• Journal of Korea Society of Industrial Information Systems
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• v.24 no.5
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• pp.115-120
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• 2019

In this paper, we present the results of the performance statistical analysis of the multi-robot formation control based on receding horizon particle swarm optimization (RHPSO). The formation control problem of multi-robot system can be defined as a constrained nonlinear optimization problem when considering collision avoidance between robots. In general, the constrained nonlinear optimization problem has a problem that it takes a long time to find the optimal solution. The RHPSO algorithm was proposed to quickly find a suboptimal solution to the optimization problem of multi-robot formation control. The computational complexity of the RHPSO increases as the number of candidate solutions and generations increases. Therefore, it is important to find a suboptimal solution that can be used for real-time control with minimal candidate solutions and generations. In this paper, we compared the formation error according to the number of candidate solutions and the number of generations. Through numerical simulations under various conditions, the results are analyzed statistically and the minimum number of candidate solutions and the minimum number of generations of the RHPSO algorithm are derived within the allowable control error.

• Journal of Korean Society of Transportation
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• v.22 no.5
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• pp.19-33
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• 2004

신호교차로 운영 최적화를 위한 4가지 변수인 주기, 현시순서, 현시녹색시간, 옵셋 중에서 지금 지 정형화된 지침이 없이 전문가의 경험이나 휴리스틱한 규칙(Heuristic rule)에 의해 결정되었던 현시순서에 대해 다양한 교통조건을 고려하여 최적현시와 지체변화를 분석하였다. 교통조건은 독립/연동교차로, 교차로 기하구조, 비혼잡/혼잡상태, 통과교통량에 대한 좌회전 교통량비(LT/Thru)에 따라 Dual ring에서 구현가능한 모든 현시순서를 대상으로 최적현시를 도출하였다. 분석과정에서 비혼잡상태의 경우 LT/Thru가 작을수록 직진 중첩 동시신호가 가장 우수하게 나왔으며, LT/Thru가 크게 증가할수록 선행양방향좌회전이 양호하게 나타났다. 혼잡상태의 경우는 LT/Thru 15%에서 공통적으로 최적현시가 변하였는데 이는 포화도와 이동류별 녹색시간비율이 크게 변하면서 급작스런 주기 증가에 기인한 것으로 판단되었다. 또한 독립교차로 및 연동교차로 현시순서 분석 결과를 보면 전반적으로 선행양방좌회전 현시와 직진 중첩 동시신호 현시가 가장 양호한 것으로 나타났으며, 양방 동시신호 현시는 대체로 지체가 높게 나타나 신호운영에 비효율적인 것을 다시 한번 입증하게 되었다. 특히 연동교차로에서는 연동에 중요한 요소인 옵셋과 진행대폭(bandwidth)의 상호관계를 탄력적으로 대응할 수 있는 직진 중첩 동시신호가 최적현시로 나타났다. 본 연구는 검지기가 설치되지 않은 고정식 신호기로 운영되는 지방부 및 도시 가로망의 교통류 효율성을 높이는 중요한 자료로 사용될 것으로 판단된다. 최근에는 실시간 교통신호 제어시스템이 활발히 연구. 운영되고 있는데 이 시스템 내에 포함되어 있는 TOD방식의 고정시간 제어(pretimed control)나 패턴선택제어(pattern selection control)에도 충분히 활용할 수 있을 것으로 사료된다.

• Journal of Korean Society of Transportation
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• v.24 no.7 s.93
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• pp.65-79
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• 2006

The ATIS(Advance Traveler Information System), as one part of ITS, is a system aiming to disperse traffic volume on transportation networks by providing traffic information to transportation users on pre-trip and en-route trips. One of tools in ATIS is usage of VMS(Variable Message Signs). It provides to the drivers with direct information about state of processing direction. which is considered as the most effective method in ATIS. The purposes of providing VMS information are classified two categories. One is to provide simple information to drivers for their convenience. The other is to manage traffic demand to improve transportation network performance. However, for more effective and reliable VMS information, several strategies should be taken into account. The main VMS management strategy is "Traffic Diversion Strategy for minimum delay" when traffic congestion or incident are occurred. For effective operation. firstly. reasonable diversion traffic volume is determined by network traffic condition Secondly, it is necessary to make providing information strategy which reflects driver response behavior for controling diversion traffic volume. This paper focuses on the providing real-time route guidance information by VMS when congestion is occurred by the incidents. This sturdy estimates time-dependent system optimal diversion rate that inflects travel time and queue lengths using traffic flow simulation model on base Cellular Automata. In addition, route choice behavior models are developed using binary logit model for traffic information variable by traffic system controller. Finally, this study provides time-dependent VMS massage contents and degree of providing information in order to optimize the traffic flow.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.6
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• pp.17-23
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• 2012

In this paper, we were proposed a new LED light device lighting control algorithm for optimal energy saving. The propose lighting control algorithm be to the LED lights devices lighting control by measuring illuminance into multi sensors. And it be to lighting control by inverting of octagon pattern during set-up time. All the LED is lighting when detecting motion by the motion sensor. And, it was designed enable remote management control by communicate with central monitoring center using Zigbee wireless network to measured data from sensors at real time. In this paper, a proposed lighting control algorithm was measured power consumption about the lighting status of LED lighting device using the lighting control program for demonstrate of energy savings effect. The measured result, the lighting method applying proposed algorithm were proved energy savings effect of more 40% more compared to the existing lighting method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.344-351
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• 2016

