• 제목/요약/키워드: Multiple Controller

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Measuring Technique For Acoustic Roughness of Rail Surface With Homogeneous Displacement Sensors (동일 변위센서를 사용한 레일표면 음향조도의 측정방법)

  • Jeong, Wootae;Jang, Seungho;Kho, Hyo-In
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.11
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    • pp.7941-7948
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    • 2015
  • Rolling noises during train operation are caused by vibration excited from irregularities of surface roughness between wheel and rail. Therefore, a proper measurement and analysis techniques of acoustic roughness between wheel and rail surface are required for transmission, prediction, and analysis of the train rolling noise. However, since current measuring devices and methods use trolley-based manual handling devices, the measurements induce unstable measuring speed and vibrational interface that increases errors and disturbances. In this paper, a new automatic rail surface exploring platform with a speed controller has been developed for improving measurement accuracy and reducing inconsistency of measurements. In addition, we propose a data integration method of the rail surface roughness with multiple homogeneous displacement sensors and verified the accuracy of the integrated data through standard test-bed railway track investigation.

Channel State-Aware Joint Dynamic Cell Coordination Scheme using Adaptive Modulation and Variable Reuse Factor in OFDMA (OFDMA 하향링크에서 적응적 변조와 여러 개의 재사용 지수를 동시에 사용하고 채널 상태를 고려한 동적 셀 코디네이션)

  • Byun, Dae-Wook;Ki, Young-Min;Kim, Dong-Ku
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.1A
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    • pp.24-33
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    • 2007
  • In this paper, two different dynamic cell coordination strategies for frequency flat and selective fading are proposed for efficient subcarrier allocation in the joint consideration of adaptive modulation and variable frequency reuse in the channel-aware OFDMA downlink multicellular environment. Compared to a conventional OFDMA system without cell coordination, where system throughput may become degraded due to the persistent interference from other cells, the proposed system dynamically allows RNC to apply different reuse factors on each subchannel and scheduling in consideration of channel and interference conditions of individual users so as to increase the system throughput and guarantee QoS of each user. In a frequency flat fading, the dynamic scheme with the proposed scheduling achieves on average three times larger throughput than the conventional dynamic scheme [8]. In a selective fading channel, the proposed schemes showed 2.6 times as large throughput as that of a single reuse factor of one for all subchannels.

Hybrid System Controlled by a $\mu-Synthesis$ Method for a Seismically Excited Cable-Stayed Bridge (지진하중을 받는 사장교를 위한 $\mu$-합성법을 이용한 복합시스템)

  • Park, Kyu-Sik;Jung, Hyung-Jo;Choi, Kang-Min;Lee, Jong-Heon;Lee, In-Won
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.574-577
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    • 2004
  • This paper presents a hybrid system combining lead rubber bearings and hydraulic actuators controlled by a $\mu-synthesis$ method for seismic response control of a cable-stayed bridge. A hybrid system could alleviate some of restrictions and limitations that exist when each system is acting alone because multiple control devices are operating. Therefore, the overall control performance of a hybrid system may be improved compared to each system, however the overall system robustness may be negatively impacted by active device in the hybrid system or active controller may cause instability due to small margins. Therefore, a $\mu-synthesis$ method that guarantees the robust performance is considered to enhance the possibility of real applications of the control system. The performances of the proposed control system are compared with those of passive, active, semiactive control systems and hybrid system controlled by a LQG algorithm. Furthermore, an extensive robust analysis with respect to stiffness and mass matrices perturbation and time delay of actuator is performed. Numerical simulation results show that the performances of the proposed control system are superior to those of passive system and slightly better than those of active and semiactive systems and two hybrid systems show similar control performances. Furthermore, the hybrid system controlled by a f-synthesis method shows the good robustness without loss of control performances. Therefore, the proposed control system could effectively be used to seismically excited cable-stayed bridge which contains many uncertainties.

