• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1631-1635
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• 2011

To consider dynamic magnification effect at the static design stage, impact load factor is applied to design load. Current impact load factor adopted EUROCODE without verification while Japan suggested impact load factor including velocity of high-speed train throughout theoretical and experimental studies. On the purpose of evaluate current impact load factor, this study investigated the calculation of impact load factor from dynamic response of running train.

• 한국가시화정보학회지
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• 제9권1호
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• pp.55-60
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• 2011

Pulsed supersonic liquid jets injected into an ambient air are empirically studied by using a high pressure ballistic range system. Ballistic range systems which are configured with high-pressure tube, pump tube, launch tube and liquid storage nozzle. Experimental studies are conducted to use with various impact nozzle geometry. Supersonic liquid jets are generated by an impact of high speed of the projectile. High speed liquid jets are injected with M = 3.2 which pressure is 1.19 GPa. Multiple jets which accompany with shock wave and pressure wave in front of the jet were observed. The shock-wave affects significantly atomization process for each spray droplets. As decreasing orifice diameter, the averaged SMD of spray jets had the decreasing tendency.

• 대한기계학회논문집A
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• 제30권11호
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• pp.1447-1454
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• 2006

The evaluation of parallel performance of a high speed impact simulation is not an easy task because not only the development of parallel explicit code is difficult but also a large number of processors is not easily accessible. In this paper, the parallel performance of a new Lagrangian FEM impact code carried out on cluster supercomputer has been described in high speed range. In the case of metal sphere impacting to oblique plate, the overall speed-up continuously increases even up to 128 CPUs. Investigation of elapsed time of each part reveals that most of the inefficiency comes from the load imbalance of contact.

• International Journal of Railway
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• 제2권1호
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• pp.1-7
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• 2009

The development of structural solutions for high-speed or very high-speed tracks that minimize total life cycle costs of the system is a key issue to improve the operational profitability of new investments. In opposition to conventional ballasted tracks, slab track solutions can be a cost-effective solution, but only in the cases where the benefits due to the increase in track availability and the reduction of track maintenance offsets its much higher construction costs. In the cases where such investment is not feasible, it is worth to evaluate possible structural improvements to ballasted track that allow reducing its maintenance needs without increasing too much its construction costs. This paper evaluates the design requirements and the impact of improving conventional high-speed ballasted tracks by using a bituminous subballast layer. It is divided into two main parts: first the design requirements of the structural solutions with bituminous subballast and its possible benefits on high-speed track deterioration, and secondly the evaluation of the economic impact, in terms of construction costs, of using this structural solution material in future Spanish high-speed lines.

• 대한기계학회논문집A
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• 제37권9호
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• pp.1093-1098
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• 2013

방탄소재로서 사파이어 재료가 대두되고 있지만 고속 충돌관련 동적거동 및 파괴특성에 관한 연구는 부족한 실정이다. 탄자와 취성세라믹재료간의 상호작용을 연구하기 위해서는 고화질의 초고속 연속영상이 필수적이다. 본 연구에서는 고속충돌 및 관통 현상을 순차적으로 촬영할 수 있는 장치를 개발하였다. 이 장치는 속도측정장치, 마이크로프로세서를 사용한 카메라 구동장치 그리고 다수의 CCD카메라로 이루어져있다. 선형배열센서를 사용한 속도측정장치는 직경 1-2 mm 탄자의 마하 3 속도를 측정할 수 있다. 발사된 탄자가 속도측정장치를 통과하면 속도와 시간이 측정되고 탄자가 비행하는 동안 카메라 구동장치가 정확한 충돌시간을 계산하여 다수의 카메라에 순차적으로 트리거 신호를 보내서 충돌 전후의 형상을 순차적으로 촬영한다. 정확한 충돌시간 예측을 못하면 고해상도의 사진촬영이 거의 불가능하다. 본 연구에서 개발된 정밀 촬영장치를 사용하여 고해상도의 영상을 확보할 수 있었다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1213-1220
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• 2008

In this study, the crashworthy design guidelines for the high speed EMU were derived and numerically evaluated. As for this high speed train, there are several different features from the KTX in that the conventional type bogies are adopted and the front end car (TC car) accommodates passengers. It is natural that the impact acceleration of the front end car should be controlled under the appropriate level stipulated at safety regulations for collision accidents. Also, car-to-car interfacing structures and devices should be deliberately designed to prevent overriding and telescoping mechanisms. As the first step for these design countermeasures, it was studied that how much impact energy should be absorbed at the energy absorbing zones and devices of each carbody to satisfy the impact acceleration regulations of the safety regulations. These results will be used as the crashworthy design guidelines for the high speed train in the next year research.

• Smart Structures and Systems
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• 제31권6호
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• pp.585-599
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• 2023

Field monitoring techniques offer an attractive approach for understanding bridge behavior under in-service loads. However, the investigations on bridge behavior under high-speed train load using field monitoring data are limited. The focus of this study is to explore the structural behavior of an in-service long-span steel truss arch bridge based on field monitoring data. First, the natural frequencies of the structure, as well as the train driving frequencies, are extracted. Then, the train-induced bearing displacement and structural strain are explored to identify the effects of train loads and bearings. Subsequently, a sensitivity analysis is performed for the impact factor of strain responses with respect to the train speed, train weight, and temperature to identify the fundamental issues affecting these responses. Additionally, a similar sensitivity analysis is conducted for the peak acceleration. The results indicate that the friction force in bearings provides residual deformations when two consecutive trains are in opposite directions. In addition, the impact factor and peak acceleration are primarily affected by train speed, particularly near train speeds that result in the resonance of the bridge response. The results can provide additional insight into the behavior of the long-span steel truss bridges under in-service high-speed train loads.

• 한국자동차공학회논문집
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• 제14권4호
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• pp.181-191
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• 2006

The most common kind of vehicular accident is the low-speed rear-end impact that result in high portion of insurance claims and Whiplash Associated Disorders(WAD). The low-speed collisions have specific characteristics that differ from high speed collisions and must be treated differently This paper presents a simple continuous contact force model for the low-speed rear-end impact to simulate the accelerations, velocities and the contact force as functions of time. A smoothed Coulomb friction force is used to represent the effect of braking, which was found to be significant in simulating low-speed rear end impact. The intervehicular contact force is modeled using nonlinear damping and spring elements with coefficients and exponents. This paper presents how to estimate analytically stiffness and damping coefficients. The exponent of the nonlinear contact force model was determined to match the overall acceleration pulse shape and magnitude. The model can be used to determine ${\Delta}Vs$ and peak accelerations for the purpose of accident reconstruction and for injury biomechanics studies.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.541-546
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• 2002

Railway noise is one of the main causes of environmental impact. Whenever a new railway line is planned or a housing project near an existing railway is proposed, an estimate of the relevant levels is usually required. For this, it is necessary to quantify those parameters that affect the railway noise. Therefore we investigated the noise and vibration level which 107 high speed trains generated passing through the block of test railway track between Chunan and Chungwon. This paper presents the status and characteristics of the high speed railway noise and an accurate prediction of the high speed railway noise.

• 한국소음진동공학회논문집
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• 제14권11호
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• pp.1161-1165
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• 2004

Railway noise Is one of the main causes of environmental impact. Whenever a new railway line is planned or a housing project near an existing railway is proposed, an estimate of the relevant noise levels is usually required. For this, it is necessary to quantify those parameters that affect the railway noise. Therefore we investigated the noise level which 107 high speed trains generated passing through the block of test railway track between Chunan and Chungwon. This paper shows the status and characteristics of the high speed rallway noise and an accurate prediction of the high speed railway noise.