In the point of view of a train operator, the main concern with a train operation is not only to maintain a time schedule, but also to decrease the energy consumption as much as possible. Generally for a manual drive, a train conductor controls the train acceleration and deceleration by controlling the notches not to exceed the regulation velocity by considering the given maximum velocity profile for an operation route. For this case, the guideline for a conductor is needed to choose the proper notches by applying the notch optimization so as to drive at the regulation velocity and minimize energy consumption simultaneously. In this paper, the real-time notch optimization plan is suggested using a genetic algorithm that optimizes the notches for the remaining route in real time when the event occurs that track information or regulation velocity profile of the remaining route changes during train operation as well as a normal operation situation. An energy saving effect and the convergence behavior of the optimal solution obtained was analyzed in a genetic algorithm.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.3
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• pp.527-534
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• 2023

Triple modular redundancy (TMR) systems can continue their mission by virtue of their structural redundancy even if one processor is attacked by faults. In this paper, we propose a new fault tolerance strategy by introducing checkpoints into the TMR system in which data saving and fault detection processes are separated while they corporate together in the conventional checkpoints. Faults in one processor are tolerated by synchronizing the state of three processors upon detecting faults. Simultaneous faults occurring to more than one processor are tolerated by re-executing the task from the latest checkpoint. We propose the checkpoint placement and fault detection strategy to maximize the probability of successful execution of a task within the given deadline. We develop the Markov chain model for the TMR system having the proposed checkpoint strategy, and derive the optimal fault detection and checkpoint interval.

• Journal of the Korean Institute of Intelligent Systems
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• v.13 no.2
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• pp.186-191
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• 2003

Skills in tracing of the MR divide into following, approaching, avoiding and warning and so on. It is difficult to have all these skills learned as neural network. To make this up for, skills consisted of each module, and Mobile Robot was controlled by the output of module adequate for the situation. A mobile Robot was equipped multi-ultrasonic sensor and a USB Camera, which can be in place of human sense, and the measured environment information data is learned through Modular Neural Network. MNN consisted of optimal combination of activation function in the Expert Network and its structure seemed to improve learning time and errors. The Gating Network(GN) used to control output values of the MNN by switching for angle and speed of the robot. In the paper, EN of Modular Neural network was designed optimal combination. Traveling with a real MR was performed repeatedly to verity the usefulness of the MNN which was proposed in this paper. The robot was properly controlled and driven by the result value and the experimental is rewarded with good fruits.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.6
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• pp.90-101
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• 2016

This study was initiated to develop an algorithm for traffic condition adaptive optimal traffic signal control for isolated intersections based on the vehicle trajectory data. The algorithm determines the optimal cycle length, phase lengths, phase sequences using the data collected under V2X communication environment every second. In addition, the algorithm utilizes a traditional feature of the actuated signal control, gap-out, using traditional detector systems to consider the mixture of normal vehicles and vehicles equipped with the V2X communication function. The performance of the algorithm was compared with that of the fixed signal timing plan which was optimized with Synchro under a microscopic traffic simulation-based test bed. As a result, the overall performance, including average delay, average stop delay, the number of stops, and average speed, are improved apparently. In addition, the amount of improvement get bigger as the traffic volume in the intersection as well as the number of vehicles equipped with the V2X communication function increase.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.343-347
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• 1994

최근의 기계 가공시스템은 가공기능이 고밀도로 압축되어, 작업자가 진행중인 가공상태를 단시간 내에 파악하기 어려울정도로 복잡하다.그러나 단위 기계별로 공정의 복합화와 자동화가 꾸준히 추진되어 가공기당 투입 작업인원 을 감소시키으로써 생산성을 증가시키고 있다. 이와 함께 작업자의 관리 영역은 오히여 증가해서 여러 대의 기계를 동시에 관리하게 되어, 그 중에 한 기계가 갑자기 이상동작을 일읠 경우 즉각적인 원인파악과 조치를 취하기가 매 우 어렵다. 그래서 요사이 작업자의 이상상태 파악을 위해 감시시스템을 설치하여 즉시 원인을 파악할수 있도록 하고 더 나아가서 자동제어 기능을 추가해서 실시간으로 이상상태를 보완,보정하도록 시도하고 있다. 본 연구에서는 공작기계의 신뢰성있는 열변형 예측을 위해 온도센서의 부착 위치를 최적으로 결정하는 방법을 일점센서와 다점 센서일 경우로 나누어 제시하였다.

• Journal of the Korean Society of Propulsion Engineers
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• v.1 no.1
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• pp.24-32
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• 1997

A nonlinear dynamic simulation of a small gas turbine engine was performed by using DYNGEN program with various environmental conditions. It was observed that the effect of the bleed air flow rate changed to overall engine performance. The real time linear model which was a function of engine rotor speed was resulted to be close to nonlinear simulation results. For optimal LQR controller, it was considered only fuel flow rate or both fuel flow rate and bleed air rate as inputs. In the comparison of both results, the LQR controller with multi input had better performance than that with single input.