• Proceedings of the KOR-KST Conference
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• 1999.10a
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• pp.141-146
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• 1999

본 연구는 평면곡선부의 차량속도변화와 교통사고에 대한 영향을 분석하기 위해 수행되었으며, 이를 위해 곡선반경별로 진입부 직선도로 - 곡선부 - 이탈부 직선도로로 구분하여 각 주행속도를 산정하였다. 본 연구에서는 선행차량에 의해 영향을 받지 않는 속도를 이용하여 평면곡선부 기하구조의 영향을 분석하였다. 이러한 곡선부의 주행 속도를 분석한 결과, 곡선반경별 최저속도와 그 속도가 나타나는 위치를 분석하였고, 해당 도로구간의 교통사고자료를 분석하여 평면곡선부의 차량주행속도변화와 교통사고 발생간의 관계를 규명하였다. 연구 결과는 다음과 같다. 첫째, 운전자들은 곡선시작지점에 도착하기 전에 충분히 속도를 줄이고, 곡선부에서 가장 낮은 속도가 나타나는 위치는 곡선시점의 후방에서 나타나고 이는 운전자의 시거에 의한 영향이다. 둘째, 곡선부에서의 속도변화폭이 클수록 사고위험성은 크고 실제 교통사고의 발생건수는 높다. 본 연구의 결과에 의해 도로 주행의 안전성을 고려한 평가지표를 개발할 수 있으며, 이에 의한 일관성 있는 도로설계를 유도할 수 있다.

• Journal of Korean Society of Transportation
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• v.18 no.1
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• pp.35-43
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• 2000

The Purpose of this Paper was to study the relationship between the change of operating speeds and the accidents on horizontal curves. For this purpose, we divided a horizontal curve section into two parts, a tangent section and a curve section, to estimate the operating speed for each vehicle. For studying relationship between the change of speed and geometric effect, the free-flow speed was used. The location and speed for the lowest speed were studied. Also, we analyzed the relationship between the change of operating speeds and the accidents. The followings are resulted in this study. First, drivers tend to reduce speeds significantly before they reach a curve. And the lowest speed was recorded at the downstream of the Point of curve (PC) due to the limited sight-distance of drivers on curve. Second, the larger the change of operating speeds become, the greater frequency of accident was recorded. These results can be used for developing the safety index on highways to check the design consistency.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3573-3578
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• 2015

Transition curves are located between curve and straight section in railway. These transition curves are vulnerable to the ride comfort of passengers and safety of a vehicle because lateral acceleration, lateral jerk and roll velocity increase as curvature and cant change along the transition curves. In this paper, ride comfort on the transition curve was calculated on the basis of lateral acceleration and roll velocity measurements. The evaluation of ride comfort was conducted according to the methodology specified in European Standard. The distribution characteristics of the comfort index were investigated for the korean conventional line from the evaluation results. The influence of the curve radius and the vehicle speed on the ride comfort index was also investigated. Finally, the relationship between ride comfort and the rate of cant changes on transition curves was analyzed.

• Journal of Korean Society of Transportation
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• v.22 no.7 s.78
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• pp.139-146
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• 2004

Road design should be conformed to the expectancy of drivers. The alignment such as long tangent followed by the sharp horizontal curve should be avoided for the road design consistency. Currently, operating speed profile model is generally used to check the consistency of the successive road alignments. In this model, the hypothesis about the drivers' behaviour on the long tangent followed by the sharp horizontal curve is also included. This study compares the hypothesized drivers' behaviour in the existing operating speed profile model with the actual drivers' behaviour observed at the two lane rural roads. In addition to this, comparison between the acceleration for the vehicles approaching and departing horizontal curves suggested by the foreign research and the value observed at this study was made, From this study, it was concluded that the hypothesis in the existing model was well representing the actual drivers' behaviour. The deceleration for vehicles approaching the horizontal curves was ranged $0.39{\sim}1.06m/s^2$ with the average of $0.66m/s^2$. The average acceleration for the vehicles departing horizontal curves was $0.22m/s^2$.

