• Biotechnology and Bioprocess Engineering:BBE
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• 제9권3호
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• pp.156-165
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• 2004

Concentrations of substrates, glucose, and ammionia in biological processes have been on-line monitored by using glucose-flow injection (FIA) and ammonia-FIA systems. Based on the on-line monitored data the concentrations of substrates have been controlled by an on-off controller, a PID controller, and a neural network (NN) based controller. A simulation program has been developed to test the control quality of each controller and to estimate the control parameters. The on-off controller often produced high oscillations at the set point due to its low robustness. The control quality of a PID controller could have been improved by a high analysis frequency and by a short residence time of sample in a FIA system. A NN-based controller with 3 layers has been developed, and a 3(input)-2(hidden)-1(output) network structure has been found to be optimal for the NN-based controller. The performance of the three controllers has been tested in a simulated process as well as in a cultivation process of Saccharomyces cerevisiae, and the performance has also been compared to simulation results. The NN-based controller with the 3-2-1 network structure was robust and stable against some disturbances, such as a sudden injection of distilled water into a biological process.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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• pp.249-250
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• 2006

In this paper, hardware design and implementation of digital controller for the High Precision Digital Power Supply (HPDPS) based on Digital Signal Processor (DSP) and Field Programmable Gate Array (FPGA) is presented. Developed digital controller is composed of high resolution Digital Pulse Width Modulation (DPWM) and high resolution analog to digital converter circuit with anti-aliasing filter. And Digital Signal Processor (DSP) has the capability of a few micro-second calculation time for one feedback loop. 32-bit DSP and DPWM with 150[ps] step resolution is used to implement the HPDPS. Also 18-bit 2 mega sample per second ADC board is adopted for the developed digital controller. Also, hardware structure of the developed digital controller and experimental results of the first prototype board for HPDPS is described.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2018년도 추계학술대회
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• pp.35-38
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• 2018

본 논문에서는 DC 유형의 에너지 하베스팅을 위한 저전력 MPPT 인터페이스 회로를 설계하였다. 제안된 회로는 크게 MPPT controller, bias generator, voltage detector로 구성된다. MPPT controller는 schmitt trigger로 구성된 MPG(MPPT Pulse Generator)와 에너지 유형(빛, 열)에 따라 동작하는 logic gate와 sample/hold 회로로 구성된다. Bias generator는 beta multiplier 구조를 적용하여 설계되었으며, voltage detector는 bulk-driven comparator와 2단 buffer를 이용하여 설계되었다. 제안된 회로는 $0.35{\mu}m$ CMOS 공정으로 설계하였다. 모의실험 결과 설계된 회로는 3V 이내의 입력전압에서 100nA보다 작은 전류를 소모하며, 최대 전력효율은 99.7%이다. 설계된 회로의 칩 면적은 $1151{\mu}m{\times}940{\mu}m$이다.

• 제어로봇시스템학회논문지
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• 제13권7호
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• pp.649-655
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• 2007

In this paper, a time-delayed controller for position control of humanoid robot arms is designed and implemented on a field programmable gate array(FPGA) chip. The time-delayed control algorithm is simple to implement, and robust to reject disturbances. The time-delayed control method uses the one sample time-delayed previous information to cancel out uncertainties in the system. Since the sampling time is so fast with the current hardware technology, the time-delayed controller can be implemented. However, inertia values should be correctly estimated to have the better performance. The position tracking tasks of humanoid robot arms are tested to compare performances of several control algorithms including the time-delayed controller.

• 조명전기설비학회논문지
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• 제12권3호
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• pp.7-13
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• 1998

본 논문에서는 시스템의 동특성이 변화 가능한 구간에서 임의의 생플올 추출하여 신경회로망을 학습시킴으로써 시스템 동특성에 따라 Pill 제어기가 자동동조하는 방법을 제시하였다. 신경회로망을 학습시키기 위해 역전파 학습 알고리즘올 사용하였고, 교사치로는 규칙기반에 의해서 얻어진 매개변수를 이용하였다. 부하 변화시 시스템의 동특성에 맞는 Pill 제어기가 자동동조됨을 시뮬레이션에 의해 확인하였다.

