• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.109-109
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• 2000

In process industries, more than 90% of the control loops have PID controller. Futhermore, the most control systems are using classical PID controllers for their process control. Various auto-tuning methods of PID gains using relay-feedback are presented recently. In order to get the desired control performance, the correct tuning of PID controller is very important. This paper suggests how to tune of digital PID gains using information for both the Nyquist critical point by conventional method and another point by the relay feedback and hidden time-delay term. Simulation results show that the proposed controller has better performance than the conventional method.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.7
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• pp.393-400
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• 2003

This paper discusses how to implement and verify a software model of the digital relay that can be added to real time digital simulator(RTDS) model library and is then subjected to the same outputs as the actual relay. The software model is stand-alone and can be used with real relays. It is also possible to conduct interactive real-time tests when the system effects of the relay action need to be investigated. The characteristics of mho type and the quadrilateral type, which is commonly used in recently developed relays, are modeled in this paper. Single circuit line and double circuit line system are used for model verification. The transmission lines are each 100 km in length and are modeled as distributed parameter lines but not frequency dependent. The transmission lines in the single circuit system are modeled as ideally transposed line. The mutual coupling data with the parallel line was taken account in the transmission lines for the double circuit system. The main CTs and PTs are included and operated in their linear region during the tests. For the purpose of testing the relay model accuracy the faults have been applied at various points on the protected line. Its accuracy is assessed against theoretical values.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.187-189
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• 2002

A relaying board is developed for the study of digital relay, which is based on Digital Signal Processor(DSP). The present development is capable of understanding and application for digital relay hardware. To support the design of relaying hardware, first A/D convertor MMI and serial port for communication are embedded, and next a booting cables of three types are supplied. More particularly the relaying board that is convinient to test digital relaying algorithm. This paper concludes by implementing the distance relaying algorithm into a relaying board, the hardware test results show practically high performance.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.3
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• pp.473-479
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• 2015

Thermal relays are sometimes used instead of long time overcurrent relays for motor protection. But, it is difficult for any relay design engineer to adequately approximate motor heating curves which represent the average of a difficult-to-define thermal zone. Thermal relays frequently may not provide sufficient protection on heavy overloads. Digital multifunction relays are microprocessor-based devices. These relays offer highly reliable and advanced protection of motors. If a situation can be mathematically described, the microprocessor in a digital relay can be programmed to tackle that problem. Today's motor protection is accomplished with digital protective relays. Digital relays offer additional, highly important features to complement protection. The best way to prevent short in motor is to not overheat and degrade the insulation.

• Journal of Korea Society of Digital Industry and Information Management
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• v.13 no.4
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• pp.213-219
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• 2017

Streaming server is that an image produced in real time or a file form of image produced ahead consists of SNS service, and the relay module of streaming server includes output management module that set an output channel more than 2 and control transmission of video content. This thesis intends to suggest how to stream through plural output channel that contains output channel of external streaming server using relay module and do streaming provided to terminal receiving image, and streaming server, streaming system for this. Thus, by extending output channel sending out image to output channel of external streaming server, the scale of streaming server is not limited and the process allotting external streaming server into output channel sending the image becomes simple, so management of output channel becomes efficient even when sending several images.

• Proceedings of the KIEE Conference
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• 2000.11a
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• pp.174-176
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• 2000

In this paper, a high speed distance relay, using a digital signal processor(DSP) is presented. The idea of the protective algorithm is based on the least square method using minimum data window to minimize the relay operating time. A new disign concept for a low-pass filter is proposed. This analog low pass filter has minimum transient response time. The main processor of the relay is TMS320C31. According to a series of real time tests, the proposed protective relay shows reliable and fast operating characteristics.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.2902-2904
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• 1999

Protective relay in power system play a prominent part, Simulators for the relay test were introduced in early 1980's, A number of open loop designs have been developed and Recently, several developments of real-time simulators have been reported. But they are very high cost. And then they are difficult to apply for relay testing in small business. This paper presents the structure and performance of a new pc based simulator for digital protective relay testing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1420-1423
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• 2015

This letter considers a ship-to-ship communication system in which two ships exchange their information with the help of multiple relay ships. For the system, we propose a novel relay scheme that allows relay ships to select a method between analog network coding (ANC) and digital network coding (DNC) adaptively based on channel state information. We also provide a relay selection criterion in supporting the proposed adaptive network coding. The simulation results show that the proposed scheme outperforms the conventional scheme employing only the ANC or only the DNC.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.311-316
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• 1991

This paper deals with designing the PID autotuner. The system parameters are identified using the relay control, where the unidirectional relay with hysteresis is adopted. The digital PID tuning rule on Nyquist plot is derived, and the statistical wordlength is adopted for the coefficient wordlength. The experimental results of temperature control exhibit the satisfactory performance and the validity of the derived statistical wordlength.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.4
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• pp.288-299
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• 1996

The co-channel digital radio-relay system improves effectively the use of radio frequency allocations by transmitting signals separately on both orthogonal allocations, and thereby not only the total transmission capacity of frequency band but also its bandwidth effciency are almost doubled, compared tothe interleaved digital radio-relay system. Therefore, the study on the development and application of the con-channel scheme is of importance, for the efficient use of limited frequency bnad. In this paper, we derived the eqations for calculating fade margin as a function of path length as well as error performance in terms of the outage probability for co-channel digital radio-relay system below 10GHz. And, simulation was given to demonstrate how to apply those equations to the real situation.