• 제어로봇시스템학회논문지
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• 제22권1호
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• pp.1-7
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• 2016

ADAS (Advanced Driver Assistance Systems) requires not only real-time robust lane detection, both straight and curved, but also predicting upcoming steering direction by detecting the curvature of lanes. In this paper, a curvature lane detection algorithm is proposed to enhance the accuracy and detection rate based on using inverse perspective images and Gaussian Mixture Model (GMM) to segment the lanes from the background under various illumination condition. To increase the speed and accuracy of the lane detection, this paper used template matching, RANSAC and proposed post processing method. Through experiments, it is validated that the proposed algorithm can detect both straight and curved lanes as well as predicting the upcoming direction with 92.95% of detection accuracy and 50fps speed.

• Journal of Astronomy and Space Sciences
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• 제26권2호
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• pp.171-186
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• 2009

이 연구에서는 미래 한국의 달 탐사에 대비, 지구-달 천이궤적을 설계하고 분석하였다. 궤적 설계는 최소연료로 지구 주차궤도에서부터 달 임무궤도까지 도달하는 모든 단계에 대해서 실시하였으며 미래 한국의 달 탐사 개발 계획에 실질적인 도움이 되기 위해 2017년, 2020년, 2022년으로 각각 나누어 설계를 하였다. 탐사선의 운동방정식의 구현을 위하여 태양, 지구, 달의 중력에 의한 섭동력이 포함된 N체 운동 방정식을 사용하였으며 보다 실질적인 우주환경의 모사를 위하여 지구의 비대칭 중력장(Geopotential), 태양 복사압(Solar radiation pressure) 그리고 달의 J2 섭동에 의한 영향도 고려하였다. 임무 설계를 위해 가정된 추력은 순간 추력(Impulsive thrust)으로 가정하였으며 발사체의 성능은 현재 개발 예정인 KSLV-2로 가정하였다. 미래 한국의 가상 달 탐사선이 지구-달 천이 궤적(Trans Lunar trajectory)에 진입하는 방법으로는 지구 주차 궤도에서 직접 진입 하는 방법과 여러번의 타원 중개 궤도를 거친 후 지구-달 천이 궤적으로 진입하는 방법을 모두 이용하였다. 아울러 TLI(Trans Lunar Injection) 기동시 탐사선의 대전 지상국에서의 가시성에 따른 기동의 크기에 대한 영향이 분석되었다. 이 연구를 통한 임무 설계 결과는 달 탐사 임무 설계를 위한 발사 가능 시기(launch opportunity), 성공적인 임무 수행을 위한 임무 단계별 최적의 기동량 및 해당 궤도의 특성 그리고 다양한 임무 파라미터등의 해석을 포함하고 있다. 임무 설계 결과, 미래 한국이 쏘아 올릴 수 있는 달 탐사선의 전체 질량은 해당 임무의 수행시기 보다는 초기 지구 출발 궤도의 초기 고도와 발사제의 초기 궤도 투입 성능에 따라 더욱 크게 좌우됨을 확인하였다.

• 대한기계학회논문집B
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• 제29권5호
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• pp.633-642
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• 2005

Nucleate pool boiling experiments for R11 under a constant wall temperature condition were carried out. A microscale heater array was used for the heating and the measurement of high temporal and spatial resolution by the Wheatstone bridge circuit. Very sensitive heat flow rate data were obtained by the control for the surface condition with high time resolution. The measured heat flow rate shows a discernable peak at the initial growth stage and reaches an almost constant value. In the thermal growth region, bubble shows a growth proportional to $t^{\frac{1}{5}}$. The bubble growth behavior is analyzed with a dimensionless parameter to compare with the previous results in the same scale. As the wall superheat increases, the departure diameter and the departure time increase, and the waiting time decreases. But the asymptotic growth rate is not affected by the wall superheat change. The effect of the wall superheat is resolved into the suggested growth equation. Dimensionless parameters of time and bubble radius characterize the thermal growth behavior well, irrespective of wall condition. The comparison between the result of this study and the previous results shows a good agreement at the thermal growth region. The quantitative analysis for the heat transfer mechanism is conducted with the measured heat flow rate behavior and the bubble growth behavior. The required heat flow rate for the volume change of the observed bubble is about twice as much as the instantaneous heat flow rate supplied from the wall.

• 한국안광학회지
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• 제7권1호
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• pp.29-34
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• 2002

Venzotriazol계를 증류수로 희석(5%)하여 만든 UV 차단 출발액을 dip 방법으로 각각 1, 2, 5, 15, 20, 30분 간격으로 유지시켜 UV 차단렌즈의 시료를 제작하였다. 각 시료에 대한 광 투과율의 spectrum은 320~450nm 영역에서 측정하였다. 그 결과 광흡수 edge는 각각 403, 408, 414, 419nm 영역이며, 각각 3.07, 3.04, 2.99, 2.96eV의 band에서 흡수 edge가 나타났다. UV 차단 렌즈 출발용액은 benzophenone계의 2-Hydroxy-4-n-octoxybenzo-phenone를 methanol에 녹여 5%, 10%을 만들고, UV 차단 렌즈는 Spray pyrolysis method로 만들었다. 등 간격으로 분무한 각 렌즈의 투과 광의 edge는 spectra에서 거의 등 간격을 보였다. 2, 4, 6분 동안 분무할 때의 광 흡수 edge는 385, 398, 417nm 영역이며, band는 각각 3.22, 3.11, 2.97eV를 이루고 있다.

