• The Journal of the Korea Contents Association
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• v.14 no.3
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• pp.451-462
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• 2014

In this paper, Coordinated Semi-Actuated Signal Control algorithm was developed and evaluated. According to the analysis of simulation, the coordinated semi-actuated signal control led to reduced vehicle delay as the difference of traffic volume between major and minor streets was getting bigger. But when there was relatively high traffic volume, or the equivalent amount of traffic volume on major and minor streets, optimized pre-timed signal control was verified to lower delay times compared to coordinated semi-actuated signal control; however, it might increase pedestrian delay. Therefore, the coordinated semi-actuated signal control should be implemented at intersections where traffic volume is relatively low.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.1
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• pp.1-12
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• 2012

Even though the semi-actuated signal control system based on image detectors has been spreading in Korea, any appropriate methods to evaluate the effectiveness and performance has not been established yet. Therefore, this research effort is aiming at developing a systematic method for evaluating the effectiveness and performance of the semi-actuated signal control system based on image detectors. To this end, this research firstly established measures of effectiveness(MOEs) and associated information to be surveyed from fields. Secondly, this research provided a procedure and methodology to evaluate any improvements due to the introduction of a semi-actuated signal control system based on image detectors. The developed methodology was examined at a case study site located in the city of Paju. As a result of the evaluation, the MOEs including traffic throughput, travel speeds, split usage rate, progression rate, etc. showed positive improvements though individual signalized intersections as well as coordinated corridors.

• Journal of Korean Society of Transportation
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• v.29 no.2
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• pp.111-121
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• 2011

This paper discusses a method for optimizing the semi-actuated traffic signal control system by adjusting the initial interval according to the number of vehicles waiting for the green light in the actuated phase. We also present a Left-Turn actuated traffic signal control strategy that examines the vehicular noise in the detection area and determines the phase extension and the gap-out. In order to detect the vehicles in real-time, an image detector's Video Image Tracking technology was adopted. A 'Zone in Zone'method was implemented, and the image detection area is segmented into three zones: 1) Zone1 for verifying a vehicles obligatory presence, 2) Zone2 for counting the standby vehicles, and 3) Zone3 for examining the number of vehicles that have passed. The on-site assessment of the Left Turn Actuated Control is carried out using CORSIM, and the results show that the Control Delay decreased by 23.10%, 15.06%, and 4.34% compared to the delays resulted from pre-timed control, semi-actuated control-1 and semi-actuated control-2 traffic signal control systems respectively. The Queue Time also decreased by 36.24%, 20.10% and the Total Time by 14.36%, 7.02% for the same scenario. Which clearly demonstrates the operational efficiency. A sensitivity analysis reveals that the improvement from the propose traffic control strategy tends to increase as the through traffic volume reaches a saturated condition and the left-turn traffic volume decreases.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.3
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• pp.19-28
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• 2013

This study evaluated the quantitative effects of the deployment of semi-actuated signal systems using field data. For this, a semi-actuted signal system was deployed in the regional roadway network extensively. This paper investigated an operating strategy of semi-actuated signal systems for field application, and implemented the functional strategy into the standard signal controller. The performance was evaluated using three measures of effectiveness such as traffic volume, travel time, and the number of delayed vehicle. From the analysis results, traffic volume increased about 9.4% and 11.3% for morning and evening peak periods, respectively. The average travel time was reduced about 6.3% and 7.8% during morning and evening peak periods, respectively because of the expansion of bandwidths for major streets. In addition, the number of delayed vehicles was reduced about 36.4% and 23.9% for morning and evening peak periods, respectively. It is expected that the effectiveness of signal control system can be improved by incorporating a properly designed semi-actuated signal system in regional roadways with directional demand variation.

• International Journal of Highway Engineering
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• v.11 no.3
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• pp.121-128
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• 2009

This study has proposed the signal operating system to use both semi-actuated signal control and pedestrian push-button as a way to make up for the problems of 3 leg intersections which are operated inefficiently in the signal operation, one of the methods of traffic operations. In case of the semi-actuated signal control, it can reduce delay inside the intersection by serving to uncongested traffic on the main road where there is not much traffic volume on the secondary road and push-button signal can reduce unnecessary waiting time it could happen to vehicles by operating it though there is no pedestrian. Quantitative analysis was tried regarding the average delay reduction per vehicle using VISSIM, microscopic simulation program regarding how much effect it has compared with the existing signal control system and semi-actuated signal control system when the above two advantages are collected. The field test was performed for one three-leg intersection of Incheon. According to respectively signal control method pedestrian traffic changed and executed a sensitivity analysis. The result which compares the average delay time per a vehicle of scenarios, the signal control method of using the pedestrian push-button system in comparison with the fixed signal control method showed to decrease effect of a minimum 3.7 second (10%), a maximum 5.8 second (16%). When the pedestrian traffic volume was 20% or less of the measurement traffic volume, The signal control method of using the pedestrian push-button system appeared to be more efficient the semi-actuated signal control with object intersection.

• Transportation Technology and Policy
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• v.10 no.5
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• pp.62-71
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• 2013

• Proceedings of the KOR-KST Conference
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• 2007.05a
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• pp.362-371
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• 2007

• Proceedings of the KOR-KST Conference
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• 2007.11a
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• pp.512-520
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• 2007

• Structural Engineering and Mechanics
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• v.76 no.4
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• pp.451-463
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• 2020

In this paper, a new semi-analytical solution for estimating the pull-in parameters of electrically actuated functionally graded (FG) nanobeams is proposed. All the bulk and surface material properties of the FG nanoactuator vary continuously in thickness direction according to power law distribution. Here, the modified couple stress theory (MCST) and Gurtin-Murdoch surface elasticity theory (SET) are jointly employed to capture the size effects of the nanoscale beam in the context of Euler-Bernoulli beam theory. According to the MCST and SET and accounting for the mid-plane stretching, axial residual stress, electrostatic actuation, fringing field, and dispersion (Casimir or/and van der Waals) forces, the nonlinear nonclassical equation of motion and boundary conditions are obtained derived using Hamilton principle. The proposed semi-analytical solution is derived by employing Galerkin method in conjunction with the Particle Swarm Optimization (PSO) method. The proposed solution approach is validated with the available literature. The freestanding behavior of nanoactuators is also investigated. A parametric study is conducted to illustrate the effects of different material and geometrical parameters on the pull-in response of cantilever and doubly-clamped FG nanoactuators. This model and proposed solution are helpful especially in mechanical design of micro/nanoactuators made of FGMs.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.6
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• pp.938-948
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• 2001

In this paper, we present an exoskeletal haptic device named SKK Hand Master. This device is directly driven linkages actuated with small ultrasonic motors. By adopting ultrasonic motors that have advantageous features useful for cybernetic actuators, a compact haptic device containing whole driving packages can be established without additional power transmissions such as tendons. Methods for measuring joint postures and joint torques are developed and a new control strategy called PWM/PS is proposed to overcome intrinsic disadvantages such as hysteresis. Issues regarding design and construction of the device are addressed and several results of experiments for the evaluations of performance are included.