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An Output Feedback Predictive Control for Stabilizing a System With Multiple Delayed Inputs (지연된 다중 입력을 갖는 시스템을 안정화하는 출력 궤환 예측 제어)

  • Yang, Janghoon
    • Journal of Advanced Navigation Technology
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    • v.23 no.5
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    • pp.424-429
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    • 2019
  • The evolution of networking technology such as commercialization of 5G systems provides foundation for information exchange and control of systems over the network. In addition, importance of controlling a system with delay is increasing significantly, since various phenomena in the network are associated with delay. In this paper, with a predictive control which has been studied for designing a controller with low complexity, we propose a novel predictive control for a system with multi-inputs such that it can keeps the complexity almost the same regardless of the number of inputs and degree of delay. The asymptotic stability of the proposed control with a static output feedback is also proved. The numerical simulation shows that the proposed method is superior in complexity and the performance of finding feasible controllers to the existing predictive control and a conventional method based on augmented states.

Development and Application of Arduino Based Multi-sensors System for Agricultural Environmental Information Collection - A Case of Hog Farm in Yeoju, Gyeonggi - (농업환경정보 수집을 위한 아두이노 기반 멀티 센서 시스템 개발 및 적용 - 경기 여주시 소재 양돈농가를 사례로 -)

  • Han, Jung-Heon;Park, Jong-Jun
    • Journal of Korean Society of Rural Planning
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    • v.25 no.2
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    • pp.15-21
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    • 2019
  • The agricultural environment is changing and becoming more advanced due to the influence of the 4th Industrial Revolution. From the basic plan of Rural Informatics to the current level of 2nd generation smart farms aimed at improving productivity using Big data, cloud network and more IoT technology. We are continuing to provide support and research and development. However, many problems remain to be solved in order to supply and settle smart farms in Korea. The purpose of this study is to provide a method of collecting and sharing data on farming environment and to help improve the income and productivity of farmers based on collected data. In the case of hog farm, the multiple sensors for environmental data like temperature, humidity and gases and the network environment for connecting the internet were established. The environment sensor was made using the ESP8266 Node MCU board as micro-controller, DHT22 sensor for temperature and humidity, and MQ series sensors for various gases in the hog pens. The network sensor was applied experimentally for one month and the environmental data of the hog farm was stored on a web database. This study is expected to raise the importance of collecting and managing the agricultural and environmental data, for the next generation farmers to understand the smart farm more easily and to try it by themselves.

Mitigating TCP Incast Issue in Cloud Data Centres using Software-Defined Networking (SDN): A Survey

  • Shah, Zawar
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.12 no.11
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    • pp.5179-5202
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    • 2018
  • Transmission Control Protocol (TCP) is the most widely used protocol in the cloud data centers today. However, cloud data centers using TCP experience many issues as TCP was designed based on the assumption that it would primarily be used in Wide Area Networks (WANs). One of the major issues with TCP in the cloud data centers is the Incast issue. This issue arises because of the many-to-one communication pattern that commonly exists in the modern cloud data centers. In many-to-one communication pattern, multiple senders simultaneously send data to a single receiver. This causes packet loss at the switch buffer which results in TCP throughput collapse that leads to high Flow Completion Time (FCT). Recently, Software-Defined Networking (SDN) has been used by many researchers to mitigate the Incast issue. In this paper, a detailed survey of various SDN based solutions to the Incast issue is carried out. In this survey, various SDN based solutions are classified into four categories i.e. TCP Receive Window based solutions, Tuning TCP Parameters based solutions, Quick Recovery based solutions and Application Layer based solutions. All the solutions are critically evaluated in terms of their principles, advantages, and shortcomings. Another important feature of this survey is to compare various SDN based solutions with respect to different performance metrics e.g. maximum number of concurrent senders supported, calculation of delay at the controller etc. These performance metrics are important for deployment of any SDN based solution in modern cloud data centers. In addition, future research directions are also discussed in this survey that can be explored to design and develop better SDN based solutions to the Incast issue.

Robust Wireless Sensor and Actuator Network for Critical Control System (크리티컬한 제어 시스템용 고강건 무선 센서 액추에이터 네트워크)

  • Park, Pangun
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.24 no.11
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    • pp.1477-1483
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    • 2020
  • The stability guarantee of wireless network based control systems is still challenging due to the lossy links and node failures. This paper proposes a hierarchical cluster-based network protocol called robust wireless sensor and actuator network (R-WSAN) by combining time, channel, and space resource diversity. R-WSAN includes a scheduling algorithm to support the network resource allocation and a control task sharing scheme to maintain the control stability of multiple plants. R-WSAN was implemented on a real test-bed using Zolertia RE-Mote embedded hardware platform running the Contiki-NG operating system. Our experimental results demonstrate that R-WSAN provides highly reliable and robust performance against lossy links and node failures. Furthermore, the proposed scheduling algorithm and the task sharing scheme meet the stability requirement of control systems, even if the controller fails to support the control task.