• 대한산업공학회지
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• 제8권1호
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• pp.29-39
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• 1982

This paper presents a practical guidence for determining an optimal traffic control system at intersections in the urban areas in Korea. Two alternative systems, unsignalized and signalized, are considered. For analyzing the unsignalized system, two kinds of simulation model are developed ; gap acceptance model and first -in -first - out model. For the signalized system the total delay function for general arrival distribution is developed under the assumption that departure time is constant and it is used to find an optimal cycle time. Finally, the results in these two alternative systems are compared under the minimum average delay criterion and an optimal traffic control system is determined. This approach supports the decision making whether to install a traffic signal system in an intersection with given traffic flows and, if installed, determines what is the optimal cycle time and how the traffic signal phases are divided. And it also gives upper bounds of traffic flows to be passed in the unsignalized and the signalized system, which can be effectively used whenever an intersection is designed.

• Journal of applied mathematics & informatics
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• 제8권1호
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• pp.199-212
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• 2001

We consider a k-out-of-n system with repair under T-policy. Life time of each component is exponentially distributed with parameter $\lambda$. Server is called to the system after the elapse of T time units since his departure after completion of repair of all failed units in the previous cycle or until accumulation of n-k failed units, whichever occurs first. Service time is assumed to be exponential with rate ${\mu}$. T is also exponentially distributed with parameter ${\alpha}$. System state probabilities in finite time and long run are derived for (i) cold (ii) warm (iii) hot systems. Several characteristics of these systems are obtained. A control problem is also investigated and numerical illustrations are provided. It is proved that the expected profit to the system is concave in ${\alpha}$ and hence global maximum exists.

• Journal of information and communication convergence engineering
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• 제15권3호
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• pp.187-192
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• 2017

Autonomous driving vehicle research demands complex road and lane understanding such as lane departure warning, adaptive cruise control, lane keeping and centering, lane change and turn assist, and driving under complex road conditions. A fast and robust road lane detection subsystem is a basic but important building block for this type of research. In this paper, we propose a method that performs road lane detection from black box input. The proposed system applies Random Sample Consensus to find the best model of road lanes passing through divided regions of the input image under HSV color model. HSV color model is chosen since it explicitly separates chromaticity and luminosity and the narrower hue distribution greatly assists in later segmentation of the frames by limiting color saturation. The implemented method was successful in lane detection on real world on-board testing, exhibiting 86.21% accuracy with 4.3% standard deviation in real time.

• International Journal of Automotive Technology
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• 제5권2호
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• pp.95-108
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• 2004

Lanekeeping assistance has the potential to save thousands of lives every year by preventing accidental road departure. This paper presents experimental validation of a potential field lanekeeping assistance system with quantitative performance guarantees. The lanekeeping system is implemented on a 1997 Corvette modified for steer-by-wire capability. With no mechanical connection between the hand wheel and road wheels the lanekeeping system can add steering inputs independently from the driver. Implementation of the lanekeeping system uses a novel combination of a multi-antenna Global Positioning System (GPS) and precision road maps. Preliminary experimental data shows that this control scheme performs extremely well for driver assistance and closely matches simulation results, verifying previous theoretical guarantees for safety. These results also motivate future work which will focus on interaction with the driver.

• 대한안전경영과학회지
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• 제3권3호
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• pp.175-190
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• 2001

We propose, a new process capability index $C_{psk}$(WV) applying the weighted variance control charting method for non-normally distributed. The main idea of the weighted variance method(WVM) is to divide a skewed or asymmetric distribution into two normal distributions from its mean to create two new distributions which have the same mean but different standard deviations. In this paper we propose an example, a distributions generated from the Johnson family of distributions, to demonstrate how the weighted variance-based process capability indices perform in comparison with another two non-normal methods, namely the Clements and the Wright methods. This example shows that the weighted valiance-based indices are more consistent than the other two methods in terms of sensitivity to departure to the process mean/median from the target value for non-normal processes. Second method show using the percentage nonconforming by the Pearson, Johnson and Burr systems. This example shows a little difference between the Pearson system and Burr system, but Johnson system underestimated than the two systems for process capability.

• Journal of the Korean Data and Information Science Society
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• 제18권2호
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• pp.457-469
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• 2007

Process Capability Indexes(PCI) are used as the measure for evaluation of process capability analysis and is the statistical method for efficient process control. The fourth generation $PCI(C_{psk})$ is constructed from $C_{pmk}$ by introducing the factor $\mid\mu-T\mid$ in the numerator as an extra penalty for the departure of the process mean from the preassigned target value T And Process Incapability Indexes(PII) are presented by inversing PCI and include the information of PCI. This paper introduces the PII $C_{ss}^*$ provide manager with various information of process and include Gage R&R. PII $C_{ss}^*$ is presented by inversing PCI $C_{psk}$ and include the information of PCI $C_{psk}$.