• Journal of Institute of Control, Robotics and Systems
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• v.10 no.4
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• pp.377-384
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• 2004

Nowadays, control systems consist of smart sensors, smart actuators, and controllers connected via fieldbus. Some devices such as motors in plant environments generate high degrees of EMI or noise. This noise may cause communication errors and make the successful transmission of data longer. Therefore, the noise condition has to be considered at the design of a reliable control system based on a network. This paper presents a scheduling method of task and message to guarantee the given end-to-end constraints under noise environments. A noise model with multi-sources of noise is used, and the analysis method of message's response time is presented when the noise model is applied to CAN (Controller Area Network). Two kinds of noise models are applied to an example system, and the effect to each control loop s end-to-end response time is analyzed. We believe that the proposed method help system designers design the control system guaranteeing its requirements under noise environment.

• Journal of the Semiconductor & Display Technology
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• v.22 no.1
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• pp.59-63
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• 2023

Various devices have been emerging as a means of measuring indoor air quality, and among them, there are devices that support real-time remote monitoring through IoT technology and a cloud environment. To improve indoor air quality, based on the results determined by measuring devices, air purifiers or ventilation systems may need to be operated, and temperature and humidity control may be required. In this paper, we propose a design of indoor air quality measuring devices required for indoor air quality evaluation, and of the system needed to control relevant devices to improve indoor air quality through the interaction with the measuring devices. Currently, the servers for the interaction of indoor air quality devices and IoT devices are divided into conventional server type and serverless type, comparing the differences in response time of IoT devices to changes of indoor air quality.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2007.11a
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• pp.253-256
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• 2007

The web server for the embedded Linux system(ELS), unlike the ones for the usual Linux or Windows, has some disadvantages such as small number of installable applications, low compatibility and limited extensibility. This fact raises some problems when data are transferred in real-time via the web server, which are mainly caused by a poor performance of the processor and small-sized memory. Conventional user interfaces adopted for the usual web servers are unsuitable for the ELS because they are platform-limited and their installations are done by the form of plug-ins. If the web server for the ELS has an Ajax engine that can be utilized without any installation procedure, the advantages of usability, accessibility and quick response time can be obtained. This paper presents the Ajax interface for the ELS web server. The efficiency of the proposed technology in the real-time remote monitoring is shown through an implementation.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06a
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• pp.170-172
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• 2012

실시간 시스템(real-time system)은 논리적 연산을 일정한 시간적 제약 하에서 수행하는 시스템이다. 시간적 제약을 충족하도록 주기적 태스크(periodic task)를 스케줄(schedule)할 때 일반적으로 태스크 오프셋(initial offset)이 0 이거나 고정된 것으로 가정한다. 그러나 오프셋에 약간의 유연성을 허용함으로써 태스크들의 평균 응답 시간을 줄일 수도 있다. 이 논문에서는 주기적 태스크의 오프셋을 주어진 허용 범위 안에서 선택하여 평균 응답 시간(response time)을 최적화할 수 있음을 보이고, 임의의 태스크 집합에 대하여 최적 오프셋이 존재하는 좁은 범위를 제시한다.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.1013-1016
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• 1999

In this paper, a real-time communication method using a PICNET-NP(Plant Instrumentation and Control Network for Nuclear Power plant) is proposed with an analysis of the control network requirements of DCS (Distributed Control System) in nuclear power plants. The method satisfies deadline in case of worst data traffics by considering aperiodic and periodic real-time data and others. In addition, the method was used to analyze the data characteristics of the DCS in existing nuclear power plant. The result shows that use of this method meets the response time requirement(100ms)

• Journal of KSNVE
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• v.8 no.4
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• pp.683-689
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• 1998