Periodic-and-on-Event Message-Aware Automotive Intrusion Detection System (Periodic-and-on-Event 메시지 분석이 가능한 차량용 침입탐지 기술)

  • Lee, Seyoung;Choi, Wonsuk
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.31 no.3
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    • pp.373-385
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    • 2021
  • To provide convenience and safety of drivers, the recent vehicles are being equipped with a number of electronic control units (ECUs). Multiple ECUs construct a network inside a vehicle to share information related to the vehicle's status; in addition, the CAN protocol is normally applied. As the modern vehicles provide highly convenient and safe services, it provides many types of attack surfaces; as a result, it makes them vulnerable to cyber attacks. The automotive IDS (Intrusion Detection System) is one of the promising techniques for securing vehicles. However, the existing methods for automotive IDS are able to analyze only periodic messages. If someone attacks on non-periodic messages, the existing methods are not able to properly detect the intrusion. In this paper, we present a method to detect intrusions including an attack using non-periodic messages. Moreover, we evaluate our method on the real vehicles, where we show that our method has 0% of FPR and 0% of FNR under our attack model.

Fuzzy neural network controller of interconnected method for civil structures

  • Chen, Z.Y.;Meng, Yahui;Wang, Ruei-yuan;Chen, Timothy
    • Advances in concrete construction
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    • v.13 no.5
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    • pp.385-394
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    • 2022
  • Recently, an increasing number of cutting-edged studies have shown that designing a smart active control for real-time implementation requires piles of hard-work criteria in the design process, including performance controllers to reduce the tracking errors and tolerance to external interference and measure system disturbed perturbations. This article proposes an effective artificial-intelligence method using these rigorous criteria, which can be translated into general control plants for the management of civil engineering installations. To facilitate the calculation, an efficient solution process based on linear matrix (LMI) inequality has been introduced to verify the relevance of the proposed method, and extensive simulators have been carried out for the numerical constructive model in the seismic stimulation of the active rigidity. Additionally, a fuzzy model of the neural network based system (NN) is developed using an interconnected method for LDI (linear differential) representation determined for arbitrary dynamics. This expression is constructed with a nonlinear sector which converts the nonlinear model into a multiple linear deformation of the linear model and a new state sufficient to guarantee the asymptomatic stability of the Lyapunov function of the linear matrix inequality. In the control design, we incorporated H Infinity optimized development algorithm and performance analysis stability. Finally, there is a numerical practical example with simulations to show the results. The implication results in the RMS response with as well as without tuned mass damper (TMD) of the benchmark building under the external excitation, the El-Centro Earthquake, in which it also showed the simulation using evolved bat algorithmic LMI fuzzy controllers in term of RMS in acceleration and displacement of the building.

Study on 2.5D Map Building and Map Merging Method for Rescue Robot Navigation (재난 구조용 로봇의 자율주행을 위한 지도작성 및 2.5D 지도정합에 관한 연구)

  • Kim, Su Ho;Shim, Jae Hong
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.21 no.4
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    • pp.114-130
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    • 2022
  • The purpose of this study was to investigate the possibility of increasing the efficiency of disaster relief rescue operations through collaboration among multiple aerial and ground robots. The robots create 2.5D maps, which are merged into a 2.5D map. The 2.5D map can be handled by a low-specification controller of an aerial robot and is suitable for ground robot navigation. For localization of the aerial robot, a six-degree-of-freedom pose recognition method using VIO was applied. To build a 2.5D map, an image conversion technique was employed. In addition, to merge 2.5D maps, an image similarity calculation technique based on the features on a wall was used. Localization and navigation were performed using a ground robot to evaluate the reliability of the 2.5D map. As a result, it was possible to estimate the location with an average and standard error of less than 0.3 m for the place where the 2.5D map was normally built, and there were only four collisions for the obstacle with the smallest volume. Based on the 2.5D map building and map merging system for the aerial robot used in this study, it is expected that disaster response work efficiency can be improved by combining the advantages of heterogeneous robots.