• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.4D
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• pp.395-402
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• 2010

The seriousness of a traffic accident appears relatively higher on the curve sections compared with the straight sections due to a change in speed caused by a change in the driver's sight. In particular, the visual distortion phenomenon, one of the dangerous factors taking place on the curve sections, appears different according to the road's geometric design. Although it is a genuinely principal design factor which should be necessarily considered in designing a road, the previous researches on establishing the design standards for it have been insufficiently conducted. As a result, the establishment of the road design standards for the curve sections considering the sight distortion phenomenon is desperately required. This research examined the previous researches on the driver's behaviors, the driver's sight characteristics and the perceived curve radius on the curve sections, and developed the theoretical model of perceived curve radius to which a mathematical technique is applied in consideration of the visual distortion phenomenon on the two-lane curve sections in a local area. In addition, after the theoretical visual distortion was calculated on the basis of the theoretical model of perceived curve radius, the range of error on the theoretical recognition radius model formula was verified through comparing it with the previous researches' experiential visual distortion level and analyzing both of them. As a result, it was observed that as the curve radius practically increases in the theoretical recognition curve radius, the range of error tends to go down, which reflects well the characteristics of the curve sections on the road. Based on this research, it is expected that this research will be helpful to eliminate the safety defects when designing the curve sections and contribute to develop the road design standards considering human factors in the future.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.7
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• pp.693-700
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• 2016

It is important that we can calculate the order of non-supersingular elliptic curves with large prime factors over the finite field GF(q) to guarantee the security of public key cryptosystems based on discrete logarithm problem(DLP). Schoof algorithm, however, which is used to calculate the order of the non-supersingular elliptic curves currently is so complicated that many papers are appeared recently to update the algorithm. To avoid Schoof algorithm, in this paper, we propose an algorithm to calculate orders of elliptic curves over finite composite fields of the forms $GF(2^m)=GF(2^{rs})=GF((2^r)^s)$ using Weil's theorem. Implementing the program based on the proposed algorithm, we find a efficient non-supersingular elliptic curve over the finite composite field $GF(2^5)^{31})$ of the order larger than $10^{40}$ with prime factor larger than $10^{40}$ using the elliptic curve $E(GF(2^5))$ of the order 36.

• 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 $0.22m/s^2$.

• 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.

• Journal of Korea Water Resources Association
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• v.49 no.3
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• pp.253-262
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• 2016

A Rating curve is a regression equation of discharge versus stage for a given point on a stream where the stream discharge is measured across the stream channel with a stage and discharge measurement. The curve is generally used to calculate discharge based on the stage. However, the existing approach showed problems in terms of estimating uncertainty associated with regression parameters including the separation parameter for low and high flow. In this regard, this study aimed to develop a new method for the aforementioned problems based on Bayesian approach, which can better estimate the parameter and its uncertainty. In addition, this study used a Bayesian Multi-Segmented (Bayesian M-S) model which is provided a comparison between the existing and proposed scheme. The proposed model showed better results for the parameter estimation than the existing approach, and provided better performance in terms of estimating uncertainty range.

• Journal of the Korea Computer Graphics Society
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• v.10 no.3
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• pp.28-33
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• 2004

본 논문에서는 자유곡면 간의 교차곡선이 갖는 위상 구조를 분석하는 방법을 제시하며, 또한 이를 이용하여 교차곡선을 효율적이고 안정적으로 계산하는 알고리즘을 제안한다. 자유곡면 간의 교차곡선 계산은 현재까지 난문제로 알려져 있으며, 그러한 가장 큰 원인 중의 하나로서 교차곡선의 위상 구조를 분석하기 어렵다는 점을 들 수 있다. 본 논문에서는 입력으로 주어지는 자유곡면 중의 하나가 매개변수 곡면 F(u, v) 이라는 가정 하에 음함수 곡면 g(x, y, z) = 0 과의 교차곡선, 그리고 또 다른 매개변수 곡면 G(s, t)와의 교차곡선 계산방법을 제시한다. 교차곡선은 uv-평면 상의 평면 곡선으로 고려되며, 이 평면곡선에서 u-방향에 대한 극점(critical point)을 먼저 계산한 뒤 이를 이용하여 위상구조를 분석한다. 또한, 분석된 위상구조를 기반으로 전체 교차곡선을 추적(tracing)하는 알고리즘을 제시한다.

• Journal of Astronomy and Space Sciences
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• v.17 no.2
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• pp.181-188
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• 2000

DO Cas is a short period (P=0.68day) eclipsing binary star and is classified as a near-contact binary by Shaw(1990). There is no published radial velocity curve for this short period binary after Mannino(1958). Hill(1991) suspected that Mannino's radial velocity curve had some serious mistake. So, we scanned the original plates used by Mannino with PDS and the spectra were employed to IRAF packages to estimate the radial velocities. The radial velocity curve and the BVR light curves made by us in 1998 were analyzed simultaneously with Wilson-Devinney code. We found that DO Cas is a contact or near-contact binary which the primary component fills its Roche lobe and we also estimated the absolute dimensions of each components of this system.

• 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.

• The Journal of the Acoustical Society of Korea
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• v.7 no.2
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• pp.65-73
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• 1988

In this paper, V(z) curve has been analyzed theoretically and compared with the experimental result, and the relation between the V(z) curve and the material characteristic has been studied. Angular spectrum and ray optics theory have been used for theoretical analysis and the acoustic microscope operating at a center frequency of 3 MHz has been used for experiment. In experiment, it has been shown that each material has a V(z) curve of a unique form and the interval of dips appearing in the V(z) curves have been used to determine the Rayleigh wave velocity.

• Journal of Korean Society of Transportation
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• v.19 no.2
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• pp.21-28
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• 2001

This study is to estimate the through car equivalent for left-turn movement according to left turn radius in the signalized intersection. The saturation flow rate for left-turn movement in 92' KHCM(Korea Highway Capacity Manual) is the same as that for through movement in the signalized intersection where the left turn radius is over 20m. This study uses Duncan 'Test's Test in order to find out the saturated position for queued vehicle in the signalized intersection. It found that the saturated flow rate of left-turn movement in the signalized intersection is less than that of through movement where the left-turn radius is less than 20m. It found that the through car equivalents for left-turn movement according to left-turn radius(8m-20m) are between 1.05 and 1.14.