A control algorithm for multi-stage dampers is developed based on the mode skyhook control concept, and implemented on the full vehicle system environment. The test vehicle system is equipped with the real time controller, four-stage variable dampers and sensors. The real time controller is developed using a digital signal processor(DSP), digital I/O, A/D and D/A converters. The dampers are driven by the electromagnetic actuators of less than 20 msec response time. The sensors include accelerometers, relative displacement transducers, and steering wheel rate sensors, etc. Through a series of tests in laboratory and proving ground, the performance of the semi-active suspension system is evaluated and it is shown that the vehicle dynamic characteristics is improved with the developed damping system. Futhermore, the parameter tuning methods to enhance vehicle dynamic performance are propsoed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.12
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• pp.1170-1178
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• 2007

Repeated hardware tests and tuning, investing cost and time, are usually required to assure a satisfactory performance of the suspension seat. In this study, an EILS(ECU-in-the-loop) method was proposed to develop a controller for a semi-active suspension seat with a MR(magneto-rheological) damper. EILS system was developed using a real-time seat dynamics model communicating with ECU hardwares under a closed loop environment utilizing Matlab/Simulink and xPC $TargetBox^{TM}$. A sky-hook based control algorithm with optimized damping coefficients was verified to reduce the energy consumption and to improve the vibration response performance.

• The Journal of Korea Robotics Society
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• v.7 no.3
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• pp.161-170
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• 2012

The Industrial Ethernet technology enables advanced control architectures and offers several advantages for high precision multiple motors actuation. This paper presents the implementation and analysis of a motor drive with EtherCAT, an industrial standard for real time Ethernet. Considering the characteristics of the implemented software and the network interface, the motion and time-response of motor actuation for the networked Mobile Inverted Pendulum have been analyzed. Using the analysis with the task execution times measured from the developed drive, the performance characteristics of the drive in respect of the maximum achievable throughput have been verified by comparing to the conventional RS232.

• Journal of the Semiconductor & Display Technology
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• v.15 no.3
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• pp.40-45
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• 2016

In this paper, the fire engine pump is controlled and monitored by the AJAX (Asynchronous Javascript and Xml) in the web server. The embedded system with built-in system having a processor and a memory of high performance occurs many problems in transmitting the large amount of data in real time through the web server. The AJAX is different from HTML (Hyper Text Makeup Language) with java script technology and can make RIA (Rich Internet Application). It process the necessary data by using asynchronous and it take advantage of usefulness, accessibility, a fast response time. Using AJAX can build up web server with real time and monitoring that fire engine pump status, check processing pump memory in the event of fire, also remotely monitors can do. The web server system can control the fire engine pump as like the black box. The experimental results show the effectiveness and commercialize possibility.

• Smart Structures and Systems
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• v.33 no.1
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• pp.1-16
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• 2024

The investigation on vehicle-bridge coupling system (VBCS) is crucial in bridge design, bridge condition evaluation, and vehicle overload control. A real-time hybrid testing (RTHT) method for VBCS (RTHT-VBCS) is proposed in this paper for accurately and economically disclosing the dynamic performance of VBCSs. In the proposed method, one of the carriages is chosen as the experimental substructure loaded by servo-hydraulic actuator loading system in the laboratory, and the remaining carriages as well as the bridge structure are chosen as the numerical substructure numerically simulated in one computer. The numerical substructure and the experimental substructure are synchronized at their coupling points in terms of force equilibrium and deformation compatibility. Compared to the traditional iteration experimental method and the numerical simulation method, the proposed RTHT-VBCS method could not only obtain the dynamic response of VBCS, but also economically analyze various working conditions. Firstly, the theory of RTHT-VBCS is proposed. Secondly, numerical models of VBCS for RTHT method are presented. Finally, the feasibility and accuracy of the RTHT-VBCS are preliminarily validated by real-time hybrid simulations (RTHSs). It is shown that, the proposed RTHT-VBCS is feasible and shows great advantages over the traditional methods, and the proposed models can effectively represent the VBCS for RTHT method in terms of the force equilibrium and deformation compatibility at the coupling point. It is shown that the results of the single-degree-of-freedom model and the train vehicle model are match well with the referenced results. The RTHS results preliminarily prove the effectiveness and accuracy of the proposed RTHT-VBCS.