• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.601-611
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• 2017

This paper proposes a simultaneous control of frequency deviation and electric vehicles (EVs) battery state of charge (SOC) using load frequency control (LFC) and EV controllers. In order to provide both frequency stabilization and SOC schedule near optimal performance within the whole operating regions, a multiple-input multiple-output model predictive control (MIMO-MPC) is employed for the coordination of LFC and EV controllers. The MIMO-MPC is an effective model-based prediction which calculates future control signals by an optimization of quadratic programming based on the plant model, past manipulate, measured disturbance, and control signals. By optimizing the input and output weights of the MIMO-MPC using particle swarm optimization (PSO), the optimal MIMO-MPC for simultaneous control of the LFC and EVs, is able to stabilize the frequency fluctuation and maintain the desired battery SOC at the certain time, effectively. Simulation study in a two-area interconnected power system with wind farms shows the effectiveness of the proposed MIMO-MPC over the proportional integral (PI) controller and the decentralized vehicle to grid control (DVC) controller.

• 한국항공우주학회지
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• 제36권10호
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• pp.988-995
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• 2008

본 논문에서는 궤환선형화를 이용한 일치기법을 사용하여 다수 무인기의 편대비행 제어기를 설계하였다. 제안한 기법은 한 대의 리더기를 중심으로 하는 집중형 방식이 아닌 분산형 방식으로, 각 개체의 제어입력은 인접한 개체만의 정보만을 이용하여 설계된다. 라플라시안 행렬을 이용하여 개체 간의 정보 교류를 정의한 후, 궤환선형화 과정을 거친 비행체에 적용하였다. 또한, 본 논문에서 제안한 제어기의 안정성 해석을 수행하였다. 또한 제안한 제어기의 성능을 검증하기 위해서 회전익 무인기 비행체 모델에 대한 수치 시뮬레이션을 수행하였다.

• 제어로봇시스템학회논문지
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• 제19권4호
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• pp.328-333
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• 2013

Since a slight malfunction of control systems in a nuclear power plant may cause huge catastrophes, such control systems usually have multiple redundancy and reliable features, and their reliability and availability should be analyzed and verified thoroughly. This paper performed the reliability analysis of the SPLC (Safety Programmable Logic Controller) that is under developed as the control systems for the next generation nuclear power plant. One of the key features of SPLC is that it has multiple redundancy modes as faults happen, which means the reliability analysis for one fixed redundant model is not enough to analyze the reliability of SPLC. With considering this reconfigurable concept, FTA (Fault Tree Analysis) was used to capture fault-relationship among sub-modules. The analysis results show that MTTF (Mean Time to Fault) of SPLC is 45,080 hours, which is a about 4.5 times longer than the regulation, 10,000 hours.

• 한국지능시스템학회논문지
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• 제13권2호
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• pp.180-185
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• 2003

본 논문은 장애물에 대한 사전 정보를 가지고 있지 않은 공간에서 장애물의 회피와 지정된 목표점으로 이동할 수 있는 자율이동로봇을 위한 지능제어 알고리즘을 제안하고, 제안된 제어기의 효용성을 실험을 통하여 검증을 한다. 제시하는 지능 제어기는 계층구조의 알고리즘으로써, 그 하부에 로봇이 목표에 도달하기 위한 퍼지 알고리즘과 주행 중 만날 수 있는 장애물들에 대한 회피를 수행하는 퍼지-뉴럴 알고리즘이 존재하고, 상부의 가중치 퍼지 알고리즘은 로봇이 이동하면서 만날 수 있는 여러 가지 상황에 따라서 하부의 두 알고리즘에 적당한 가중치를 부여하여 장애물 회피동작과 목표점 도달동작을 수행할 수 있도록 구성되어 있다. 그리고 로봇의 현재 운동정보와 장애물까지의 거리정보를 바탕으로 가중치 퍼지 알고리즘의 출력부 소속도 함수를 조절함으로서 오목한 장애물에 대해서도 장애물 회피 동작을 수행하도록 하였다. 제작된 로봇으로 제시한 알고리즘의 실효성을 검증하였다.

• Journal of Power Electronics
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• 제18권3호
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• pp.757-765
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• 2018

This paper deals with the instability and resonant phenomena in distribution systems with multiple grid-connected inverters with an LCL output filter. The penetration of roof-top and other types of small photovoltaic (PV) grid-connected systems is rapidly increasing in distribution grids due to the attractive incentives set forth by different governments. When the number of such grid-connected inverters increases, their interaction with the distribution grid may cause undesirable effects such as instability and resonance. In this paper, a grid system with several grid-connected inverters is studied. Since proportional-resonant (PR) controllers are becoming more popular, it is assumed that most inverters use this type of controller. An LCL filter is also considered at the inverters output to make the case as realistic as possible. A complete modeling of this system is presented. Consequently, it is shown that such a system is prone to instability due to the interactions of the inverter controllers. A modification of PR controllers is presented where the output capacitor is virtually decreased. As a result, the instability is avoided. Simulation results are presented and show a good agreement with the theoretical studies. Experimental results obtained on a laboratory setup show the validity of the analysis.

