to the car body, respectively. Simulations for dynamic characteristics analyses were conducted based on the capsule train dynamic model to investigate the effects of the damping control devices on the ride comfort. As a result, it was confirmed that the ride comfort requirements according to the ISO standard can be satisfied by applying the damping control in the capsule train suspension.

Development of Proving Ground Test Mode for Durability Test of Active Suspension System (사용자 주행 환경을 고려한 능동 현가 시스템의 PG 내구 시험 모드 개발)

  • Woo, Jongwoon;Lee, Seonbong
    • Transactions of the Korean Society of Automotive Engineers
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    • v.21 no.6
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    • pp.16-23
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    • 2013
  • It is important that proving ground damage is correlated with target customer usage. This paper describes the test mode for durability test of active suspension control system for proving ground correlation and optimization. Acceleration, strain, wheel force and other types of data are collected on a vehicle as it traverses different proving ground surfaces. The primary objective of the analysis is to determine which mixture of proving ground surfaces offers the best representation of customer usage while minimizing the total test time. And durability testing offers the best way to assess the capability of a product to reach its reliability target. The test should be representative of the real environmental load and replicate the same customer usage.

Ride Sensitivity Analysis of a Train With Non-linear Suspension Elements (비선형 현가요소를 가진 철도차량의 승차감 민감도 해석)

  • 전형호;탁태오
    • Journal of the Korean Society for Railway
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    • v.5 no.1
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    • pp.40-47
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    • 2002
  • In this study, and analytical method for ride sensitivity analysis of a train with non-linear suspension elements are proposed. Non-linear characteristics of springs and dampers for primary and secondary suspensions of a train are parameterized using polynomial interpolation. Vertical dynamic model of a three-body train running on straight rail with the predetermined roughness expressed in terms of spectral density function is set up and its equations of motion for ride analysis are derived. Using the direct differentiation method, sensitivity equations of the vertical dynamic model with respect to design parameters associated with non-linearity of suspensions are obtained. Based on the sensitivity analysis, improvement of ride is achieved by varying appropriate suspension parameters.

FRACTAL DIMENSION OF SIMULATED SEDIMENTS (모의류사의 쪽거리 차원)

  • 김형수;윤용남
    • Water for future
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    • v.27 no.3
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    • pp.115-121
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    • 1994
  • Cohesie sediment movement in estuarine systems is strongly affected by the phenomena of aggregation and flocculation. Aggregation is the process where primary particles are clustered together in tightly-packed formations; flocculation is the process where aggregates and single particles are bonded together to form large particle groups of very low specific density. The size, shape and strength of the flocculants control the rate of deposition and the processes of pollutant exchange between suspended sediments and ambient water. In estuarine waters, suspended sediments above the lutocline form the mobile suspension zone while below the lutocline they form the stationary suspension zone. Suspended particles in the mobile zone are generally in a dispersed state and the controlling forces are the Brownian motion and the turbulent flow fluctuations. In the stationary suspension zone, the driving force is the gravity. This paper discusses the settling and particle flocculation characteristics under quiescient flow conditions. Particles are entering the study domain randomly. Particles in the mobile suspension zone are simulated by using the Smoluchowski's model. Flocs created in the mobil suspension zone are moving into the stationary suspension zone where viscosity and drag effects are important. Utilizing the concepts of the maximum Feret's diameter and the Minkowski's sausage logic, the fractal dimension of the flocs within the stationary suspension is estimated and then compared with results obtained by other studies.

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GENIAL ADVANCEMENT, INFRAHYOID MYOTOMY AND SUSPENSION IN TREATMENT OF OBSTRUCTIVE SLEEP APNEA SYNDROME (이부전방이동술, 하설골근절개술 및 설골현수법을 이용한 폐쇄성 수면 무호흡증 환자의 치료:증례보고)

  • Kim, Jae-Jin;Kim, Eun-Seok;Kim, Tae-Sup
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.27 no.2
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    • pp.162-166
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    • 2001
  • Obstructive sleep apnea syndrome(OSAS) is a complex sleep disorder characterized by intermittent apnea secondary to sleep-induced obstruction of the upper airway. It occurs because of an airway obstruction anywhere between the trachea and the oronasal apparatus. The hallmark of OSAS is snoring, which is caused by vibration of the tissues of the pharynx as the airway narrows. The consequences of OSAS have focused on excessive daytime sleepiness resulting from sleep fragmentation and the cardiovascular derangements producing hypertension and arrhythmias. The primary method of controlling OSAS has been surgery. The current surgical procedures used for OSAS are tracheostomy, tonsillectomy, nasal septoplasty, uvulopalatopharyngoplasty, anterior mandibular osteotomy with hyoid myotomy and suspension, and maxillary, mandibular and hyoid advancement. We report a case of OSAS that was improved by genial advancement with infrahyoid myotomy and suspension. The patient was objectively documented by polysomnography, cephalometric analysis, and physical examination before the surgical procedure. The patient underwent genial advancement with infrahyoid myotomy and suspension. Patient had a good response from surgery.

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