• 한국정밀공학회지
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• 제25권6호
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• pp.71-79
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• 2008

In the manufacture of flat panel display devices, there is a strong demand for contactless glass panel handling devices that can manipulate a glass panel without contaminating or damaging it. To fulfill this requirement, an electrostatic suspension device far glass panels where the glass panel is supported by electrostatic forces without any mechanical contact is proposed. To implement the system with low cost and compactness, switched-voltage control scheme that is based on the relay feedback control is utilized. Relay feedback control method deploys only a single high-voltage power supply that can deliver a DC voltage of positive and/or negative polarity and thus high voltage amplifiers that are costly and bulky are not needed any more. It is shown that despite the inherent limit cycle property of the relay feedback based control, an excellent performance in vibration suppression is attained due to the presence of a relatively large squeeze film damping originating from the electrodes and levitated object. Using this scheme, a $100{\times}100mm^2$ glass panel was levitated stably with airgap variation decreasing down to $1\;{\mu}m$ at an airgap of $100\;{\mu}m$.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.969-974
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• 2003

A simple and cost-effective method for the electrostatic suspension of thin plates like silicon wafers is proposed which is based on a switched voltage control scheme. It operates according to a relay feedback control and deploys only a single high-voltage power supply that can deliver a dc voltage of positive and/or negative polarity. This method possesses the unique feature that no high-voltage amplifiers are needed which leads to a remarkable system simplification relative to conventional methods. It is shown that despite the inherent limit cycle property of the relay feedback based control, an excellent performance in vibration suppression is attained due to the presence of a relatively large squeeze film damping origination from the air between the electrodes and levitated object. Using this scheme, a 4-inch silicon wafer was levitated stably with airgap variation decreasing down to 1 $\mu\textrm{m}$ at an airgap of 100 $\mu\textrm{m}$

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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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.

• 한국정밀공학회지
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• 제22권10호
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• pp.56-64
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• 2005

A simple and cost-effective method for the electrostatic suspension of thin plates like silicon wafers is proposed which is based on a switched voltage control scheme. It operates according to a relay feedback control and deploys only a single high-voltage power supply that can deliver a DC voltage of positive and/or negative polarity. This method possesses the unique feature that no high-voltage amplifiers are needed which leads to a remarkable system simplification relative to conventional methods. It is shown that despite the inherent limit cycle property of the relay feedback based control, an excellent performance in vibration suppression is attained due to the presence of a relatively large squeeze film damping origination from the air between the electrodes and levitated object. Using this scheme, a 4-inch silicon wafer was levitated stably with airgap variation decreasing down to $1 {\mu}m$ at an airgap of $100{\mu}m$.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 추계학술대회
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• pp.709-711
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• 2016

산업현장에서 자동화시스템은 PLC(Program Logic Control)를 사용하여 시스템을 제어하고, 감지기에서 전달되는 정보로 시스템의 상태를 계측하고 생산성 향상을 위해 사용되고 있다. 본 연구에서 제안하는 진단 모니터링시스템은 릴레이모듈, 원칩프로세서모듈 그리고 컴퓨터 모니터링시스템으로 구성된다. 보조계전기의 고장을 실시간으로 파악하여 고장 난 시스템을 수리하고, 정상 가동에 소요되는 시간을 최소화하여 생산성을 향상시키고자 한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.124.4-124
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• 2001

It needs a skillful experience to design and implement sequential circuits with a relay circuit or LD (Ladder Diagram). One makes out the operation of relay contacts sequentially in case of analyzing a relay circuit or LD. Still more, the design and analyzing of a complex relay circuit or LD are difficult. In this paper, we propose the EMFG (Extended Mark Graph) representation on relay circuits and LD.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.60.5-60
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• 2001

It is very difficult to design and analyze the relay circuit because one have to consider and analyze in order the behavior in which the relay contacts. In this paper, we propose the relay circuit to EMPG (Extended Mark Flow Graph) convension with a box´s characteristic equation. It will give you a lot of benefits in case of analysis and check of the relay circuit to convert the relay circuit into EMPG.

• 제어로봇시스템학회논문지
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• 제9권11호
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• pp.952-957
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• 2003

We propose how to translate relay circuits to the EMFGs(Extended Mark Flow Graphs) formally and analyze the original one by using the mark flow of it. Firstly, the concepts of the output condition, the output-on condition and the output-off condition are introduced in the relay circuits. These can be used to find the structure and the operation of respective relay outputs but the sequential operations of them cannot be obtained from these. Secondly, a relay circuit is translated to the corresponding EMFG as the all output-on conditions and all output-off conditions of it are translated to EMFGs. For the adequate translation, the condition arc and the concepts of the generation transition and the degeneration transition are introduced, and the duality for the simplification of the result. Thirdly, we analyze the operation of the original circuit by analyzing the mark flow of the resulting EMFG. We can achieve easy and fast analysis based on the EMFG's operation algorithm. Finally, we apply these to the relay circuit for an electric furnace and analyze its operation with the mark flow of the resulting EMFG. The formal translation from relay circuits to EMFGs makes the analysis easy so that these results can be used to design, modelling, the fault detection and the maintenance.

• 전기전자학회논문지
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• 제15권1호
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• pp.64-69
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• 2011

본 논문에서는 복호 후 전달(decode-and-forward: DF) 릴레이 시스템에 대한 레일리 페이딩 채널에서의 의사-성능 분석 기법을 제안하였다. 우선, 각 릴레이가 복호 오류 유무에 상관없이 전송하는 경우에 대한 성능분석을 릴레이 노드단의 오류 사건을 기반으로 유도한다. 분석된 성능 분석 결과를 통하여 각 릴레이 단의 복호 오류가 수신 SNR 및 평균 오류율 성능 저하를 야기할 수 있음을 확인한다. 또한 제안된 분석 기법을 복호 오류가 없는 경우에만 전송하는 SDF의 경우로 확장함으로써 제안된 분석 기법이 DF 릴레이 시스템에 대한 일반적인 성능 분석 기법임을 확인한다. 그리고 제안된 분석기법의 정확성은 모의실험을 통하여 비교 검증되었다.

• Journal of Communications and Networks
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• 제17권1호
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• pp.47-57
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• 2015

With the ever growing demand of data applications, the joint macro-relay networks are emerging as a promising heterogeneous deployment to provide coverage extension and throughput enhancement. However, the current cellular networks are usually designed to be performance-oriented without enough considerations on the traffic variation, causing substantial energy waste. In this paper, we consider a joint macro-relay network with densely deployed relay stations (RSs), where the traffic load varies in both time and spatial domains. An energy-efficient scheme is proposed to dynamically adjust the RS working modes (active or sleeping) according to the traffic variations, which is called traffic-aware relay sleep control (TRSC). To evaluate the performance of TRSC,we establish an analytical model using stochastic geometry theory and derive explicit expressions of coverage probability, mean achievable rate and network energy efficiency (NEE). Simulation results demonstrate that the derived analytic results are reasonable and the proposed TRSC can significantly improve the NEE when the network traffic varies dynamically.