• Journal of Information Processing Systems
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• 제7권4호
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• pp.581-594
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• 2011

Due to the recent advancement of networking and high-performance computing technologies, scientists can easily access large-scale data captured by scientific measurement devices through a network, and use huge computational power harnessed on the Internet for their analyses of scientific data. However, visualization technology, which plays a role of great importance for scientists to intuitively understand the analysis results of such scientific data, is not fully utilized so that it can seamlessly benefit from recent high-performance and networking technologies. One of such visualization technologies is SAGE (Scalable Adaptive Graphics Environment), which allows people to build an arbitrarily sized tiled display wall and is expected to be applied to scientific research. In this paper, we present a multi-application controller for SAGE, which we have developed, in the hope that it will help scientists efficiently perform scientific research requiring high-performance computing and visualization. The evaluation in this paper indicates that the efficiency of completing a comparison task among multiple data is increased by our system.

• 대한전자공학회논문지SD
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• 제42권5호
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• pp.39-46
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• 2005

본 논문은 SoC 상에서 정적인 고장 뿐 아니라 동적인 고장도 점검하고 진단할 수 있는 새로운 At-speed Interconnect Test Controller (ASITC)를 소개한다. SoC는 IEEE 1149.1과 P1500 래퍼의 코아들로 구성되고 다중 시스템 클럭에 의해 동작될 수 있으며, 이러한 복잡한 SoC를 테스트하기 위해 P1500 래퍼의 코아를 위한 인터페이스 모듈과 update부터 capture까지 1 시스템 클럭으로 연결선의 지연 고장을 점검할 수 있는 ASITC를 설계하였다. 제안한 ASITC는 FPGA로 구현하여 기능검증을 하였으며 기존의 방식에 비해 테스트 방법이 쉽고, 면적의 오버헤드가 적다는 장점이 있다.

• 한국정보과학회논문지:데이타베이스
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• 제35권6호
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• pp.533-543
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• 2008

USB 저장장치는 반도체 메모리 저장 용량에 대한 기순 발전에 따라, 대용량 저장공간을 제공하는 제품으로 생산되고 있다. 따라서 소비자는 저장공간이 상대적으로 작은 기존 USB 저장장치를 폐기하거나, 효율적으로 사용하지 않는다. 본 논문에서는 메모리 저장 용량이 다른, 다수의 USB 저장장치를 USB 허브를 통하여 그룹화 하여 사용자가 컴퓨터에서 논리적 단일 저장공간으로 사용할 수 있는 개선된 USB 허브인 시그마 허브(Sigma Hub)를 제안한다. 제안된 시그마 허브는 다수의 USB 저장장치를 단일화하기 위한 관리 모듈로서 시그마 콘트롤러(Sigma Controller)를 포함한다. 시그마 콘트롤러는 USB 저장장치 통합 알고리즘을 통하여 트랜잭션을 제어하여 논리적 단일 저장장치 사용을 가능하게 한다.

• Industrial Engineering and Management Systems
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• 제4권1호
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• pp.54-67
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• 2005

This paper provides an evaluation of an optimization-based, multiple-input double-output (MIDO) run-to-run (R2R) control scheme for general semiconductor manufacturing processes. The controller in this research, termed adaptive dual response optimizing controller (ADROC), can serve as a process optimizer as well as a recipe regulator between consecutive runs of wafer fabrication. In evaluation, it is assumed that the equipment model could be appropriately described by a pair of second-order polynomial functions in terms of a set of controllable variables. Of practical relevance is to consider a drifting effect in the equipment model since in common semiconductor practice the process tends to drift due to machine aging and tool wearing. We select a typical application of R2R control to chemical mechanical planarization (CMP) in semiconductor manufacturing in this evaluation, and there are five different CMP process scenarios demonstrated, including mean shift, variance increase, and IMA disturbances. For the controller, ADROC, an on-line estimation technique is implemented in a self-tuning (ST) control manner for the adaptation purpose. Subsequently, an ad hoc global optimization algorithm based on the dual response approach, arising from the response surface methodology (RSM) literature, is used to seek the optimum recipe within the acceptability region for the execution of next run. The main components of ADROC are described and its control performance is assessed. It reveals from the evaluation that ADROC can provide excellent control actions for the MIDO R2R situations even though the process exhibits complicated, nonlinear interaction effects between control variables, and the drifting disturbances.

• 한국기계가공학회지
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• 제18권2호
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• pp.1-6
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• 2019

With the increase in number of the athletic population and elderly demographic, the demand for orthopedic splints, which are used to support a damaged body, has rapidly increased. Current splints mainly consist of inner and outer parts, which are multiple fabrics covered with polyurethane and nonwoven fabrics, respectively. However, the laminated materials with directly applied pre-polymer coating lead to a high defect rate because of the uneven thickness on the surface. Thus, this study proposes an indirect coating method using a precise clearance controller, which enables the even application of the coating material on multiple inner parts while maintaining a constant thickness. In addition, a roll-to-roll (R2R) technique is applied instead of the sewing mechanism to bond the inner and outer materials together and enhance the productivity in the final stage. In the advanced methods, there is a storage tank that contains polyurethane, a clearance controller, and pairs of rollers in the upper and lower rows. To improve the quality of the products and optimize the equipment, three controllable factors are determined: the viscosity of polyurethane, angle of the gap controller and number of pairs of rollers in the R2R system.