• 한국정보통신학회논문지
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• 제2권1호
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• pp.19-26
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• 1998

본 논문에서는 추적 성능 개선을 위해 기존의 신경망 제어기에 PID제어기를 직렬로 연결하여 시뮬레이션 결과를 고찰했다. 추적 성능을 평가하기 위해 신경망모델은 2계층으로 구성하고 Widrow-Hoff델타 규칙을 이용하여 예측 오차가 최소화되도록 정규적인 동특성을 학습하였다. 이 학습 결과, 기존의 신경망제어기의 경우보다 PID를 연결하였을 경우가 추적 성능이 다소 개선되었음을 확인했으며, 251샘플에서 추적할 플랜트 파라메터가 시변인 경우에도 빠른 속도로 수렴되는 결과를 얻었다.

• 한국식품과학회지
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• 제20권6호
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• pp.845-849
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• 1988

저장실, 저장상자, 공기분배장치 등을 포함한 실험실 규모의 저장실을 설계, 제작하였다. 과실류를 수용할 수 있는 저장상자(1.7 l)는 투명아크릴을 재질로 일정 공기가 계속해서 순환되도록 하고 저장실은 $0{\sim}30^{\circ}C$ 범위내에서 ${\pm}0.5^{\circ}C$의 정확도로 온도제어가 가능하였다. 저장상자로 유입되는 공기는 공기분배 장치를 통하여 예냉과 공기압의 균일화가 이루어지도록 하였고 Solenoid valve를 사용한 저장상자 선택장치를 제작하였다. 이와 같은 저장시설의 환경제어와 계측을 전담할 수 있는 마이크로프로셰서 시스템을 8 bit 마이크로프로쎄서와 기억장치, 그리고 입출력장치 등의 IC chip을 이용하여 설계 제작하였다. 동 시스템을 활용하기 위하여 저장환경의 제어를 위한 소프트웨어를 개발하고 운영프로그램을 ROM화 할 수 있었다. 제작된 저장 자동제어장치 시스템을 이용 밀감류 저장에 적용하여 저장시설의 운영 및 온도의 자료수집을 성공적으로 수행할 수 있었다.

• Structural Engineering and Mechanics
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• 제36권3호
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• pp.381-399
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• 2010

A fuzzy hybrid control technique using a semi-active tuned mass damper (STMD) has been proposed in this study for mitigation of wind induced motion of a tall building. For numerical simulation, a third generation benchmark is employed for a wind-excited 76-story building. A magnetorheological (MR) damper is used to compose an STMD. The proposed control technique employs a hierarchical structure consisting of two lower-level semi-active controllers (sub-controllers) and a higher-level fuzzy hybrid controller. Skyhook and groundhook control algorithms are used as sub-controllers. When a wind load is applied to the benchmark building, each sub-controller provides different control commands for the STMD. These control commands are appropriately combined by the fuzzy hybrid controller during realtime control. Results from numerical simulations demonstrate that the proposed fuzzy hybrid control technique can effectively reduce the STMD motion as well as building responses compared to the conventional hybrid controller. In addition, it is shown that the control performance of the STMD is superior to that of the sample TMD and comparable to an active TMD, but with a significant reduction in power consumption.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1998년도 The Third Asian Fuzzy Systems Symposium
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• pp.51-56
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• 1998

In this paper, we analyze the effects of scaling factors on the performance of a fuzzy logic controller(FLC). The quantitative relation between input and output variables of FLC is obtained by using a qualsi-linear fuzzy model, and an approximate transfer function of FLC is dervied from the comparison of it with the conventional PID controller. Then we analyze in detail the effects of scaling factor using this approximate transfer function and root locus method. Also we suggest an on-line tuning method for scaling factors which employs an sample performance function and a variable reference for tuning index.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.516-518
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• 2000

This paper presents a methodology for effective control of fuel cell devices connected to the electric utility distribution network. A controller is designed for a fuel cell power plant to assist the conventional generators to damp out oscillations, which is possible by utilizing the fast response characteristic of fuel cells. Computer model of the controller is proposed and its effectiveness is proved by a sample test. Fuel cell devices can be used to improve power system stability when these are connected to a distribution system.