• Journal of Energy Engineering
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• v.4 no.3
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• pp.402-406
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• 1995

다리우스 풍력터빈의 속도설정을 터빈이 만드는 토크와 발전기가 요구하는 토크의 \평형을 통해 찾아 낼 수 있음을 검토하였다. 풍속에 따른 속도-토크곡선에서 일정충력곡선이 만나는 점이 터빈의 동작점으로 되며 이는 안정 및 불안정이 될 수도 있다. 풍속과 출력이 각각 변할 때 이 동작점이 어떻게 이동되는가 하는 점을 제시하였다. 또한 터빈의 속도에 관한 제어 블록선도를 제시하여 그 출력변화에 따른 속도변화의 전달함수를 알아내고 이의 형태는 1차 시지연 함수로 유도된다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.22 no.4
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• pp.391-400
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• 2004

Railway curved zone have crucial effects on the speed of train. Length of transition curve is one of the important factor for alignment compatibility estimation in this sections, this value is decided by running speed and Cant. In this study, the extension method of transition curve is evaluated, based on the alignment of Jang Hang-Line, investigated field conditions of the sections in the curves exist. This research result show that changing of transition curve was proved by necessary to approximately two thirds of the curved sections, and method of fixing central point of track centerline and changing radius of curvature minimize the maximum shift in track centerline and deviation of radius, and also may be effective method for alignment suitability and speed up in case overall improvement is difficult.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.6D
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• pp.663-673
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• 2009

Driver's perceived curve radius is different from actual curve radius at curve sections. This is called visual distortion. It has effect on operation speed according to driver's perception and finally bad effect on safety at curve sections. At present, however, there is no research on quantitatively analysis of visual distortion and no criteria for curve section design considering the visual distortion. Therefore, this study focus on finding degree of visual distortion and suggesting design criteria by visual distortion analysis. The process of this study is as below; First, a calculaiton model of perceived curve radius was developed by survey using computer simulation. In this model, a dependent variable is perceived curve radius and an independent variable is geometric factors. Second, degree of visual distortion was calculated from ratio of perceived curve radius to actual curve radius. Finally, design criteria were suggested through influencing factor analysis of visual distortion at curve sections.

• Composites Research
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• v.18 no.1
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• pp.38-44
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• 2005

In this paper, the group velocity dispersion curves of the $S_o$ symmetric mode in unidirectional CFRP plate was calculated as varying the propagating direction. The group velocity curve was obtained with the group velocities of the $S_o$ symmetric mode corresponding to 0.2 MHz-mm under the first cut-off frequency in the dispersion curves, and corrected by introducing the slowness curve. The velocities of the $S_o$ symmetric mode in the unidirectional CFRP plate were measured as varying the propagating direction and compared with the col?rotted group velocity curve. The measured velocities were good agreement with the corrected group velocity curve except near the fiber direction which was called the cusp region. It implies that the direction of the group velocities incline toward the fiber direction of the unidirectional CFRP plates when the propagation direction is not accorded with the principal axis. It is supposed that this phenomenon rerults from the preferential propagating the energy toward the direction with the faster propagation velocity.

• International Journal of Highway Engineering
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• v.10 no.2
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• pp.135-143
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• 2008

According to the present highway design criteria, there are minimum standards which re ade from special design speeds. If some highways are satisfied the standards, it regards he highway as safety. In reality, however, most drivers drive a car at different speed compared with design speed. It is very dangerous for drivers especially at transition sections between curve and horizontal curve sections. Hence, this study calculated the rate of changing and horizontal acceleration at each section. Moreover, this study evaluated thesafety of design at curve transition sections and then calculated lateral acceleration and curve radii. This study found the minimum standards which are using as basic safety standards are not appropriate for measuring driver's safety.

• Journal of Korean Society of Transportation
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• v.23 no.8 s.86
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• pp.153-162
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• 2005

This study is carried out to evaluate the sight distance change due to construction errors of vertical crest curves. Various design speeds and grades as well as various size of construction errors are incorporated in this study. After showing theoretical methodology numerical results are compared and analysed for the given ranges of parameters. New vertical curve change rate(m/%) is suggested to guarantee minimum sight distance under construction errors. As to the results, the reduction of sight distance are $2.8{\sim}21.3m$ at 120km/h, $2.0{\sim}15.1m$ at 100km/h, $1.4{\sim}10.6m$ at 80km/h, $1.0{\sim}7.5m$ at 60km/h $0.5{\sim}3.9m$ at 40km/h. Vortical curve change rates need to be increased about $6{\sim}25%$ to provide minimum stopping sight distance according to design speed.