• International Journal of Control, Automation, and Systems
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• v.2 no.1
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• pp.39-54
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• 2004

We developed an automatic blood pressure control system to maintain the blood pressure of patients at a substantially low level during a surgical operation. The developed system discharges two functions, continuous feedback control of the mean arterial pressure (MAP) by a state-predictive servo controller and risk control based on the inference by fuzzy-like logics and rules using measured data. Twenty-eight clinical applications were made beginning in November 1995, and the effects of the automatic blood pressure control on the operation time and on bleeding were assessed affirmatively by means of Wilcoxon testing. This paper essentially reports the engineering details of the control system.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1758-1763
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• 2004

This paper focuses on congestion control for ATM network with uncertain time-variant delays. The time-variant delays can be distinguished into two distinct components. The first one is represented by time-variant queueing delays in the intermediate switches that are occurred in the return paths of RM cells. The next one is a forward path delay. It is solved by the VBR model which quantifies the data propagation from the sources to the switch. Robust $H_8$ control is studied for solving congestion problem with norm-bounded time-varying uncertain parameters. The suitable robust $H_8$ controller is obtained from the solution of a convex optimization problem through LMI technique.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.969-974
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• 2004

For a maneuvering unmanned autonomous helicopter, it is necessary to design a proper controller of each flight mode. In this paper, overall helicopter dynamics is derived and hovering model is linearized and transformed into a state equation form. However, since it is difficult to obtain parameters of stability derivatives in the state equation directly, a linear control model is derived by time-domain parametric system identification method with real flight data of the model helicopter. Then, two different controllers - a linear feedback controller with proportional gains and a robust controller - are designed and their performance is compared. Both proposed controllers show outstanding results by computer simulation. These validated controllers can be used to autonomous flight controller of a real unmanned model helicopter.

• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.4
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• pp.405-410
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• 2012

This paper presents an inductorless 8-Gb/s adaptive passive equalizer with low-power consumption and small chip area. The equalizer has a tunable RC filter which provides high-frequency gain boosting and a limiting amplifier that restores the signal level from the filter output. It also includes a feedback loop which automatically adjusts the filter gain for the optimal frequency response. The equalizer fabricated in $0.18-{\mu}m$ CMOS technology can successfully equalize 8-Gb/s data transmitted through up to 50-cm FR4 PCB channels. It consumes 6.75 mW from 1.8-V supply voltage and occupies $0.021mm^2$ of chip area.

• Journal of Industrial Technology
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• v.21 no.B
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• pp.125-132
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• 2001

Heat dissipation technology using flow resonant phenomenon is a kind of new concept in heat transfer area. A vibration exciter is needed to generate air turbulence which has the natural shedding frequency of heat system. A mechanical vibrating device for the air flow oscillation is introduced, which is driven by a moving coil actuator. An analytical dynamic model for this mechanical vibration exciter is presented and its' validity is verified by the comparison with experimental data. Values of some unknown system parameters in the analytic model are estimated through the system identification approach. Based on this mathematical model, the vibration exciter using strain displacement estimator is developed. And in the experiment, the feedback control is used. During the experimental verification phase, it turns out the high modal resonant characteristics of vibrating plate are the major barrier against obtaining a high bandwidth vibration exciter.

• Korean Journal of Computational Design and Engineering
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• v.21 no.4
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• pp.409-416
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• 2016

This study aims to investigate dynamic interaction characteristics between Maglev train and 3 span continuous guideway. The integrated model including a 3D full vehicle model based on multibody dynamics, flexible guideway by a modal superposition method, and levitation electromagnets with the feedback controller is proposed. The proposed model was applied to the Incheon Airport Maglev Railway to analyze the dynamic response of the vehicle and guideway from the numerical simulation. Using field test data of air gap and guideway deflections, obtained from the Incheon Airport Maglev Railway, the analysis method is verified. From the results, it is confirmed that Maglev railway system are designed and constructed safely according to the design criteria.

• 전기의세계
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• v.25 no.5
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• pp.59-62
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• 1976

Applications of the digital computers in the control systems are not new. But when one tries to integrate the control system with a digital computer to form a feedback loop, he has to solve a great deal of problems in both hardware and software aspects. Such problems are investigated in this paper. For the hardware aspect, one has to design interfaces for both ADC and DAC. Since these are absolutely necessary pieces of hardware, one can notavoid from using them. The interface which employ the programmed data transfer method was designed for this research. For the software aspect, one has to build models for the digital compensator and the controlled system. In order to do that it is necessary to utilize the real time clock and to write his own interrupt service routine. As a sample case, a deadbeat compensator was desinged and tested.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.7 no.1
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• pp.38-44
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• 2011

In this study, heating performance and energy consumption characteristics with control strategies for central heating system were researched by the simulation. The simulation analysis is made by TRNSYS ver. 15 with the actual data. The parametric study on proportional factor, control time interval and outdoor air temperatures changes were done to compare control characteristics and energy performance, respectively. As a result, the simulation results with various parameter changes show good heating performance and energy saving.

• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.337-341
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• 2017

This paper reviews the requirements for far-infrared astronomy in the period following the SPICA satellite in the late 2020's. We take a very long view of the state of FIR astronomy and what facilities will be required in a twenty year timeframe. We show that spatial resolution to match that of observatories operating in the optical and mid-infrared and the radio will be a necessity. Moreover this high spatial resolution must be combined with high spectral and photometric sensitivity to provide the data required to further our understanding of planetary formation mechanisms, the history of star formation through cosmic time and the feedback between active galactic nuclei and their host galaxies in controlling star formation. We review three possible conceptual mission scenarios and comment on the possibility of realising them in the coming deades.

• ETRI Journal
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• v.30 no.5
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• pp.729-734
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• 2008

Wireless communication systems, such as WLAN or Bluetooth receivers, employ preamble data to estimate the channel characteristics, introducing stringent settling-time constraints. This makes the use of traditional closed-loop feedback automatic gain control (AGC) circuits impractical for these applications. In this paper, a compact feedforward AGC circuit is proposed to obtain a fast-settling response. The AGC has been implemented in a 0.35 ${\mu}m$ standard CMOS technology. Supplied at 1.8 V, it operates with a power consumption of 1.6 mW at frequencies as high as 100 MHz, while its gain ranges from 0 dB to 21 dB in 3 dB steps through a digital word. The settling time of the circuit is below 0.25 ${\mu}s$.